CN109854550B - Hydraulic control system and engineering machinery - Google Patents
Hydraulic control system and engineering machinery Download PDFInfo
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- CN109854550B CN109854550B CN201711240010.2A CN201711240010A CN109854550B CN 109854550 B CN109854550 B CN 109854550B CN 201711240010 A CN201711240010 A CN 201711240010A CN 109854550 B CN109854550 B CN 109854550B
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Abstract
The invention discloses a hydraulic control system and engineering machinery. The hydraulic control system comprises a hydraulic cylinder, a pump, a main control valve and an inserting control valve, wherein the main control valve is respectively connected with a pump outlet of the pump, an oil discharge pipeline and a first working cavity and a second working cavity of the hydraulic cylinder; when the main control valve controls the oil inlet of the plug-in control valve to be disconnected from the pilot oil source, the plug-in control valve is in one-way conduction from the first working oil port to the second working oil port. The invention strengthens the position maintaining function of the hydraulic cylinder.
Description
Technical Field
The invention relates to the field of engineering machinery, in particular to a hydraulic control system and engineering machinery.
Background
In the prior art, hydraulic control systems of engineering machinery such as loaders and the like adopt hydraulic multi-way valves, and in the working process, the action of a hydraulic cylinder is controlled by reversing the main control valve of the hydraulic multi-way valves, so that the action of an executing mechanism is controlled. When the actuating mechanism is required to be stationary, the valve core of the main control valve of the hydraulic multi-way valve is matched with the valve body to ensure the position of the hydraulic cylinder, so that the clearance between the valve core of the main control valve and the valve body is required to be small enough to meet the requirement of the settlement of the hydraulic cylinder.
In the process of realizing the invention, the inventor finds that in the hydraulic control system in the prior art, as the working time of the hydraulic control system increases, the gap between the valve core and the valve body of the main control valve gradually increases, and the settlement of the hydraulic oil cylinder is difficult to meet the requirement.
Disclosure of Invention
The invention aims to provide a hydraulic control system and engineering machinery, and aims to enable a hydraulic cylinder in the hydraulic control system to have a strong position maintaining function.
A first aspect of the present invention provides a hydraulic control system comprising: the hydraulic control system comprises a hydraulic cylinder, a pump and a main control valve, wherein the main control valve is correspondingly arranged with the hydraulic cylinder, is respectively connected with a pump outlet of the pump, an oil discharge pipeline, a first working cavity and a second working cavity of the hydraulic cylinder and is used for controlling the hydraulic cylinder to act, the hydraulic control system further comprises an inserting control valve which is correspondingly arranged with the hydraulic cylinder, the inserting control valve comprises an oil inlet, an oil return port, a first working oil port and a second working oil port, the main control valve is connected with the first working cavity through the first working oil port and the second working oil port of the inserting control valve, the oil inlet of the inserting control valve is connected with a pilot oil source through the main control valve, the oil return port of the inserting control valve is connected with the oil discharge, and when the oil inlet of the inserting control valve is communicated with the pilot oil source, the first working oil port of the inserting control valve is communicated with the second working oil port of the inserting control valve; when the main control valve controls the oil inlet of the plug-in control valve to be disconnected with the pilot oil source, the plug-in control valve is conducted unidirectionally from the first working oil port to the second working oil port.
Further, the main control valve comprises an oil inlet connected with the pump outlet, an oil outlet connected with the oil outlet pipeline, a first working oil port connected with a first working oil port of the plug-in control valve, a second working oil port connected with the second working cavity, a pilot oil inlet connected with the pilot oil source and a pilot oil outlet connected with the oil inlet of the plug-in control valve, and the main control valve is provided with a first working position, a second working position and a third working position, wherein when the main control valve is in the first working position, the pilot oil inlet of the main control valve is communicated with the pilot oil outlet of the main control valve, the first working oil port of the main control valve is communicated with the oil outlet of the main control valve, and the second working oil port of the main control valve is communicated with the pump outlet; when the main control valve is in the second working position, the pilot oil inlet and the pilot oil outlet of the main control valve are disconnected, and the first working oil port and the second working oil port of the main control valve are disconnected from the pump outlet; when the main control valve is in the third working position, the pilot oil inlet is disconnected from the pilot oil outlet, the first working oil port is communicated with the pump outlet, and the second working oil port is communicated with the oil discharge port.
Further, the plug-in control valve comprises a pilot valve core, a main valve core and a main valve spring, when the main control valve controls the oil inlet of the plug-in control valve to be communicated with the pilot oil source, pilot oil from the pilot oil source controls the pilot valve core to be opened so as to enable a main valve spring cavity where oil for keeping the main valve core closed is located to be communicated with the oil return port of the plug-in control valve, the main valve core is opened under the oil pressure action of the second working oil port of the plug-in control valve, the first working oil port of the plug-in control valve is communicated with the second working oil port, and the main valve spring is located in the main valve spring cavity and applies a force in a closing direction to the main valve core.
Further, the main valve spring cavity is communicated with the second working oil port through a first damping structure.
Further, the plug-in control valve comprises a pilot valve spring cavity and a pilot valve spring, wherein the pilot valve spring cavity is used for containing oil liquid for maintaining the pilot valve core to be closed, the pilot valve spring cavity is communicated with the main valve spring cavity, and the pilot valve spring is positioned in the pilot valve spring cavity and is used for applying a force in a closing direction to the pilot valve core.
