Hydraulic equipment with overload protection function

Abstract

The invention relates to the technical field of hydraulic elements, in particular to hydraulic equipment with an overload protection function, which comprises a cylinder body and a piston slidably mounted in the cylinder body, a piston rod is fixedly connected to the center of the piston, and the piston divides the interior of the cylinder body into a lower rod cavity and an upper rodless cavity. The cylinder body is internally provided with buffer parts which are symmetrical up and down and are used for reducing the movement speed of the piston, and the piston is internally provided with a protection part which is used for carrying out pressure induction and rapid pressure relief on bidirectional overload in the extending and retracting processes of the piston rod. The pressure overrun of the rodless cavity and the pressure overrun of the rod cavity are responded respectively, a reversing valve or a sensor is not needed to judge the direction, bidirectional overload protection of the whole stroke of the piston rod is achieved, especially for sudden loads, meanwhile, the buffering part slows down the tail end impact through the throttling effect, and the protection part starts pressure relief when buffering fails or pressure suddenly increases.

Description

Technical Field

[0001] The present invention relates to the technical field of hydraulic components, and more specifically, it relates to a hydraulic device with an overload protection function. Background Art

[0002] Overload protection means that during the operation of a hydraulic cylinder, when there are situations such as sudden load changes, abnormal increase in system pressure, or mechanical jamming, which cause the internal pressure of the equipment to exceed the designed bearing range, the equipment is protected to prevent the hydraulic cylinder from being damaged due to overload.

[0003] Currently, hydraulic overload protection mainly relies on an external overflow valve, which realizes safety boundary protection by monitoring the common pressure of the system (such as the pump outlet pressure). However, this solution has the following fundamental defects: The overflow valve can only set the global protection threshold (such as taking the minimum rated pressure in a multi-cylinder system) and cannot meet the overload requirements of a single cylinder. When a certain cylinder retracts (the rod chamber is overloaded), if the system pressure does not reach the overflow valve threshold (such as other cylinders are unloaded), even if the pressure of this cylinder has exceeded the rated value, the overflow valve still does not act, resulting in overload failure of the single cylinder.

[0004] At the same time, the overflow valve can only recognize the positive pressure at the pump outlet. When the cylinder retracts, the pressure increase in the rod chamber is "abnormal pressure on the oil return side", rather than the positive pressure at the pump outlet exceeding the limit. The overflow valve spool will not act because the force direction is opposite (the pressure oil flows out from the valve port). If two-way protection is to be achieved, overflow valves need to be set on both chambers of the cylinder and coordinated with the commutation logic (that is, by judging the movement direction of the cylinder through the signal of the electromagnetic directional valve) to determine whether to trigger the protection of the corresponding chamber, resulting in an increase in system cost, doubling of the volume, and there is a delay in electrical signal transmission, making it impossible to respond to sudden overloads in real time and difficult to implement in a compact working condition. Summary of the Invention

[0005] The present invention provides a hydraulic device with an overload protection function to solve the above technical problems.

[0006] The present invention provides a hydraulic device with an overload protection function, including a cylinder block and a piston slidably installed in the cylinder block. A piston rod is fixedly connected to the central position of the piston. The piston divides the inside of the cylinder block into a lower rod chamber and an upper rodless chamber. The characteristic is that buffer parts which are symmetric up and down and used to slow down the movement speed of the piston are arranged inside the cylinder block, and a protection part which is used for pressure sensing and rapid pressure relief for bidirectional overload during the extension and retraction of the piston rod is arranged inside the piston.

[0007] Further, both ends of the cylinder block are fixedly connected with end covers, and two oil valves which are symmetric up and down are fixedly installed on the outer sides of the end covers. The upper and lower oil valves are respectively communicated with the rodless chamber and the rod chamber.

[0008] Furthermore, the buffer portion includes two plungers fixedly installed on the piston and symmetrically arranged up and down. A buffer oil passage is provided on the side of the end cover close to the cylinder block, and the right opening of the buffer oil passage is aligned with the connection port between the oil valve and the end cover.

