Differential pressure mechanical seal structure and compressor

Abstract

The application discloses a differential pressure mechanical sealing structure and a compressor, and relates to the technical field of mechanical sealing structures, and in particular relates to a differential pressure mechanical sealing structure and a compressor. The structure comprises a shell, an input shaft, a sealing static ring and a sealing dynamic ring, opposite sides of a mounting cavity on the shell are provided with shaft holes which are respectively connected with the inside of the shell and the outside; the input shaft passes through the mounting cavity and the shaft holes on the opposite sides of the mounting cavity and is connected with the sealing static ring; the dynamic friction surface of the end of the sealing dynamic ring is opposite to and adheres to the static friction surface of the sealing static ring, and the outer side of the sealing dynamic ring is provided with a ring of sealing pairs, so that the closed cavity of the mounting cavity is divided into an internal pressure cavity which is connected with the inside of the shell and an oil pressure cavity which is connected with an oil return channel. The sealing structure of the application divides high and low pressure areas by arranging the sealing pairs with comb-shaped sealing on the sealing dynamic ring, forms high and low pressure differences on both sides of the sealing dynamic ring, and forms a pre-tightening force difference between the sealing dynamic ring and the sealing static ring by combining the projection area corresponding to the pressure. The pre-tightening force difference does not decay with the abrasion of the mechanical sealing dynamic ring and the mechanical sealing static ring, but is only related to the current working pressure difference.

Description

Technical Field

[0001] This invention relates to the field of mechanical seal technology, specifically to a differential pressure mechanical seal structure and compressor. Background Technology

[0002] Fluid machinery such as compressors has an input shaft externally mounted on a sealed housing. The output shaft of an external drive device, such as a motor, transmits torque to the input shaft through a coupling, driving the rotational motion of the compressor and other fluid machinery shaft system. Mechanical seals are used to achieve dynamic sealing of the relative movement position between the input shaft of the shaft system and the sealed housing.

[0003] Taking a screw compressor as an example:

[0004] The mechanical seal's rotating ring is fixed to the output shaft, and an O-ring seal is formed between the rotating ring and the output shaft, resulting in a static seal as there is no relative movement between them. The mechanical seal's stationary ring is fixed to the pressure housing, and an O-ring seal is formed between the stationary ring and the mechanical seal seat, also resulting in a static seal as there is no relative movement between them. Ultimately, the relative movement between the output shaft and the pressure housing occurs on the mating surfaces of the rotating and stationary rings, meaning that the rotating and stationary rings form a friction pair, achieving the dynamic seal function.

[0005] Figure 1 This diagram illustrates a classic mechanical seal structure. During equipment operation, driven by the output shaft, the dynamic and stationary rings of the mechanical seal form a friction pair and generate a large amount of heat. Therefore, a cooling oil circuit is established, including the mechanical seal oil supply and return. Considering the flow requirements, the mechanical seal oil supply is set to a relatively high value to ensure sufficient oil flow. However, once the cooling oil enters the mechanical seal area, it remains at a low pressure until it leaves the mechanical seal oil return point. Taking an external oil station as an example, the mechanical seal oil return goes directly back to the external oil tank, and the pressure is consistent with the local atmospheric pressure.

[0006] To ensure a tight seal, the dynamic and stationary rings of a mechanical seal must fit together closely to prevent media leakage. Therefore, compensating components such as dynamic ring preload springs are usually used to achieve this tight fit. However, after prolonged operation, the dynamic and stationary rings of the mechanical seal will wear (usually the softer dynamic ring will wear more noticeably). As the compression decreases, the elasticity of compensating components, such as springs, decreases, leading to increased leakage or even complete seal failure. Summary of the Invention

[0007] In order to solve the technical problem of the decrease in elasticity of the spring compensation component due to long-term use, which leads to sealing failure or decrease in preload, the present invention proposes a differential pressure mechanical seal structure and compressor.

[0008] The technical solution adopted in this invention is:

[0009] This invention proposes a differential pressure mechanical seal structure, comprising:

[0010] The housing has a mounting cavity, and the opposite sides of the mounting cavity have shaft holes that connect the inside of the housing to the outside.

[0011] A sealing ring is provided at the shaft hole on the side of the mounting cavity facing the outside.

