CN115289089A

CN115289089A - Piston rod built-in one-way cone valve buffer device

Info

Publication number: CN115289089A
Application number: CN202110486975.XA
Authority: CN
Inventors: 金成毅; 王力; 苟辽; 刘瑞
Original assignee: SICHUAN LINGFENG AVIATION HYDRAULIC MACHINERY CO Ltd
Current assignee: SICHUAN LINGFENG AVIATION HYDRAULIC MACHINERY CO Ltd
Priority date: 2021-05-03
Filing date: 2021-05-03
Publication date: 2022-11-04

Abstract

The piston rod built-in one-way cone valve buffering device disclosed by the invention is simple in structure and reliable in buffering. The invention is realized by the following technical scheme: the hydraulic cylinder comprises a stepped shaft of a piston, an oil through hole which radially penetrates through the stepped shaft and a one-way cone valve which is axially provided with a spring, wherein the one-way cone valve provided with a stepped cone head is axially coupled with a conical surface of a valve seat to realize one-way throttling after being provided with a compression spring; along with the retraction of the piston, the pressure of hydraulic oil in a low-pressure cavity of the hydraulic actuating cylinder rises, a compression spring of the one-way cone valve is attached to the conical surface of the valve seat, the hydraulic oil in the low-pressure cavity of the actuating cylinder can only flow out through a circular seam gap between the buffer end cover and a buffer sleeve at the front end of the piston, the speed of the piston rod is slowed down along with the increase of the buffer distance of the low-pressure cavity, the piston is connected with the end part, the oil return resistance is increased, the piston bears counter pressure, and the movement speed of the piston rod is slowed down to achieve buffering.

Description

Piston rod built-in one-way cone valve buffer device

Technical Field

The invention relates to a piston rod built-in one-way cone valve buffering device, which is used for buffering at the stroke tail end of a hydraulic actuating cylinder, is applied to the hydraulic actuating cylinder and belongs to the technical field of hydraulic pressure.

Background

With the development of mechanical hydraulic technology, the moving speed of a piston of a hydraulic cylinder of a hydraulic system is higher and higher, and the reciprocating frequency and the moving speed are also higher and higher, and some hydraulic cylinders even reach dozens of meters per second. In order to avoid strong impact and vibration, ensure stable operation of the system, prevent damage to transmission components, improve the working performance and the service life of the system, the system must be buffered before the movement is finished. The buffering method of the hydraulic oil cylinder is basically divided into two methods: one is that the hydraulic cylinder is controlled externally, namely install the choke valve or other forms of flow control device to buffer on the control circuit of the hydraulic cylinder, its structure is more complicated: the other is the control in the hydraulic cylinder, namely, a buffer device is designed in the hydraulic cylinder to realize the buffer, and the hydraulic cylinder has simple structure, reliable operation, small volume and better buffer, thereby being widely applied. The main factor for the normal stability of the double-acting hydraulic cylinder buffer device adopting the internal buffer device is that the piston rod and the cylinder barrel have better coaxiality. The coaxiality is ensured through clearance fit of the piston rod and the cylinder barrel with the front end cover, the rear end cover and the piston and form and position tolerance of each part, and is often difficult to control due to the influence of factors such as design, manufacture, assembly, use and the like in practice, so that the buffer device is difficult to be normal, and the situations of pulling injury, gluing and even damage to the hydraulic cylinder are often caused.

