Plunger structure and plunger device

Abstract

The present invention relates to a plunger structure and plunger device, belonging to the technical field of plunger devices, and comprises a cylinder body and a plunger body slidably disposed within a second cavity of the cylinder body; a first groove for accommodating a sealing ring is formed on the circumferential surface of the plunger body, and the plunger body is further provided with at least one through-hole, the first groove communicating with the first cavity of the plunger body via the through-hole; the sealing ring is configured to deform under the pressure of the oil in the first cavity to seal the gap between the plunger body and the inner wall of the second cavity. The present invention has the beneficial effects of improving the sealing performance between the plunger body and the cylinder body, avoiding leakage of hydraulic oil, and thus not reducing the volumetric efficiency of the plunger device.

Description

Technical Field

[0001] The present invention relates to the technical field of plunger devices, and in particular to a plunger structure and a plunger device. Background Art

[0002] During operation, a common hydraulic plunger pump uses a pair of sliding seals and friction pairs between the plunger body and the plunger hole in the cylinder. These two pairs primarily seal the oil within the plunger cavity of the cylinder through a small clearance. Due to the inherent characteristics of this clearance seal, a certain amount of leakage still occurs between the plunger body and the cylinder during operation, reducing the volumetric efficiency of the hydraulic pump. Summary of the Invention

[0003] The object of the present invention is to provide a plunger structure and a plunger device for solving the technical problem of hydraulic oil leakage between the plunger body and the cylinder body, thereby reducing the volumetric efficiency of the hydraulic device.

[0004] In order to achieve the above object, the present invention provides the following technical solutions:

[0005] A plunger structure includes a cylinder body and a plunger body slidably arranged in a second cavity of the cylinder body; at least one first groove for accommodating a sealing ring is provided on the circumferential surface of the plunger body, and the plunger body is also provided with at least one through hole, the first groove is connected to the first cavity of the plunger body through the through hole, and the sealing ring is used to deform under the pressure of the oil in the first cavity to seal the gap between the plunger body and the inner wall of the second cavity.

[0006] Preferably, the plunger structure further includes an annular second groove opened at the bottom of the first groove, the width of the second groove is smaller than the width of the first groove, and the through hole is used for communication between the second groove and the first cavity.

[0007] Preferably, the cross-section of the sealing ring is one of a rectangular cross-section and a circular cross-section, and the sealing ring is coordinated with the first groove; the material of the sealing ring is one of polytetrafluoroethylene and polyetheretherketone; when the cross-section of the sealing ring is a rectangular cross-section, the radial thickness of the sealing ring is less than or equal to the radial depth of the first groove.

[0008] Preferably, the width of the first groove along the length direction of the plunger body is a, and the depth of the first groove along the radial direction is b, wherein the ratio of b to a is c, and c is 40% to 60%.

[0009] Preferably, the width of the first groove along the length direction of the plunger body is a, the width of the second groove along the length direction of the plunger body is d, wherein the ratio of d to a is e, and e is 20% to 30%.

[0010] Preferably, when there are multiple through holes, each through hole is evenly distributed along the circumference of the bottom of the first groove; the direction of the through hole is the radial direction of the plunger body, or the direction of the through hole forms a certain angle with the radial direction of the plunger body.

[0011] Preferably, the plunger body has a ball head and a first end face facing away from the ball head, the plunger body is a cylinder, or, along the direction from the ball head to the first end face, the diameters of each cross section of the plunger body increase between the ball head and the first groove, and the diameters of each cross section of the plunger body are the same between the first groove and the first end face; and / or, the distance between the first groove and the first end face is f, and the distance between the first groove and the ball head is h, where f<h.

[0012] Preferably, between the ball head and the first groove, the plunger body is a truncated cone structure, and the cone angle of the truncated cone structure is 5°-10°.