[0012] The input shaft passes through the mounting cavity and the shaft holes on opposite sides of the mounting cavity and the sealing ring, and is used to drive the connection between the inside of the housing and the outside of the housing;

[0013] A sealing ring is fitted onto the input shaft. A sealing pair is provided on the outer ring surface of the sealing ring, which divides the sealed chamber of the mounting cavity into an internal pressure chamber that connects to the inside of the housing and an oil pressure chamber that connects to the oil supply and return channels. The preload force for the dynamic friction surface at the end of the sealing ring to fit against the static friction surface of the sealing ring is provided by the pressure difference.

[0014] In a specific embodiment, a mounting groove is provided on the outer surface of the housing, and a cover is also provided on the outer surface of the housing to cover the mounting groove and form the mounting cavity. A first shaft hole is provided on the housing corresponding to the mounting groove, and a second shaft hole is provided on the cover coaxially with the first shaft hole.

[0015] The present invention also includes: a preload compensation structure for pushing the sealing moving ring or sealing stationary ring to compensate for the preload force.

[0016] The pre-tightening compensation structure includes: a dynamic sealing seat, which is located in the mounting groove and mounted on the input shaft; one end of the sealing ring is elastically connected to the dynamic sealing seat, and the other end is a dynamic friction surface.

[0017] The mounting groove is annular and coaxially arranged with the first shaft hole. An annular sealing spacer is also installed in the mounting groove. The outer wall of the sealing spacer is sealed to the inner wall of the mounting groove, and the inner wall is sealed to the outer sealing pair of the sealing ring.

[0018] The sealing pair is sealed with the comb-like teeth on the inner wall surface of the sealing spacer.

[0019] The inner wall of the second shaft hole of the cover is recessed to form an installation step, and the sealing stationary ring is installed on the installation step.

[0020] The housing is provided with an oil supply channel and an oil return channel that connect to the mounting groove.

[0021] During operation, the internal pressure P1 inside the housing is greater than the sum of atmospheric pressure PA and preset pressure yPA; the return oil pressure P3 of the oil pressure chamber is equal to atmospheric pressure, or not greater than P1 / n and P1-yPA, where n is a preset value.

[0022] The present invention also proposes a compressor, including the aforementioned differential pressure mechanical seal structure, wherein the drive component of the compressor is connected to the portion of the input shaft located outside the housing.

[0023] Compared with existing technologies, the sealing structure of this invention divides the interior of the sealing ring into high and low pressure regions by using a comb-like seal on the rotating sealing ring. This creates a pressure difference on both sides of the compensation ring (usually the rotating sealing ring), and the resulting difference in the projected area corresponding to the pressure forms a preload difference between the rotating and stationary sealing rings. This preload difference does not decrease with wear on the rotating and stationary mechanical seal rings, but is only related to the current operating pressure difference. Furthermore, it perfectly matches the requirements of high preload under large pressure differences and low preload under small pressure differences. The preload compensation structure also compensates for the preload, preventing insufficient preload when the internal pressure is too low or sudden changes in the position of the rotating sealing ring or excessive vibration when the internal pressure changes too much. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a diagram of a sealing structure in the prior art;

[0026] Figure 2 This is a schematic diagram of the sealing structure in an embodiment of the present invention;

[0027] Figure 3 This is a schematic diagram showing the location of each pressure zone of the sealing structure in an embodiment of the present invention;

[0028] Figure 4 This is a schematic diagram of the mounting cavity region in an embodiment of the present invention;

[0029] Figure 5 This is a cross-sectional view of the upper half of the sealing ring in an embodiment of the present invention;

[0030] Figure 6 This is a schematic diagram of the pressure chambers and shaft diameter of the sealing structure in an embodiment of the present invention.

[0031] 1. Housing; 11. Cover; 12. Mounting cavity; 13. Sealing spacer;

[0032] 111. Oil supply channel; 112. Oil return channel;

[0033] 121. Hydraulic chamber;

[0034] 2. Input axis;

[0035] 3. Sealing ring; 31. Spring; 32. Dynamic sealing seat; 33. Sealing pair;

[0036] 4. Sealing stationary ring;

[0037] 5. Sealing ring. Detailed Implementation

[0038] To make the technical problems to be solved, the technical solutions, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0039] The principles and structure of the present invention will be described in detail below with reference to the accompanying drawings and embodiments.