[0009] Furthermore, the protection portion includes a protection oil cavity formed in a ring shape inside the piston. A number of protection oil holes are provided on the side of the protection oil cavity close to the plunger. A protection oil passage communicating with the protection oil cavity is provided inside the piston rod, and the protection oil passage communicates with an external oil tank.

[0010] Furthermore, two sealing assemblies symmetrically arranged up and down are provided in the protection oil cavity. The sealing assembly includes a number of guide rods fixedly installed on the inner wall of the protection oil cavity far from the plunger. A sliding plate is slidably installed on the outer sides of the number of guide rods. A number of sealing plugs for sealing the protection oil holes are fixedly installed on the side of the sliding plate close to the protection oil holes.

[0011] Furthermore, a return spring is installed between the sliding plate and the inner wall of the protection oil cavity far from the plunger. The return spring is sleeved on the outer side of the guide rod, and a limit plate is fixedly installed on the side of the guide rod far from the plunger.

[0012] Furthermore, a number of sealing rings are fixedly sleeved on the outer side of the piston, and the sealing rings are slidably connected with the inner wall of the cylinder block.

[0013] Furthermore, a stepped transition is adopted at the connection between the protection oil passage and the protection oil cavity.

[0014] The beneficial effects of the present invention are as follows: 1. In the present application, through the sealing assemblies symmetrically arranged up and down in the protection oil cavity, the overpressure of the rodless cavity (extended) and the rod cavity (retracted) are respectively responded to. Without using a reversing valve or a sensor to judge the direction, two-way overload protection for the full stroke (any position of extension / retraction) of the piston rod is achieved. Especially in the face of sudden loads, at the same time, the buffer portion first slows down the end impact through the throttling effect, and the protection portion starts to relieve pressure when the buffer fails or the pressure suddenly increases, forming a gradient protection with buffer priority and overload backup, thereby greatly extending the service life of the cylinder block. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is a three-dimensional structural schematic diagram of the present invention.

[0016] Figure 2 is a three-dimensional structural schematic diagram of the interior of the cylinder block of the present invention.

[0017] Figure 3 is a cross-sectional view of the present invention.

[0018] Figure 4 is the present invention Figure 3 is a partial enlarged view of part A in the present invention.

[0019] In the figure: 1. Cylinder block; 11. Rod chamber; 12. Rodless chamber; 2. Piston; 3. Piston rod; 4. Protection part; 41. Protection oil chamber; 42. Protection oil passage; 43. Sealing assembly; 431. Guide rod; 432. Sliding plate; 433. Sealing plug; 434. Return spring; 435. Limit plate; 436. Protection oil hole; 5. Buffer part; 51. Plunger; 52. Buffer oil passage; 6. Oil valve; 7. End cover; 8. Sealing ring. Specific embodiments

[0020] Now, the subject matter described herein will be discussed with reference to exemplary embodiments. It should be understood that these embodiments are discussed so that those skilled in the art can better understand and thus implement the subject matter described herein. Changes can be made to the functions and arrangements of the elements discussed without departing from the scope of protection of the content of this specification. Each example can omit, substitute, or add various processes or components as needed. Additionally, the features described relative to some examples can also be combined in other examples.

[0021] Refer to Figure 1 、 Figure 2 and Figure 3 In this embodiment, a hydraulic device with an overload protection function is proposed, which includes a cylinder block 1 and a piston 2 slidably installed in the cylinder block 1. A piston rod 3 is fixedly connected to the central position of the piston 2. The piston 2 divides the inside of the cylinder block 1 into a lower rod chamber 11 and an upper rodless chamber 12. A buffer part 5 is arranged symmetrically up and down in the cylinder block 1 and is used to slow down the movement speed of the piston 2. A protection part 4 is arranged in the piston 2 and is used for pressure sensing and rapid pressure relief of bidirectional overload during the extension and retraction of the piston rod 3. A plurality of sealing rings 8 are fixedly sleeved on the outer side of the piston 2, and the sealing rings 8 are slidably connected with the inner wall of the cylinder block 1.

[0022] Refer to Figure 2 and Figure 3 Both ends of the cylinder block 1 are fixedly connected with end covers 7, and two oil valves 6 are symmetrically installed up and down on the outer side of the end covers 7. The upper and lower oil valves 6 are respectively communicated with the rodless chamber 12 and the rod chamber 11.