Further, the main valve spring chamber communicates with the pilot valve spring chamber through a communication hole provided on a chamber wall of the pilot valve spring chamber.
Further, the plug-in control valve further comprises a valve sleeve and a control piston arranged in the valve sleeve, the control piston divides the valve sleeve into an oil inlet cavity and an oil return cavity, the oil inlet cavity is communicated with the oil inlet of the plug-in control valve, the oil return cavity is communicated with the oil return opening of the plug-in control valve, a driving part is arranged on the end face of the oil return cavity, when the main control valve controls the oil inlet of the plug-in control valve to be communicated with the pilot oil source, pilot oil from the pilot oil source controls the control piston to move towards the pilot valve core, and the driving part drives the pilot valve core to be opened.
Further, the oil inlet cavity is communicated with the oil return cavity through a second damping structure; the cartridge control valve also includes a piston spring that applies a force to the control piston that moves it away from the pilot spool.
Further, the plug-in control valve further comprises a sealing structure for preventing oil leakage
A second aspect of the invention provides a construction machine comprising a hydraulic control system according to any of the first aspects of the invention.
Based on the hydraulic control system and the engineering machinery provided by the invention, the hydraulic control system comprises an inserting control valve, wherein the inserting control valve comprises an oil inlet, an oil return port, a first working oil port and a second working oil port, the main control valve is connected with the first working cavity through the first working oil port and the second working oil port of the inserting control valve, the oil inlet of the inserting control valve is connected with a pilot oil source through the main control valve, the oil return port of the inserting control valve is connected with oil discharge, and when the main control valve controls the oil inlet of the inserting control valve to be communicated with the pilot oil source, the first working oil port of the inserting control valve is communicated with the second working oil port; when the main control valve controls the oil inlet of the plug-in control valve to be disconnected from the pilot oil source, the plug-in control valve is in one-way conduction from the first working oil port to the second working oil port. In the hydraulic control system, the plug-in control valve can be opened or conducted unidirectionally under the control of the main control valve, when the plug-in control valve is opened, the oil in the first working cavity can be smoothly discharged, when the plug-in control valve is conducted unidirectionally, the oil at the outlet of the pump can smoothly enter the first working cavity to prevent the oil in the first working cavity from flowing out, so that when the hydraulic cylinder is required to be kept at a certain position, the plug-in control valve is conducted unidirectionally from the first working oil port to the second working oil port through the main control valve, and at the moment, even if the clearance between the valve core and the valve body of the main control valve is properly increased, the piston rod position of the hydraulic cylinder can be kept, thereby, on one hand, the position keeping function of the hydraulic cylinder is enhanced, the precision requirement on the main control valve is slightly reduced, the processing difficulty is reduced, and the manufacturing cost is saved.
Other features of the present invention and its advantages will become apparent from the following detailed description of exemplary embodiments of the invention, which proceeds with reference to the accompanying drawings.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiments of the invention and together with the description serve to explain the invention and do not constitute a limitation on the invention. In the drawings:
fig. 1 is a schematic diagram of a hydraulic control system according to an embodiment of the present invention.
Fig. 2 is a schematic diagram of a matching structure of a main control valve and an insertion control valve of a hydraulic control system according to an embodiment of the present invention.
Fig. 3 is a schematic structural diagram of an insertion control valve of a hydraulic control system according to an embodiment of the present invention.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. The following description of at least one exemplary embodiment is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
The relative arrangement of the components and steps, numerical expressions and numerical values set forth in these embodiments do not limit the scope of the present invention unless it is specifically stated otherwise. Meanwhile, it should be understood that the sizes of the respective parts shown in the drawings are not drawn in actual scale for convenience of description. Techniques, methods, and apparatus known to one of ordinary skill in the relevant art may not be discussed in detail, but should be considered part of the specification where appropriate. In all examples shown and discussed herein, any specific values should be construed as merely illustrative, and not a limitation. Thus, other examples of the exemplary embodiments may have different values. It should be noted that: like reference numerals and letters denote like items in the following figures, and thus once an item is defined in one figure, no further discussion thereof is necessary in subsequent figures.
In the description of the present invention, it should be understood that the terms "first," "second," and the like are used for defining the components, and are merely for convenience in distinguishing the corresponding components, and the terms are not meant to have any special meaning unless otherwise indicated, so that the scope of the present invention is not to be construed as being limited.
In order to solve the problem that the settlement of a hydraulic cylinder is difficult to meet the requirement after a hydraulic control system in the prior art runs for a long time, the embodiment of the invention provides the hydraulic control system and engineering machinery with the hydraulic control system.