The hydraulic cylinder is an energy conversion device for converting input hydraulic energy into mechanical energy, and is a hydraulic actuator which makes linear reciprocating motion (or swinging motion). When the undercarriage is used for realizing reciprocating motion in the retraction and extension process, a speed reducing device can be omitted, no transmission gap exists, and the output force of the hydraulic cylinder with stable motion is in direct proportion to the effective area of the piston and the pressure difference between the two sides of the piston; the hydraulic cylinder is basically composed of a cylinder barrel and a cylinder cover, a piston and a piston rod, a sealing device, a buffering device and an exhaust device. To reduce oil leakage, the hydraulic cylinder needs to be sealed. The end cover and the cylinder barrel of the hydraulic cylinder, and the piston rod need static sealing, and an O-shaped sealing ring is generally adopted. The piston and the cylinder barrel of the hydraulic cylinder, and the piston rod and the end cover need to be sealed dynamically, and Y-shaped and V-shaped sealing rings are generally adopted. The leakage of the hydraulic cylinder includes inner leakage and outer leakage. The internal leakage is the leakage from the high pressure area of the oil liquid in the hydraulic cylinder to the low pressure area, and the internal leakage can cause the oil liquid to generate heat and the volumetric efficiency of the hydraulic cylinder to be reduced. The external leakage is the leakage of oil liquid in the hydraulic cylinder to the atmosphere, and the external leakage not only causes the loss of the oil liquid to influence the environment, but also has the risk of firing.

The hydraulic cylinder is provided with a buffer device which can reduce the speed and make the speed close to zero when the piston part travels to the tail end so as to reduce the inertia force of the piston moving part and relieve the mechanical impact between the piston and the end cover, thereby reducing the noise and the vibration and preventing the hydraulic cylinder from being damaged. The working principle of the hydraulic cylinder buffer device is that when the piston moves to be close to the cylinder cover, the oil in the low-pressure cavity 10 is reduced in speed through the throttling device, so that the buffering effect is achieved. The piston rod (or plunger rod) of the hydraulic cylinder has a certain mass and has a large momentum when driven by hydraulic force. At the end of their stroke, when the rod head enters the end cover and the bottom part of the hydraulic cylinder, mechanical collision can be caused, and great impact and noise are generated, the impact pressure is about twice of the rated working pressure, so that the strength and normal operation of the hydraulic cylinder and the whole hydraulic system are necessarily seriously affected, and a buffer device is adopted to avoid the mechanical collision. The buffer device can prevent and reduce the impact of moving parts such as a piston, a piston rod and the like of the hydraulic cylinder on the cylinder bottom or the end cover when moving, and can realize the speed reduction at the stroke end of the moving parts until the speed is zero. The working principle of the damping device is that when the piston reaches a certain distance before the stroke end, a part or all of the oil discharge cavity liquid is sealed, and the liquid is discharged through a throttling small opening (or a gap), so that the sealed liquid generates proper damping pressure to act on the oil discharge side of the piston and oppose the inertial force of the piston, and the aim of braking is fulfilled. Because the highest part in the hydraulic cylinder often accumulates air, which is caused by air mixed in hydraulic oil or air invading into the hydraulic cylinder when the hydraulic cylinder is not used for a long time, the air can cause the hydraulic cylinder to move unstably and generate vibration or crawl. The creeping fault phenomenon is that after air is mixed, the friction resistance is too large or the friction resistance is changed due to improper processing and assembly between relatively moving parts, the lubrication between the surfaces of the moving parts is poor, the sealing and centering of a piston and a piston rod of a hydraulic cylinder are poor, the leakage of the hydraulic cylinder is serious, the minimum stable flow of a flow valve is large, the hydraulic cylinder and the flow valve are connected by a hose (the hose is deformed greatly), and the friction resistance is increased due to more impurities in oil liquid, so that the failure of a check valve/a throttle valve in a buffer device can be caused.

