A shaft end seal for a concrete mixer and the concrete mixer thereof

Abstract

This invention provides a shaft end seal for a concrete mixer, comprising a protective ring A and a protective ring B. The protective ring A and protective ring B have a stepped stop fit. The radial gap between the stepped-fitting protective rings A and B includes a first gap and a second gap. A centrifugal device is installed in the first gap to pressurize and discharge impurities from the gap between protective rings A and B. At least one set of liquid film vibration damping devices is installed in the second gap, each with a slit to form a water film. This invention can reduce the amount of sand and mud entering the sealing surface between the second sealing ring and the shaft locking assembly, effectively balance the unbalanced force generated during the rotation of the centrifugal device, or reduce the axial vibration experienced by the shaft end seal structure.

Description

Technical Field

[0001] This invention relates to the field of mixer equipment or sealing and vibration resistance, and in particular to a shaft end seal for a concrete mixer and the concrete mixer thereof. Background Technology

[0002] With the rapid development of industries such as construction, high-speed rail, and hydropower, concrete mixing plants are springing up everywhere, leading to a surge in demand for horizontal concrete mixers. Horizontal shaft concrete mixers utilize blades mounted on a horizontally arranged mixing shaft to achieve forced mixing of the mixture through shearing, compression, tumbling, and throwing, ensuring uniform mixing through vigorous relative motion. During mixing, cement slurry in the mixture easily seeps into the gaps between the transmission and stationary components on both sides of the mixing tank, resulting in leakage. Because the slurry contains solid particles such as sand, once it squeezes into the gap between the moving and stationary components, it will wear down these components. If cement slurry clogs the lubrication port, it will partially harden within the gap, accelerating wear and damage to the components, and causing leakage at the shaft end. If cement slurry breaches the seal of the bearing assembly and enters and damages the bearing, the mixer will malfunction. The performance of the shaft head sealing structure is a key technology for horizontal concrete mixers. To ensure the sealing performance of the shaft head, the shaft head sealing structure usually needs to be lubricated with grease to ensure the sealing effect and the service life of the shaft head seal.

[0003] Currently, most horizontal shaft mixers both domestically and internationally employ floating oil seal structures for their shaft end seals. The key feature is that the contact surfaces of the two floating sealing rings maintain an oil film during operation. Grease should be replenished randomly in the assembly gap channel to ensure the lubricating grease fills the gap, guaranteeing that the floating sealing rings, while tightly sealing under force, can also generate good relative rotation under good lubrication and press against the inner wall of the mixing tank during operation, preventing cement slurry from penetrating. While this type of floating seal effectively seals the shaft end, the harsh working environment of mixers means that if the seal before the floating seal is faulty or damaged, fine mortar particles can still enter, causing the floating ring seal to quickly fail. In actual mixers, shaft end seals using floating seals often have 3-4 or more sealing layers, which increases the machining precision and manufacturing cost of the mixer housing.

[0004] Furthermore, with the development of horizontal shaft mixers with vibrating mixing shafts, the mixing shaft and its blades can be driven to vibrate while being forcibly mixed, greatly improving the mixing quality and efficiency of concrete. However, the vibration of the mixer causes the shaft end seal to fail quickly, making it easier for cement mortar to enter the shaft end gap, resulting in mortar leakage, severe wear on the shaft end and bearings, and shortening its service life. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a shaft end sealing structure for a concrete mixer. A centrifugal device is installed in the first gap between protective ring A and protective ring B. The centrifugal device pressurizes and discharges impurities from the gap between protective ring A and protective ring B, which can reduce the entry of sand and mud into the sealing surface between the second sealing ring and the shaft locking assembly, reduce the wear risk of the second sealing ring, and improve the sealing life of the shaft end sealing structure.

[0006] The present invention achieves the above-mentioned technical objectives through the following technical means.

[0007] A shaft end seal for a concrete mixer includes a protective ring A and a protective ring B. The protective ring A and the protective ring B are fitted with a stepped stop. The radial gap between the stepped-fitting protective ring A and the protective ring B includes a first gap and a second gap. A centrifugal device is provided in the first gap to pressurize and discharge impurities in the gap between the protective ring A and the protective ring B. At least one set of liquid film vibration damping devices is provided in the second gap. The liquid film vibration damping devices have gaps. By forming a water film at the gaps, the unbalanced force generated by the centrifugal device during rotation can be effectively balanced, or the axial vibration of the shaft end seal structure can be reduced, thereby improving its service life.

