Medium isolation type pressure conversion device

Abstract

The invention provides a medium isolation type pressure conversion device. The medium isolation type pressure conversion device comprises a first sealing flange and a second sealing flange which are oppositely arranged; two ends of the limiting rod are fixedly connected with axial end surfaces of the two sealing flanges; the metal isolation flange is arranged between the two sealing flanges and is in sliding connection with the limiting rod; the first corrugated pipe mechanism is connected with the first sealing flange and the isolation flange to form a first medium space; the second corrugated pipe mechanism is connected with the isolation flange and the second sealing flange to form a second medium space; a pressure receiving end for transmitting a first medium is arranged outside the first sealing flange; the outer side of the second sealing flange is provided with a liquid supplementing port for supplementing the second medium, and the pressure output end outputs pressure to the to-be-tested piece. Pressure source equipment drives the first corrugated pipe to axially extend to push the isolation flange to move, the limiting rod restrains the total length to force the second corrugated pipe to be shortened, static sealing isolation type conversion of two pressure media is achieved, and the problem that in a hydraulic test, the pressure media of the pressure source equipment are not compatible with the pressure media of a to-be-tested piece is solved.

Description

Technical Field

[0001] This invention relates to the field of fluid pressure transmission technology, and more particularly to a medium-isolated pressure conversion device. Background Technology

[0002] In hydraulic testing systems, water or anti-wear hydraulic oil is used as the pressure medium to conduct pressure tests on various products. However, when the test piece is required to withstand pressure in a low-temperature environment, water will freeze and fail; similarly, oil-based media are unsuitable when the test piece undergoes a physicochemical reaction with the oil-based medium under high-temperature conditions. This incompatibility of pressure media severely limits the applicability and testing accuracy of hydraulic testing.

[0003] To address the issue of incompatible pressure media, existing technologies employ mechanical pressure conversion devices based on piston structures. These devices transmit pressure through the reciprocating motion of a piston within two sealed chambers, and their structure includes components such as a piston rod, sealing rings, and a hydraulic cylinder.

[0004] However, in mechanical pressure conversion devices with piston structures, the piston rod must pass through two chambers, and the sealing ring is prone to aging and failure after long-term use, leading to cross-contamination of the media on both sides, making it unable to truly isolate incompatible media such as water and oil. Summary of the Invention

[0005] This invention provides a medium-isolated pressure conversion device, which physically separates the double-corrugated pipe chambers through an isolation flange, and combines the push-pull deformation under the rigid constraint of the limiting rod to achieve physical isolation pressure transmission of different pressure media.

[0006] To achieve the above objectives, the present invention provides a medium-isolated pressure conversion device for use in a hydraulic testing system, comprising:

[0007] The first sealing flange and the second sealing flange are positioned opposite to each other;

[0008] The limiting rod has its two ends fixedly connected to the axial end face of the first sealing flange and the axial end face of the second sealing flange, respectively.

[0009] An isolation flange, which is a disc-shaped metal component, is located between the first sealing flange and the second sealing flange, and is slidably connected to the limit rod.

[0010] The first bellows mechanism has its first end fixedly connected to the first sealing flange and its second end fixedly connected to the isolation flange.

[0011] The first sealing flange, the first bellows mechanism, and the isolation flange form a space for containing the first pressure medium;

[0012] The second bellows mechanism has its first end fixedly connected to the isolation flange and its second end fixedly connected to the second sealing flange.

[0013] The second sealing flange, the second bellows mechanism, and the isolation flange form a space for accommodating the second pressure medium;

[0014] The pressure receiving end is disposed on the axial end face of the first sealing flange away from the first bellows mechanism. The pressure receiving end is used to transmit the first pressure medium into the space of the first bellows mechanism.

[0015] The liquid inlet is located on the axial end face of the second sealing flange away from the second bellows mechanism. The liquid inlet is used to replenish the second pressure medium into the space of the second bellows mechanism when testing different test pieces.

[0016] The pressure output end is located on the axial end face of the second sealing flange away from the second bellows mechanism. The pressure output end is used to transmit the second pressure medium in the space of the second bellows mechanism to the test piece.

[0017] Preferably, the two axial end faces of the isolation flange are respectively provided with a first sealing surface and a second sealing surface;

[0018] The first bellows mechanism includes: a first bellows flange, a first bellows, and a second bellows flange;

[0019] The sealing surface of the first bellows flange is connected to the sealing surface of the first sealing flange by a fastening method.