[0013] Preferably, it also includes a swash plate and a sliding shoe coordinated with the swash plate; one end of the sliding shoe is connected to the plunger body through a ball joint, and the other end is slidably connected to the swash plate; a countersunk hole is provided at the end of the sliding shoe connected to the swash plate, and the countersunk hole is connected to the first cavity, so that an oil film layer is provided between the swash plate and the sliding shoe at the countersunk hole.

[0014] Compared with the prior art, in the plunger structure provided by the present invention, a sealing ring is provided between the plunger body and the cylinder body, thereby improving the sealing performance between the plunger body and the cylinder body and avoiding hydraulic oil leakage, thereby not reducing the volumetric efficiency of the plunger device.

[0015] The present invention also provides a plunger device, comprising the plunger structure, wherein the plunger device is a plunger pump or a plunger motor.

[0016] Compared with the prior art, the beneficial effects of the plunger structure provided by the present invention are the same as those described in the above technical solution, and will not be described in detail here. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The accompanying drawings illustrate exemplary embodiments of the present invention and together with the description serve to explain the principles of the present invention. These drawings are included to provide a further understanding of the present invention and are incorporated in and constitute a part of this specification.

[0018] Figure 1 It is a structural schematic diagram of an embodiment of a plunger structure;

[0019] Figure 2 It is a structural schematic diagram of another embodiment of the plunger structure;

[0020] Figure 3 1 is a schematic structural diagram of an embodiment of a plunger body;

[0021] In the figure: 1-cylinder body, 2-plunger body, 3-first cavity, 4-second cavity, 5-through hole, 6-first groove, 7-second groove, 8-sealing ring, 9-ball head, 10-first end face, 11-swash plate, 12-slip shoe, 13-oil film layer. DETAILED DESCRIPTION

[0022] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It will be understood that the specific embodiments described herein are intended only to explain the relevant content and are not intended to limit the present invention. It should also be noted that, for ease of description, only portions relevant to the present invention are shown in the accompanying drawings.

[0023] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments of the present invention can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0024] like Figure 1-Figure 3 As shown, a plunger structure includes a cylinder body 1 and a plunger body 2 slidably arranged in the second cavity 4 of the cylinder body 1; at least one first groove 6 for accommodating a sealing ring 8 is provided on the circumferential surface of the plunger body 2, and the plunger body 2 is also provided with at least one through hole 5. The first groove 6 is connected to the first cavity 3 of the plunger body 2 through the through hole 5, and the sealing ring 8 is used to deform and seal the gap between the plunger body 2 and the inner wall of the second cavity 4 under the pressure of the oil in the first cavity 3.

[0025] The first cavity 3 can be a hole distributed along the axial direction of the plunger body 2. For example, the first cavity 3 is distributed along the axis of the plunger body 2 and is a cylindrical hole. One end of the first cavity 3 is connected to the inner cavity of the cylinder body 1, so that the oil in the cylinder body 1 enters the first cavity 3. Figure 1 The arrow in the middle indicates the direction of oil entry.

[0026] Compared with the prior art which seals the plunger body 2 and the cylinder body 1 through a gap, in the plunger structure provided by the present invention, a sealing ring 8 is arranged between the plunger body 2 and the cylinder body 1, and sealing is provided by the deformation of the sealing ring 8, which significantly improves the sealing performance between the plunger body 2 and the cylinder body 1, avoids hydraulic oil leakage, and thus does not reduce the volumetric efficiency of the plunger device.

[0027] It is understood that the plunger structure provided by the present invention can be a sealing structure with only one sealing ring 8, or it can also adopt multiple first grooves 6 and provide multiple sealing rings 8 to achieve a better sealing effect. With this structure, the friction resistance between the plunger body 2 and the cylinder body 1 can be reduced to avoid jamming. A gap sealing structure can also be provided at the same time, that is, a gap seal is formed between at least a portion of the outer circle of the plunger body 2 and the inner wall of the cylinder body 1, so that the sealing structure of the sealing ring 8 and the gap sealing structure work simultaneously, and the sealing is more reliable.

