Mechanical sealing structure of vacuum pump

Abstract

The invention relates to the technical field of vacuum pumps, in particular to a vacuum pump mechanical sealing structure which comprises a rotating shaft, the rotating shaft is sleeved with a fixed cylinder, a sealing assembly is arranged between the rotating shaft and the fixed cylinder and comprises a movable sealing piece and a fixed sealing piece, and the movable sealing piece can slide along the rotating shaft; a movable sealing cavity is defined by the rotating shaft, the movable sealing piece, the fixed cylinder and the fixed sealing piece, an overflowing channel is formed in the fixed cylinder, the overflowing channel is communicated with the two ends of the movable sealing cavity to form a circulating oil way, a spiral telescopic assembly is arranged in the movable sealing cavity, and the end, close to the movable sealing piece, of the movable sealing cavity is a jacking end; when the pressure of the vacuum pump working cavity is larger than that in the movable sealing cavity, the spiral telescopic assembly enables the pressure of the top pressure end of the movable sealing cavity to be increased. When the pressure of the vacuum pump working cavity is smaller than that in the movable sealing cavity, the spiral telescopic assembly enables the pressure of the top pressure end of the movable sealing cavity to be reduced, and abrasion of the movable sealing piece is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of vacuum pumps, and in particular to a mechanical sealing structure of a vacuum pump. Background Art

[0002] A screw vacuum pump is a vacuum device that uses a pair of screws to rotate synchronously at high speed in opposite directions in a pump housing to generate suction and exhaust. In the prior art, the rotating shafts of the screw vacuum pumps at both ends need to be equipped with bearings, and the bearings and the working chamber of the vacuum pump need to be isolated and sealed with a sealing structure.

[0003] However, when the vacuum pump is started, the compressed gas will form a positive pressure in the working chamber when it has no time to be discharged. After the compressed gas is discharged, a negative pressure will be formed in the working chamber. This will easily cause the ordinary sealing structure to be unable to meet the constantly changing pressure in the working chamber, making the sealing structure prone to wear and tear, and thus causing the vacuum pump to leak. Summary of the invention

[0004] Based on this, it is necessary to provide a vacuum pump mechanical seal structure to address the technical problem that the current rotor seal structure is prone to wear.

[0005] The above purpose is achieved through the following technical solutions: A vacuum pump mechanical seal structure comprises a rotating shaft, one end of which is externally sleeved with a fixed cylinder, the other end of which extends into a working chamber of the vacuum pump, a sealing assembly is arranged between the rotating shaft and the fixed cylinder, the sealing assembly comprises a movable seal and a fixed seal arranged axially apart from each other along the rotating shaft, the movable seal can slide along the length direction of the rotating shaft, so that a movable sealing chamber is formed between the rotating shaft, the movable seal, the fixed cylinder and the fixed seal, flowing lubricating oil is arranged in the movable sealing chamber, a flow channel extending axially thereof is arranged inside the fixed cylinder, the flow channel is connected with two ends of the movable sealing chamber to form a circulating oil circuit, the side of the movable seal away from the movable sealing chamber is arranged in contact with the working chamber of the vacuum pump, a spiral telescopic assembly is arranged in the movable sealing chamber, and a movable seal is defined. The end of the sealing chamber close to the movable seal is the top pressure end; when the pressure in the working chamber of the vacuum pump is greater than the pressure in the movable sealing chamber, the movable seal gradually approaches the fixed seal and compresses the spiral telescopic assembly, causing the spiral telescopic assembly to shrink radially inwardly, thereby pressing the outer circumferential surface of the rotating shaft, guiding the lubricating oil to circulate forward along the circulating oil circuit, thereby the lubricating oil in the movable sealing chamber flows toward the direction close to the top pressure end, and the pressure at the top pressure end of the movable sealing chamber increases; when the pressure in the working chamber of the vacuum pump is less than the pressure in the movable sealing chamber, the movable seal gradually moves away from the fixed seal and stretches the spiral telescopic assembly, causing the spiral telescopic assembly to expand radially outwardly, thereby pressing the inner circumferential surface of the fixed cylinder, guiding the lubricating oil to circulate reversely along the circulating oil circuit, thereby the lubricating oil in the movable sealing chamber flows toward the direction away from the top pressure end, and the pressure at the top pressure end of the movable sealing chamber decreases.