[0020] The first bellows, the first end of the first bellows is fixedly connected to the first bellows flange;

[0021] The second bellows flange is fixedly connected to the second end of the first bellows, and the sealing surface of the second bellows flange is connected to the first sealing surface of the isolation flange by a fastening method.

[0022] The second bellows mechanism includes: a third bellows flange, a second bellows, and a fourth bellows flange;

[0023] The sealing surface of the third bellows flange is connected to the second sealing surface of the isolation flange by a fastening method.

[0024] The second bellows, the first end of the second bellows is fixedly connected to the flange of the third bellows;

[0025] The fourth bellows flange is fixedly connected to the second end of the second bellows, and the sealing surface of the fourth bellows flange is connected to the second sealing flange by a fastening method.

[0026] Preferably, the first sealing flange, the first bellows flange, the second bellows flange, the isolation flange, the third bellows flange, the fourth bellows flange, and the second sealing flange are each provided with through holes, and all the through holes are coaxial;

[0027] The limiting rod passes through the through holes of the first sealing flange, the first bellows flange, the second bellows flange, the isolation flange, the third bellows flange, the fourth bellows flange, and the second sealing flange in sequence along the horizontal axis.

[0028] Preferably, the first and second corrugated pipes are metal corrugated pipes;

[0029] The first and second corrugated pipes have the same axial stiffness; the axial elongation of the first corrugated pipe is equal to the axial shortening of the second corrugated pipe.

[0030] Preferably, the sealing interfaces between the first sealing flange and the first bellows flange, between the second bellows flange and the isolation flange, between the isolation flange and the third bellows flange, and between the second sealing flange and the fourth bellows flange are all in direct contact to form a sealed connection; the sealing interfaces do not move relative to each other in the working state.

[0031] Preferably, the limiting rod is a non-extendable rigid rod, and both ends of the limiting rod are provided with threaded sections, on which locking nuts are screwed.

[0032] Preferably, the pressure receiving end includes: a first pressure-bearing pipe;

[0033] A first connection hole is opened on the axial end face of the first sealing flange, and a first pressure-bearing pipe is sealed and welded into the first connection hole opened on the axial end face of the first sealing flange; the first end of the first pressure-bearing pipe away from the first sealing flange is connected to the pressure source equipment; the second end of the first pressure-bearing pipe is spatially connected to the first bellows mechanism.

[0034] Preferably, a threaded hole is provided on the axial end face of the second sealing flange, and the sealing bolt is screwed into the threaded hole. The sealing bolt and the threaded hole form an openable and closable sealing structure, and the threaded hole and the sealing bolt together constitute the liquid inlet.

[0035] Preferably, the pressure output end includes a second pressure-bearing pipe;

[0036] A second connection hole is opened on the axial end face of the second sealing flange, and the second pressure-bearing pipe is sealed and welded into the second connection hole opened on the axial end face of the second sealing flange; the first end of the second pressure-bearing pipe away from the second sealing flange is connected to the test piece; the second end of the second pressure-bearing pipe is spatially connected to the second bellows mechanism.

[0037] Preferably, the connections between the sealing surfaces of the first bellows flange and the first sealing flange, between the sealing surfaces of the second bellows flange and the first sealing surface of the isolation flange, between the sealing surfaces of the third bellows flange and the second sealing surface of the isolation flange, and between the sealing surfaces of the fourth bellows flange and the second sealing flange are all made by bolts and nuts.

[0038] This invention provides a media-isolated pressure conversion device that achieves physical isolation and lossless pressure conversion between two media through a double-bellows push-pull linkage structure and a rigid limiting rod design. When the first bellows elongates under the pressure of the medium, it pushes the isolation flange to move. The limiting rod constrains the distance between the first and second sealing flanges to remain constant, causing the second bellows to shorten synchronously. This push-pull linkage structure allows pressure to be directly transmitted through the deformation of the bellows, eliminating the need for moving parts such as pistons and valves, thus eliminating friction loss and seal wear. The isolation flange physically separates the two bellows chambers, solving the problem of transmitting incompatible media such as water-based and oil-based media. During device operation, the sealing interface maintains zero relative displacement, significantly reducing the risk of leakage. The flexible deformation of the bellows replaces reciprocating motion, eliminating vibration and noise, and simplifying the structure by reducing the number of vulnerable parts. Attached Figure Description

[0039] To more clearly illustrate the technical solution of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, those skilled in the art can obtain other drawings based on these drawings without creative effort.