[0040] Semi-hermetic compressors have an external power source, meaning the compressor housing is connected to the power source via an input shaft, and couplings or other devices are also used to transmit power from the external power source to the compressor's enclosed housing, driving the compressor to perform work. Because the power source is external, the sealing between the input shaft and the housing becomes crucial. Common sealing methods include magnetohydrodynamic seals, direct shaft sleeve seals, and mechanical dynamic and static ring seals. Taking mechanical dynamic and static ring seals as an example:

[0041] The rotating ring of the mechanical seal is fixed on the output shaft, and an O-ring seal is formed between the rotating ring and the output shaft. There is no relative movement between the two, so the rotating ring provides a static seal relative to the output shaft. The stationary ring of the mechanical seal is fixed on the pressure housing, and an O-ring seal is formed between the stationary ring and the mechanical seal seat. There is no relative movement between the stationary ring and the mechanical seal seat, so it is also a static seal. The relative movement between the output shaft and the pressure housing occurs on the mating surfaces of the rotating and stationary rings of the mechanical seal. In other words, the rotating and stationary rings of the mechanical seal form a friction pair, which achieves the dynamic seal function.

[0042] Meanwhile, when the equipment is running alternately under large and small differential pressure conditions, the compensation components represented by springs are difficult to meet the different preload requirements: large differential pressure conditions require large preload to ensure sealing, while small differential pressure conditions require small preload to reduce unnecessary shaft power consumption and wear.

[0043] Figure 1The diagram illustrates a classic mechanical seal structure. During equipment operation, driven by the input shaft 2, the stationary sealing ring 4 and the moving sealing ring 3 in the mounting cavity of the housing 1 form a friction pair and generate a large amount of heat through friction. Therefore, a cooling oil circuit is established, including mechanical seal oil supply and mechanical seal oil return. Considering the flow requirements, the mechanical seal oil supply is set to a relatively high value to ensure sufficient oil flow. However, once the cooling oil enters the mechanical seal area, it remains at a low pressure until it leaves the mechanical seal oil return point. Taking the external oil station type as an example, the mechanical seal oil return goes directly back to the external oil tank, and the pressure is consistent with the local atmospheric pressure.

[0044] To ensure a tight seal, the mechanical seal's rotating and stationary rings must fit together to prevent media leakage. Therefore, compensating components such as spring 31 are typically used to achieve this tight fit. However, after prolonged operation, the mechanical seal's rotating and stationary rings will wear down (usually the softer rotating ring will wear down more noticeably). As the compression decreases, the elasticity of compensating components, represented by spring 31, decreases, leading to increased leakage or even complete seal failure.

[0045] In response, this invention proposes a differential pressure mechanical seal structure, which makes the preload of the sealing ring 3 mainly related to the current working pressure and will not continuously decrease, thus ensuring the constant and reliable sealing performance of the mechanical seal throughout its entire service life.

[0046] Specifically, such as Figure 2 , 3As shown, the differential pressure mechanical seal structure specifically includes: a housing 1, an input shaft 2, a stationary sealing ring 4, and a rotating sealing ring 3. The housing 1 has a mounting cavity 12 near its outer surface. The mounting cavity 12 has shaft holes on both opposite sides. The input shaft 2 is inserted into the mounting cavity from the outside of the housing 1, specifically through the shaft hole on the left side of the mounting cavity, and then through the mounting cavity again and into the housing 1 from the shaft hole on the right side of the mounting cavity. This serves to connect the internal components of the housing 1 with the power source outside the housing 1. The rotating sealing ring 3 is located inside the mounting cavity and is fitted onto the input shaft 2. It can move back and forth along the axis of the input shaft 2. The right end of the rotating sealing ring 3 is a dynamic friction surface, which rotates with the input shaft 2. The stationary sealing ring 4 is installed on the inner wall of the right side of the mounting cavity and is located at the shaft hole on the right side of the mounting cavity. This allows the input shaft 2 to pass through the shaft hole on the right side of the mounting cavity 12 and simultaneously pass through the stationary sealing ring 4. The outer ring surface is sealed to the housing 1, meaning that air outside the housing 1 can only enter the mounting cavity through the gap between the sealing stationary ring 4 and the input shaft 2. The left side of the sealing stationary ring 4 is the static sealing surface, which is directly opposite the dynamic friction surface of the sealing rotating ring 3. When the static sealing surface of the sealing stationary ring 4 and the dynamic friction surface of the sealing rotating ring 3 are in contact and rotated to seal, since the sealing rotating ring 3 is also sealed to the outer wall surface of the input shaft 2, the external air cannot continue to penetrate into the housing 1 along the gap between the sealing rotating ring 3 and the input shaft 2. That is, the sealing rotating ring 3 and the sealing stationary ring 4 separate the atmospheric cavity (connected to the outside, with the same air pressure as the outside atmosphere) between the inner ring surface of the rotating and sealing stationary ring 4 and the input shaft 2, and the sealed chamber between the outer ring surface of the rotating and sealing stationary ring 4 and the inner wall directly opposite the mounting cavity. The left side of the sealed chamber is connected to the inside of the housing 1, and the right side is connected to the oil supply channel 111 and the oil return channel 112.

