Single-action hydraulic cylinder stable in operation

Abstract

The invention relates to the technical field of hydraulic cylinders, and aims to provide a stable-operation single-action hydraulic cylinder which comprises a cylinder body, a piston, a pipe joint, a connecting piece and a spring, a first oil feeding cavity and an oil feeding channel which are communicated are formed in the pipe joint, the connecting piece comprises a limiting piece and a connecting rod, and a second oil feeding cavity is formed in the connecting rod; the connecting rod penetrates through the pipe joint and extends into the cavity of the cylinder body, the second oil feeding cavity is communicated with the cavity, a throttling hole is formed in the side wall of the second oil feeding cavity and communicated with the first oil feeding cavity and the second oil feeding cavity, and the through-flow section of the throttling hole is smaller than the through-flow section of the cavity and the through-flow section of the second oil feeding cavity. During oil feeding, certain resistance is applied through the spring, and the phenomenon that the piston climbs or vibrates due to water flow impact is avoided; during oil return, the flow blocking phenomenon occurs at the throttling hole with the through-flow section smaller than that of the second oil feeding cavity, the piston rod retracts stably, and vibration is avoided.

Description

Technical Field

[0001] This invention relates to the field of hydraulic cylinder technology, and more specifically, to a stable single-acting hydraulic cylinder. Background Technology

[0002] In modern industry, single-acting hydraulic cylinders, as actuators driven by unidirectional hydraulic pressure and reset by external forces (such as springs or gravity), are widely used in key equipment such as bolt tensioning machines, construction machinery, and heavy equipment due to their simple structure, low cost, and wide applicability. However, as industrial equipment develops towards higher pressure, precision, and efficiency, traditional single-acting hydraulic cylinders have gradually revealed many stability problems in actual operation, becoming a significant bottleneck restricting the improvement of equipment performance.

[0003] The structural design of traditional single-acting hydraulic cylinders often has the following defects: Insufficient operational stability: During the oil inlet stage, hydraulic oil enters the cylinder cavity directly through the pipeline. Due to factors such as instantaneous changes in oil pressure and flow fluctuations, the piston is easily subjected to strong impacts, resulting in "creeping" phenomenon (i.e., discontinuous or intermittent piston movement) or high-frequency vibration, which seriously affects the output accuracy of the hydraulic cylinder and the operational stability of the equipment.

[0004] Vibration hazards during the oil return phase: During the oil return process, the oil needs to be discharged from the cylinder cavity through the oil delivery channel. Traditional structures lack effective flow control components, and the oil flow rate fluctuates with changes in system pressure, resulting in uneven force on the piston during retraction, causing vibration or even abnormal noise, and shortening the service life of the equipment.

[0005] Sealing performance defects: An unreasonable design of the sealing structure between the piston and the inner wall of the cylinder cavity can easily lead to oil leakage. Especially under high-pressure conditions, leakage not only reduces the efficiency of the hydraulic system and reduces thrust, but may also further aggravate operational failures by contaminating internal components with oil.

[0006] Structural adaptability limitations: Some application scenarios (such as bolt tensioning machines) have strict limitations on the structural size of hydraulic cylinders. Traditional hydraulic cylinders, due to their scattered layout and redundant components, are difficult to meet the requirements of "miniaturization" and "integration", which makes it difficult to install in a small space. Moreover, the excessively large structural size can easily cause the center of gravity of the overall equipment to shift, indirectly affecting the operational stability.

[0007] While existing technologies have addressed these issues by optimizing piston materials and adding buffer pads, they have failed to fundamentally resolve the core problems of oil shock, flow fluctuations, and seal failure. Therefore, developing a single-acting hydraulic cylinder that is compact, stable in operation, and reliably sealed has become a crucial requirement for improving the performance of industrial equipment and reducing failure rates. Summary of the Invention

[0008] To address the problems of existing technologies, such as mechanical failures, crawling, leakage, and insufficient thrust caused by the structural size limitations and instability of hydraulic cylinders, which lead to overall equipment instability and high failure rates in bolt tensioning machines, this invention provides a single-acting high-pressure mini hydraulic cylinder.