At present, hydraulic actuating cylinders widely applied to various industries are used as actuating mechanisms of hydraulic systems, hydraulic cylinders sometimes have high moving speed, when pistons move to two ends of the hydraulic cylinders, impact occurs on end parts to generate noise, and related parts can be damaged when the noise is serious. When the hydraulic actuating cylinder drives a large-mass mechanism to move rapidly, the momentum is large, and when a piston rod of the hydraulic actuating cylinder moves to the tail end of a stroke, the piston and a cylinder body or an end cover are in mechanical collision, so that large impact and noise are generated. Not only can the hydraulic actuating cylinder damage be caused, but also the pressure of a hydraulic system fluctuates due to the sudden stop of the movement of the piston rod, and the pipeline, various valves and other related elements can be damaged. To reduce and prevent such impacts, a damping device is typically employed at the end of the stroke of the hydraulic ram to generate a relatively large amount of resistance to smooth braking of the working member and to avoid collision between the piston and the end cap/outer cylinder. As the buffer device is arranged at the stroke tail end of the hydraulic actuating cylinder, the axial and radial spaces of the hydraulic actuating cylinder are correspondingly increased according to the buffer distance, and the buffer device has a complex structure and higher processing precision requirement, so that the volume and the weight of a product are increased, and the cost is high. When the hydraulic cylinder with the buffer device is started reversely, the phenomenon that the piston is temporarily stopped or reversely retreated often occurs, the orifice of the one-way valve is too small, so that the oil quantity entering the buffer cavity is too small, and even vacuum occurs, and therefore the fault phenomenon can occur at the moment that the buffer plunger is separated from the end cover. When the movement speed of the piston is high, the steel ball of the one-way valve flows along with the oil flow, so that a valve hole is blocked, and the hydraulic cylinder causes irregular action. Because the hydraulic pump operation has irregularity, and the pump rotates and has the retardation or slightly to bite the dead phenomenon, if the piston seals excessive wearing and tearing, speed control valve adjusts improperly, can cause too high backpressure and sealing member improper installation or hydraulic oil pollution, and secondly there is the foreign matter entering during the assembly and the sealing material quality is not good. The consequence is slow and weak movement, which can cause the damage of the piston and the cylinder barrel in serious condition and the cylinder pulling phenomenon.

The damping device is generally based on the principle that when the piston moves to the near end part, the oil return resistance is increased, and the piston is subjected to larger counter pressure in an oil return cavity or unloads an oil inlet cavity, so that the movement speed is reduced, and the aim of avoiding or reducing impact on a cylinder cover is fulfilled. The references and practical applications disclosed in the prior art are all for buffering the tail end of the pneumatic hydraulic actuator cylinder in a fixed orifice or variable orifice type, a buffering throttle valve, a buffering plug and the like. The throttling port variable type buffer device is characterized in that a buffer plunger is provided with a triangular groove, the through-flow section of a throttling hole is smaller and smaller, the problem that the buffer effect is too weak in the final stage of the stroke is solved, but the throttling port is independently adopted for buffering, so that the throttling port variable type buffer device has the defects of small throttling caliber, easiness in blockage, large buffer pressure and the like. The damping throttle valve has an adjustable damping effect due to the adjustable throttle valve, but the disadvantage of the damping effect weakening after the speed reduction cannot be solved. After the buffering plunger piston buffering device enters the matching hole, oil return oil can be discharged only through the throttle valve. When the buffering is started, the generated buffering power is large, but the generated buffering power is reduced quickly and finally does not work, and the buffering effect is not ideal. The buffer device can only play a buffer role when the hydraulic cylinder moves to the end cover, and when the movement of the actuating element is stopped at the middle stroke position, the buffer device does not play a role,

disclosure of Invention

The invention aims to overcome the defects in the prior art and provide the buffer device with the one-way cone valve arranged in the piston rod of the hydraulic actuator cylinder, which improves the tail end buffer technology of the existing hydraulic actuator cylinder, has a simple structure and reliable buffer function and is used for improving the tail end buffer function of the hydraulic actuator cylinder.