As shown in fig. 1 to 3, the hydraulic control system of the embodiment of the present invention includes a hydraulic cylinder, a pump 20, a main control valve 18 provided corresponding to the hydraulic cylinder, and a cartridge control valve 16 provided corresponding to the hydraulic cylinder. The main control valve 18 is connected to the pump outlet P of the pump 20 B Oil drain pipeline L T And the first working cavity and the second working cavity of the hydraulic cylinder are connected and used for controlling the action of the hydraulic cylinder. The cartridge control valve 16 includes an oil inlet P CZ Oil return port L CZ A first working oil port A CZ1 And a second working oil port A CZ2 . The main control valve 18 passes through the first working oil port A of the plug-in control valve 16 CZ1 And a second working oil port A CZ2 Is connected with the first working chamber. Oil feed for cartridge control valve 16Port P CZ Through the main control valve 18 and the pilot oil source P Y And (5) connection. Oil return port L of plug-in control valve 16 CZ Is connected with oil discharge. The main control valve 18 controls the oil inlet P of the cartridge control valve 16 CZ With a pilot oil source P Y When communicating, the first working oil port A of the plug-in control valve 16 CZ1 And a second working oil port A CZ2 And (5) communication. The main control valve 18 controls the oil inlet P of the cartridge control valve 16 CZ With a pilot oil source P Y When disconnected, the plug-in control valve 16 is plugged from the first working oil port A CZ1 To the second working oil port A CZ2 One-way conduction.
In the hydraulic control system provided by the invention, the plug-in control valve 16 can be opened or one-way conducted under the control of the main control valve 18. When the plug-in control valve 16 is opened, the oil in the first working chamber can be smoothly discharged. The plug-in control valve 16 can make the pump outlet P when being conducted unidirectionally B The oil liquid in the first working cavity is prevented from flowing out. Therefore, when the hydraulic cylinder needs to be kept at a certain position, the main control valve 18 causes the plug-in control valve 16 to extend from the first working port a CZ1 To the second working oil port A CZ2 One-way conduction is achieved. At this time, even if the clearance between the valve core and the valve body of the main control valve 18 is properly increased, the piston rod position of the hydraulic cylinder can be maintained, so that on one hand, the position maintaining function of the hydraulic cylinder is enhanced, the accuracy requirement on the main control valve 18 can be slightly reduced, the processing difficulty is reduced, and the manufacturing cost is saved.
The engineering machinery of the embodiment of the invention has the same advantages as the hydraulic control system of the embodiment of the invention.
Embodiments of the present invention will be described in detail below with reference to fig. 1 to 3, taking a hydraulic control system of a bucket of a loader and a boom connected to the bucket as an example.
As shown in fig. 1, in the present embodiment, the hydraulic control system includes an oil tank 25, a hydraulic cylinder, a pump 2, a main control valve 18 and an insertion control valve 16 provided corresponding to the hydraulic cylinder.
In the present embodiment, the pump 2 is a variable displacement pump, but the hydraulic system of the present invention is not limited to the use of a variable displacement pump.
In the present embodiment, the hydraulic control system includes a plurality of hydraulic cylinders and a plurality of main control valves 18 provided in correspondence with the plurality of hydraulic cylinders. As shown in fig. 1, the plurality of hydraulic cylinders includes a bucket cylinder 22 and a boom cylinder 23, the plurality of main control valves 18 includes a first main control valve provided corresponding to the bucket cylinder 22 and a second main control valve provided corresponding to the boom cylinder 23, the bucket cylinder 22 controls the bucket operation, and the boom cylinder 23 controls the boom operation.
In the present embodiment, the number of bucket cylinders 22 is one. The number of the movable arm oil cylinders 23 is two, and the two movable arm oil cylinders 23 are arranged in parallel and are controlled by the second main control valve to synchronously act.
The main control valve 18 is connected to the pump outlet P of the pump 20 B Oil drain pipeline L T And the first working cavity and the second working cavity of the hydraulic cylinder are connected and used for controlling the action of the hydraulic cylinder.
As shown in fig. 1, the first main control valve and the second main control valve are two control valves inside the multiplex control valve 21.
The multiplex control valve 21 has a first working port A1 connected to a first working chamber (rodless chamber) of the bucket cylinder 22, a second working port B1 connected to a second working chamber (rodless chamber) of the bucket cylinder 22, a third working port A2 connected to a first working chamber (rodless chamber) of the boom cylinder 23, a fourth working port B2 connected to a second working chamber (rodless chamber) of the boom cylinder 23, and a pump outlet P connected to the pump 2 B Connected oil inlet P K And oil discharge pipeline L T Oil drain port T connected with oil tank 25 K A feedback oil port L connected with a feedback oil inlet X of the pump 2 S And a pilot oil source P Y And a pilot oil inlet P of the main control valve ST1 Respectively connected pilot oil ports P ST 。
In the present embodiment, as shown in fig. 1, the first main control valve passes through the oil inlet P K Pump outlet P with pump 2 B Is connected through an oil drain port T K And oil discharge pipeline L T And an oil tank 25 connected to the first working chamber of the bucket cylinder 22 via a first working port A1 and the insertion control valve 16, and connected to the corresponding bucket cylinder via a second working port B1The second working chamber of the bucket cylinder 22 is connected. The first main control valve controls the pump outlet P B Is communicated with the first working chamber of the bucket cylinder 22 and the second working chamber is communicated with the oil discharge pipeline L T When in communication, the piston rod of the bucket cylinder 22 extends out; the first main control valve controls the pump outlet P B Is communicated with the second working chamber of the bucket cylinder 22 and the first working chamber is communicated with the oil discharge pipeline L T When in communication, the piston rod of the bucket cylinder 22 is retracted. The feedback oil port of the first main control valve passes through the feedback oil port L of the multi-way control valve 21 S Is connected with a feedback oil inlet X of the pump 2.