[0040] Figure 1 This is a schematic diagram of the structure of the medium-isolated pressure conversion device provided in an embodiment of the present invention;

[0041] Figure 2 This is a cross-sectional structural schematic diagram of the medium-isolated pressure conversion device provided in an embodiment of the present invention;

[0042] Figure 3 This is a schematic diagram of the replenishment port structure of the medium-isolated pressure conversion device provided in an embodiment of the present invention.

[0043] Illustration:

[0044] Among them, 1. First sealing flange; 2. Second sealing flange; 3. Limiting rod; 4. Isolation flange; 5. First bellows mechanism; 51. First bellows flange; 52. First bellows; 53. Second bellows flange; 6. Second bellows mechanism; 61. Third bellows flange; 62. Second bellows; 63. Fourth bellows flange; 7. Pressure receiving end; 71. First pressure-bearing pipe; 8. Liquid replenishment port; 9. Pressure output end; 91. Second pressure-bearing pipe. Detailed Implementation

[0045] The embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described below do not represent all embodiments consistent with this application. They are merely examples of systems and methods consistent with some aspects of this application.

[0046] It should be noted that the brief descriptions of terms in this application are only for the convenience of understanding the embodiments described below, and are not intended to limit the embodiments of this application. Unless otherwise stated, these terms should be understood in their ordinary and common meaning.

[0047] The terms "first," "second," "third," etc., used in the specification, claims, and accompanying drawings of this application are used to distinguish similar or related objects or entities, and do not necessarily imply a specific order or sequence, unless otherwise specified. It should be understood that such terms are interchangeable where appropriate.

[0048] The terms “comprising” and “having”, and any variations thereof, are intended to cover but not exclude inclusion, for example, a product or device that includes a range of components is not necessarily limited to all of the components that are clearly listed, but may include other components that are not clearly listed or that are inherent to such product or device.

[0049] In the field of hydraulic testing, existing technologies employ mechanical pressure conversion devices based on piston structures. These devices transmit pressure through the reciprocating motion of a piston within two sealed chambers, and their structure includes components such as a piston rod, sealing rings, and a hydraulic cylinder. However, because the piston rod must traverse both chambers in these mechanical pressure conversion devices, the sealing rings are prone to aging and failure after prolonged use, leading to cross-contamination of the media on both sides. This makes it impossible to truly isolate incompatible media such as water and oil.

[0050] To address the above problems, the present invention provides a medium-isolated pressure conversion device.

[0051] The following description will be provided in conjunction with the accompanying drawings and specific embodiments.

[0052] In some embodiments, see Figures 1-3 The medium-isolated pressure conversion device includes: a first sealing flange 1, a second sealing flange 2, a limit rod 3, an isolation flange 4, a first bellows mechanism 5, a second bellows mechanism 6, a pressure receiving end 7, a liquid replenishment port 8, and a pressure output end 9.

[0053] It should be noted that the first sealing flange 1 and the second sealing flange 2 are arranged opposite to each other; the two ends of the limiting rod 3 are fixedly connected to the axial end faces of the first sealing flange 1 and the second sealing flange 2, respectively; the isolation flange is a disc-shaped metal component, and the isolation flange 4 is disposed between the first sealing flange 1 and the second sealing flange 2. The isolation flange 4 is slidably connected to the limiting rod 3, and its function is to physically isolate the two pressure media; the first end of the first bellows mechanism 5 is fixedly connected to the first sealing flange 1, and the second end of the first bellows mechanism 5 is fixedly connected to the isolation flange 4; the first sealing flange 1, the first bellows mechanism 5, and the isolation flange 4 form a space for accommodating the first pressure medium; the first end of the second bellows mechanism 6 is fixedly connected to the isolation flange 4, and the second bellows mechanism... The second end of the structure 6 is fixedly connected to the second sealing flange 2; the second sealing flange 2, the second bellows mechanism 6, and the isolation flange 4 form a space for accommodating the second pressure medium; the pressure receiving end 7 is disposed on the axial end face of the first sealing flange 1 away from the first bellows mechanism 5; the pressure receiving end 7 is used to transmit the first pressure medium into the space of the first bellows mechanism 5; the liquid replenishment port 8 is disposed on the axial end face of the second sealing flange 2 away from the second bellows mechanism 6; the liquid replenishment port 8 is used to replenish the second pressure medium into the space of the second bellows mechanism 6 when testing different test pieces; the pressure output end 9 is disposed on the axial end face of the second sealing flange 2 away from the second bellows mechanism 6; the pressure output end 9 is used to transfer the second pressure medium in the space of the second bellows mechanism 6 to the test piece.