[0028] In some embodiments, the plunger structure further includes an annular second groove 7 formed at the bottom of the first groove 6. The width of the second groove 7 is smaller than that of the first groove 6. The through hole 5 is used to connect the second groove 7 with the first cavity 3. That is, the through hole 5 simultaneously connects the first groove 6, the second groove 7, and the first cavity 3. If the second groove 7 is not provided, in the initial state, the sealing ring 8 may fill the first groove 6. After the oil is introduced, due to the obstruction of the sealing ring 8, the oil cannot quickly enter the first groove 6 and form a coherent hydraulic oil to provide uniform pressure to the sealing ring 8, thereby causing sealing failure. The present invention provides the second groove 7 at the bottom of the first groove 6, so that an annular, coherent cavity, namely the second groove 7, is always present between the sealing ring 8 and the through hole 5. After the oil is introduced, the oil can quickly fill the second groove 7 and provide a coherent, uniform pressure to the sealing ring 8, thereby improving sealing reliability.

[0029] In some embodiments, the cross-section of the sealing ring 8 is one of a rectangular cross-section and a circular cross-section, and the sealing ring 8 is coordinated with the first groove 6; the material of the sealing ring 8 is one of polytetrafluoroethylene and polyetheretherketone; the sealing ring 8 is deformed after being squeezed by the high-pressure oil in the first cavity 3, and the deformed sealing ring 8 prevents the oil from leaking from between the outer circumferential surface of the plunger body 2 and the inner wall of the rod body, and also prevents the oil from leaking from between the sealing ring 8 and the first groove 6;

[0030] Furthermore, when the cross section of the sealing ring 8 is a circular cross section, because the oil between the outer circular surface of the plunger body 2 and the inner wall of the rod body is low-pressure oil, after being squeezed by the high-pressure oil in the first cavity 3, the circular sealing ring 8 is squeezed and deformed to seal.

[0031] Furthermore, when the cross-section of the sealing ring 8 is a rectangular cross-section, the radial thickness of the sealing ring 8 is less than or equal to the radial depth of the first groove 6. When the radial thickness of the sealing ring 8 is less than the radial depth of the first groove 6, in the initial state, the sealing ring 8 is in a compressed state and plays a pre-sealing role. The sealing ring 8 provides an initial sealing effect and improves the sealing reliability.

[0032] In some embodiments, the width of the first groove 6 along the length of the plunger body 2 is a, and the depth of the first groove 6 along the radial direction is b, wherein the ratio between b and a is c, and c is 40% to 60%. The pressure provided by the oil in the first cavity 3 is proportional to the width a of the first groove 6. The larger the width, the greater the pressure provided. However, if the width a is too large, the frictional resistance between the plunger body 2 and the cylinder body 1 will increase. Therefore, the width a should be of appropriate size. The radial thickness of the sealing ring 8 is positively correlated with the depth b. If the depth b is too large, the required radial thickness of the sealing ring 8 will increase, thereby requiring greater pressure to achieve sealing. After testing, the ratio c of the two is most suitable at 40% to 60%, exemplarily at 48% to 55%, and preferably at 50%.

[0033] In some embodiments, the width of the first groove 6 along the length direction of the plunger body 2 is a, and the width of the second groove 7 along the length direction of the plunger body 2 is d, where the ratio of d to a is e, and e is 20% to 30%, exemplarily 25%. The size of the ratio e should be appropriate. If it is too large, the sealing ring 8 will enter the second groove 7 in the initial state, and after the oil is introduced, it will not be able to provide coherent and uniform pressure, thereby causing sealing failure. If it is too small, the oil flow rate will be too small and the second groove 7 cannot be quickly filled. Therefore, after testing, e is set to 20% to 30%, which can not only prevent the sealing ring 8 from entering the second groove 7 and improve the sealing reliability, but also enable the oil to quickly fill the second groove 7 and quickly form a seal.