In order to solve the technical problem, the technical scheme adopted by the invention is that the piston rod built-in one-way cone valve buffer device comprises: the assembly is at 1 buffer chamber of buffering end cover piston rod and the piston 2 of having assembled sealing washer 7 of reciprocating motion, its characterized in that: the hydraulic actuating cylinder is divided into a high-pressure cavity 11 and a low-pressure cavity 10 by a piston 2, a stepped shaft, an oil through hole 6 which radially penetrates through the stepped shaft, an axial assembly spring of the oil through hole and an assembly hole of a one-way cone valve are formed in the front end of the piston 2, the one-way cone valve 4 with a stepped conical head is axially coupled with a conical surface of a valve seat 3 after being assembled with a compression spring 5 to realize one-way throttling, when hydraulic pressure force overcomes prepressure of the compression spring 5, the one-way cone valve 4 is separated from a sealing conical surface of the valve seat 3, and hydraulic oil is communicated with a right cavity of the hydraulic actuating cylinder through the oil through hole 6 in the piston 2; along with the retraction of the piston 2, the buffer sleeve 8 at the front end of the piston 2 enters the buffer inner hole 9 on the buffer end cover, the pressure of hydraulic oil in the low-pressure cavity 10 of the hydraulic actuator cylinder starts to rise, the conical surface of the one-way cone valve 4 is attached to the conical surface of the valve seat 3 under the action of hydraulic pressure and the spring force of the compression spring 5, at the moment, the hydraulic oil in the low-pressure cavity 10 of the hydraulic actuator cylinder can only flow out through a circular seam gap between the buffer end cover 1 and the buffer sleeve 8 at the front end of the piston 2, along with the slow retraction of the piston 2, the distance of the buffer sleeve 8 entering the buffer inner hole 9 is increased, the buffer length is increased, at the moment, the pressure of the low-pressure cavity 10 rises, the piston 2 is subjected to larger buffer force, the movement speed of the piston is reduced, and an ideal buffer effect can be realized by adjusting the gap between the buffer sleeve 8 and the buffer inner hole 9.

Compared with the prior art, the buffering device of the hydraulic actuating cylinder piston rod built-in one-way cone valve has the beneficial technical effects that:

the structure is simple. The compression spring, the one-way cone valve and the valve seat are sequentially assembled in the large cylindrical inner hole in the center of the piston rod, so that the piston rod assembly has the advantages of compact structure, simple structure, easiness in processing and low production cost. The central line of the small column part of the buffering plunger piston body is arranged to coincide with the central line of the buffering inner hole of the buffering end cover, so that the buffering plunger piston 8 is smoothly guided into the buffering inner hole of the buffering end cover when the piston rod retracts.

The buffering is reliable. According to the invention, the stepped shaft, the oil through hole radially penetrating through the stepped shaft and the assembly hole axially assembling the spring one-way cone valve are arranged at the front end of the piston 2, the one-way cone valve 4 of the stepped cone head is assembled with the compression spring 5 and then realizes one-way throttling axially through the valve seat 3, hydraulic oil can only flow out through a circular seam gap between the buffering end cover and the buffering sleeve 8 at the front end of the piston 2 in a buffering stage, the buffering performance is good, the mechanical impact between the piston and the end cover is reduced, the internal and external impact and noise are reduced, and the service life of the hydraulic cylinder is prolonged.

The function is reliable. The piston rod structure ingeniously utilizes the space in the piston rod, the one-way cone valve is arranged in the piston rod, the axial space of the hydraulic actuating cylinder is saved, meanwhile, the built-in one-way valve can enable hydraulic pressure to sensitively push the piston, and the phenomenon that the hydraulic actuating cylinder stretches out and starts slowly or difficultly due to insufficient thrust is avoided. The oil enters the low-pressure cavity 10 of the hydraulic actuating cylinder through the oil through hole of the piston rod, the hydraulic pressure acts on the annular surface of the whole piston rod rapidly, the piston rod is pushed to move rapidly, and the phenomenon that the piston rod of the hydraulic actuating cylinder stretches out and starts slowly or difficultly due to insufficient thrust is avoided. When the piston rod retracts to the bottom, the oil passages among all parts are ensured to be communicated with the oil holes of the buffering end cover in the small cylindrical part of the buffering plunger piston as oil through holes; when the sealing conical surface of the one-way cone valve is separated from the conical surface of the valve seat under the action of hydraulic pressure, the inner part of the small cylindrical part of the buffering plunger is provided with an oil through hole communicated with the oil hole on the large cylindrical part of the buffering plunger, and finally the oil way is connected to the low-pressure cavity 10 of the hydraulic actuator cylinder. When the piston reaches the bottom of the cylinder within a specified distance range and when the piston is started, the damping device has the functions of buffering and damping and reducing pressure pulse.