[0054] Understandably, when the device is working, the second pressure medium is first added to the second bellows mechanism 6 through the replenishment port 8 and then sealed. The pressure receiving end 7 is connected to the pressure source device, and the pressure output end 9 is connected to the test piece. When the pressure source device inputs the first pressure medium into the space of the first bellows mechanism 5 through the pressure receiving end 7, the first bellows mechanism 5 undergoes axial elongation under the action of internal pressure. Since the limiting rod 3 rigidly fixes the relative distance between the first sealing flange 1 and the second sealing flange 2 to a constant value, the isolation flange 4 is forced axially toward the second bellows mechanism 6. The displacement of the isolation flange 4 compresses the second bellows mechanism 6, causing it to shorten axially. This results in a reduction in the volume of the sealed second pressure medium inside the second bellows mechanism 6, and an increase in pressure. The increased pressure is transmitted to the test piece through the pressure output end 9.

[0055] Deformation continues until the system reaches a force balance: the pressure of the first pressure medium acts on the first sealing surface of the isolation flange 4, and the pressure of the second pressure medium acts on the second sealing surface of the isolation flange 4. The pressure difference between the two is balanced by the stiffness and deformation forces of the first bellows mechanism 5 and the second bellows mechanism 6. At this point, the pressure conversion is completed. The first pressure medium drives the isolation flange 4 to shift through the deformation of the first bellows mechanism 5, and then transmits the pressure to the second pressure medium through the deformation of the second bellows mechanism 6. The entire process requires no external control; the pressure and deformation are automatically adjusted to a balanced state.

[0056] This implementation method physically separates the two media using an isolation flange, fundamentally solving the media compatibility problem. The double bellows mechanism, in conjunction with the limit rod, eliminates mechanical friction and relative movement during pressure conversion, thus eliminating the wear and leakage risks associated with traditional piston structures. The static sealing structure prevents blockage malfunctions in electrically controlled valves, reducing maintenance requirements.

[0057] In some embodiments, see Figure 2 The isolation flange 4 has a first sealing surface and a second sealing surface on its two axial end faces, respectively; the first bellows mechanism 5 includes: a first bellows flange 51, a first bellows 52, and a second bellows flange 53; the sealing surface of the first bellows flange 51 is connected to the sealing surface of the first sealing flange 1 by a fastening method, and the dimensions of the first bellows flange 51 and the first sealing flange 1 are matched; the first end of the first bellows 52 is fixedly connected to the first bellows flange 51; the second bellows flange 53 is fixedly connected to the second end of the first bellows 52, and the sealing surface of the second bellows flange 53 is connected to the first sealing surface of the isolation flange 4 by a fastening method. The second bellows flange 53 is sized to match the isolation flange 4; the second bellows mechanism 6 includes: a third bellows flange 61, a second bellows 62, and a fourth bellows flange 63; the sealing surface of the third bellows flange 61 is connected to the second sealing surface of the isolation flange 4 by a fastening method, and the third bellows flange 61 is sized to match the isolation flange 4; the first end of the second bellows 62 is fixedly connected to the third bellows flange 61; the fourth bellows flange 63 is fixedly connected to the second end of the second bellows 62, and the sealing surface of the fourth bellows flange 63 is connected to the second sealing flange 2 by a fastening method, and the fourth bellows flange 63 is sized to match the second sealing flange 2.

[0058] In some embodiments, see Figure 2The first sealing flange 1, the first bellows flange 51, the second bellows flange 53, the isolation flange 4, the third bellows flange 61, the fourth bellows flange 63 and the second sealing flange 2 are each provided with through holes, and all the through holes are kept coaxial; the limiting rod 3 passes through the through holes of the first sealing flange 1, the first bellows flange 51, the second bellows flange 53, the isolation flange 4, the third bellows flange 61, the fourth bellows flange 63 and the second sealing flange 2 in sequence along the horizontal axis.

[0059] It should be noted that the through-hole diameter of the isolation flange 4 is larger than the diameter of the limit rod 3, forming a sliding clearance. The through-hole diameters of the other flanges match the diameter of the limit rod 3. The coaxiality of the through-holes ensures that the limit rod 3 passes through the entire media isolation pressure conversion device in a straight line.