[0009] The technical solution is as follows: A stable single-acting hydraulic cylinder includes a cylinder body, a piston, a pipe joint, a connecting component, and a spring. The cylinder body has a cylindrical cavity. A piston rod is fixed to one side of the piston and slidably disposed within the cavity, dividing the cavity into a rodless cavity and a rod cavity. The piston rod is placed within the rod cavity, with the end of the piston rod away from the piston extending out of the cavity. The pipe joint has a first oil delivery chamber and an oil delivery channel that communicate with each other. The oil delivery channel is used to connect to an external oil delivery pipe. The connecting component includes a limiting component and a connecting rod with a second oil delivery chamber. The connecting rod passes through the pipe joint and extends into the cylinder body cavity. The second oil delivery chamber communicates with the cavity, and a throttling orifice is formed on the side wall of the second oil delivery chamber. The throttling orifice connects the first and second oil delivery chambers. The flow cross-section at the throttling orifice is smaller than the flow cross-section of the cavity and the second oil delivery chamber. The spring is installed in the rod cavity of the cylinder body to push the piston back for oil return.

[0010] By adopting the above technical solution, during oil inlet, oil is supplied inward through the external oil supply pipe, pushing the piston to move and causing the piston rod to push outward. During the pushing out process, a certain resistance is applied by the spring to prevent water flow impact from causing crawling or vibration. During oil return, the flow direction of the oil circuit is adjusted by the reversing valve preset on the oil supply pipe. The spring resets and drives the piston to move downward, causing the oil to return. At the throttling orifice where the flow cross-section is smaller than that of the second oil supply chamber, a flow blockage occurs, keeping the flow velocity through the throttling orifice at a constant value. This achieves stable and continuous piston movement and stable piston rod retraction, avoiding vibration.

[0011] The invention is further configured such that a first threaded hole and a second threaded hole are respectively opened at both ends of the cavity of the cylinder, and a cap is threadedly connected to the second threaded hole, and a guide hole for the piston rod to extend is opened on the cap.

[0012] The present invention is further configured such that a first through hole and a second through hole are respectively provided at both ends of the first oil delivery chamber of the pipe joint, and the connecting rod passes through the first through hole, the first oil delivery chamber and the second through hole in sequence and is threadedly connected to the first threaded hole.

[0013] The invention is further configured such that the limiting member is used to press the pipe fitting between itself and the cylinder body.

[0014] The invention is further configured such that a first mounting groove is provided on the top of the cap, and a lip seal is provided in the first mounting groove and fitted outside the piston rod, which serves to prevent oil, dirt and dust.

[0015] The invention is further configured such that an annular groove is formed on the piston sidewall, and a sealing element is installed in the annular groove to improve the sealing performance between the piston and the inner wall of the cylinder cavity, and to prevent oil from entering the rod cavity and causing oil leakage.

[0016] The present invention is further configured such that the sealing elements are an O-ring and a square sealing ring fitted together.

[0017] The present invention is further configured such that a square sealing ring is fitted over an O-ring, and both the O-ring and the square sealing ring are preferably from the SKF brand, and their material is preferably PTFE.

[0018] The present invention is further configured such that the contact surfaces of the pipe joint, the limiting member, and the cylinder are all provided with sealing gaskets to improve the sealing performance at the contact points. The sealing gaskets can be directly placed between the contact surfaces, or sealing grooves for placing the sealing gaskets can be opened on the contact surfaces.

[0019] The present invention is further configured such that the piston rod includes a limiting section and a telescopic section, the telescopic section slides within the guide hole, and the diameter of the limiting section is larger than the inner diameter of the guide hole, for limiting the stroke of the piston rod.

[0020] Compared with the prior art, the present invention provides a stable single-acting hydraulic cylinder with the following advantages: 1. During oil intake, oil is supplied through the external oil supply pipe, which pushes the piston to move and causes the piston rod to push outward. During the pushing process, a certain resistance is applied by the spring to make it run smoothly and avoid the intermittent impact of water flow, which may cause crawling or vibration, thus making the operation more stable.

[0021] 2. During oil return, the flow direction of the oil circuit is adjusted by the reversing valve preset on the oil delivery pipe. The spring reset drives the piston to move downward, causing the oil to return. At the throttling orifice where the flow cross-section is smaller than that of the second oil delivery chamber, the flow blockage occurs, keeping the flow velocity through the throttling orifice at a constant value. This enables the piston to move stably and continuously, and the piston rod to retract stably, avoiding vibration.