[0047] A sealing pair 33 protrudes from the outer side of the sealing ring 3. This sealing pair 33 further divides the sealed chamber of the mounting groove into an internal pressure chamber located on the left and connected to the inside of the housing 1, and an oil pressure chamber 121 located on the right and connected to the oil supply channel 111 and the oil return channel 112. This allows the internal pressure P1 inside the housing 1 to directly push the sealing ring 3 to the right to provide a preload between the sealing ring and the sealing stationary ring. In other words, the magnitude of the preload can be determined based on the working pressure inside the equipment housing.

[0048] This invention separates the sealing ring by adding an additional sealing pair 33 on the sealing moving ring, thereby providing preload between the sealing moving ring and the sealing stationary ring through the internal pressure inside the equipment. The preload difference does not decrease with the wear of the sealing moving ring and the sealing stationary ring, but is only related to the current operating pressure difference of the equipment; at the same time, it is fully adapted to the equipment's requirements of high preload under large pressure difference and low preload under small pressure difference.

[0049] In specific embodiments, such as Figure 2 , 3As shown, the structure of the housing is as follows: A circular mounting groove is provided on the right side of the housing 1. A cover 11, which closes the mounting groove, is correspondingly installed on the right side of the housing 1, covering the mounting groove and forming the aforementioned mounting cavity. The cover 11 also has a second shaft hole, which is the shaft hole on the right side of the aforementioned mounting cavity. A second shaft hole is also provided on the left side wall of the mounting groove, which is the shaft hole on the left side of the aforementioned mounting cavity. The cover 11 is sealed to the right side of the housing 1, meaning that outside air can only enter the mounting cavity through the second shaft hole in the center of the cover 11.

[0050] Furthermore, the inner wall of the second shaft hole of the cover 11 near the left end is recessed to form an installation step. The sealing ring 4 is sealed and installed on the installation step, that is, the outer ring surface of the sealing ring 4 is sealed and connected with the step of the cover 11, so as to prevent outside air from entering the installation cavity from the gap between the sealing ring 4 and the cover 11, and can only flow into the installation cavity from the gap between the middle of the sealing ring 4 and the input shaft 2.

[0051] Specifically, the outer ring surface of the sealing stationary ring 4 is also stepped, that is, the sealing stationary ring 4 has two outer ring surfaces with different outer diameters. The sealing ring 5 used to seal the sealing stationary ring 4 and the cover 11 is set at the step of the outer ring surface of the sealing stationary ring 4 for sealing, without the need to set an annular groove. At the same time, the step of the sealing stationary ring 4 can also squeeze the sealing ring 5 to achieve the sealing effect.

[0052] Specifically, the sealing structure proposed in this invention also includes a pre-tightening compensation structure, which is used to push the sealing moving ring 3 or the sealing stationary ring 4 to compensate for the pre-tightening force.