[0006] Furthermore, the spiral telescopic assembly includes a spiral baffle, a pull rope is passed through the spiral baffle, the spiral baffle is coaxially arranged with the rotating shaft, and the spiral baffle is provided with a plurality of connecting holes evenly distributed around the spiral direction, and the interval between two adjacent connecting holes is larger than one circle of the spiral baffle, and the pull rope is passed through the plurality of connecting holes, and when the spiral baffle is in a compressed state, the pull rope is in a bent state, and when the spiral baffle is in a stretched state, the pull rope is in a straightened state.

[0007] Furthermore, the two ends of the pull rope are respectively connected to a first bearing assembly and a second bearing assembly, the first bearing assembly includes a first bearing, an installation groove is provided inside the movable seal, the bearing inner ring of the first bearing is fixedly set in the installation groove, a first sleeve is slidably provided on the bearing outer ring of the first bearing, the first sleeve slides axially along the rotating shaft in the installation groove, the second bearing assembly includes a second bearing, the bearing inner ring of the second bearing is fixedly set on the rotating shaft, a second sleeve is fixedly provided on the bearing outer ring of the second bearing, and the two ends of the pull rope are respectively fixedly set on the first sleeve and the second sleeve.

[0008] Further, the pull rope is fixedly connected to one of the connection holes, and the pull rope is slidably connected to the remaining connection holes. Further, a locking member is provided on the first sleeve, and the locking member limits the first sleeve from rotating relative to the movable seal when the spiral barrier strip is stretched.

[0009] Furthermore, the locking member includes a bearing baffle, which is arranged corresponding to the first bearing in the axial direction of the rotating shaft, and a spring is provided between the bearing baffle and the first bearing, and a plurality of grooves are provided in the circumferential direction of the bearing baffle, and a clamping block corresponding to the groove is provided on the movable seal, and when the clamping block is engaged with the groove, the bearing baffle is restricted from rotating relative to the movable seal, and the spring has a tendency to separate the clamping block and the groove from each other.

[0010] Furthermore, the movable sealing component is provided with a baffle extending radially along the rotating shaft, the bearing baffle plate and the first bearing are respectively located on two side surfaces of the baffle along the axial direction of the rotating shaft, and the clamping groove is located on the baffle.

[0011] Furthermore, a sliding plate is fixedly provided on the movable sealing component, and a long groove and a connecting hole are provided on the sliding plate, which are interconnected. The long groove extends along the axial direction of the rotating shaft, and the connecting hole extends along the radial direction of the rotating shaft. A sliding block is provided on the inner wall of the fixed cylinder, and the sliding block is slidably matched with the long groove, and the connecting hole and the long groove jointly connect the movable sealing cavity and the flow channel.

[0012] Furthermore, a throttle valve is provided in the flow passage, and the throttle valve can control the flow rate of the flow passage.

[0013] Furthermore, a third bearing is provided in the movable sealing chamber, and the third bearing enables the rotating shaft to rotate relative to the fixed cylinder, and the interior of the third bearing is communicated with the movable sealing chamber.

[0014] The beneficial effects of the present invention are: The mechanical seal structure of the vacuum pump provided by the present invention has the following characteristics: when the pressure in the working chamber of the vacuum pump is greater than the pressure in the movable seal chamber, that is, when the working chamber of the vacuum pump generates a positive pressure, the pressure at the top pressure end in the movable seal chamber also increases, so that the top pressure end can resist the positive pressure in the working chamber of the vacuum pump; when the pressure in the working chamber of the vacuum pump is less than the pressure in the movable seal chamber, that is, when the working chamber of the vacuum pump generates a negative pressure, the pressure at the top pressure end in the movable seal chamber also decreases, so that the top pressure end can resist the negative pressure in the working chamber of the vacuum pump, thereby reducing the pressure difference between the working chamber of the vacuum pump and the movable seal chamber, reducing the wear of the movable seal, and thus ensuring the sealing effect of the sealing assembly.