[0022] 3. The hydraulic cylinder has a simple structure, with compact connections between its components. The oil inlet and outlet channels are located on the side of the hydraulic cylinder in the direction of extension and retraction, which greatly reduces the longitudinal length of the hydraulic cylinder and allows it to be used in relatively narrow areas. Attached Figure Description

[0023] Figure 1 A schematic diagram of the overall structure of a single-acting hydraulic cylinder for stable operation; Figure 2 A top view of the overall structure of a stable single-acting hydraulic cylinder; Figure 3 for Figure 2Schematic diagram of the cross section of AA; Figure 4 This is a schematic diagram of the overall exploded structure; Figure 5 A cross-sectional structural diagram of the cap, cylinder, pipe fittings, and connectors; Figure 6 This is a structural schematic diagram of one of the states in Example 5; Figure 7 This is a structural schematic diagram of another state of Example 5.

[0024] In the diagram: 1. Cylinder body; 101. Cavity; 102. First threaded hole; 103. Second threaded hole; 2. Piston; 201. Annular groove; 202. Seal; 3. Piston rod; 301. Limiting section; 302. Telescopic section; 4. Pipe joint; 401. First oil delivery chamber; 402. Oil delivery channel; 403. First through hole; 404. Second through hole; 5. Connector; 501. Limiting component; 502. Connecting rod; 5021. Second oil delivery chamber; 5022. Throttling orifice; 6. Spring; 7. Cover; 701. Guide hole; 702. First mounting groove; 8. Lip seal; 9. Sealing gasket. Detailed Implementation

[0025] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0026] It should be noted that, unless otherwise specified, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0027] In this invention, unless otherwise stated, the directional terms such as "up" and "down" generally refer to the directions shown in the accompanying drawings, or to the vertical, perpendicular, or gravitational direction; similarly, for ease of understanding and description, "left" and "right" generally refer to the left and right shown in the accompanying drawings; "inner" and "outer" refer to the inner and outer contours of each component itself, but the above directional terms are not intended to limit this invention.

[0028] Example 1:

[0029] A stable single-acting hydraulic cylinder includes a cylinder body 1, a piston 2, a pipe joint 4, a connecting piece 5, a spring 6, and a cover 7. The cylinder body 1 has a first threaded hole 102 and a second threaded hole 103 at both ends of its cavity 101. The cover 7 is threadedly connected to the second threaded hole 103 and has a guide hole 701. A piston rod 3 is fixed to one side of the piston 2 and slidably disposed within the cylindrical cavity 101 of the cylinder body 1, dividing the cavity 101 into a rodless cavity and a rod cavity. The piston rod 3 is placed in the rod cavity and extends from the guide hole 701. The spring 6 is sleeved on the piston rod 3. The pipe joint 4 has a communicating first oil delivery cavity 401 and an oil delivery channel 402. The first oil delivery cavity 401 has a first through hole 403 and a second through hole 404 at both ends. The connecting piece... 5 includes a limiting member 501 and a connecting rod 502 having a second oil delivery chamber 5021 inside. The connecting rod 502 passes through the first through hole 403, the first oil delivery chamber 401 and the second through hole 404 in sequence and is threadedly connected to the first threaded hole 102. The second oil delivery chamber 5021 communicates with the cavity 101, and a throttling hole 5022 is opened on the side wall of the second oil delivery chamber 5021. The throttling hole 5022 communicates with the first oil delivery chamber 401 and the second oil delivery chamber 5021. The flow cross section at the throttling hole 5022 is smaller than the flow cross section of the cavity 101 and the second oil delivery chamber 5021. The piston rod 3 includes a limiting section 301 and a telescopic section 302. The telescopic section 302 slides in the guide hole 701. The diameter of the limiting section 301 is larger than the inner diameter of the guide hole 701, which is used to limit the stroke of the piston rod 3.

[0030] In this embodiment, the external oil supply pipe and the oil supply channel 402 of the pipe joint 4 are connected by a reversing valve. The oil inlet or outlet is adjusted by adjusting the reversing valve. When oil is inlet, the oil enters the first oil supply chamber 401 through the oil supply channel 402 via the reversing valve, and then enters the cavity 101 through the throttle orifice 5022 and the second oil supply chamber 5021, pushing the piston 2 to move and pushing the piston rod 3 out until the limit section 301 abuts against the top cover. At this time, the piston rod 3 moves to the maximum stroke and reaches the limit position of movement. When no thrust is required, the reversing valve reverses the direction, the spring 6 resets and pushes the piston 2 to move for oil return. During the oil return process, the oil flows through the throttle orifice 5022, blocking the flow and preventing the flow rate from increasing with the increase of pressure difference, maintaining it at a certain value, thus achieving smooth retraction of the hydraulic cylinder.