[0060] In some embodiments, see Figure 2 The first corrugated pipe 52 and the second corrugated pipe 62 are metal corrugated pipes; the first corrugated pipe 52 and the second corrugated pipe 62 have the same axial stiffness; the corrugation depth, corrugation pitch and corrugation number of the first corrugated pipe 52 and the second corrugated pipe 62 are the same, ensuring that the axial elongation of the first corrugated pipe 52 is equal to the axial shortening of the second corrugated pipe 62.

[0061] It is understandable that the first bellows 52 and the second bellows 62 are metal bellows with axial elastic deformation capability. When the first pressure medium is input into the first bellows mechanism 5, the first bellows 52 elongates axially under the action of the first pressure medium. The elongation of the first bellows 52 pushes the isolation flange 4 to move towards the second bellows mechanism 6, and the displacement of the isolation flange 4 forces the second bellows 62 to shorten axially. Since the first bellows 52 and the second bellows 62 have the same axial stiffness, the shortening of the first bellows 52 is equal to the elongation of the second bellows 62.

[0062] In some embodiments, see Figure 1 and Figure 2 The sealing interfaces between the first sealing flange 1 and the first bellows flange 51, between the second bellows flange 53 and the isolation flange 4, between the isolation flange 4 and the third bellows flange 61, and between the second sealing flange 2 and the fourth bellows flange 63 are all in direct contact to form a sealed connection. Under operating conditions, there is no relative movement between these sealing interfaces. This characteristic of no relative movement between the directly contacting metal sealing interfaces under operating conditions eliminates frictional loss and avoids the risk of leakage caused by wear of the seals.

[0063] In some embodiments, see Figure 2 The limiting rod 3 is a non-extendable rigid rod. Both ends of the limiting rod 3 are machined with external thread sections, and the thread sections of the limiting rod 3 are matched with the locking nut.

[0064] Understandably, the limiting rod 3 penetrates the through holes of the first sealing flange 1, the first bellows flange 51, the second bellows flange 53, the isolation flange 4, the third bellows flange 61, the fourth bellows flange 63, and the second sealing flange 2. The threaded sections at both ends of the limiting rod 3 extend beyond the axial end faces of the first sealing flange 1 and the second sealing flange 2. The locking nut is screwed into the threaded sections at both ends of the limiting rod 3, ensuring a tight fit between the axial end faces of the first sealing flange 1 and the second sealing flange 2 and the inner end face of the nut. The limiting rod 3 maintains a constant distance between the first sealing flange 1 and the second sealing flange 2. The non-extensible rigid rod ensures a constant overall length of the device, eliminating pressure conversion errors caused by elastic deformation. The engagement of the threaded sections and the locking nut forms a detachable rigid constraint structure, facilitating assembly and maintenance.

[0065] In some embodiments, see Figure 2 The pressure receiving end 7 includes a first pressure-bearing pipe 71; a first connecting hole is opened on the axial end face of the first sealing flange 1, and the first pressure-bearing pipe 71 is sealed and welded into the first connecting hole opened on the axial end face of the first sealing flange 1; the first end of the first pressure-bearing pipe 71 away from the first sealing flange 1 is connected to the pressure source equipment; the second end of the first pressure-bearing pipe 71 is spatially connected to the first bellows mechanism 5. The pressure source equipment transmits a first pressure medium to the first bellows mechanism 5 through the pressure receiving end 7.

[0066] Understandably, when the pressure source equipment is started, the first pressure medium is transmitted to the space of the first bellows mechanism 5 through the first pressure-bearing pipe 71. The first pressure medium drives the first bellows mechanism 5 to extend axially along the horizontal axis. The amount of extension of the first bellows mechanism 5 changes with the input first pressure medium. The deformation of the first bellows mechanism 5 is transmitted to the isolation flange 4, and the isolation flange 4 pushes the second bellows mechanism 6 to shorten in the opposite direction. The second bellows mechanism 6 transmits pressure to the pressure output end 8.

[0067] In some embodiments, see Figure 1 and Figure 3 The second sealing flange 2 has a threaded hole on its axial end face. The sealing bolt is screwed into the threaded hole, and the sealing bolt and the threaded hole form an openable and closable sealing structure. The threaded hole and the sealing bolt together form the liquid replenishment port 8.