[0023] Refer to Figure 3 and Figure 4 The buffer part 5 includes two plungers 51 fixedly installed on the piston 2 and symmetrically arranged up and down. A buffer oil passage 52 is opened on the side of the end cover 7 close to the cylinder block 1, and the right opening of the buffer oil passage 52 is aligned with the connection port of the oil valve 6 and the end cover 7.

[0024] During specific use: Process of the piston rod 3 extending: The upper oil valve 6 is opened, and hydraulic oil flows into the rodless cavity 12 through this oil valve 6. As the hydraulic oil in the rodless cavity 12 continuously increases, the pressure inside the cavity gradually rises. Under the action of the pressure, the piston 2 receives a downward thrust and thus begins to slide downward. At this time, the hydraulic oil in the rod chamber 11 flows out through the lower oil valve 6 and returns to the fuel tank. The piston rod 3 extends downward synchronously with the piston 2, realizing the extension action of the equipment.

[0025] Meanwhile, during the process of the piston rod 3 extending, initially, the piston 2 is far from the lower end cover 7, and the plunger 51 does not block the gap between the inner wall of the end cover 7 and the rod chamber 11. The hydraulic oil in the rod chamber 11 can flow back bidirectionally (mainly through the annular gap) through the gap between the inner wall of the end cover 7 and the rod chamber 11 and the buffer oil passage 52. The oil return resistance is small, and the piston 2 moves smoothly at a relatively fast speed, and the piston rod 3 extends synchronously.

[0026] As the piston 2 continues to move, the lower plunger 51 will insert and block the gap between the inner wall of the lower end cover 7 and the rod chamber 11 along with the movement of the piston 2, causing the flow of hydraulic oil to be blocked. It can only flow through the buffer oil passage 52 on the end cover 7 to the oil valve 6, and the movement speed of the piston 2 slows down. Due to the throttling effect, strong impacts between the piston 2 and the cylinder block 1 and the end cover 7 are prevented.

[0027] Refer to Figure 3 and Figure 4 As shown in [relevant figures], the protection part 4 includes a protection oil cavity 41 formed in a ring shape inside the piston 2. A number of protection oil holes 436 are opened on the side of the protection oil cavity 41 close to the plunger 51. A protection oil passage 42 connected to the protection oil cavity 41 is opened inside the piston rod 3, and the protection oil passage 42 is connected to the external fuel tank.

[0028] It should be noted that the connection between the protection oil passage 42 and the protection oil cavity 41 adopts a stepped transition (chamfering treatment) to avoid stress concentration and oil fluid eddy current; the outlet of the protection oil passage 42 is connected to the special pressure relief interface of the external fuel tank through a high-pressure hose, and a check valve is set at the interface. When overloading and relieving pressure, the high-pressure oil fluid in the protection oil cavity 41 pushes open the check valve and quickly flows into the fuel tank; during normal operation, the check valve is closed to prevent the oil fluid in the fuel tank from flowing back into the protection oil passage 42 due to vibration.

[0029] Refer to Figure 3 and Figure 4 As shown in [relevant figures], two symmetrically arranged sealing components 43 are provided inside the protection oil cavity 41. The sealing component 43 includes a number of guide rods 431 fixedly installed on the inner wall of the protection oil cavity 41 far from the plunger 51. A sliding plate 432 is slidably installed on the outer sides of the number of guide rods 431. A number of sealing plugs 433 for sealing the protection oil holes 436 are fixedly installed on the side of the sliding plate 432 close to the protection oil holes 436.

[0030] Refer to Figure 3 and Figure 4 A return spring 434 is installed between the sliding plate 432 and the inner wall of the protection oil chamber 41 on the side away from the plunger 51. The return spring 434 is sleeved outside the guide rod 431, and a limit plate 435 is fixedly installed on the side of the guide rod 431 away from the plunger 51.

