Sealing structure and force measuring device using the same

Abstract

The present invention relates to a sealing structure and a force measuring device using the sealing structure. The sealing structure comprises a sealing ring, the sealing ring comprises a sealing ring bottom edge and a sealing skirt connected to the sealing ring bottom edge at the upper end for sealing contact with other components. The sealing ring bottom edge and the sealing skirt are both annular structures, and an annular gap is provided between the lower end of the sealing skirt and the sealing ring bottom edge. The sealing structure also comprises a sealing ring frame, the sealing ring bottom edge and the lower end of the sealing skirt are fixed to the sealing ring frame, and a liquid guide channel for introducing pressure liquid into the annular gap is provided on the sealing ring frame. The present invention solves the technical problem in the prior art that the friction force between the sealing skirt and the moving part changes greatly during the reciprocating movement of the moving part due to different constraints at the two ends of the sealing skirt.

Description

Technical Field

[0001] The invention relates to a sealing structure in the hydraulic field and a force measuring device using the sealing structure. Background Art

[0002] In the field of mechanics, a force measuring device is required to measure the output force values ​​of various tools. Existing force measuring devices such as the "hydraulic bearing device and force sensor" disclosed in Chinese patent CN112128166A, the force sensor includes a first piston and a second piston, the first piston and the second piston have piston guide sections with the same diameter, the piston guide sections on the first piston and the second piston are sealed and guided to move with a moving part, and the force sensor also includes a driving mechanism for driving the moving part to move axially relative to the first piston and the second piston along the piston guide section. The moving part is sealed with the first piston and the second piston by a sealing ring.

[0003] When in use, the device being tested applies force to the first piston or the second piston, and drives the moving part to move axially relative to the first piston and the second piston through the driving mechanism, generating dynamic friction between the moving part and the first piston and the second piston. The dynamic friction can be calculated through the indication of the force sensor. Compared with static friction, dynamic friction is more stable and easier to measure.

[0004] The existing problem of this force sensor is that in the selection of sealing rings, O-rings are generally not rotated, because O-rings are only suitable for working environments with low internal pressure. K-rings with internal pressurization are more often used. However, for K-rings, the K-rings include a sealing bottom edge and a sealing skirt that contacts and seals with the moving part. One end of the sealing skirt is connected to the sealing bottom edge, and the other end of the sealing skirt is cantilevered. Since the two ends of the sealing skirt are constrained differently, the deformation of the sealing skirt is inconsistent when the moving part moves axially back and forth, which affects the friction between the K-ring and the moving part. That is to say, in the prior art, when the moving part moves axially in two directions, because the deformation of the sealing skirt is different, the contact area and contact force between the sealing skirt and the moving part will change, resulting in different friction between the K-ring and the moving part, which will affect the measurement of dynamic friction and thus affect the detection of force value. Summary of the invention

[0005] The object of the present invention is to provide a sealing structure to solve the technical problem in the prior art that the friction force between the sealing skirt and the moving part varies greatly during the reciprocating movement of the moving part due to different constraints at both ends of the sealing skirt; the object of the present invention is also to provide a force measuring device using the sealing structure.

[0006] In order to solve the above technical problems, the technical solution of the sealing structure in the present invention is as follows:

[0007] A sealing structure includes a sealing ring, which includes a sealing ring bottom edge and a sealing skirt edge whose upper end is connected to the sealing ring bottom edge and is used for sealing contact with other components. The sealing ring bottom edge and the sealing skirt edge are both annular structures, and an annular gap is provided between the lower end of the sealing skirt edge and the sealing ring bottom edge. The sealing structure also includes a sealing ring frame, and the sealing ring bottom edge and the lower end of the sealing skirt edge are fixed to the sealing ring frame. The sealing ring frame is provided with a liquid guide channel for introducing pressure liquid into the annular gap.

[0008] A spring ring is arranged at the upper end of the annular gap.

[0009] The sealing ring frame is provided with an inner ring groove and an outer ring groove arranged inside and outside, the lower end of the sealing skirt is clamped and fixed in the inner ring groove, and the lower end of the bottom edge of the sealing ring is clamped and fixed in the outer ring groove.

[0010] The sealing skirt has a sliding contact portion for sealingly contacting and cooperating with other components, and the sliding contact portion is a vertically symmetrical structure.

[0011] The technical solution of the force measuring device in the present invention is:

[0012] The force measuring device comprises a cylinder body and a piston which can move axially relative to the cylinder body. A sealing structure is arranged on one of the cylinder body and the piston. The sealing structure comprises a sealing ring. The sealing ring comprises a sealing ring bottom edge and a sealing skirt which is connected to the sealing ring bottom edge at an upper end and is used for sealing contact with another component. Both the sealing ring bottom edge and the sealing skirt are annular structures. An annular gap is provided between the lower end of the sealing skirt and the sealing ring bottom edge. The sealing structure also comprises a sealing ring frame. The sealing ring bottom edge and the lower end of the sealing skirt are fixed to the sealing ring frame. A liquid guide channel for introducing pressure liquid into the annular gap is provided on the sealing ring frame.