[0053] In specific embodiments, such as Figures 2 to 3 As shown, the pre-tightening compensation structure includes a dynamic sealing seat 32;

[0054] The input shaft 2 is also fixedly installed with a rotating dynamic seal seat 32. The dynamic seal seat 32 is located in the mounting cavity and on the left side of the sealing dynamic ring 3. The dynamic seal seat 32 is provided with a spring 31, which is connected to the left end of the sealing dynamic ring 3. That is, the spring 31 of the dynamic seal seat 32 can provide part of the warning force to push the sealing dynamic ring 3 to the right to fit against the sealing stationary ring 4.

[0055] To prevent the sealing ring 3 from losing its sealing effect when the equipment is not working and no internal pressure is provided, or to prevent the sealing ring 3 from wobbling left and right along the input shaft 2 when the internal pressure changes significantly, the elastic connection of the dynamic seal seat 32 can buffer the pre-tightening force, thus preventing the sealing ring 3 from vibrating violently and affecting the equipment's operating conditions when the pressure changes drastically.

[0056] In other embodiments (not shown in the figures), the preload compensation structure may include a static seal seat mounted on the cover, located to the right of the stationary sealing ring, which can push the stationary sealing ring to the left to provide preload force between it and the moving sealing ring.

[0057] It can also prevent the sealing ring from losing its sealing effect when the equipment is not working and no internal pressure is provided, or from swaying left and right when the internal pressure changes greatly. The static sealing seat can buffer the pre-tightening force to prevent the sealing ring from vibrating violently when the pressure changes drastically, thus avoiding affecting the equipment's operating conditions.

[0058] It should be noted that only one dynamic sealing seat 32 or one static sealing seat needs to be set, and both can achieve the effect of compensation and early warning.

[0059] In specific embodiments, such as Figure 2 , 5 As shown in Figure 6, the mounting groove on the right side of the housing 1 is coaxially arranged with the first shaft hole, and a circular sealing spacer 13 is also installed in the mounting groove. The sealing spacer 13 is located at the middle position in the axial direction of the mounting groove. The outer wall surface of the sealing spacer 13 is sealed and fitted with the annular inner wall surface of the mounting groove, and the inner wall surface of the sealing spacer 13 is sealed and connected with the sealing pair 33 on the outer side of the sealing moving ring 3.

[0060] Adding a sealing spacer 13 can reduce the difficulty of sealing and at the same time reduce the size of the sealing pair 33.

[0061] Specifically, the outer wall surface of the sealing pair 33 is comb-shaped, and the inner wall surface of the sealing pair 33 is sealed with the comb teeth of the sealing spacer 13. That is, when the sealing pair 33 rotates with the sealing ring 3, the comb teeth on the outer ring surface of the sealing pair 33 and the inner ring surface of the sealing spacer 13 are in a rotational sealing state, so that the inner pressure chamber on the left side of the sealing pair 33 is separated from the oil pressure chamber 121 on the right side.

[0062] Specifically, because the preload is primarily supplied by the internal pressure of the equipment, which drives the sealing ring, the internal pressure P1 is greater than the sum of the external atmospheric pressure PA and the preset pressure, which is 100 kPa. Therefore, the internal pressure P1 must not be less than PA + 100 kPa. If the internal pressure P1 is less than (PA + 100 kPa), the preload spring on the dynamic seal seat can act as a compensation component to correct the preload value and meet the minimum requirement. Furthermore, the selected preload spring and other compensation components are significantly lower in terms of preload, size, and cost compared to those used in conventional mechanical seals.

[0063] In a specific embodiment, the hardness of the material of the sealing dynamic ring is lower than that of the sealing stationary ring, that is, the sealing dynamic ring is the softer and more significantly worn one, and the pre-tightening compensation structure is set on the mechanical seal dynamic ring.

[0064] like Figure 5 , 6 As shown, the outer diameter of the sealing pair on the sealing ring is D1, the outer diameter of the sealing ring is D3, and the inner diameters of the sealing ring and the sealing stationary ring are the same, both being D2.

[0065] As attached Figure 3 As shown, the internal pressure P1 is on the left side of the rotating ring comb seal, the atmospheric pressure PA is on the inner hole of the rotating ring and stationary ring of the mechanical seal and further to the right, and the pressure in the annular area above the rotating ring and stationary ring of the mechanical seal is the mechanical seal return oil pressure P3.

[0066] At this time, the preload between the dynamic ring and the stationary ring of the mechanical seal is: (P1-P3)·(D1^2-D3^2) / 4·π+(P1-PA)·(D3^2-D2^2) / 4·π.