[0031] The single-acting high-pressure hydraulic cylinder has an overall design length of 83mm (non-working state), a maximum outer diameter of 28mm, a theoretical stroke of 19mm, a maximum working pressure of 35MPa, an actual working pressure of 16-21MPa, a theoretical thrust of 11KN, and an effective oil chamber area of ​​3.3cm². 2 The oil capacity is 6.6 cm³, and the theoretical opening pressure is 4 MPa.

[0032] Example 2:

[0033] Based on Embodiment 1, an annular groove 201 is provided on the side wall of piston 2, and a seal 202 is installed in the annular groove 201. The seal 202 can be one or more of O-rings, square rings or V-rings, preferably SKF brand and PTFE material.

[0034] Example 3:

[0035] The difference from Example 2 is that the sealing element 202 is an O-ring and a square sealing ring fitted together, with the square sealing ring fitted outside the O-ring. Both the O-ring and the square sealing ring are preferably from the SKF brand, and their material is preferably PTFE.

[0036] Example 4:

[0037] Based on Embodiment 1, the top of the cover 7 is provided with a first mounting groove 702, and a lip seal 8 is provided in the first mounting groove 702 and sleeved on the piston rod 3. In actual use, the lip seal 8 improves the oil-proof, stain-proof and waterproof performance.

[0038] Example 5:

[0039] See Figure 6 A sealing gasket 9 is provided between the contact surfaces of the pipe joint 4, the limiting member 501, and the cylinder body 1 to improve the sealing performance at the contact point.

[0040] See Figure 7 The sealing gasket 9 can also be placed in the sealing groove opened on the contact surface.

[0041] In all the solutions mentioned above, although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A stable single-acting hydraulic cylinder, characterized in that it comprises: The cylinder body has an internal cavity. A piston, with a piston rod fixed to one side, is slidably disposed within a cavity, dividing the cavity into a rodless chamber and a rod chamber. The piston rod is placed in the rod chamber, with the end of the piston rod away from the piston extending out of the cavity. The pipe fitting has a first oil delivery chamber and an oil delivery channel inside, the latter for connecting to an external oil delivery pipe. The connector includes a limiting member and a connecting rod with a second oil delivery chamber inside. The connecting rod passes through the pipe joint and extends into the cylinder cavity. The second oil delivery chamber communicates with the cavity, and a throttling orifice is provided on the side wall of the second oil delivery chamber. The throttling orifice connects the first oil delivery chamber and the second oil delivery chamber. The flow cross-section at the throttling orifice is smaller than the flow cross-section of the cavity and the second oil delivery chamber. A spring, installed in the rod chamber of the cylinder, is used to push the piston back for oil return.

2. The stable single-acting hydraulic cylinder according to claim 1, characterized in that, An annular groove is formed on the side wall of the piston, and a seal is installed in the annular groove.

3. The stable-operating single-acting hydraulic cylinder according to claim 2, characterized in that, The sealing element is an O-ring, a square ring, or a V-ring.

4. The stable single-acting hydraulic cylinder according to claim 2, characterized in that, The sealing element is an O-ring and a square sealing ring fitted on its outer side.

5. The stable-operating single-acting hydraulic cylinder according to claim 1, characterized in that, The cylinder body has a first threaded hole and a second threaded hole at both ends of its cavity. A cap is threadedly connected to the second threaded hole, and a guide hole for the piston rod to extend out is provided on the cap.

6. The stable-operating single-acting hydraulic cylinder according to claim 5, characterized in that, The first oil delivery chamber of the pipe joint has a first through hole and a second through hole at both ends, and the connecting rod passes through the first through hole, the first oil delivery chamber and the second through hole in sequence and is threadedly connected to the first threaded hole.

7. The stable-operating single-acting hydraulic cylinder according to claim 6, characterized in that, The limiting member is used to press the pipe joint between itself and the cylinder body.

8. The stable-operating single-acting hydraulic cylinder according to any one of claims 5-7, characterized in that, The top of the cover has a first mounting groove, and a lip seal is provided in the first mounting groove and fitted outside the piston rod.

9. The stable-operating single-acting hydraulic cylinder according to claim 5, characterized in that, The piston rod includes a limiting section and a telescopic section. The telescopic section slides within the guide hole, and the diameter of the limiting section is larger than the inner diameter of the guide hole, which is used to limit the stroke of the piston rod.

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