[0015] Secondly, during the movement of the movable seal, the lubricating oil can circulate and promote the flow of the lubricating oil inside the first bearing, the second bearing and the third bearing, thereby ensuring the lubrication effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 A schematic diagram of the three-dimensional structure of a mechanical seal structure of a vacuum pump provided by an embodiment of the present invention; Figure 2 A schematic cross-sectional view of a fixed cylinder in a mechanical seal structure of a vacuum pump provided by an embodiment of the present invention; Figure 3 A schematic structural diagram of a mechanical seal structure of a vacuum pump provided by an embodiment of the present invention without a fixed cylinder; Figure 4 A cross-sectional view of a mechanical seal structure for a vacuum pump provided by an embodiment of the present invention without a fixed cylinder; Figure 5 for Figure 4 A magnified view of the structure at center; Figure 6 for Figure 5 A magnified view of the structure at B in the middle; Figure 7 A cross-sectional view of a first state of a mechanical seal structure of a vacuum pump provided by an embodiment of the present invention; Figure 8 A cross-sectional view of a second state of a mechanical seal structure of a vacuum pump provided by an embodiment of the present invention; Fig. 9 for Figure 7 A magnified view of the structure at C in the middle; Fig.10 for Figure 8 A magnified view of the structure at D in the middle; Fig.11 A schematic diagram of a stretched state of a spiral telescopic assembly in a mechanical seal structure of a vacuum pump provided by an embodiment of the present invention; Fig.12 A schematic diagram of a compressed state of a spiral telescopic assembly in a mechanical seal structure of a vacuum pump provided in an embodiment of the present invention.

[0017] in: 101. rotating shaft; 102. fixed seal; 103. stop ring; 104. third bearing; 105. sliding plate; 1051. long groove; 1052. connecting hole; 106. fixed cylinder; 1061. flow passage; 1062. throttle valve; 107. movable seal; 1071. slot; 108. second bearing; 1081. second bushing; 109. first bushing; 1091. bearing baffle; 1092. spring; 1093. block; 1094. fixed block; 110. first bearing; 200. spiral telescopic assembly; 201. spiral baffle; 202. pull rope; 2021. fixed ring. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below through embodiments and in conjunction with the accompanying drawings. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0019] The serial numbers assigned to the components herein, such as "first", "second", etc., are only used to distinguish the objects described and do not have any order or technical meaning. The "connection" and "coupling" mentioned in the present invention, unless otherwise specified, include direct and indirect connections (couplings). In the description of the present invention, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", etc., indicating the orientation or position relationship are based on the orientation or position relationship shown in the accompanying drawings, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the present invention.

[0020] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0021] like Figures 1 to 12 As shown, a vacuum pump mechanical seal structure provided by an embodiment of the present invention includes a rotating shaft 101, one end of which is sleeved with a fixing cylinder 106, and the other end of the rotating shaft 101 extends into a working chamber of the vacuum pump (not shown in the figure, the working chamber corresponds to Figure 1The left blank position in the middle), a sealing assembly is provided between the rotating shaft 101 and the fixed cylinder 106, and the sealing assembly includes a movable seal 107 and a fixed seal 102 which are arranged axially apart from each other along the rotating shaft 101, and the movable seal 107 can slide along the length direction of the rotating shaft 101, so that a movable sealing chamber is surrounded by the rotating shaft 101, the movable seal 107, the fixed cylinder 106 and the fixed seal 102, and flowing lubricating oil is provided in the movable sealing chamber, and a flow passage extending along the axial direction of the fixed cylinder 106 is provided inside, and the flow passage 1061 is connected with both ends of the movable sealing chamber to form a circulating oil circuit, and the side of the movable seal 107 away from the movable sealing chamber is arranged in contact with the working chamber of the vacuum pump, and a spiral telescopic assembly 200 is provided in the movable sealing chamber, and the end of the movable sealing chamber close to the movable seal 107 is defined as Top pressure end; when the pressure in the working chamber of the vacuum pump is greater than the pressure in the movable sealing chamber, the movable seal 107 gradually approaches the fixed seal 102 and compresses the spiral telescopic assembly 200, so that the spiral telescopic assembly 200 shrinks radially inwardly to press the outer circumferential surface of the rotating shaft 101, and guides the lubricating oil to circulate in the positive direction along the circulating oil circuit, so that the lubricating oil in the movable sealing chamber flows toward the direction close to the top pressure end, and the pressure at the top pressure end of the movable sealing chamber increases; when the pressure in the working chamber of the vacuum pump is less than the pressure in the movable sealing chamber, the movable seal 107 gradually moves away from the fixed seal 102, and stretches the spiral telescopic assembly 200, so that the spiral telescopic assembly 200 expands radially outwardly to press the inner circumferential surface of the fixed cylinder 106, and guides the lubricating oil to circulate in the reverse direction along the circulating oil circuit, so that the lubricating oil in the movable sealing chamber flows in the direction away from the top pressure end, and the pressure at the top pressure end of the movable sealing chamber is reduced.