[0008] Furthermore, the centrifugal device includes a first blade and a second blade. Several second blades are evenly distributed on one side of the protective ring B. The second blades have a frontal surface and a backal surface. One end of the frontal surface of the second blade extends radially to the edge of the protective ring B. At least one first blade is provided on the upper surface of each second blade. The outline of the first blade is smaller than that of the second blade. The second blade uses centrifugal force to throw out the sand and mud that enter the first gap. However, some fine sand will still enter the root of the second blade, and the purpose of the first blade is to throw out this part of fine sand.

[0009] Furthermore, the radius of curvature of the first blade's frontal surface is R1 = (0.4~0.6)R, and the radius of curvature of the first blade's backal surface is R2 = (0.2~0.3)R, where R is the radius of the outer circle of the protective ring B.

[0010] Furthermore, the thickness of the second blade increases radially, while the thickness of the first blade decreases radially, and the maximum thickness of the first blade does not exceed the maximum thickness of the second blade; an arc-shaped guide vane is provided at the junction of the frontal and back surfaces of the first blade.

[0011] Furthermore, the liquid film vibration damping device includes a stationary ring and a moving ring. One end of the stationary ring is mounted on a protective ring A; one end of the moving ring is mounted on a protective ring B; a gap is provided between the stationary ring and the moving ring to form a water film at the gap.

[0012] Furthermore, the gap between the stationary ring and the moving ring is an inclined gap, and the water film formed by the inclined gap is frustoconical.

[0013] Furthermore, the protective ring A is provided with an annular groove, one end of the stationary ring is located in the annular groove, and the gap between the stationary ring and the moving ring is located in the annular groove. The water film is located in the annular groove, and the water film can be regarded as elastic damping, which can reduce some vibration. In addition, the vibration generated by the water film will collide and bounce on the wall of the annular groove, which will further slow down the vibration generated by the water film.

[0014] Furthermore, the axial gap between the protective ring A and the protective ring B in the stepped fit is the third gap. A hydrophilic texture is provided on the surface of the third gap to form a hydrophilic surface. The hydrophilic surface is used to form a water film for sealing in the third gap, which prevents the fine sand and mud-water mixture that enters the first and second gaps from entering the shaft head seal.

[0015] Furthermore, it also includes a liquid replenishment device, which includes a water film replenishment channel. The protective ring A is provided with a water film replenishment channel. One end of the water film replenishment channel is connected to an external dripping system, and the outlet of the other end of the water film replenishment channel is located directly above the gap, replenishing the liquid film by dripping.

[0016] A concrete mixer, wherein the shaft end of the mixer is fitted with the shaft end seal of the concrete mixer.

[0017] The beneficial effects of this invention are as follows:

[0018] 1. The shaft end sealing structure of the concrete mixer of the present invention has a centrifugal device in the first gap between the protective ring A and the protective ring B. The centrifugal device pressurizes and discharges impurities in the gap between the protective ring A and the protective ring B, which can reduce the entry of sand and mud into the sealing surface between the second sealing ring and the shaft locking assembly, reduce the wear risk of the second sealing ring, and improve the sealing life of the shaft end sealing structure.

[0019] 2. The shaft end sealing structure of the concrete mixer of the present invention includes a centrifugal device comprising a first blade and a second blade; a plurality of second blades are evenly distributed on one side of the protective ring B, the second blades having a frontal surface and a backal surface, one end of the frontal surface of the second blades extending radially to the edge of the protective ring B; at least one first blade is provided on the upper surface of each second blade; the outline of the first blade is smaller than the outline of the second blade, the second blades use centrifugal force to throw out the sand and mud entering the first gap, but some fine sand will still enter the root of the second blade, and the purpose of the first blades is to throw out this part of fine sand.

[0020] 3. The shaft end sealing structure of the concrete mixer of the present invention has at least one set of liquid film vibration damping devices installed in the second gap. The liquid film vibration damping devices have gaps, and water films are formed in the gaps to reduce vibration. By forming water films in the gaps, the unbalanced forces generated by the centrifugal device during rotation can be effectively balanced, or the axial vibration of the shaft end sealing structure can be reduced, thereby improving the service life.

[0021] 4. The shaft end sealing structure of the concrete mixer of the present invention has an annular groove on the protective ring A, one end of the first stationary ring is located in the annular groove, and the gap between the first stationary ring and the first moving ring is located in the annular groove. The water film is located in the annular groove. The water film can be regarded as elastic damping, which can reduce some vibration. In addition, the vibration generated by the water film will collide and rebound on the wall of the annular groove, thereby further slowing down the vibration generated by the water film.

[0022] 5. In the shaft end sealing structure of the concrete mixer of the present invention, the axial gap between the stepped protective ring A and the protective ring B is a third gap. A hydrophilic texture is provided on the surface at the axial gap to form a hydrophilic surface. The hydrophilic surface can more easily form a sealing water film in the third gap, which prevents the fine sand and mud-water mixture that enters the first and second gaps from entering the shaft end seal.