In the present embodiment, as shown in fig. 1, the second main control valve passes through the oil inlet P K Pump outlet P with pump 2 B Is connected through an oil drain port T K And oil discharge pipeline L T And the oil tank 25 is connected with the first working chamber of the corresponding boom cylinder 23 through the third working oil port A2 and the plug-in control valve, and is connected with the second working chamber of the corresponding boom cylinder 23 through the fourth working oil port B2. The second main control valve controls the pump outlet P B Is communicated with the first working chamber of the movable arm cylinder 23 and the second working chamber is communicated with the oil discharge pipeline L T When in communication, the piston rod of the movable arm oil cylinder 23 extends out; the second main control valve controls the pump outlet P B Is communicated with the second working chamber of the movable arm cylinder 23 and the first working chamber is communicated with the oil discharge pipeline L T When communicating, the piston rod of the boom cylinder 23 is retracted. The feedback oil port of the second main control valve passes through the feedback oil port L of the multi-way control valve 21 S Is connected with a feedback oil inlet X of the pump 2.
In the following, the present embodiment will be described by taking the bucket cylinder 22 and the main control valve 18 (first main control valve) and the insertion control valve 16 provided corresponding thereto as an example, and the boom cylinder 23 and the main control valve (second main control valve) and the insertion control valve provided corresponding thereto have similar structures, movement relationships, and connection relationships, and will not be described repeatedly.
As shown in fig. 1 to 3, in the present embodiment, the plug-in control valve 16 includes an oil inlet P CZ Oil return port L CZ A first working oil port A CZ1 And a second working oil port A CZ2 。
The main control valve 18 is controlled by plug-in mounting16, a first working oil port a CZ1 And a second working oil port A CZ2 Is connected with the first working chamber. Oil inlet P of plug-in control valve 16 CZ Through the main control valve 18 and the pilot oil source P Y And (5) connection. Oil return port L of plug-in control valve 16 CZ Is connected with oil discharge.
The main control valve 18 controls the oil inlet P of the cartridge control valve 16 CZ With a pilot oil source P Y When communicating, the first working oil port A of the plug-in control valve 16 CZ1 And a second working oil port A CZ2 And (5) communication. The main control valve 18 controls the oil inlet P of the cartridge control valve 16 CZ With a pilot oil source P Y When disconnected, the plug-in control valve 16 is plugged from the first working oil port A CZ1 To the second working oil port A CZ2 One-way conduction.
As shown in fig. 1 and 2, in the present embodiment, the main control valve 18 includes a pump outlet P B Connected oil inlet P ZF And oil discharge pipeline L T Connected oil drain port T ZF First working oil port A of plug-in control valve 16 CZ1 A first working oil port A connected with ZF A second working oil port B connected with the second working cavity ZF And a pilot oil source P Y Connected pilot oil inlet P ST1 And an oil inlet P to the cartridge control valve 16 CZ Connected pilot oil outlet P ST2 。
The main control valve 18 has a first operating position, a second operating position and a third operating position. When the main control valve 18 is in different working positions, the plug-in control valve 16 and the corresponding hydraulic cylinder can be controlled to act simultaneously.
As shown in fig. 1, the main control valve 18 is in its first operating position, i.e. the lower position shown in fig. 1, with its pilot oil inlet P ST1 With the pilot oil outlet P ST2 Is communicated with a first working oil port A ZF And an oil drain port T ZF Is communicated with a second working oil port B ZF And pump outlet P B And (5) communication. At this time, the first working chamber of the bucket cylinder 22 discharges oil and the second working chamber discharges oil, and the piston rod descends.
As shown in fig. 1, the main control valve 18 is in the second operating position, i.e. the neutral position shown in fig. 1, with its pilot oil inlet P ST1 With the pilot oil outlet P ST2 Disconnected, the first working oil port A thereof ZF And a second working oil port B ZF And pump outlet P B Are all disconnected. At this time, the first and second working chambers of the bucket cylinder 22 neither feed nor discharge oil, and the piston rod is held at a position before the main control valve 18 is switched to the second working position.
As shown in fig. 1, when the main control valve 18 is in the third operating position, i.e., the upper position shown in fig. 1, the pilot oil is introduced into the inlet P ST1 With the pilot oil outlet P ST2 Disconnected, the first working oil port A thereof ZF And pump outlet P B Is communicated with a second working oil port B ZF And an oil drain port T ZF And (5) communication. At this time, the first working chamber of the bucket cylinder 22 is filled with oil and the second working chamber is discharged with oil, and the piston rod is raised.
It can be seen that, in this embodiment, when the main control valve 18 controls the corresponding hydraulic cylinder to operate, the plug-in control valve 16 is also controlled to operate synchronously, and when the main control valve 18 controls the piston rod of the corresponding hydraulic cylinder to move up or down, the plug-in control valve 16 does not prevent the hydraulic cylinder from executing corresponding operation, and when the main control valve 18 is in a position for keeping the hydraulic cylinder in place, the plug-in control valve 16 is controlled to intercept the oil in the first working chamber, so as to prevent the oil in the first working chamber from flowing to the main control valve 18, and further prevent the oil in the first working chamber from flowing back to the oil tank 25, thereby playing a role of maintaining the pressure in the first working chamber, and adding a means for keeping the position of the piston rod of the hydraulic cylinder.