[0022] After such arrangement, when the pressure in the working chamber of the vacuum pump is greater than the pressure in the movable sealing chamber, that is, when the working chamber of the vacuum pump generates a positive pressure, the pressure at the top pressure end in the movable sealing chamber also increases, so that the top pressure end can resist the positive pressure in the working chamber of the vacuum pump; when the pressure in the working chamber of the vacuum pump is less than the pressure in the movable sealing chamber, that is, when the working chamber of the vacuum pump generates a negative pressure, the pressure at the top pressure end in the movable sealing chamber also decreases, so that the top pressure end can resist the negative pressure in the working chamber of the vacuum pump; in this way, the pressure difference between the working chamber of the vacuum pump and the movable sealing chamber can be reduced, and the wear degree of the movable seal 107 can be reduced, thereby ensuring the sealing effect of the sealing assembly.

[0023] The movable seal 107 and the fixed seal 102 are rotatably arranged on the rotating shaft 101 , so that they will not rotate along with the rotation of the rotating shaft 101 .

[0024] Furthermore, the spiral telescopic assembly 200 includes a spiral baffle 201, a pull rope 202 is passed through the spiral baffle 201, the spiral baffle 201 is coaxially arranged with the rotating shaft 101, and the spiral baffle 201 is provided with a plurality of connection holes evenly distributed around the spiral direction, the interval between two adjacent connection holes is greater than one circle of the spiral baffle, and the pull rope 202 is passed through the plurality of connection holes. Figure 8 As shown, when the spiral barrier strip 201 is in a compressed state, the pull rope 202 is in a bent state (corresponding to the second state). Figure 7 As shown, when the spiral baffle 201 is in a stretched state, the pull rope 202 is in a straightened state (corresponding to the first state). Specifically, the interval between two adjacent connection holes is greater than one circle of the spiral baffle and less than one and a half circles of the spiral baffle, so as to ensure that the spiral baffle 201 can be radially expanded to a suitable size after the pull rope 202 is straightened.

[0025] Further, the two ends of the pull rope 202 are respectively connected to a first bearing assembly and a second bearing assembly, the first bearing assembly includes a first bearing 110, the movable seal 107 is provided with a mounting groove inside, the bearing inner ring of the first bearing 110 is fixedly arranged in the mounting groove, the bearing outer ring of the first bearing 110 is slidably provided with a first sleeve 109, the first sleeve 109 slides in the mounting groove along the axial direction of the rotating shaft 101, and the second bearing assembly is fixedly arranged in the movable sealing cavity; the second bearing assembly includes a second bearing 108, the bearing inner ring of the second bearing 108 is fixedly arranged on the rotating shaft 101, the bearing outer ring of the second bearing 108 is fixedly provided with a second sleeve 1081, and the two ends of the pull rope 202 are respectively fixedly arranged on the first sleeve 109 and the second sleeve 1081. The first sleeve 109 and the second sleeve 1081 are both provided with a fixing block 1094, and the fixing block 1094 is provided with a mounting hole, and the pull rope 202 is passed through the mounting hole and fixed by bolts.

[0026] Furthermore, the pull rope 202 is fixedly connected to one of the connection holes, and the pull rope 202 is slidably connected to the remaining connection holes. Fig.11 As shown, the pull rope 202 is fixed with two fixing rings 2021 distributed along the length direction thereof, and the two fixing rings 2021 sandwich one of the connecting holes in the middle, so that the pull rope 202 cannot move relative to the connecting hole.

[0027] Furthermore, a locking member is provided on the first sleeve 109, and the locking member limits the first sleeve 109 from rotating relative to the movable seal 107 when the spiral baffle 201 is stretched. In this way, both ends of the pull rope 202 cannot rotate, ensuring the radial expansion of the spiral baffle 201.

