Electro-hydraulic directional control valve with buffer spool

Abstract

The present invention relates to an electro-hydraulic reversing valve with a buffer spool. Springs are respectively connected to both ends of the main spool in the hydraulic three-position four-way valve and arranged in the spring chambers. Buffer inclined surfaces are respectively provided on both sides of the boss of the main spool, so that the oil passage openings in the hydraulic three-position four-way valve can be gradually opened or closed, reducing the impact. An inclined angle arranged circumferentially is provided at the place where the surface of the boss of the main spool is in close contact with the valve body. Pilot oil grooves are arranged circumferentially on the buffer inclined surfaces, and the pilot oil grooves are communicated with the inclined angle, making the opening and closing of the oil passage in the hydraulic three-position four-way valve smoother, further prolonging the commutation time and reducing the impact. A fillet is provided between the buffer inclined surface and the side surface of the boss of the main spool to avoid cavitation during fluid flow and reduce the impact. The present invention can reduce the hydraulic impact caused by the commutation of the hydraulic valve, reduce noise and equipment vibration, and prolong the service life of the equipment. Compared with the original reversing valve, the electro-hydraulic reversing valve has the same basic structure, usage method and function, and has strong replaceability.

Description

Technical Field

[0001] The present invention relates to a hydraulic control system for an adjustable pitch propeller, in particular to a hydraulic system that realizes a commutation function to replace a common electromagnetic directional control valve. Background Art

[0002] Under different sailing conditions, an adjustable pitch propeller can achieve stepless pitch adjustment according to requirements, and can arbitrarily adjust the main engine load, thrust magnitude and thrust direction within a certain range, enhancing the adaptability of the ship to various sailing conditions. Moreover, with the rapid development of control technology, hydraulic technology and shipbuilding technology, equipping a ship with a controllable pitch propeller device has become a development trend. In terms of the power form of the pitch adjustment mechanism, the widely used controllable pitch propeller is hydraulic, and the pitch is mainly adjusted by the working position of an electro-hydraulic directional control valve.

[0003] However, when the oil circuit in the directional control valve is suddenly connected, the fluid in the pipeline immediately moves, which will cause an impact on the valve body; similarly, when the oil circuit in the directional control valve is suddenly disconnected, the fluid in the pipeline immediately stops moving, and at this time the kinetic energy of the oil flow will be converted into extrusion energy, resulting in a sharp increase in pressure and causing hydraulic shock. The hydraulic shock pressure can be as high as 3 to 4 times the normal working pressure, damaging the hydraulic valve and causing vibration and noise at the same time.

[0004] Currently, the commonly used methods to prevent hydraulic shock include: (1) slowing down the closing speed of the directional control valve and prolonging the commutation time. (2) increasing the pipe diameter and reducing the flow rate. (3) shortening the pipe length and avoiding unnecessary bends. (4) reducing the control pressure for the electro-hydraulic directional control valve to commutate. (5) improving the structure and adding a throttle valve to the control pipeline or the return pipeline. (6) adopting an electrical control method. These methods can effectively reduce hydraulic shock, but they require relatively large modifications to the hydraulic components or circuits. Summary of the Invention

[0005] The present invention aims to provide an electro-hydraulic directional control valve with a buffer spool. Without changing the overall structure of the directional control valve, only the spool is modified to obtain a good buffering effect and reduce hydraulic shock.

[0006] To achieve the above object, the technical solution of the present invention is: a electro-hydraulic directional control valve with a buffer spool, which has an electromagnetic pilot valve and a hydraulic three-position four-way valve. Springs are respectively connected to both ends of the main spool in the hydraulic three-position four-way valve and arranged in spring chambers. Buffer inclined surfaces are respectively provided on both sides of the boss of the main spool, so that the oil passage openings in the hydraulic three-position four-way valve can be gradually opened or closed, and at the same time, the commutation time can be prolonged and the impact can be reduced. An inclined angle arranged circumferentially is provided at the place where the surface of the boss of the main spool is in close contact with the valve body. Pilot oil grooves are arranged circumferentially on the buffer inclined surfaces, and the pilot oil grooves are communicated with the inclined angle, so that the opening and closing of the oil passage in the hydraulic three-position four-way valve are smoother, the commutation time is further prolonged, and the impact is reduced. A fillet is provided between the buffer inclined surface and the side surface of the boss of the main spool to avoid cavitation phenomenon during fluid flow and reduce the impact.

[0007] Further, the inclined angle is 135°.

[0008] Further, the four inclined angles are evenly distributed on the circumference of the boss of the main spool.

[0009] Further, the four pilot oil grooves are evenly distributed on the circumference of the buffer inclined surface of the main spool.

[0010] Further, when the electromagnet of the pilot solenoid valve is energized for commutation, the pressure oil acts on one end face of both ends of the main spool, pushes the main spool to move, connects the corresponding oil ports, and thus changes the flow direction of the liquid flow.

[0011] Further, when the electromagnet of the pilot solenoid valve is de-energized, the main spool returns to the initial position. The two spring chambers are communicated with the oil tank through the pilot solenoid valve. Under the action of the spring force, the main spool returns to the middle position, and the oil in the spring chamber is discharged through the external discharge port Y or the internal channel T.