In some preferred embodiments, as shown in fig. 1 to 3, the cartridge control valve 16 is disposed inside the multiplex control valve 21 and integrated on the valve body 17 where the main control valve 18 is located. The plug-in control valve 16 adopts a plug-in structure, and can be connected with the multi-way control valve 21, namely, the valve body where the main control valve 18 is positioned in a threaded connection mode, so that the space occupation of a hydraulic control system can be reduced, the connection with each related hydraulic component can be realized through the internal flow passage of the valve body of the multi-way control valve 21, and the connection relationship between the plug-in control valve 16 and the related hydraulic component is simplified.
As shown in fig. 2 and 3, in the present embodiment, the cartridge control valve 16 mainly includes the valve housing 3, the pilot spool 10, the main spool 8, and the main valve spring 7.
The main control valve 18 controls the oil inlet P of the cartridge control valve 16 CZ With a pilot oil source P Y When communicating, from the pilot oil source P Y The pilot oil of (2) controls the pilot valve core 10 to be opened so that a main valve spring cavity 8B where the oil maintaining the main valve core 8 closed is located and an oil return port L of the plug-in control valve 16 CZ A second working oil port A of the main valve core 8 at the plug-in control valve 16 is communicated with CZ2 Is opened by the oil pressure of the plug-in control valve 16 to enable the first working oil port A of the plug-in control valve CZ1 And a second working oil port A CZ2 And (5) communication.
The main valve spring 7 applies a force in the closing direction to the main valve spool 8. In this embodiment, the main valve spring 7 is located in the main valve spring chamber 8B, and is disposed between the main valve element 8 and the valve housing 3.
Preferably, the main valve spring chamber 8B and the second working oil port A CZ2 Is communicated through a first damping structure. In this embodiment, the first damping structure is a first damping hole 8A provided in the main spool 8. The first damping structure is arranged to enable the second working oil port A to be CZ2 Is communicated with the main valve spring cavity 8B, so that the main valve spring cavity 8B can be filled with oil pressure and a second working oil port A when the pilot valve core 10 is in a closed state CZ2 The main valve element 8 is closed by the combined action of the main valve spring chamber 8B and the spring force of the main valve spring 7.
As shown in fig. 2 and 3, a cartridge valve mounting hole and a main valve seat 17A are provided in the valve body 17. The main valve core 8 is arranged in the cartridge valve mounting hole. A first working oil port A for inserting the control valve 16 is arranged at the right end of a main valve seat 17A of the valve body 17 CZ1 And with the first working oil port A CZ1 An oil duct C communicated with the first working oil port A of the main control valve 18 ZF And (5) communication. A second working oil port A for inserting the control valve 16 is arranged at the left end of a main valve seat 17A of the valve body 17 CZ2 The working oil chamber 17B is communicated. When the main valve core 8 is closed, the main valve core 8 is matched with the main valve seat 17A to isolate the first working oil port A CZ1 And a working oil chamber 17B, thereby disconnecting the first working oil port a CZ1 And a second working oil port A CZ2 . When the main valve core 8 is opened, the main valve core 8 is disengaged from the main valve seat 17A, and the first working oil port A CZ1 Is communicated with the working oil cavity 17B through a clearance between the main valve core 8 and the main valve seat 17A, thereby leading to a first working oil port A CZ1 And a second working oil port A CZ2 And (5) communication.
In this embodiment, the main valve core 8 is a conical valve core, and the main valve core 8 and the main valve seat 17A are matched to form a linear seal, so that the main valve core 8 can be tightly closed.
In this embodiment, the right end of the valve housing 3 is provided with a pilot valve hole and a pilot valve seat 3A. The pilot spool 10 is located in the pilot valve bore. The right end of the pilot valve hole of the valve sleeve 3 is provided with a spring seat 9.
As shown in fig. 2 and 3, in the present embodiment, the cartridge control valve 16 includes a pilot valve spring chamber 3D that accommodates oil for maintaining the pilot valve spool 10 kept closed, the pilot valve spring chamber 3D being formed by a cylinder section of the right part of the valve housing 3 and the spring seat 9. Wherein the pilot valve spring chamber 3D communicates with the main valve spring chamber 8B. In the present embodiment, the main valve spring chamber 8B communicates with the pilot valve spring chamber 3D through a communication hole 9A provided on a chamber wall of the main valve spring chamber 8B. Specifically, the communication hole 9A is provided on the spring seat 9. The communication hole 9A enables the pilot valve spring cavity 3D to be communicated with the main valve spring cavity 8B, on the one hand, oil is provided for the pilot valve spring cavity 3D, and when the pilot valve core 10 and the main valve core 8 are closed, the pilot valve spring cavity 3D is filled with oil pressure and a second working oil port A CZ2 The same oil applies a force to close the pilot valve element 10, and when the pilot valve element 10 is opened, the main valve spring chamber 8B and the oil return hole L are connected CZ Providing a communication channel.
The cartridge control valve 16 further includes a pilot valve spring 6, and the pilot valve spring 6 applies a force in the closing direction to the pilot valve spool 10. In this embodiment, the pilot valve spring 6 is located in the pilot valve spring chamber 3D and is disposed between the spring seat 9 and the valve sleeve 3.
