Linear power cylinder with combined seal, and knee joint device

Abstract

The utility model relates to a linear power cylinder with combined seal and knee joint device, including cylinder body and install in the piston rod of cylinder body, still include the combined seal mechanism of setting between piston rod and cylinder body, the combined seal mechanism includes outside seal ring and inside seal ring, outside seal ring and inside seal ring all suit on the piston rod, and have the gap between both, inside seal ring is located outside seal ring one side towards high pressure working chamber, the inner hole surface of inside seal ring and piston rod close contact is equipped with a circle coaxial first annular groove, and first annular groove gradually becomes smaller in the direction along from the slot mouth to the groove bottom width, the end face of inside seal ring one side towards high pressure chamber part is equipped with a circle coaxial second annular groove, and second annular groove gradually becomes smaller in the direction along from the slot mouth to the groove bottom width. Linear power cylinder includes this linear power cylinder, is used for providing damping buffer for the activity of knee joint device.

Description

Technical Field

[0001] This utility model relates to the field of power machinery technology, specifically to a linear power cylinder with combined sealing and a knee joint device. Background Technology

[0002] To enable amputees to live, study, and work normally like healthy individuals, fitting them with suitable prosthetic limbs is crucial. Thigh prostheses incorporate a knee joint device to mimic the movement of the human knee. This knee joint device typically features a pneumatically or hydraulically driven linear actuator, providing the patient with a stable support period and effectively preventing accidental falls. The linear actuator uses a large-diameter piston to generate the necessary damping force, making the feeling of walking extremely similar to that of a natural human knee joint. Therefore, it is highly popular with patients and widely used clinically.

[0003] In linear power cylinders, the piston rod, as a key component for transmitting force and motion, directly impacts system stability, sealing, and operating efficiency. A sealing ring is installed between the piston rod and the cylinder body to seal and stabilize the piston rod's movement, preventing leakage of high-pressure working fluid (gas or hydraulic oil) from the piston rod and cylinder body. Currently, traditional sealing rings suffer from insufficient wear resistance and high-pressure resistance. Under conditions requiring high-frequency reciprocating motion of the piston rod and high-pressure hydraulic environments, they have a high risk of failure, affecting system reliability and operating efficiency. Utility Model Content

[0004] In view of the shortcomings of the prior art described above, the technical problem to be solved by this utility model is to provide a linear power cylinder with combined sealing and a knee joint device. The combined sealing mechanism can improve the sealing effect between the piston rod 2 and the cylinder 1 under high pressure, making it stable and reliable.

[0005] To achieve the above objectives, this utility model provides a linear power cylinder with a combined seal, including a cylinder body and a piston rod installed in the cylinder body. The cylinder body has a high-pressure working chamber for injecting working fluid. It also includes a combined sealing mechanism disposed between the piston rod and the cylinder body. The combined sealing mechanism includes an outer sealing ring and an inner sealing ring, both of which are fitted onto the piston rod with a gap between them. The inner sealing ring is located on the side of the outer sealing ring facing the high-pressure working chamber. A coaxial first annular groove is provided on the inner bore surface of the inner sealing ring that is in close contact with the piston rod, and the width of the first annular groove gradually decreases from the groove opening to the groove bottom. A coaxial second annular groove is provided on the end face of the inner sealing ring facing the high-pressure chamber, and the width of the second annular groove gradually decreases from the groove opening to the groove bottom.

[0006] Furthermore, the outer sealing ring includes an inner ring layer that is in close contact with the piston rod, and an outer ring layer that is fixed to the outer side of the inner ring layer and in close contact with the cylinder body. The inner ring layer is made of polyurethane, and the outer ring layer is made of hydrogenated nitrile rubber.

[0007] Furthermore, the inner sealing ring is made of polyurethane.

[0008] Furthermore, the cross-section of the first annular groove is V-shaped, and the cross-section of the second annular groove is V-shaped.

[0009] Furthermore, the combined sealing mechanism comprises two components, and the high-pressure working chamber is located between the inner sealing rings of the two combined sealing mechanisms.

[0010] Furthermore, the cylinder body includes a cylinder barrel and a cylinder head fixedly installed on the cylinder barrel, with one combined sealing mechanism located in the cylinder barrel and the other located in the cylinder head.