[0034] Specifically, the width d of the second groove 7 is greater than or equal to the diameter of the through hole 5 , ensuring that the oil in the through hole 5 can quickly fill the second groove 7 .

[0035] In some embodiments, at least one through hole 5 is provided, for example, 1, 2, 3, 4, 6, 8, or 10 through holes 5 are provided. Preferably, 2-4 through holes 5 are provided, and further 4 through holes 5 are provided. When there are multiple through holes 5, each through hole 5 is evenly distributed along the circumference of the bottom of the first groove 6. The direction of the through hole 5 is the radial direction of the plunger body 2, or the direction of the through hole 5 forms a certain angle with the radial direction of the plunger body 2, illustratively 5°-15°. The direction of the through hole 5 is adjusted according to the difficulty of processing and the number of through holes 5. The number of through holes 5 should be set appropriately, and 2-4 through holes 5 can enable the oil to quickly fill the second groove 7 and provide uniform pressure to the sealing ring 8, thereby avoiding uneven deformation of the sealing ring 8 due to uneven pressure, thereby preventing leakage, and improving sealing reliability.

[0036] like Figure 2 、 Figure 3 As shown, in some embodiments, the plunger body 2 has a ball head 9 and a first end face 10 facing away from the ball head 9. The plunger body 2 is cylindrical and has low processing difficulty. It can simultaneously form two sealing structures, namely the gap seal and the sealing ring 8.

[0037] like Figure 1 As shown, in another embodiment, along the direction from the ball head 9 to the first end face 10, the diameters of the various cross sections of the plunger body 2 increase between the ball head 9 and the first groove 6, and the diameters of the various cross sections of the plunger body 2 remain the same between the first groove 6 and the first end face 10. With this structure, the aforementioned gap seal is formed between the first groove 6 and the first end face 10. At the same time, the gap between the portion of the plunger body 2 located between the first groove 6 and the ball head 9 and the cylinder body 1 is relatively large, thus preventing friction. This significantly reduces the frictional resistance between the plunger body 2 and the cylinder body 1, prevents jamming, and improves the efficiency of the plunger device.

[0038] In a further solution, the distance between the first groove and the first end face is f, and the distance between the first groove and the ball head is h, where f<h. The distance f between the first groove and the first end face should not be too large, otherwise a longer second cavity 4 will be required, which will increase the volume of the cylinder body 1 and the friction resistance between the cylinder body 1 and the plunger body 2. Therefore, further, on the premise of leaving enough distance between the first groove and the first end face to provide gap sealing, the first groove is set as close to the first end face as possible, so that the plunger structure is more compact and the friction resistance between the cylinder body 1 and the plunger body 2 is smaller.

[0039] In a specific solution, between the ball head 9 and the first groove 6, the plunger body 2 is a truncated cone structure, and the cone angle of the truncated cone structure is 5°-10°, exemplarily 5°. The size of the cone angle can ensure the structural strength of the plunger body 2 while avoiding friction between the plunger body 2 and the cylinder body 1.

[0040] In some embodiments, the plunger structure further includes a swash plate 11 and a sliding shoe 12 coordinated with the swash plate 11. One end of the sliding shoe 12 is connected to the plunger body 2 via a ball joint, and the other end is slidably connected to the swash plate 11. A countersunk hole is defined at the end of the sliding shoe 12 connected to the swash plate 11, and the countersunk hole communicates with the first cavity 3, creating an oil film 13 between the swash plate 11 and the sliding shoe 12 at the countersunk hole. The oil film 13 causes the high-pressure oil to exert a certain separating force on the bottom end surface of the sliding shoe 12, thereby balancing the compressive force transmitted by the high-pressure oil to the right plunger body 2 and reducing frictional resistance.

[0041] The present invention also provides a plunger device, including a plunger structure, and the plunger device is a plunger pump or a plunger motor.