When the pilot valve spool 10 is closed, the pilot valve spool 10 cooperates with the pilot valve seat 3A, thereby isolating the pilot valve spring chamber 3D from the return oil chamber 3C. Oil return cavity 3C and oil return port L CZ Is communicated with an oil return port L to isolate a pilot valve spring cavity 3D CZ Holding a main valve springOil pressure of cavity 8B and second working oil port A CZ2 Maintains the main spool 8 in the closed state, with the same oil pressure. When the pilot valve core 10 is opened, the pilot valve core 10 is disengaged from the pilot valve seat 3A, the pilot valve spring cavity 3D is communicated with the oil return cavity 3C through a gap between the pilot valve core 10 and the pilot valve seat 3A, and the pilot valve spring cavity 3D is communicated with the oil return port L CZ Is communicated with a main valve spring cavity 8B through a communication hole 9A, a pilot valve spring cavity 3D and an oil return port L CZ Is communicated with the main valve spring cavity 8B through an oil return port L CZ Decompression, the oil pressure of the main valve 8 in the working oil chamber 17B, namely the second working oil port A CZ2 Is opened under the action of oil pressure of the second working oil port A CZ2 With the first working oil port A CZ1 Is communicated with the first working oil port A of the main control valve 18 through the flow passage C so as to discharge the oil in the first working chamber to the first working oil port A of the main control valve 18 ZF And then passes through the oil drain port T of the main control valve 18 ZF And back to the tank 25.
In this embodiment, the pilot valve core 10 is a conical valve core, and the pilot valve core 10 and the pilot valve seat 3A are matched to form a linear seal, so that the pilot valve core 10 can be tightly closed.
As shown in fig. 2 and 3, the control piston 12 divides the valve housing 3 into an oil intake chamber 3B and the aforementioned oil return chamber 3C. Oil inlet cavity 3B and oil inlet P of plug-in control valve 16 CZ And (5) communication. Oil return cavity 3C and oil return port L of plug-in control valve 16 CZ And (5) communication. The control piston 12 is provided with a driving portion 12A on an end surface of the oil return chamber 3C. The main control valve 18 controls the oil inlet P of the cartridge control valve 16 CZ With a pilot oil source P Y When communicating, from the pilot oil source P Y The pilot oil control piston 12 of (a) moves toward the pilot valve element 10, and the drive portion 12A pushes the pilot valve element 10 to open.
In this embodiment, preferably, the oil inlet chamber 3B communicates with the oil return chamber 3C through a second damping structure. Specifically, the control piston 12 has an axial port 12C, and the second damping structure includes a second damping hole 12B provided in the control piston 12 between the axial port 12C and the oil return chamber 3C. The second damping structure can balance the oil pressure of the oil inlet cavity 3B and the oil return cavity 3C, release the oil in the oil inlet cavity 3B to enable the control piston 12 to reset, and after the control piston 12 resets, the pilot valve core 10 is sprung by the pilot valve spring 6The spring force is closed, the main valve spring cavity 8B builds oil pressure, thereby closing the main valve core 8, and enabling the second working oil port A to be CZ2 The oil liquid in the hydraulic oil cylinder can not leak into the flow channel C, so that the position of the hydraulic oil cylinder is well maintained, the actuating mechanism is positioned at a certain position for a long time, and the requirement of a specific working condition is met.
As shown in fig. 2 and 3, the cartridge control valve 16 further includes a piston spring 5, the piston spring 5 exerting a force on the control piston 12 to move it away from the pilot spool 10. The piston spring 5 is located in the oil return chamber 3C and is disposed between the control piston 12 and the valve sleeve 3. At the oil inlet P CZ With a pilot oil source P Y In the disconnected state, the piston spring 5 separates the control piston 12 from the pilot valve element 10.
The valve housing 3 is fixedly arranged in a cartridge valve mounting hole of the valve body 17. The valve sleeve 3 and the valve body 17 can be connected through threads, so that the mounting and dismounting of the plug-in control valve 16 are facilitated, and the maintenance is facilitated.
The plug-in control valve 16 further comprises a plug 1 arranged at the outer end of the valve sleeve 3, and the plug 1 seals the control piston 12 inside the valve sleeve 3. The plug 1 not only plugs the oil in the plug-in control valve 16, but also limits the movement of the control piston 12 in the valve sleeve 3.
To prevent leakage of hydraulic oil, the cartridge control valve 16 also includes a sealing structure. In the present embodiment, the sealing structure includes a first sealing unit 13, a second sealing unit 2, a third sealing unit 4, and a fourth sealing unit 11. As shown in fig. 2 and 3, the first sealing unit 13 is disposed between the plug 1 and the valve housing 3; the second sealing unit 2, the third sealing unit 4 and the fourth sealing unit 11 are arranged axially spaced between the valve body 17 and the valve sleeve 3. Wherein, the oil inlet P CZ Is arranged between the second sealing unit 2 and the third sealing unit 4, and is provided with an oil return port L CZ Is arranged between the third sealing unit 4 and the fourth sealing unit 11. In this embodiment, the first sealing unit 13, the second sealing unit 2, the third sealing unit 4 and the fourth sealing unit 11 are all O-rings.
In addition, as shown in fig. 1, the hydraulic control system in the present embodiment further includes a pilot valve 24. Pilot valve 24 includes an oil inlet P X A plurality of oil outlets and oil discharge ports T X . Specifically, pilot valve 24 includes four oil outlets, namely, a first oil outlet a1, a second oil outlet b1, a third oil outlet a2, and a fourth oil outlet b2. Oil inlet P of pilot valve 24 X With a pilot oil source P Y And (5) connection.