[0013] A spring ring is arranged at the upper end of the annular gap.

[0014] The sealing ring frame is provided with an inner ring groove and an outer ring groove arranged inside and outside, the lower end of the sealing skirt is clamped and fixed in the inner ring groove, and the lower end of the bottom edge of the sealing ring is clamped and fixed in the outer ring groove.

[0015] The sealing skirt has a sliding contact portion for sealingly contacting and cooperating with a corresponding component, and the sliding contact portion is a vertically symmetrical structure.

[0016] The beneficial effects of the present invention are as follows: in the present invention, a sealing ring skeleton is used to fix and constrain the bottom edge of the sealing ring and the lower end of the sealing skirt, so that for the sealing skirt, the upper end of the sealing skirt is connected to the bottom edge of the sealing ring and is constrained, and the lower end of the sealing ring edge is fixed to the sealing ring skeleton and is constrained, which is equivalent to having a constraint structure at both ends of the sealing ring. The liquid guide channel on the sealing ring skeleton can guide the pressure liquid into the annular gap between the sealing skirt and the bottom edge of the sealing ring, thereby ensuring the contact pressure between the sealing skirt and the moving part, thereby ensuring the sealing ability. When the moving part moves up and down and rubs against the sealing skirt, since both ends of the sealing skirt are constrained, the deformation of the sealing skirt can be guaranteed, thereby avoiding a large change in the friction between the sealing skirt and the moving part during the reciprocating movement of the moving part. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a schematic structural diagram of an embodiment of a force measuring device in the present invention;

[0018] Figure 2 yes Figure 1 A schematic cross-sectional view of the middle sealing ring;

[0019] Figure 3 yes Figure 1 A schematic cross-sectional view of the middle sealing ring skeleton;

[0020] Figure 4 It is a schematic diagram of the cooperation between the sealing ring and the sealing ring frame in the present invention. DETAILED DESCRIPTION

[0021] Implementation of the force measuring device Figures 1 to 4 As shown: it includes a cylinder body 4, which is a sleeve structure. The two ends of the inner cavity of the cylinder body are equipped with pistons 2 that can move axially relative to the cylinder body. The inner wall of the cylinder body is provided with a mounting groove 5, and a sealing structure for sealing with the corresponding piston is provided in the mounting groove. A hydraulic chamber 3 is formed between the cylinder body and the piston, and there is a pressure liquid in the hydraulic chamber. A pressure sensor (not shown in the figure) is connected to the hydraulic chamber. The force measuring device also includes a cylinder driving mechanism (not shown in the figure) for driving the cylinder body to move up and down, and a tension and pressure sensor is provided on the transmission path between the cylinder driving mechanism and the cylinder body.

[0022] The upper sealing structure and the lower sealing structure are designed to be symmetrical in the upper and lower parts. Now, only the upper sealing structure is described in detail. The sealing structure includes a sealing ring 6 and a sealing ring frame 10 arranged in the installation groove. The sealing ring includes a sealing ring bottom edge 7 and a sealing skirt 8 connected to the sealing ring bottom edge 7 at the upper end for contacting and cooperating with the corresponding piston. The sealing ring bottom edge 7 is attached to the bottom of the installation groove 5, and the upper end of the sealing ring bottom edge 7 is integrally connected to the upper end of the sealing skirt 8. There is an annular gap 9 between the lower end of the sealing skirt 8 and the sealing ring bottom edge 7.

[0023] The sealing ring skeleton is provided with an inner ring groove 12 and an outer ring groove 11 arranged inside and outside, the lower end of the sealing skirt 8 is clamped and fixed in the inner ring groove 12, and the lower end of the sealing ring bottom edge 7 is clamped and fixed in the outer ring groove 11. The sealing ring skeleton 10 is provided with a liquid guide channel for introducing pressure liquid into the annular gap. In this embodiment, the liquid guide channel includes a connected axial channel part 13 and a radial channel part 14. The axial channel part 13 is connected to the annular gap 9, and the radial channel part 14 extends to the inner circumference of the sealing ring skeleton 10. The sealing skirt has a sliding contact part 10 for sealing contact with the corresponding component, and the sliding contact part is a vertically symmetrical structure.

[0024] The upper end of the annular gap 9 is provided with a spring ring 1, which expands inwardly. The spring ring 15 is used to make the sealing skirt 8 apply an initial sealing pressure to the piston. Under the action of this pressure, the initial contact pressure between the sealing skirt and the piston is P0. When in use, the device to be tested, such as the pressure head of the pressure gauge, acts on the upper piston, and the cylinder drive mechanism drives the cylinder to move up and down.