[0068] It should be noted that when replenishing the pressure medium at the replenishment port 8, the sealing bolt is rotated to unscrew the threaded hole on the axial end face of the second sealing flange 2, and the second pressure medium is injected into the space of the second bellows mechanism 6 through the threaded hole on the axial end face of the second sealing flange 2. After replenishing the second pressure medium, the sealing bolt is tightened to close the replenishment port 8.

[0069] In some embodiments, see Figure 2The pressure output end 9 includes a second pressure-bearing pipe 91; a second connection hole is opened on the axial end face of the second sealing flange 2, and the second pressure-bearing pipe 91 is sealed and welded to the second connection hole opened on the axial end face of the second sealing flange 2; the first end of the second pressure-bearing pipe 91 away from the second sealing flange 2 is connected to the test piece; the second end of the second pressure-bearing pipe 91 is spatially connected to the second bellows mechanism 6.

[0070] Understandably, when the isolation flange 4 is driven by the first bellows mechanism 5 to undergo axial elongation, the second bellows mechanism 6 simultaneously undergoes axial shortening. The axial shortening of the second bellows mechanism 6 results in a reduction in the volume of its sealed space, causing the pressure of the pre-filled second pressure medium within the sealed space to increase due to volume compression. This increased pressure is transmitted to the external test piece through the second pressure-bearing pipe 91, which connects the space of the second bellows mechanism 6.

[0071] In some embodiments, see Figure 1 and Figure 2 The connections between the sealing surfaces of the first bellows flange 51 and the first sealing flange 1, the sealing surfaces of the second bellows flange 53 and the first sealing surface of the isolation flange 4, the sealing surfaces of the third bellows flange 61 and the second sealing surface of the isolation flange 4, and the sealing surfaces of the fourth bellows flange 63 and the second sealing flange 2 are all secured by applying axial preload with bolts and nuts, so that each sealing surface is in direct contact to form a rigid sealing structure without relative movement.

[0072] Understandably, when the input pressure increases, the first bellows 52 extends axially, pushing the isolation flange 4. Since all flanges are rigidly connected by bolts and nuts, the displacement of the isolation flange 4 is transmitted to the second sealing flange 2 through the flange. The absence of relative motion eliminates interfacial fretting wear and solves the dynamic sealing leakage problem.

[0073] Similar parts between the embodiments provided in this invention can be referred to mutually. The specific embodiments provided above are merely examples under the overall concept of this invention and do not constitute a limitation on the scope of protection of this invention. For those skilled in the art, any other embodiments extended from the solution of this invention without creative effort are within the scope of protection of this invention.

Claims

1. A medium-isolated pressure conversion device, characterized in that, include: The first sealing flange (1) and the second sealing flange (2) are arranged opposite to each other; The limiting rod (3) has two ends fixedly connected to the axial end face of the first sealing flange (1) and the axial end face of the second sealing flange (2), respectively. Isolation flange (4), the isolation flange (4) is a disc-shaped metal component, the isolation flange (4) is disposed between the first sealing flange (1) and the second sealing flange (2), and the isolation flange (4) is slidably connected to the limiting rod (3); The first bellows mechanism (5) has its first end fixedly connected to the first sealing flange (1) and its second end fixedly connected to the isolation flange (4). The first sealing flange (1), the first bellows mechanism (5), and the isolation flange (4) form a space for accommodating the first pressure medium; The second bellows mechanism (6) has its first end fixedly connected to the isolation flange (4) and its second end fixedly connected to the second sealing flange (2). The second sealing flange (2), the second bellows mechanism (6), and the isolation flange (4) form a space for accommodating the second pressure medium; Pressure receiving end (7), the pressure receiving end (7) is disposed on the axial end face of the first sealing flange (1) away from the first bellows mechanism (5), the pressure receiving end (7) is used to transmit the first pressure medium into the space of the first bellows mechanism (5). The liquid inlet (8) is located on the axial end face of the second sealing flange (2) away from the second bellows mechanism (6). The liquid inlet (8) is used to replenish the second pressure medium into the space of the second bellows mechanism (6) when testing different test pieces. Pressure output end (9) is provided on the axial end face of the second sealing flange (2) away from the second bellows mechanism (6). The pressure output end (9) is used to transmit the second pressure medium in the space of the second bellows mechanism (6) to the test piece.