As shown in fig. 1, each main control valve includes two pilot oil ports respectively disposed at two ends of the corresponding main control valve 18, and the two pilot oil ports are used for controlling the action of the main control valve 18, so as to control the extension and retraction of the piston rod of the corresponding hydraulic cylinder.
As shown in fig. 1, the multiplex control valve 21 includes four pilot ports corresponding to the two main control valves, and includes a first pilot port Xa1 and a second pilot port Xb1 connected to the two pilot ports of the first main control valve for controlling the operation of the bucket cylinder 22, and a third pilot port Xa2 and a fourth pilot port Xb2 connected to the two pilot ports of the second main control valve for controlling the operation of the boom cylinder 23.
As shown in fig. 1, the first oil outlet a1 of the pilot valve 24 is connected to the first pilot oil port Xa1 of the multiplex control valve 21, and the second oil outlet b1 is connected to the second pilot oil port Xb1 of the multiplex control valve 21, thereby realizing connection with the upper and lower pilot oil ports of the first main control valve. The third oil outlet a2 of the pilot valve 24 is connected with the third pilot oil port Xa2 of the multi-way control valve 21, and the fourth oil outlet b2 is connected with the fourth pilot oil port Xb2 of the multi-way control valve 21, thereby realizing the connection with the upper and lower pilot oil ports of the second main control valve.
The working principle of the hydraulic control system of this embodiment is as follows:
as shown in fig. 2 and 3, when the main control valve 18 is shifted to the left to switch to the first operation position, the pilot oil source P Y Is communicated with the oil inlet cavity 3B, and the runner C is communicated with an oil discharge port T of the main control valve 18 ZF The control piston 12 moves to the right to push up the pilot valve core 10, the main valve spring cavity 8B and the oil drain port L CZ Communicating with a second working oil port A CZ2 Flows to the oil drain port L through the first damping hole 8A, the main valve spring cavity 8B and the communication hole 9A CZ The left and right ends of the main valve core 8 form a pressure difference to be opened, and a second working oil port A CZ2 Oil in (a) passes through the first working oil port A CZ1 And the flow channel C flows to an oil drain port T of the main control valve ZF The first working cavity discharges oil, and a piston rod of the hydraulic oil cylinder acts downwards.
As shown in fig. 2 and 3, when the main control valve 18 is switched to the second operating position, specifically, the position shown in fig. 2, since the main valve spool 8 is always closed, the oil pressure of the main valve spring chamber 8 in which the main valve spring 7 is located and the second operating oil port a CZ2 The main valve core 8 is in a closed state due to the spring force of the main valve spring 7, and the second working oil port A CZ2 The oil in the first working cavity is sealed, and thus the good effect of maintaining the position of the hydraulic oil cylinder is achieved.
When the main control valve 18 is switched to the third operating position, the pressure oil passes from the flow passage C through the second operating port L CZ2 The pressure oil pushes up the main valve core 8 to enter the second working oil port L CZ2 And then the first working cavity of the hydraulic oil cylinder is communicated, and a piston rod of the hydraulic oil cylinder acts upwards.
In summary, the hydraulic control system of the above embodiment realizes the function of maintaining the position of the hydraulic cylinder by the cartridge control valve 16 while ensuring the normal function of the hydraulic cylinder.
The hydraulic control system of the present invention is not limited to use on a loader, but may be used in other construction machines that require a hydraulic control system with a variable displacement pump, such as an excavator or the like.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present invention and not for limiting the same; while the invention has been described in detail with reference to the preferred embodiments, those skilled in the art will appreciate that: modifications may be made to the specific embodiments of the present invention or equivalents may be substituted for part of the technical features thereof; without departing from the spirit of the invention, it is intended to cover the scope of the invention as claimed.
Claims (10)
1. A hydraulic control system, comprising: the hydraulic oil cylinder, the pump (20) and the main control valve (18) which is arranged corresponding to the hydraulic oil cylinder, wherein the main control valve (18) is respectively connected with the pump outlet (P) of the pump (20) B ) Oil discharge pipeline (L) T ) The hydraulic control system is connected with the first working cavity and the second working cavity of the hydraulic cylinder and is used for controlling the hydraulic cylinder to act, and is characterized by further comprising a plug-in control valve (16) which is arranged corresponding to the hydraulic cylinder, wherein the plug-in control valve (16) comprises an oil inlet (P CZ ) Oil return port (L) CZ ) First working oil port (A) CZ1 ) And a second working oil port (A) CZ2 ) The main control valve (18) passes through the first working oil port (A) of the plug-in control valve (16) CZ1 ) And the second working oil port (A CZ2 ) Is connected with the first working cavity, and the oil inlet (P) of the plug-in control valve (16) CZ ) Through the main control valve (18) and a pilot oil source (P) Y ) Is connected to the return port (L) of the plug-in control valve (16) CZ ) Is connected with the oil discharge, wherein,
the main control valve (18) controls the oil inlet (P) of the plug-in control valve (16) CZ ) With the pilot oil source (P Y ) When in communication, the first working oil port (A) of the plug-in control valve (16) CZ1 ) And the second working oil port (A CZ2 ) Communicating;
the main control valve (18) controls the oil inlet (P) of the plug-in control valve (16) CZ ) With the pilot oil source (P Y ) When disconnected, the plug-in control valve (16) is connected with the first working oil port (A CZ1 ) To the second working oil port (A CZ2 ) One-way conduction.