[0011] Furthermore, the cylinder body includes a cylinder barrel, which is made of titanium alloy.

[0012] Furthermore, the piston rod is made of S136 stainless steel.

[0013] Furthermore, the piston rod extending from the drive end of the cylinder body is provided with an internal threaded hole.

[0014] Furthermore, the aforementioned linear power cylinder is used to provide damping cushioning for the movement of the knee joint device.

[0015] This utility model also provides a knee joint device, including the aforementioned linear power cylinder, which provides damping and cushioning for the movement of the knee joint device.

[0016] As described above, the linear power cylinder and knee joint device of this utility model have the following beneficial effects:

[0017] 1. The linear power cylinder is equipped with a combined sealing mechanism. The two annular grooves of the outer sealing ring achieve stable sealing under high pressure. The cooperation between the outer and inner sealing rings forms two stable seals, which meet the needs of high pressure use and improve the stability of operation.

[0018] 2. The outer sealing ring of the combined sealing mechanism adopts an outer ring layer of hydrogenated nitrile rubber and an inner ring layer of polyurethane, which takes into account both elasticity and weather resistance. It has the characteristics of oil resistance, wear resistance and high pressure resistance, and can fit well with the piston rod to form a static seal. In addition, the inner sealing ring is also made of polyurethane, which makes the combined sealing mechanism have good overall wear resistance, effectively improving its service life and meeting the needs of frequent piston movement.

[0019] 3. The piston rod is made of S136 stainless steel and the cylinder is made of titanium alloy. Combined with a wear-resistant composite sealing mechanism, the three can be designed together to improve the working stability, sealing performance and service life of the linear power cylinder.

[0020] 4. The knee joint device including the linear power cylinder enhances the damping and cushioning effect of its movement through the linear power cylinder. The linear power cylinder can well meet the frequent movement needs of the knee joint device, effectively improving the working stability and service life of the knee joint device. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the external structure of the linear power cylinder in this utility model.

[0022] Figure 2 This is a schematic diagram of the installation of the combined sealing mechanism in the linear power cylinder of this utility model.

[0023] Figure 3 for Figure 2 Enlarged view of circle A in the image.

[0024] Figure 4 This is a schematic diagram showing the installation of the two combined sealing mechanisms on the piston rod in this utility model.

[0025] Figure 5 This is a schematic diagram of the outer sealing ring in this utility model.

[0026] Figure 6 This is a schematic diagram of the inner sealing ring in this utility model.

[0027] Figure 7 This is a schematic diagram of the external structure of the knee joint device in this utility model.

[0028] Explanation of icon numbers

[0029] 1. Cylinder block

[0030] 11 Cylinder

[0031] 12 Cylinder Head

[0032] 13 High-pressure working chamber

[0033] 2 Piston rod

[0034] 21 Internal threaded hole

[0035] 3. Outer sealing ring

[0036] 31 Inner Circle

[0037] 32 Outer ring layer

[0038] 4. Inner sealing ring

[0039] 41 First annular groove

[0040] 42 Second annular groove

[0041] 43. Seal the main lip.

[0042] 5 Connecting disks

[0043] 6. Motion linkage mechanism

[0044] 61 Lower Linkage

[0045] 62 outer linkage

[0046] 63 Upper linkage

[0047] 64 Inner Link

[0048] 7. Lower connector

[0049] 8. Connecting rod Detailed Implementation

[0050] The following specific embodiments illustrate the implementation of this utility model. Those skilled in the art can easily understand other advantages and effects of this utility model from the content disclosed in this specification.

[0051] It should be understood that the structures, proportions, sizes, etc., depicted in the accompanying drawings are merely for illustrative purposes to aid those skilled in the art and to facilitate understanding. They are not intended to limit the scope of this invention and therefore have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to size, provided they do not affect the effectiveness or purpose of this invention, should still fall within the scope of the technical content disclosed herein. Furthermore, terms such as "upper," "lower," "left," "right," and "middle" used in this specification are merely for clarity and not intended to limit the scope of this invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of this invention.