[0028] Furthermore, the locking member includes a bearing baffle 1091, and the bearing baffle 1091 and the first bearing 110 are correspondingly arranged in the axial direction of the rotating shaft 101, and a spring 1092 is provided between the bearing baffle 1091 and the first bearing 110, and a plurality of grooves 1071 are provided on the circumference of the bearing baffle 1091, and a block 1093 corresponding to the groove 1071 is provided on the movable seal 107, and when the block 1093 is engaged with the groove 1071, the bearing baffle 1091 is restricted from rotating relative to the movable seal 107, and the spring 1092 has a tendency to separate the block 1093 and the groove 1071 from each other.

[0029] Furthermore, the movable seal 107 is provided with a stopper extending radially along the rotating shaft 101 , the bearing stopper 1091 and the first bearing 110 are respectively located on two side surfaces of the stopper along the axial direction of the rotating shaft 101 , and the clamping groove 1071 is located on the stopper.

[0030] Furthermore, a sliding plate 105 is fixedly provided on the movable seal 107, and a long groove 1051 and a connecting hole 1052 are provided on the sliding plate 105, which are connected to each other, and the long groove 1051 extends along the axial direction of the rotating shaft 101, and the connecting hole 1052 extends along the radial direction of the rotating shaft 101. A slider is provided on the inner wall of the fixed cylinder 106, and the slider is slidably matched with the long groove 1051, and the connecting hole 1052 and the long groove 1051 jointly connect the movable seal cavity and the flow passage 1061. The long groove 1051 and the slider are provided to prevent the movable seal 107 from being separated from the fixed cylinder 106, and to prevent the connecting hole 1052 from being unable to connect the movable seal cavity and the flow passage 1061 after the movable seal 107 moves.

[0031] Furthermore, a throttle valve 1062 is provided in the flow passage 1061, and the throttle valve 1062 can control the flow of the flow passage 1061. Figure 7 and Figure 8 As shown, the throttle valve 1062 is a throttle bolt, and a threaded hole penetrating the flow channel 1061 is provided on the fixed cylinder 106. The throttle bolt is rotated to move in the threaded hole to control the flow in the flow channel 1061. By controlling the flow in the flow channel 1061, the flow speed of the hydraulic oil can be reduced, ensuring that the pressure at the top pressure end increases when the circulating oil circuit flows in the forward direction, and the pressure at the top pressure end decreases when the circulating oil circuit flows in the reverse direction.

[0032] Furthermore, a third bearing 104 is provided in the movable sealing chamber, and the third bearing 104 enables the rotating shaft 101 to rotate relative to the fixed cylinder 106, and the third bearing 104 and the rotating shaft 101 are stopped and matched in the axial direction of the rotating shaft 101, and the interior of the third bearing 104 is connected to the movable sealing chamber. Figure 7As shown, two third bearings 104 are provided, and a stop ring 103 is provided between the third bearing 104 and the fixed seal 102. In other implementations, more than three third bearings 104 can be provided. During the movement of the movable seal 107, the lubricating oil can circulate to promote the flow of the lubricating oil inside the first bearing 110, the second bearing 108 and the third bearing 104, thereby ensuring the lubrication effect.

[0033] In combination with the above embodiments, the use principle and working process of the embodiments of the present invention are as follows: In the initial state, the inner circumference of the spiral baffle 201 is not pressed against the outer circumference of the rotating shaft 101, and the outer circumference of the spiral baffle 201 is not pressed against the inner circumference of the fixed cylinder 106. Under the action of the lubricating oil, the rotation of the rotating shaft 101 can drive the spiral baffle 201 to rotate slowly, so that the spiral baffle 201 stirs the lubricating oil in the movable sealing chamber.

[0034] When the pressure in the working chamber of the vacuum pump is greater than the pressure in the movable sealing chamber, that is, when the working chamber of the vacuum pump generates positive pressure, the movable sealing member 107 gradually approaches the fixed sealing member 102 and compresses the spiral telescopic assembly 200, so that the spiral baffle 201 of the spiral telescopic assembly 200 is radially retracted and presses the outer peripheral surface of the rotating shaft 101, the pull rope 202 is further bent, and the spiral baffle 201 rotates synchronously with the rotating shaft 101. Under the guidance of the spiral of the spiral baffle 201 itself, the lubricating oil flows from the second bearing 108 to the first bearing 110 in the movable sealing chamber, and flows to the third bearing 104 through the flow channel 1061. At this time, the circulating oil circuit is a positive circulation flow. Since the throttle valve 1062 limits the flow in the flow channel 1061, the pressure at the top pressure end of the movable sealing chamber is increased, so that the top pressure end can resist the positive pressure of the working chamber of the vacuum pump.