2. The hydraulic control system according to claim 1, characterized in that the main control valve (18) comprises a valve opening (P B ) Connected oil inlet (P) ZF ) And the oil discharge pipeline (L T ) Oil drain port of connection (T) ZF ) And a first working oil port (A) of the plug-in control valve (16) CZ1 ) Connected first working oil port (A) ZF ) A second working oil port (B) connected to the second working chamber ZF ) And the pilot oil source (P Y ) Connected pilot oil inlet (P ST1 ) And an oil inlet (P) to the cartridge control valve (16) CZ ) First of all connectionOil outlet (P) ST2 ) The main control valve (18) has a first operating position, a second operating position and a third operating position, wherein,
when the main control valve (18) is in the first working position, the pilot oil inlet (P) ST1 ) With its pilot oil outlet (P ST2 ) Is communicated with a first working oil port (A ZF ) And oil drain (T) ZF ) Is communicated with a second working oil port (B) ZF ) And the pump outlet (P B ) Communicating;
when the main control valve (18) is in the second working position, the pilot oil inlet (P) ST1 ) With its pilot oil outlet (P ST2 ) Disconnected, the first working oil port (A ZF ) And its second working oil port (B) ZF ) And the pump outlet (P B ) All are disconnected;
when the main control valve (18) is in the third working position, the pilot oil inlet (P) ST1 ) With its pilot oil outlet (P ST2 ) Disconnected, the first working oil port (A ZF ) And the pump outlet (P B ) Is communicated with a second working oil port (B) ZF ) And oil drain (T) ZF ) And (5) communication.
3. The hydraulic control system according to claim 1, characterized in that the cartridge control valve (16) comprises a pilot spool (10), a main spool (8) and a main valve spring (7), the main control valve (18) controlling the oil inlet (P) of the cartridge control valve (16) CZ ) With the pilot oil source (P Y ) When communicating, from the pilot oil source (P Y ) The pilot oil of the pilot valve core (10) is controlled to be opened so as to ensure that a main valve spring cavity (8B) where the oil liquid which keeps the main valve core (8) closed is positioned and the oil return port (L) of the plug-in control valve (16) CZ ) Is communicated with the main valve core (8) at the second working oil port (A) of the plug-in control valve (16) CZ2 ) Is opened by the oil pressure of the plug-in control valve (16) to enable the first working oil port (A) CZ1 ) And the second working oil port (A CZ2 ) And the main valve spring (7) is positioned in the main valve spring cavity (8B) and is used for applying a closing force to the main valve core (8).
4. A hydraulic control system according to claim 3, characterized in that the main valve spring chamber (8B) and the second working oil port (a CZ2 ) Is communicated through a first damping structure.
5. A hydraulic control system according to claim 3, characterized in that the cartridge control valve (16) comprises a pilot spring chamber (3D) containing oil to maintain the pilot valve spool (10) closed and a pilot spring (6), the pilot spring chamber (3D) being in communication with the main valve spring chamber (8B), the pilot spring (6) being located within the pilot spring chamber (3D) exerting a force in the closing direction on the pilot valve spool (10).
6. The hydraulic control system according to claim 5, characterized in that the main valve spring chamber (8B) communicates with the pilot valve spring chamber (3D) through a communication hole (9A) provided on a chamber wall of the pilot valve spring chamber (3D).
7. A hydraulic control system according to claim 3, characterized in that the cartridge control valve (16) further comprises a valve housing (3) and a control piston (12) arranged in the valve housing (3), the control piston (12) dividing the valve housing (3) into an oil inlet chamber (3B) and an oil return chamber (3C), the oil inlet chamber (3B) and the oil inlet (P) of the cartridge control valve (16) CZ ) The oil return cavity (3C) is communicated with the oil return port (L) of the plug-in control valve (16) CZ ) The oil return cavity (3C) is communicated with the oil inlet (P) of the plug-in control valve (16) through the main control valve (18), and the control piston (12) is provided with a driving part (12A) on the end face of the oil return cavity (3C) CZ ) With the pilot oil source (P Y ) When communicating, from the pilot oil source (P Y ) The control piston (12) is controlled to move toward the pilot valve element (10), and the driving part (12A) drives the pilot valve element (10) to open.
8. The hydraulic control system according to claim 7, characterized in that the oil inlet chamber (3B) communicates with the oil return chamber (3C) through a second damping structure; the cartridge control valve (16) further comprises a piston spring (5), the piston spring (5) exerting a force on the control piston (12) that moves it away from the pilot spool (10).
9. The hydraulic control system of claim 1, wherein the cartridge control valve (16) further includes a seal arrangement for preventing leakage of oil.
10. A construction machine, characterized by comprising a hydraulic control system according to any one of claims 1-9.
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| CN110158697B (en) * | 2019-06-14 | 2024-04-30 | 江苏徐工工程机械研究院有限公司 | Signal cut-off valve and hydraulic control system |
| CN114396405B (en) * | 2021-12-21 | 2024-07-09 | 无锡市汉为液压气动有限公司 | Feeding and hydraulic driving system for biomass power generation equipment and material forming method thereof |
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