[0052] See Figures 1 to 6This invention provides a linear power cylinder with a combined seal, comprising a cylinder body 1 and a piston rod 2 installed in the cylinder body 1. The cylinder body 1 has a high-pressure working chamber 13 for injecting working fluid. The working fluid can be gas (in which case the linear power cylinder is a pneumatic cylinder) or hydraulic oil (in which case the linear power cylinder is a hydraulic cylinder). The working fluid is used to drive the movement of the piston rod 2 (in which case the piston rod 2 is a driven member), or the piston rod 2 moves to drive the working fluid (in which case the piston rod 2 is a driving member). The cylinder body 1 generally includes a cylinder barrel 11 and a cylinder head 12. The high-pressure working chamber 13 is located in the cylinder barrel 11, and the cylinder head 12 is fixed to the open end of the cylinder barrel 11. The driving end of the piston rod 2 extends from the cylinder head 12, and the piston rod 2 moves linearly within the cylinder barrel 11 and the cylinder head 12. Both the cylinder body 1 and the piston rod 2 can adopt existing structures.

[0053] The main improvement of this linear power cylinder is that it also includes a combined sealing mechanism disposed between the piston rod 2 and the cylinder body 1. The combined sealing mechanism includes an outer sealing ring 3 and an inner sealing ring 4. Both the outer sealing ring 3 and the inner sealing ring 4 are fitted on the piston rod 2, and there is a gap between them. The size of the gap can be set according to actual needs. The inner sealing ring 4 is located on the side of the outer sealing ring 3 facing the high-pressure working chamber 13. A coaxial first annular groove 41 is provided on the inner hole surface of the inner sealing ring 4 that is in close contact with the piston rod 2. The width of the first annular groove 41 gradually decreases along the direction from the groove opening to the groove bottom. A coaxial second annular groove 42 is provided on the end face of the inner sealing ring 4 facing the high-pressure chamber. The width of the second annular groove 42 gradually decreases along the direction from the groove opening to the groove bottom.

[0054] In this linear power cylinder, the number and position of the combined sealing mechanism can be set according to actual needs. The combined sealing mechanism forms two mating seals between the piston rod 2 and the cylinder body 1 through an outer sealing ring 3 and an inner sealing ring 4. The inner sealing ring 4 is close to the high-pressure working chamber 13 and withstands the high pressure from the working fluid in the high-pressure working chamber 13. The inner sealing ring 4 forms an annular sealing lip 43 between the first annular groove 41 and the second annular groove 42. When the pressure in the high-pressure working chamber 13 increases, the pressure in the second annular groove 42 on the end face near the high-pressure working chamber 13 increases, causing radial deformation of the inner sealing ring 4, thereby enhancing the sealing performance of the inner sealing ring 4. The lip 43 contacts the piston rod 2 more tightly, and the outer circle of the inner sealing ring 4 also contacts the cylinder 1 more tightly. The greater the pressure in the high-pressure working chamber 13, the greater this contact force, which effectively prevents high-pressure working fluid from leaking out between the inner sealing ring 4 and the piston rod 2. The second annular groove 42 forms the main sealing effect of the inner sealing ring 4, while the first annular groove 41 on the inner hole surface can store some lubricating oil, which can reduce the pressure impact of the sealing lip 43 and increase the lubrication between the piston rod 2 and the inner sealing ring 4. The first annular groove 41 can assist in the sealing effect. Combined with the static seal formed by the outer sealing ring 3, the gap between the outer sealing ring 3 and the inner sealing ring 4 can form a vacuum zone, which can greatly improve the sealing effect. The outer sealing ring 3 forms a second seal, and even if a small amount of working fluid leaks out from the inner sealing ring 4, it will be blocked by the outer sealing ring 3. The combined sealing mechanism can improve the sealing effect between the piston rod 2 and the cylinder 1, meeting the needs of high-pressure use.