[0035] When the pressure in the working chamber of the vacuum pump is less than the pressure in the movable sealing chamber, that is, when the working chamber of the vacuum pump generates negative pressure, the movable sealing member 107 gradually moves away from the fixed sealing member 102, and the movable sealing member 107 slides relative to the first shaft sleeve 109, and then the stopper of the movable sealing member 107 and the bearing baffle 1091 approach each other, the spring 1092 is compressed, and at the same time, the block 1093 on the bearing baffle 1091 cooperates with the groove 1071 on the movable sealing member 107, so that the first shaft sleeve 109 cannot rotate relative to the movable sealing member 107. As the first shaft sleeve 109 moves, the spiral telescopic assembly 200 is stretched, and the pull rope 202 is straightened, so that the spiral telescopic assembly 200 can be stretched. The spiral baffle 201 of the shrink assembly 200 expands radially outward to press against the inner circumference of the fixed cylinder 106. At this time, since the spiral baffle 201 does not rotate with the rotating shaft 101, the spiral baffle 201 rotates in the opposite direction relative to the rotating shaft 101. Under the guidance of the spiral of the spiral baffle 201 itself, the lubricating oil flows from the first bearing 110 to the second bearing 108 in the movable sealing chamber, and then flows through the third bearing 104 and the flow channel 1061. At this time, the circulating oil circuit is a reverse circulation flow. Since the throttle valve 1062 limits the flow in the flow channel 1061, the pressure at the top pressure end of the movable sealing chamber is reduced, so that the top pressure end can resist the negative pressure of the working chamber of the vacuum pump.

[0036] As the pressure in the working chamber of the vacuum pump gradually increases to be equal to the pressure in the movable sealing chamber, the spiral telescopic assembly 200 will gradually shrink and return to its original state. During this process, the elastic force of the spiral telescopic assembly 200 pulls the bearing baffle 1091, so that the block 1093 on the bearing baffle 1091 is always matched with the slot 1071 on the movable seal 107. After the spiral telescopic assembly 200 returns to its original state, the spiral telescopic assembly 200 no longer shrinks, so that the spring 1092 will stretch, so that the block 1093 on the bearing baffle 1091 is disengaged from the slot 1071 on the movable seal 107, and the spiral baffle 201 can rotate freely and slowly.

[0037] It should be noted that the rotation direction of the spiral baffle 201 is related to the rotation direction of the shaft 101 , and it is only necessary to ensure that the spiral baffle 201 can achieve the above-mentioned flow direction of the lubricating oil in the movable sealing chamber during the rotation of the shaft 101 .

[0038] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0039] The above-described embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the present invention. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the attached claims.

Claims

1. A vacuum pump mechanical seal structure, characterized in that: It comprises a rotating shaft, one end of which is externally sleeved with a fixed cylinder, and the other end of the rotating shaft extends into the working chamber of the vacuum pump, a sealing assembly is arranged between the rotating shaft and the fixed cylinder, and the sealing assembly comprises a movable seal and a fixed seal arranged axially apart from each other along the rotating shaft, and the movable seal can slide along the length direction of the rotating shaft, so that a movable sealing chamber is surrounded by the rotating shaft, the movable seal, the fixed cylinder and the fixed seal, and flowing lubricating oil is arranged in the movable sealing chamber, and a flow channel extending along the axial direction of the fixed cylinder is arranged inside the fixed cylinder, and the flow channel is connected with two ends of the movable sealing chamber to form a circulating oil circuit, and a side of the movable seal away from the movable sealing chamber is arranged in contact with the working chamber of the vacuum pump, and a spiral telescopic assembly is arranged in the movable sealing chamber, which defines the movable sealing chamber close to the movable sealing chamber. One end of the seal is the top pressure end; when the pressure in the working chamber of the vacuum pump is greater than the pressure in the movable sealing chamber, the movable seal gradually approaches the fixed seal and compresses the spiral telescopic assembly, causing the spiral telescopic assembly to shrink radially inwardly, thereby pressing the outer circumferential surface of the rotating shaft, and guiding the lubricating oil to circulate forward along the circulating oil circuit, so that the lubricating oil in the movable sealing chamber flows toward the direction close to the top pressure end, and the pressure at the top pressure end of the movable sealing chamber increases; when the pressure in the working chamber of the vacuum pump is less than the pressure in the movable sealing chamber, the movable seal gradually moves away from the fixed seal and stretches the spiral telescopic assembly, causing the spiral telescopic assembly to expand radially outwardly, thereby pressing the inner circumferential surface of the fixed cylinder, and guiding the lubricating oil to circulate reversely along the circulating oil circuit, so that the lubricating oil in the movable sealing chamber flows toward the direction away from the top pressure end, and the pressure at the top pressure end of the movable sealing chamber decreases.