[0023] 6. The shaft end sealing structure of the concrete mixer of the present invention has a water film replenishment channel inside the protective ring A. One end of the water film replenishment channel is connected to an external dripping system, and one outlet of the other end of the water film replenishment channel is located directly above the gap of the second set of liquid film vibration damping devices, and the liquid film is replenished by dripping.

[0024] 7. The shaft end sealing structure of the concrete mixer of the present invention has an arc-shaped guide plate at the junction of the front and back surfaces of the first blade, which makes it easier to throw out fine sand and gravel when mixing high-strength concrete. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. The drawings described below are some embodiments of the present invention. For those skilled in the art, it is obvious that other drawings can be obtained from these drawings without creative effort.

[0026] Figure 1 This is an assembly drawing of the shaft end sealing structure of a concrete mixer in the prior art.

[0027] Figure 2 This is a partial half-sectional view of the shaft end sealing structure of the concrete mixer described in this invention.

[0028] Figure 3 This is a front view of the centrifuge device described in this invention.

[0029] Figure 4 This is an enlarged view of the liquid film vibration damping device of Embodiment 1 of the present invention.

[0030] Figure 5 This is an enlarged view of the liquid film vibration damping device of Embodiment 2 of the present invention.

[0031] Figure 6 This is an enlarged view of the liquid film vibration damping device of Embodiment 3 of the present invention.

[0032] Figure 7 This is a cross-sectional view showing the gradual thickness change of the first and second blades of the present invention.

[0033] Figure 8 This is a front view of the mixer described in this invention.

[0034] In the picture:

[0035] 1-Shaft head housing; 2-Shaft locking assembly; 3-End cover; 4-Rotary seal; 5-First sealing ring; 6-Second sealing ring; 7-Protective ring A; 7-1-Water film replenishment channel; 8-Protective ring B; 9-Cylinder side wall; 10-Side liner; 11-Side stirring arm; 12-Reinforcing plate; 13-Centrifugal device; 13-1-First blade; 13-2-Second blade; 14-Liquid film vibration damping device; 14-1-First moving ring; 14-2-First stationary ring; 14-3-Second moving ring; 14-4-Second stationary ring; 15-Stirring shaft; 16-First gap; 17-Second gap; 18-Third gap; 19-Shaft end seal. Detailed Implementation

[0036] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0037] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "axial," "radial," "vertical," "horizontal," "inner," and "outer," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and simplifying the description, and 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 of the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0038] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0039] like Figure 1 As shown, the existing shaft end sealing structure is installed on the cylinder side wall 9, and a reinforcing plate 12 is welded on the cylinder side wall 9. The housing of the shaft end sealing structure is installed on the reinforcing plate 12. The shaft end sealing structure includes a shaft head housing 1, a shaft locking assembly 2, an end cover 3, a rotary seal 4, a first sealing ring 5, and a second sealing ring 6. The shaft head housing 1 is installed on the reinforcing plate 12, and the shaft locking assembly 2 is installed between the inner ring of the shaft head housing 1 and the stirring shaft. The shaft locking assembly 2 rotates synchronously with the stirring shaft 15. The end cap 3 is mounted on the shaft head housing 1, and a rotary seal 4 is provided between the end cap 3 and the stirring shaft 15; the first sealing ring 5 is located between the shaft locking assembly 2 and the inner ring of the shaft head housing 1; the second sealing ring 6 is mounted on the shaft head housing 1 through a locking steel frame, and the second sealing ring 6 is tightly fitted with the conical surface of the shaft locking assembly 2; a protective ring A7 is installed on the other side of the reinforcing plate 12, and for ease of installation, the protective ring A7 is a symmetrical structure with two halves; a protective ring B8 is installed on one side of the side stirring arm 11, and rotates with the side stirring arm 11; the side stirring arm 11 is mounted on the stirring shaft 15; the protective ring A7 and the protective ring B8 are steppedly fitted. A bearing housing is installed at one end of the stirring shaft 15, and the bearing housing is connected to the shaft head housing 1.

[0040] like Figure 2As shown, in the shaft end sealing structure of the present invention, the radial gap between the stepped-fitted protective ring A7 and protective ring B8 includes a first gap 16 and a second gap 17. The first gap 16 is away from the stirring shaft 15; the second gap 17 is close to the stirring shaft 15. A centrifugal device 13 is provided in the first gap 16 between the protective ring A7 and the protective ring B8. The centrifugal device 13 pressurizes and discharges impurities in the gap between the protective ring A7 and the protective ring B8, which can reduce the entry of sand and mud into the sealing surface between the second sealing ring 6 and the shaft locking assembly 2, reduce the wear risk of the second sealing ring 6, and improve the sealing life of the shaft end sealing structure.