The invention is suitable for the buffer device of the one-way cone valve arranged in the piston rod of the hydraulic actuating cylinder, and can be applied to various industries due to the simple structure of the buffer device.

Drawings

FIG. 1 is a cross-sectional view of a piston rod built-in one-way cone valve cushioning device of the present invention;

FIG. 2 is a schematic view of the piston rod of FIG. 1 retracting to begin cushioning transient;

FIG. 3 is a schematic view of the piston rod of FIG. 2 in a state of being retracted to a buffer end;

in the figure: 1, a buffer end cover, 2 pistons, 3 valve seats, 4 one-way cone valves, 5 compression springs and 6 oil through holes; 7 sealing rings, 8 buffer sleeves, 9 buffer inner holes, 10 bottom pressure cavities and 11 high pressure cavities; the invention will be described in further detail with reference to the accompanying drawings and specific embodiments.

Detailed Description

See fig. 1-3. In a preferred embodiment described below, a piston rod built-in one-way cone valve cushioning device comprises: the assembly is at 1 buffering intracavity of buffering end cover piston rod and the piston 2 of having assembled sealing washer 7 of reciprocating motion, wherein: the piston 2 divides the hydraulic actuating cylinder into a high-pressure cavity 11 and a low-pressure cavity 10, the front end of the piston 2 is provided with a stepped shaft, an oil through hole 6 which radially penetrates through the stepped shaft and an assembly hole of a spring one-way cone valve which is axially assembled by the oil through hole 6, the one-way cone valve 4 provided with a stepped conical head is assembled by the compression spring 5 and then is axially coupled with the conical surface of the valve seat 3 to realize one-way throttling, when hydraulic pressure force overcomes the pre-pressure of the compression spring 5, the one-way cone valve 4 is separated from the sealing conical surface of the valve seat 3, and hydraulic oil is communicated with the right cavity of the hydraulic actuating cylinder through the oil through hole 6 on the piston 2; along with the retraction of the piston 2, the buffer sleeve 8 at the front end of the piston 2 enters the buffer inner hole 9 on the buffer end cover, the pressure of hydraulic oil in the low-pressure cavity 10 of the hydraulic actuator cylinder starts to rise, the conical surface of the one-way cone valve 4 is attached to the conical surface of the valve seat 3 under the action of hydraulic pressure and the spring force of the compression spring 5, at the moment, the hydraulic oil in the low-pressure cavity 10 of the hydraulic actuator cylinder can only flow out through a circular seam gap between the buffer end cover and the buffer sleeve 8 at the front end of the piston 2, along with the slow retraction of the piston 2, the distance of the buffer sleeve 8 entering the buffer inner hole 9 is increased, the buffer length is increased, at the moment, the pressure of the low-pressure cavity 10 rises, the piston 2 is subjected to larger buffer force, the movement speed of the piston is reduced, and an ideal buffer effect can be realized by adjusting the gap between the buffer sleeve 8 and the buffer inner hole 9.

The front end of the piston 2 is provided with a stepped shaft and a buffer sleeve 8 which is connected with the same body, and the one-way cone valve 4 sleeved with the spring 5 is fixed in a stepped inner hole of the buffer sleeve 8 through a valve seat 3 by screw threads.

The buffer sleeve 8 is communicated with a buffer inner hole 9 communicated with the nozzle on the end cover 1, and the buffer inner hole 9 is in clearance fit.