[0067] If an external oil tank or oil station is configured, the mechanical seal return oil pressure P3 can be directly made to equal PA. If other return oil methods are used, it is necessary to ensure that P3 is not greater than the smaller value between (P1 / 10) and (P1-100kPa). That is, the preset value n can be 10, and the preset pressure yPa can be 100kPa. In addition, the preset value n and the preset pressure yPa can be set to other reasonable numbers as needed, all of which are within the protection scope of this invention.

[0068] The present invention also proposes a compressor including the above-described differential pressure mechanical seal structure.

[0069] Specifically, the compressor is a semi-hermetic compressor, and the compressor's drive component is connected to the portion of the input shaft located outside the housing.

[0070] The sealing structure of this invention divides the interior of the sealing ring into high and low pressure regions by using a comb-like seal on the rotating sealing ring. This creates a pressure difference on both sides of the compensation ring (usually the rotating sealing ring), and the resulting difference in the projected area corresponding to the pressure forms a preload difference between the rotating and stationary sealing rings. This preload difference does not decrease with wear on the rotating and stationary mechanical seal rings, but is only related to the current operating pressure difference. It is perfectly suited to the requirements of high preload under large pressure differences and low preload under small pressure differences. Furthermore, the preload compensation structure compensates for the preload, preventing insufficient preload when the internal pressure is too low or sudden changes in the position of the rotating sealing ring or excessive vibration when the internal pressure changes too much.

[0071] It should be noted that the terminology used above is for describing particular embodiments only and is not intended to limit the exemplary embodiments of the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is intended to include the plural form as well. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0072] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0073] In the description of this invention, it should be understood that the orientation or positional relationship indicated by directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" is generally based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this invention and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the scope of protection of this invention; the directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

[0074] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0075] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this invention.

[0076] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A differential pressure mechanical seal structure, characterized by, The application relates to a pressure-difference type mechanical seal structure. The housing is provided with a mounting cavity, and opposite sides of the mounting cavity are provided with shaft holes which are connected with the inside of the housing and the outside. An input shaft passes through the mounting cavity and the shaft holes on the opposite sides of the mounting cavity and is used for transmission connection between the inside of the housing and the outside of the housing. A sealing dynamic ring is sealingly sleeved on the input shaft, and an outer ring surface of the sealing dynamic ring is provided with a sealing pair, so that a closed chamber of the mounting cavity is divided into an inner pressure cavity connected with the inside of the housing and an oil pressure cavity connected with oil supply and return channels. The outer side of the housing is provided with a mounting groove, and the outer side of the housing is further provided with a cover which covers the mounting groove and forms the mounting cavity.

2. The differential pressure mechanical seal structure of claim 1, wherein The housing is further provided with a pre-tightening compensation structure which is used for pushing the sealing dynamic ring or the sealing static ring to compensate the pre-tightening force.

3. The differential pressure mechanical seal structure as claimed in claim 2, wherein The pre-tightening compensation structure comprises a dynamic sealing seat which is located in the mounting groove and is mounted on the input shaft, one end of the sealing dynamic ring is elastically connected with the dynamic sealing seat, and the other end is a dynamic friction surface. The mounting groove is in a circular ring shape and is coaxially arranged with the first shaft hole.

4. The differential pressure mechanical seal structure of claim 3, wherein The sealing pair is comb-shaped sealed with the inner wall surface of the sealing spacer.

5. The differential pressure mechanical seal structure of claim 2, wherein The second shaft hole of the cover is concave to form a mounting step, and the sealing static ring is mounted on the mounting step.

6. The differential pressure mechanical seal structure of claim 5, wherein The housing is provided with an oil supply channel and an oil return channel which are connected with the mounting cavity.

7. The differential pressure mechanical seal structure of claim 2, wherein The oil return pressure P3 of the oil pressure cavity is equal to the atmospheric pressure or is not greater than P1 / n and P1-yPA, and n is a preset value.

8. The differential pressure mechanical seal structure of claim 1, wherein The application further relates to a compressor which comprises the pressure-difference type mechanical seal structure.

9. The differential pressure mechanical seal structure of claim 1, wherein ​ 10. A compressor characterized by, ​

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