[0031] During specific use, if the load suddenly increases during the extension of the piston rod 3 (for example, the connecting piece at the output end of the hydraulic cylinder is stuck), the pressure in the rodless chamber 12 rises rapidly. Under the action of the pressure, the sealing plug 433 overcomes the elastic force of the return spring 434 and slides along the guide rod 431 to open the protection oil hole 436. The high-pressure oil enters the protection oil chamber 41 through the protection oil hole 436, and the hydraulic oil entering the protection oil chamber 41 is discharged from the cylinder block 1 through the protection oil passage 42 in the piston rod 3 and returns to the external oil tank.

[0032] After the overload pressure is released, the return spring 434 releases its elastic potential energy, pushing the sliding plate 432 to slide in the reverse direction along the guide rod 431, and the sealing plug 433 re-inserts into the protection oil hole 436 to seal the protection oil hole 436.

[0033] It should be noted that the principle of the retraction process of the piston rod 3 is the same as that of the extension process of the piston rod 3, so it will not be described in detail in this application.

[0034] Finally, it should be noted that: Obviously, the above embodiments are only examples for clearly explaining the present invention, rather than limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to enumerate all the implementation manners here. And the obvious changes or modifications derived therefrom are still within the protection scope of the present invention.

Claims

1. A hydraulic device with an overload protection function, comprising: A cylinder block (1) and a piston (2) slidably installed in the cylinder block (1). A piston rod (3) is fixedly connected to the central position of the piston (2). The piston (2) divides the interior of the cylinder block (1) into a rod chamber (11) below and a rodless chamber (12) above. It is characterized in that a buffer part (5) is provided symmetrically up and down in the cylinder block (1) and is used to slow down the movement speed of the piston (2), and a protection part (4) is provided in the piston (2) for pressure sensing and rapid pressure relief of the two-way overload during the extension and retraction of the piston rod (3).

2. The hydraulic device with an overload protection function according to claim 1, characterized in that, Both ends of the cylinder block (1) are fixedly connected with end covers (7). Two oil valves (6) are symmetrically installed up and down on the outer side of the end covers (7). The upper and lower oil valves (6) are respectively communicated with the rodless chamber (12) and the rod chamber (11).

3. A hydraulic device with an overload protection function according to claim 2, characterized in that, The buffer part (5) includes two plungers (51) fixedly installed on the piston (2) and symmetrically up and down. A buffer oil passage (52) is opened on the side of the end cover (7) close to the cylinder block (1). The right opening of the buffer oil passage (52) is aligned with the connection port of the oil valve (6) and the end cover (7).

4. A hydraulic device with an overload protection function according to claim 3, characterized in that, The protection part (4) includes a protection oil cavity (41) opened in a ring shape inside the piston (2). A number of protection oil holes (436) are opened on the side of the protection oil cavity (41) close to the plunger (51). A protection oil passage (42) communicated with the protection oil cavity (41) is opened inside the piston rod (3). The protection oil passage (42) is communicated with an external oil tank.

5. A hydraulic device with an overload protection function according to claim 4, characterized in that, Two sealing components (43) are provided symmetrically up and down in the protection oil cavity (41). The sealing component (43) includes a number of guide rods (431) fixedly installed on the inner wall of the protection oil cavity (41) far from the plunger (51). A sliding plate (432) is slidably installed on the outer sides of the number of guide rods (431). A number of sealing plugs (433) for sealing the protection oil holes (436) are fixedly installed on the side of the sliding plate (432) close to the protection oil holes (436).

6. A hydraulic device with an overload protection function according to claim 5, characterized in that, A return spring (434) is installed between the sliding plate (432) and the inner wall of the protection oil cavity (41) far from the plunger (51). The return spring (434) is sleeved on the outer side of the guide rod (431). A limit plate (435) is fixedly installed on the side of the guide rod (431) far from the plunger (51).

7. A hydraulic device with an overload protection function according to claim 1, characterized in that, A number of sealing rings (8) are fixedly sleeved on the outer side of the piston (2). The sealing rings (8) are slidably connected with the inner wall of the cylinder block (1).

8. A hydraulic device with an overload protection function according to claim 4, characterized in that, The connection between the protection oil passage (42) and the protection oil cavity (41) adopts a stepped transition.

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