When the piston 2 retracts to the bottom, hydraulic oil enters the buffering inner hole 9 through the pipe nozzle on the buffering end cover 1, the hydraulic pressure overcomes the spring force of the spring 5, the conical surface of the one-way cone valve 4 is pushed to be separated from the conical surface of the valve seat 3, at the moment, the hydraulic oil passes through the conical surface of the one-way cone valve 4 and then reaches the low-pressure cavity 10 through the oil through hole 6, the hydraulic oil acts on the end surface of the piston 2 rapidly, and the piston 2 is pushed to move towards the high-pressure cavity side rapidly. Therefore, the problem that the piston 2 cannot extend out and start slowly or difficultly due to insufficient thrust is solved.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.

Claims

1. A piston rod built-in one-way cone valve buffering device comprises: the assembly is at piston rod and piston (2) of having assembled sealing washer (7) that buffer end cover (1) buffering intracavity is reciprocating motion, its characterized in that: the hydraulic actuating cylinder is divided into a high-pressure cavity (11) and a low-pressure cavity (10) by a piston (2), a stepped shaft, an oil through hole (6) which radially penetrates through the stepped shaft, an axial assembly spring of the oil through hole and an assembly hole of a one-way cone valve are formed in the front end of the piston (2), the one-way cone valve (4) with a stepped cone head is assembled with a compression spring (5) and then is axially coupled with the conical surface of a valve seat (3) to realize one-way throttling, when hydraulic pressure overcomes the pre-pressure of the compression spring (5), the one-way cone valve (4) is separated from the sealing conical surface of the valve seat (3), and hydraulic oil is communicated with the right cavity of the hydraulic actuating cylinder through the oil through hole (6) in the piston (2); along with the retraction of the piston (2), a buffer sleeve (8) at the front end of the piston (2) contacts a buffer inner hole (9) in a buffer end cover, the pressure of hydraulic oil in a low-pressure cavity (10) of the hydraulic actuator cylinder starts to rise, the conical surface of the one-way cone valve (4) is attached to the conical surface of the valve seat (3) under the action of hydraulic pressure and spring force of the compression spring (5), at the moment, the hydraulic oil in the low-pressure cavity (10) of the hydraulic actuator cylinder can only flow out through a circular seam gap between the buffer end cover and the buffer sleeve (8) at the front end of the piston (2), along with the increase of the buffer distance of the low-pressure cavity (10), the speed of the piston rod is slowed down, when the piston (2) moves to a near end, the oil return resistance is increased, the piston (2) bears larger counter pressure in an oil return cavity, the movement speed of the piston rod is slowed down, and the buffer is achieved.

2. The piston rod built-in one-way cone valve buffering device as defined in claim 1, wherein: the front end of the piston (2) is provided with a stepped shaft and a buffering sleeve (8) which is connected with the same body, and the one-way cone valve (4) sleeved with the spring (5) is fixed in a stepped inner hole of the buffering sleeve (8) through a valve seat (3) in a threaded manner.

3. The piston rod built-in one-way cone valve buffering device as defined in claim 2, wherein: the buffer sleeve (8) is communicated with a buffer inner hole (9) communicated with a nozzle on the end cover (1), and the buffer inner hole (9) is in clearance fit.

4. The piston rod built-in one-way cone valve buffering device as defined in claim 1, wherein: when piston (2) retract to the end, hydraulic oil gets into buffering hole (9) through nozzle on buffering end cover (1), and hydraulic pressure overcomes the spring force of spring (5), promotes the conical surface of one-way cone valve (4) and breaks away from the conical surface of disk seat (3), and hydraulic oil crosses oil through hole (6) behind the conical surface of one-way cone valve (4) and reachs low-pressure chamber (10) this moment, and hydraulic oil acts on the terminal surface of piston (2) rapidly, promotes piston (2) to high-pressure chamber side rapid draing.