[0025] but,

[0026]

[0027]

[0028] μ---the contact friction coefficient between the sealing ring and the piston; D---the piston diameter; P---the working pressure of the pressure chamber; P0---the initial contact pressure between the sealing skirt and the piston; h---the axial height of the contact surface between the sealing ring and the piston, that is, the axial height of the sliding contact part;

[0029] A spring ring is set inside the sealing ring to make the sealing ring produce a contact pressure P0 on the piston. The friction force is:

[0030] F0=hπDP0μ

[0031] The hydraulic oil in the pressure chamber generates a working pressure because the piston is acted upon by force. The sealing ring generates a positive pressure on the contact surface of the piston. The friction force is:

[0032] F1=hπDPμ

[0033] The force exerted on the piston by the hydraulic oil in the pressure chamber is:

[0034]

[0035] If the upper piston tends to move downward after the piston is subjected to force F, and the forces F0 and F1 on the piston are both upward, then:

[0036] F=F0+F 1+F y

[0037] Now we take the working pressure of the pressure chamber as the standard value, F0+F1 is the main factor causing the error, and its percentage error is:

[0038]

[0039] Generally, a polytetrafluoroethylene seal ring with a smaller friction coefficient is used. When processing and installing, P0 is much smaller than P. Then the error value is approximately: It is found that the magnitude of the friction error has nothing to do with the current working pressure P of the pressure chamber, but is proportional to the contact friction coefficient μ between the sealing ring and the piston; proportional to the axial height h of the contact surface between the sealing ring and the piston; and inversely proportional to the piston diameter D. Therefore, the axial height h of the contact surface between the sealing skirt and the piston determines the error value. In this embodiment, the sliding contact portion adopts a vertically symmetrical structure, and the upper and lower ends of the sealing skirt have constraint structures. Therefore, when the cylinder body moves upward with the sealing skirt relative to the piston, and when the cylinder body moves downward with the sealing skirt relative to the piston, the deformation of the sealing skirt is consistent, that is, the length of the contact surface between the sealing skirt and the piston is the same, thereby ensuring the stability of the friction magnitude.

[0040] In other embodiments of the present invention: the spring ring may not be provided; of course, the bottom edge of the sealing ring and the sealing skirt may also be vulcanized and fixed on the sealing ring frame.

[0041] The implementation of the sealing structure is as follows Figures 1 to 4 As shown, the specific structure of the sealing structure is the same as the sealing structure in the above-mentioned force measurement device embodiments, and will not be described in detail here.

[0042] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A sealing structure, characterized in that: The sealing ring comprises a sealing ring, which comprises a sealing ring bottom edge and a sealing skirt whose upper end is connected to the sealing ring bottom edge for sealing contact with other components. The sealing ring bottom edge and the sealing skirt are both annular structures, and an annular gap is provided between the lower end of the sealing skirt and the bottom edge of the sealing ring. The sealing structure also comprises a sealing ring frame. The sealing ring bottom edge and the lower end of the sealing skirt are fixed to the sealing ring frame. A liquid guide channel for introducing pressure liquid into the annular gap is provided on the sealing ring frame. An inner ring groove and an outer ring groove arranged inside and outside are provided on the sealing ring frame. The lower end of the sealing skirt is clamped and fixed in the inner ring groove, and the lower end of the sealing ring bottom edge is clamped and fixed in the outer ring groove. The sealing skirt has a sliding contact portion for sealing contact with other components, and the sliding contact portion is a vertically symmetrical structure. The liquid guide channel comprises an axial channel portion and a radial channel portion that are connected. The axial channel portion is connected to the annular gap, and the radial channel portion extends to the inner circumferential surface of the sealing ring frame.

2. The sealing structure according to claim 1, characterized in that: A spring ring is arranged at the upper end of the annular gap.

3. A force measuring device, comprising a cylinder and a piston capable of axial movement relative to the cylinder, wherein a sealing structure is provided on one of the cylinder and the piston, and characterized in that: The sealing structure includes a sealing ring, which includes a sealing ring bottom edge and a sealing skirt whose upper end is connected to the sealing ring bottom edge and is used for sealing contact and cooperation with another component. The sealing ring bottom edge and the sealing skirt are both annular structures, and an annular gap is provided between the lower end of the sealing skirt and the bottom edge of the sealing ring. The sealing structure also includes a sealing ring frame, and the sealing ring bottom edge and the lower end of the sealing skirt are fixed to the sealing ring frame. A liquid guide channel for introducing pressure liquid into the annular gap is provided on the sealing ring frame. An inner ring groove and an outer ring groove arranged inside and outside are provided on the sealing ring frame. The lower end of the sealing skirt is clamped and fixed in the inner ring groove, and the lower end of the sealing ring bottom edge is clamped and fixed in the outer ring groove. The sealing skirt has a sliding contact portion for sealing contact and cooperation with a corresponding component, and the sliding contact portion is a vertically symmetrical structure. The liquid guide channel includes an axial channel portion and a radial channel portion that are connected. The axial channel portion is connected to the annular gap, and the radial channel portion extends to the inner circumferential surface of the sealing ring frame.

4. The force measuring device according to claim 3, characterized in that: A spring ring is arranged at the upper end of the annular gap.

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