2. The vacuum pump mechanical seal structure according to claim 1, characterized in that: The spiral telescopic assembly includes a spiral baffle, a pull rope is passed through the spiral baffle, the spiral baffle is coaxially arranged with the rotating shaft, and the spiral baffle is provided with a plurality of connection holes evenly distributed around the spiral direction, and the interval between two adjacent connection holes is greater than one circle of the spiral baffle, the pull rope is passed through the plurality of connection holes, when the spiral baffle is in a compressed state, the pull rope is in a bent state, and when the spiral baffle is in a stretched state, the pull rope is in a straightened state.

3. The vacuum pump mechanical seal structure according to claim 2, characterized in that: The two ends of the pull rope are respectively connected to the first bearing assembly and the second bearing assembly, the first bearing assembly includes a first bearing, the interior of the movable seal is provided with an installation groove, the bearing inner ring of the first bearing is fixedly set in the installation groove, the bearing outer ring of the first bearing is slidably provided with a first sleeve, the first sleeve slides axially along the rotating shaft in the installation groove, the second bearing assembly includes a second bearing, the bearing inner ring of the second bearing is fixedly set on the rotating shaft, the bearing outer ring of the second bearing is fixedly provided with a second sleeve, and the two ends of the pull rope are respectively fixedly set on the first sleeve and the second sleeve.

4. The vacuum pump mechanical seal structure according to claim 3, characterized in that: The pull rope is fixedly connected to one of the connection holes, and the pull rope is slidably connected to the remaining connection holes.

5. The vacuum pump mechanical seal structure according to claim 3, characterized in that: A locking piece is arranged on the first shaft sleeve, and the locking piece restricts the first shaft sleeve from rotating relative to the movable sealing piece when the spiral baffle is stretched.

6. The vacuum pump mechanical seal structure according to claim 5, characterized in that: The locking member includes a bearing baffle, which is arranged corresponding to the first bearing in the axial direction of the rotating shaft, and a spring is arranged between the bearing baffle and the first bearing, and a plurality of grooves are arranged in the circumferential direction of the bearing baffle, and a clamping block corresponding to the groove is provided on the movable seal, and when the clamping block is engaged with the groove, the bearing baffle is restricted from rotating relative to the movable seal, and the spring has a tendency to separate the clamping block and the groove from each other.

7. The vacuum pump mechanical seal structure according to claim 6, characterized in that: The movable seal is provided with a baffle extending along the radial direction of the rotating shaft, the bearing baffle plate and the first bearing are respectively located on two side surfaces of the baffle along the axial direction of the rotating shaft, and the clamping groove is located on the baffle.

8. The vacuum pump mechanical seal structure according to claim 1, characterized in that: A sliding plate is fixed on the movable sealing component, and a long groove and a connecting hole are provided on the sliding plate, which are interconnected. The long groove extends along the axial direction of the rotating shaft, and the connecting hole extends along the radial direction of the rotating shaft. A sliding block is provided on the inner wall of the fixed cylinder, and the sliding block is slidably matched with the long groove. The connecting hole and the long groove jointly connect the movable sealing cavity and the flow channel.

9. The vacuum pump mechanical seal structure according to claim 1, characterized in that: A throttle valve is provided in the flow passage, and the throttle valve can control the flow rate of the flow passage.

10. The vacuum pump mechanical seal structure according to claim 1, characterized in that: A third bearing is also provided in the movable sealing chamber. The third bearing enables the rotating shaft to rotate relative to the fixed cylinder. The interior of the third bearing is communicated with the movable sealing chamber.

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