[0055] See Figures 1 to 6 The following is a specific embodiment to further illustrate the linear power cylinder of this utility model:

[0056] In this embodiment, see Figure 2 , Figure 3 and Figure 5 As a preferred design, the outer sealing ring 3 includes an inner ring layer 31 that is in close contact with the piston rod 2, and an outer ring layer 32 that is fixed to the outer side of the inner ring and in close contact with the cylinder body 1. The outer ring layer 32 is preferably made of hydrogenated nitrile rubber, which combines elasticity and weather resistance. The inner ring layer 31 is made of polyurethane (PU), which is machined by a high-precision lathe and can be well adapted to the working conditions of the hydraulic system. Utilizing its oil resistance, wear resistance, and high pressure resistance, it fits the piston rod 2 to form a static seal. The inner ring layer 31 and outer ring layer 32 of the outer sealing ring 3 can also be made of other materials with similar properties.

[0057] In this embodiment, see Figure 2 , Figure 3 and Figure 6As a preferred design, the inner sealing ring 4 is made of polyurethane (PU), which is machined by a high-precision lathe and has elasticity and good wear resistance and high pressure resistance. It can fit tightly against the outer circle of the piston rod 2, increasing the sealing and wear resistance.

[0058] In this embodiment, see Figure 2 , Figure 3 and Figure 6 In the inner sealing ring 4, the cross-section (plane passing through its central axis) of the first annular groove 41 is V-shaped, and the cross-section (plane passing through its central axis) of the second annular groove 42 is also V-shaped. In other embodiments, the first annular groove 41 and the second annular groove 42 may also be other shapes, such as semicircle, semi-ellipse, etc.

[0059] See in this embodiment Figure 2 , Figure 3 and Figure 4 As a preferred design, there are two combined sealing mechanisms, with the high-pressure working chamber 13 located between the inner sealing rings 4 of the two combined sealing mechanisms. The cylinder body 1 includes a cylinder barrel 11 and a cylinder cover 12 fixedly installed at the opening of the cylinder barrel 11. One combined sealing mechanism is located in the cylinder cover 12 to seal the cylinder cover 12 and the piston rod 2, preventing working fluid (hydraulic oil or gas) from leaking out from the outlet end of the cylinder body 1 (the end from which the piston rod 2 extends). The other is located in the cylinder barrel 11, near the bottom of the inner cavity, to prevent working fluid from leaking to the bottom of the cylinder barrel 11. In other embodiments, depending on actual sealing needs, the number of combined sealing mechanisms can be different, and they can be located at other positions requiring sealing.

[0060] In this embodiment, see Figure 1 and Figure 2 As a preferred design, the cylinder 11 is made of titanium alloy, preferably aerospace-grade titanium alloy. Compared to traditional aluminum alloy cylinders 11, titanium alloy cylinders 11 offer higher strength, superior corrosion resistance, high-temperature resistance, and non-magnetic properties, making them ideal for high-precision machining. The inner wall surface of the cylinder 11 can achieve a mirror finish. This mirror finish effectively avoids problems caused by plating wear, thus extending the product's lifespan and reducing maintenance costs. The titanium alloy cylinder 11 significantly enhances the wear resistance and durability of the cylinder 11. Furthermore, the cylinder 11 is available in a variety of colors for patients to choose from, greatly improving the product's aesthetic appeal and making it highly suitable for use in knee joint devices within prostheses.

[0061] In this embodiment, see Figure 2 and Figure 4As a preferred design, the piston rod 2 is made of S136 stainless steel. After quenching, the hardness of S136 stainless steel reaches HRC52-55, possessing good strength, toughness, wear resistance, and a certain degree of corrosion resistance. This allows it to be well-suited for the high pressure in hydraulically driven linear power cylinders, meeting the complex conditions of frequent reciprocating motion and ensuring the long-term stable operation of the piston rod 2. Furthermore, the piston rod 2 has an internally threaded hole 21 at its driving end extending from the cylinder body 1, facilitating the connection between the piston rod 2 and the object to be driven.

[0062] Since various sealing rings, snap rings, piston rings, sleeves, and other structures need to be installed on the piston rod 2, a multi-step shaft structure is preferred to meet the installation requirements. During machining, a high-precision lathe is used to sequentially machine the outer diameter, end face, and internal threaded hole 21 of each cylindrical section, strictly controlling dimensional tolerances while ensuring coaxiality and other geometric tolerances. When machining the internal threaded hole 21, a suitable tap is selected to ensure thread profile accuracy and engagement. The machined workpiece undergoes vacuum quenching, controlling the quenching temperature, holding time, and cooling rate to achieve a workpiece hardness of HRC52-55, improving strength and wear resistance. After quenching, tempering and other auxiliary treatments are performed to eliminate internal stress and stabilize dimensions. Key mating surfaces (such as the outer cylindrical surface) undergo surface treatments such as fine grinding or polishing to achieve a surface roughness of Ra0.05, reducing frictional resistance during movement, improving the sealing performance with components such as sealing rings, and reducing wear.