2. The medium-isolated pressure conversion device according to claim 1, characterized in that, The two axial end faces of the isolation flange (4) are respectively provided with a first sealing surface and a second sealing surface; The first bellows mechanism (5) includes: The sealing surface of the first bellows flange (51) is connected to the sealing surface of the first sealing flange (1) by a fastening method. The first bellows (52) has its first end fixedly connected to the first bellows flange (51). The second bellows flange (53) is fixedly connected to the second end of the first bellows (52), and the sealing surface of the second bellows flange (53) is connected to the first sealing surface of the isolation flange (4) by a fastening method. The second bellows mechanism (6) includes: The sealing surface of the third bellows flange (61) is connected to the second sealing surface of the isolation flange (4) by a fastening method; The second corrugated pipe (62) has its first end fixedly connected to the third corrugated pipe flange (61); The fourth bellows flange (63) is fixedly connected to the second end of the second bellows (62), and the sealing surface of the fourth bellows flange (63) is connected to the second sealing flange (2) by a fastening method.

3. The medium-isolated pressure conversion device according to claim 2, characterized in that, The first sealing flange (1), the first bellows flange (51), the second bellows flange (53), the isolation flange (4), the third bellows flange (61), the fourth bellows flange (63) and the second sealing flange (2) are each provided with through holes, and all the through holes are coaxial; The limiting rod (3) passes through the through holes of the first sealing flange (1), the first bellows flange (51), the second bellows flange (53), the isolation flange (4), the third bellows flange (61), the fourth bellows flange (63), and the second sealing flange (2) in sequence along the horizontal axis.

4. The medium-isolated pressure conversion device according to claim 2, characterized in that, The first corrugated pipe (52) and the second corrugated pipe (62) are metal corrugated pipes; The first bellows (52) and the second bellows (62) have the same axial stiffness; The axial elongation of the first bellows (52) is equal to the axial shortening of the second bellows (62).

5. The medium-isolated pressure conversion device according to claim 2, characterized in that, The sealing interfaces between the first sealing flange (1) and the first bellows flange (51), between the second bellows flange (53) and the isolation flange (4), between the isolation flange (4) and the third bellows flange (61), and between the second sealing flange (2) and the fourth bellows flange (63) are all in direct contact to form a sealing connection; the sealing interfaces do not move relative to each other in the working state.

6. The medium-isolated pressure conversion device according to claim 1, characterized in that, The limiting rod (3) is a non-extendable rigid rod. Both ends of the limiting rod (3) are provided with threaded sections, and locking nuts are screwed onto the threaded sections at both ends of the limiting rod (3).

7. The medium-isolated pressure conversion device according to claim 1, characterized in that, The pressure receiving end (7) includes: a first pressure-bearing pipe (71); A first connection hole is opened on the axial end face of the first sealing flange (1), and the first pressure-bearing pipe (71) is sealed and welded to the first connection hole opened on the axial end face of the first sealing flange (1). The first end of the first pressure-bearing pipe (71) away from the first sealing flange (1) is connected to the pressure source equipment; The second end of the first pressure-bearing pipe (71) is spatially connected to the first bellows mechanism (5).

8. The medium-isolated pressure conversion device according to claim 1, characterized in that, A threaded hole is provided on the axial end face of the second sealing flange (2), and a sealing bolt is screwed into the threaded hole. The sealing bolt and the threaded hole form an openable and closable sealing structure; the threaded hole and the sealing bolt together constitute the liquid replenishment port (8).

9. The medium-isolated pressure conversion device according to claim 1, characterized in that, The pressure output end (9) includes a second pressure-bearing pipe (91); A second connection hole is opened on the axial end face of the second sealing flange (2), and the second pressure-bearing pipe (91) is sealed and welded into the second connection hole opened on the axial end face of the second sealing flange (2); The first end of the second pressure-bearing pipe (91) away from the second sealing flange (2) is connected to the test piece; The second end of the second pressure-bearing pipe (91) is spatially connected to the second bellows mechanism (6).

10. The medium-isolated pressure conversion device according to claim 2, characterized in that, The connections between the sealing surface of the first bellows flange (51) and the sealing surface of the first sealing flange (1), between the sealing surface of the second bellows flange (53) and the first sealing surface of the isolation flange (4), between the sealing surface of the third bellows flange (61) and the second sealing surface of the isolation flange (4), and between the sealing surface of the fourth bellows flange (63) and the second sealing flange (2) are all made by bolts and nuts.

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