[0042] Compared with the prior art, the beneficial effects of the plunger structure provided by the present invention are the same as those of the above technical solution, which will not be described in detail here.

[0043] In the description of this specification, the description with reference to the terms "one embodiment / method", "some embodiments / methods", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment / method or example are included in at least one embodiment / method or example of the present application. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment / method or example. Moreover, the specific features, structures, materials or characteristics described may be combined in an appropriate manner in any one or more embodiments / methods or examples. In addition, those skilled in the art may combine and combine different embodiments / methods or examples described in this specification and the features of different embodiments / methods or examples, unless they are contradictory.

[0044] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of such features. Throughout the description of this application, "plurality" means at least two, for example, two, three, etc., unless otherwise specifically defined.

[0045] It should be understood by those skilled in the art that the above embodiments are merely for the purpose of illustrating the present invention clearly, and are not intended to limit the scope of the present invention. For those skilled in the art, other changes or modifications may be made based on the above disclosure, and such changes or modifications are still within the scope of the present invention.

Claims

1. A plunger structure, characterized in that: It comprises a cylinder body and a plunger body slidably arranged in the second cavity of the cylinder body; The plunger body is provided with at least one first groove on its circumferential surface for accommodating a sealing ring. The plunger body is also provided with at least one through hole. The first groove is connected to the first cavity of the plunger body through the through hole. The sealing ring is used to deform under the pressure of the oil in the first cavity to seal the gap between the plunger body and the inner wall of the second cavity. The plunger structure further includes an annular second groove formed at the bottom of the first groove, wherein the width of the second groove is smaller than that of the first groove, and the through hole is used for communication between the second groove and the first cavity; The width of the first groove along the length direction of the plunger body is a, and the width of the second groove along the length direction of the plunger body is d, wherein the ratio of d to a is e, and e is 20% to 30%; When there are multiple through holes, each of the through holes is evenly distributed along the circumference of the bottom of the first groove; The direction of the through hole is the radial direction of the plunger body, or the direction of the through hole forms a certain angle with the radial direction of the plunger body.

2. The plunger structure according to claim 1, characterized in that: The cross section of the sealing ring is one of a rectangular cross section and a circular cross section, and the sealing ring is coordinated with the first groove; The sealing ring is made of one of polytetrafluoroethylene and polyetheretherketone; When the cross section of the sealing ring is a rectangular cross section, the thickness of the sealing ring in the radial direction is less than or equal to the depth of the first groove in the radial direction.

3. The plunger structure according to claim 1, characterized in that: The width of the first groove along the length direction of the plunger body is a, and the depth of the first groove along the radial direction is b, wherein the ratio of b to a is c, and c is 40% to 60%.

4. The plunger structure according to claim 1, characterized in that: The plunger body has a ball head and a first end face facing away from the ball head, and the plunger body is a cylinder, or, Along the direction from the ball head to the first end face, the diameters of the various cross sections of the plunger body increase between the ball head and the first groove, and the diameters of the various cross sections of the plunger body are the same between the first groove and the first end face; and / or, The distance between the first groove and the first end surface is f, and the distance between the first groove and the ball head is h, wherein f<h.

5. The plunger structure according to claim 4, characterized in that: Between the ball head and the first groove, the plunger body is a truncated cone structure, and the cone angle of the truncated cone structure is 5°-10°.

6. The plunger structure according to any one of claims 1 to 5, characterized in that: Also included is a swash plate and a sliding shoe coordinated with the swash plate; One end of the sliding shoe is connected to the plunger body through a ball joint, and the other end is slidably connected to the swash plate; A countersunk hole is formed at one end of the sliding shoe connected to the swash plate, and the countersunk hole is communicated with the first cavity, so that an oil film layer is formed between the swash plate and the sliding shoe at the countersunk hole.

7. A plunger device, characterized in that: It comprises the plunger structure according to any one of claims 1 to 6, wherein the plunger device is a plunger pump or a plunger motor.

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