[0063] In this embodiment, when the linear power cylinder uses an S136 stainless steel piston rod 2, traditional O-rings and lip seals for this type of high-precision, high-hardness hydraulic piston rod 2 suffer from problems such as easy wear of the sealing lip, poor dimensional adaptability (e.g., inability to match the piston rod 2's shoulder and outer diameter accuracy), and rapid elastic failure under high pressure. However, the combined sealing mechanism in this embodiment can well match the characteristics of the S136 stainless steel piston rod 2, maintaining stability and reliability even under high-frequency reciprocating motion and high-pressure hydraulic environments, thereby improving the overall reliability, working efficiency, and service life of the linear power cylinder.

[0064] See Figure 7 This utility model also provides a knee joint device, including the above-mentioned linear power cylinder, for providing damping and cushioning for the movement of the knee joint device. The linear power cylinder is preferably hydraulically driven, but it can also be pneumatically driven.

[0065] See Figure 7In this embodiment, the knee joint device includes a connecting plate 5, a motion linkage mechanism 6, and a lower connecting body 7. The connecting plate 5 has a four-sided pyramid for connecting to the thigh prosthesis, and the lower connecting body 7 is used for connecting to the lower leg prosthesis. The motion linkage mechanism 6 is used to perform the flexion and extension movements of the knee joint device. The motion linkage mechanism 6 includes a lower linkage frame 61, an outer linkage 62, an upper linkage frame 63, and an inner linkage 64. The lower linkage frame 61, the lower connecting body 7, and the cylinder body 1 of the linear power cylinder are fixedly connected and can be a single integrated structure. The upper linkage frame 63 is connected to the connecting plate 5. One end of the lower linkage frame 61 is hinged to one end of the outer linkage 62, and the other end is hinged to one end of the inner linkage 64. The other ends of the outer linkage 62 and the inner linkage 64 are respectively hinged to both ends of the upper linkage frame 63, thereby forming a four-bar linkage mechanism. The piston rod 2 of the linear power cylinder is connected to the upper connecting rod frame 63 via a hook rod 8, and both ends of the hook rod 8 are hinged to the piston rod 2 and the upper connecting rod frame 63, respectively. When the knee joint device performs leg raising or lowering movements with the thigh prosthesis, the motion linkage mechanism 6 moves, driving the piston rod 2 of the linear power cylinder to extend or retract, providing a damping and buffering effect, making the movement smoother and more stable. The aforementioned linear power cylinder is stable and reliable in operation, has good wear resistance, can perform frequent extension and retraction movements, and has a long service life, meeting the needs of long-term and frequent use of the knee joint device.

[0066] The knee joint device of this invention is not limited to the examples described above, and can also adopt various existing structural designs, especially the specific structure of the motion linkage mechanism 6, which can adopt various suitable existing structural designs. The installation method of the linear power cylinder will also be adjusted according to the specific structure of the knee joint device, as long as it can provide a stable and reliable damping and cushioning effect.

[0067] For linear power cylinders used in knee joint devices, adjustment mechanisms for adjusting the damping and cushioning effect, as well as other functional mechanisms, will also be provided. The adjustment mechanisms and other functional mechanisms can adopt existing suitable designs and are not limited in this application, as long as the linear power cylinder achieves the damping and cushioning effect required by the knee joint device.

[0068] As can be seen from the above, the linear power cylinder and the knee joint device of this utility model have the following beneficial effects:

[0069] 1. The linear power cylinder is equipped with a combined sealing mechanism. The two annular grooves of the outer sealing ring 3 are used to achieve stable sealing under high pressure. The outer sealing ring 3 and the inner sealing ring 4 cooperate to form two stable seals, which meet the needs of high pressure use and improve the working stability.