[0012] The beneficial effects of the present invention are:

[0013] The electro-hydraulic directional control valve with a buffer spool of the present invention is an improved design based on the original electro-hydraulic directional control valve, and has the characteristics of simple structure, convenient use and strong replaceability. The electro-hydraulic directional control valve is composed of an electromagnetic pilot valve and a hydraulic three-position four-way valve. The hydraulic three-position four-way valve part maintains the original structure, and the electromagnetic pilot valve part is improved. By improving the spool of the electromagnetic directional control valve as the pilot valve and adding pilot oil grooves, the flow rate gradually increases during commutation.

[0014] The present invention can reduce the hydraulic shock caused by the commutation of the hydraulic valve, reduce the noise and equipment vibration, and prolong the service life of the equipment. Compared with the original directional control valve, the electro-hydraulic directional control valve has the same basic structure, usage method and function, and has very strong replaceability. Description of the Drawings

[0015] Figure 1 It is the overall structure diagram of an electro-hydraulic directional control valve with a buffer spool;

[0016] Figure 2 It is the schematic diagram of the spool structure of the electromagnetic directional control valve before improvement

[0017] Figure 3 It is the schematic diagram of the spool structure of the electromagnetic directional control valve after improvement

[0018] Among them, (a) is the front view of the spool after improvement, and (b) is the partial enlarged view of the spool at position K after improvement;

[0019] Figure 4 It is the working flow rate and pressure change diagram of the electromagnetic directional control valve with a buffer spool;

[0020] Among them, (a) is time-flow rate, and (b) is time-pressure. Specific implementation manners

[0021] The present invention will be further described below in conjunction with the accompanying drawings.

[0022] As Figure 1 shown, the electro-hydraulic directional control valve with a buffer spool of the present invention mainly consists of a main valve body 1, a main spool 2, a return spring 3, a pilot solenoid valve 4, an electromagnet 5, a spring chamber 6, a control oil inlet passage 7, and a manual button 8. The main spool 2 is held in the middle position by two springs 3, and the two spring chambers 6 communicate with the oil tank through the pilot solenoid valve 4. The control oil enters the pilot solenoid valve 4 through the pipeline 7. When one of the electromagnets of the pilot solenoid valve 4 is energized, the pressure oil acts on one end face of the two ends of the main spool 2, pushing the main spool 2 to move, connecting the corresponding oil ports, and thus changing the flow direction of the liquid flow.

[0023] When the electromagnet is de-energized, the main spool 2 returns to the initial position. The two spring chambers 6 communicate with the oil tank through the pilot valve 4. Under the action of the spring force, the main spool 2 returns to the middle position, and the oil in the spring chamber 6 is discharged through the external discharge port Y or the internal passage T.

[0024] Figure 2 It is the spool before improvement. For the improved spool, as Figure 3 (a), (b) shown, the improvement of the spool includes four parts: In the figure: The angle at 2-1 is 135°, and the spool surface fits tightly with the valve body. The position at 2-2 is a buffer inclined surface, and this design enables the oil passage opening to gradually open or close, while prolonging the commutation time and reducing the impact. The position at 2-3 is a fillet, and this design can avoid phenomena such as cavitation during fluid flow and reduce the impact. The position at 2-4 is a pilot oil groove, and there are four on each circular surface, evenly distributed on the circumference of the spool. This design can make the opening and closing of the oil passage smoother, further prolong the commutation time, and reduce the impact.

[0025] AsFigure 4 (a) and (b) show the working flow rate and pressure change diagrams of the electromagnetic directional valve with a buffer spool. After the structure is improved, both the flow rate change and pressure shock during the hydraulic valve commutation will be reduced, meeting the design expectations.

Claims

1. An electro-hydraulic reversing valve with a buffer spool, comprising an electromagnetic pilot valve and a hydraulic three-position four-way valve. Springs are respectively connected to both ends of the main spool in the hydraulic three-position four-way valve and are arranged in spring chambers. It is characterized in that: On both sides of the boss of the main spool, there are buffer inclined surfaces respectively, so that the oil passage opening in the hydraulic three-position four-way valve can be gradually opened or closed, and at the same time, the commutation time can be extended and the impact can be reduced; at the place where the surface of the boss of the main spool is in close contact with the valve body, there is an angled surface arranged circumferentially, and a pilot oil groove is arranged circumferentially on the buffer inclined surface, and the pilot oil groove is communicated with the angled surface, so that the opening and closing of the oil passage in the hydraulic three-position four-way valve is smoother, further extending the commutation time and reducing the impact; there is a fillet between the buffer inclined surface and the side surface of the boss of the main spool, which is used to avoid cavitation phenomenon during fluid flow and reduce the impact; the four angled surfaces are evenly distributed on the circumference of the boss of the main spool; the four pilot oil grooves are evenly distributed on the circumference of the buffer inclined surface of the main spool.

2. The electro-hydraulic directional control valve with a buffer spool according to claim 1, wherein: The angled surface is a 135° angle.

3. The electro-hydraulic directional control valve with a buffer spool according to claim 1, characterized in that: When the electromagnet of the pilot solenoid valve is energized and commutated, the pressure oil acts on one end face of the two ends of the main spool, pushing the main spool to move and connecting the corresponding oil ports, thereby changing the flow direction of the liquid flow.

4. The electro-hydraulic directional control valve with a buffer spool according to claim 1, characterized in that: When the electromagnet of the pilot solenoid valve is de-energized, the main spool returns to the initial position, and the two spring chambers are communicated with the oil tank through the pilot solenoid valve. Under the action of the spring force, the main spool returns to the middle position, and the oil in the spring chamber is discharged through the external drain port Y or the internal channel T.

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