[0070] 2. The outer sealing ring 3 of the combined sealing mechanism adopts an outer ring layer 32 made of hydrogenated nitrile rubber and an inner ring layer 31 made of polyurethane, which takes into account both elasticity and weather resistance. It has the characteristics of oil resistance, wear resistance and high pressure resistance, and can fit well with the piston rod 2 to form a static seal. In addition, the inner sealing ring 4 is also made of polyurethane, which makes the combined sealing mechanism have good overall wear resistance, effectively improving its service life and meeting the needs of frequent piston movement.

[0071] 3. The piston rod 2 is made of S136 stainless steel and the cylinder 11 is made of titanium alloy. Combined with a wear-resistant combined sealing mechanism, the three can be designed together to improve the working stability, sealing performance and service life of the linear power cylinder.

[0072] 4. The knee joint device including the linear power cylinder enhances the damping and cushioning effect of its movement through the linear power cylinder. The linear power cylinder can well meet the frequent movement needs of the knee joint device, effectively improving the working stability and service life of the knee joint device.

[0073] In summary, this utility model effectively overcomes the various shortcomings of the prior art and has high industrial application value.

[0074] The above embodiments are merely illustrative of the principles and effects of this utility model and are not intended to limit the scope of this utility model. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of this utility model. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in this utility model should still be covered by the claims of this utility model.

Claims

1. A linear power cylinder with combined sealing, comprising a cylinder body (1) and a piston rod (2) mounted in the cylinder body (1), the cylinder body (1) having a high-pressure working chamber (13) for injecting a working fluid; characterized in that: It also includes a combined sealing mechanism disposed between the piston rod (2) and the cylinder (1). The combined sealing mechanism includes an outer sealing ring (3) and an inner sealing ring (4). The outer sealing ring (3) and the inner sealing ring (4) are both fitted on the piston rod (2) and there is a gap between them. The inner sealing ring (4) is located on the side of the outer sealing ring (3) facing the high-pressure working chamber (13). The inner hole surface of the inner sealing ring (4) that is in close contact with the piston rod (2) is provided with a coaxial first annular groove (41), and the width of the first annular groove (41) gradually decreases along the direction from the groove opening to the groove bottom. The end face of the inner sealing ring (4) facing the high-pressure chamber is provided with a coaxial second annular groove (42), and the width of the second annular groove (42) gradually decreases along the direction from the groove opening to the groove bottom.

2. Linear power cylinder according to claim 1, characterized in that The outer sealing ring (3) includes an inner ring layer (31) that is in close contact with the piston rod (2) and an outer ring layer (32) that is fixed to the outer side of the inner ring layer (31) and in close contact with the cylinder body (1). The inner ring layer (31) is made of polyurethane and the outer ring layer (32) is made of hydrogenated nitrile rubber.

3. The linear power cylinder of claim 1, wherein: The inner sealing ring (4) is made of polyurethane.

4. The linear power cylinder of claim 1, wherein: The first annular groove (41) has a V-shaped cross-section, and the second annular groove (42) has a V-shaped cross-section.

5. The linear power cylinder of claim 1, wherein: The combined sealing mechanism consists of two parts, and the high-pressure working chamber (13) is located between the inner sealing rings (4) of the two combined sealing mechanisms.

6. Linear power cylinder according to claim 5, characterized in that The cylinder body (1) includes a cylinder barrel (11) and a cylinder head (12) fixedly installed on the cylinder barrel (11). One combined sealing mechanism is located in the cylinder barrel (11) and the other is located in the cylinder head (12).

7. The linear power cylinder of claim 1, wherein: The cylinder body (1) includes a cylinder barrel (11), which is made of titanium alloy.

8. The linear power cylinder of claim 1, wherein: The piston rod (2) is made of S136 stainless steel.

9. The linear power cylinder according to claim 1, characterized in that: The piston rod (2) extending out of the driving end of the cylinder (1) is provided with an internal threaded hole (21).

10. A knee joint device, characterized in that: Includes a linear power cylinder as described in any one of claims 1 to 9, the linear power cylinder being used to provide damping cushioning for the movement of the knee joint device.

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