[0041] like Figure 3 As shown, the centrifugal device 13 of the present invention includes a first blade 13-1 and a second blade 13-2; a plurality of second blades 13-2 are evenly distributed on one side of the protective ring B8, the second blades 13-2 having a frontal surface and a backal surface, one end of the frontal surface of the second blades 13-2 extending radially to the edge of the protective ring B8; at least one first blade 13-1 is provided on the upper surface of each second blade 13-2; the outline of the first blade 13-1 is smaller than the outline of the second blade 13-2. The thickness of the first blade 13-1 does not exceed the thickness of the second blade 13-2. The radius of curvature of the frontal surface of the first blade 13-1 is R1 = (0.4~0.6)R, and the radius of curvature of the backal surface of the first blade 13-1 is R2 = (0.2~0.3)R, where R is the radius of the outer circle of the protective ring B8. The second blade 13-2 uses centrifugal force to throw out the sand and mud that have entered the first gap 16. However, some fine sand will still enter the root of the second blade 13-2. The purpose of the first blade 13-1 is to throw out this fine sand. The first blade 13-1 is made of wear-resistant rubber or polyurethane. The first blade 13-1 is vulcanized and bonded to the second blade 13-2. This makes it convenient to re-vulcanize and bond a new first blade 13-1 after the first blade 13-1 wears out. It also makes it convenient to install the protective ring B 8.

[0042] like Figure 7 As shown, the thickness of the second blade 13-2 increases radially, while the thickness of the first blade 13-1 decreases radially. An arc-shaped guide plate 13-3 is provided at the junction of the upstream and downstream surfaces of the first blade 13-1 to facilitate the ejection of fine sand and gravel. The arc-shaped guide plate 13-3 is only needed when mixing high-strength concrete, which refers to concrete with a strength of C60 or higher.

[0043] Combination Figure 1 and Figure 2Based on the existing technology, the size of the second gap 17 is slightly increased, and at least one set of liquid film vibration damping device 14 is installed in the second gap 17. The liquid film vibration damping device 14 is provided with gaps, and a water film is formed in the gaps to reduce vibration. By forming a water film in the gaps, the unbalanced force generated by the centrifugal device 13 during rotation can be effectively balanced, or the axial vibration of the shaft end sealing structure can be reduced, thereby improving the service life.

[0044] like Figure 2 and Figure 4 As shown, the axial gap between the protective rings A7 and B8 in the stepped fit is the third gap 18. A hydrophilic texture is provided on the surface of the axial gap to form a hydrophilic surface. It can be seen from the figure that both the inner hole of the stepped part of the protective ring A7 and the outer ring of the stepped part of the protective ring B8 have hydrophilic textures, forming hydrophilic surfaces. The hydrophilic surface makes it easier to form a sealing water film in the third gap 18, preventing the fine sand and muddy water mixture that enters the first and second gaps from entering the shaft head seal.

[0045] The liquid film vibration damping device 14 described in Example 1, as follows: Figure 4 As shown, the liquid film vibration damping device 14 includes a first stationary ring 14-2 and a first rotating ring 14-1. One end of the first stationary ring 14-2 is mounted on a protective ring A7; one end of the first rotating ring 14-1 is mounted on a protective ring B8; a gap is provided between the first stationary ring 14-2 and the first rotating ring 14-1 to form a water film at the gap, which can effectively balance the unbalanced force generated by the centrifugal device 13 during rotation, or reduce the axial vibration of the shaft end sealing structure.

[0046] In Example 1, the gap between the first stationary ring 14-2 and the first moving ring 14-1 is perpendicular to the axis of the stirring shaft 15, and the water film formed therefrom is also perpendicular to the axis of the stirring shaft 15. Based on Example 1, the gap between the first stationary ring 14-2 and the first moving ring 14-1 can be inclined, and the water film formed therefrom is frustoconical, which can also partially reduce radial vibration.

[0047] The liquid film vibration damping device 14 described in Example 2, as follows: Figure 5 As shown, based on Embodiment 1, the protective ring A7 is provided with an annular groove. One end of the first stationary ring 14-2 is located within the annular groove, and the gap between the first stationary ring 14-2 and the first moving ring 14-1 is located within the annular groove. Since the gap between the first stationary ring 14-2 and the first moving ring 14-1 is located within the annular groove, the water film is located within the annular groove. The water film can be considered as elastic damping, which can reduce some vibration. Furthermore, the vibration generated by the water film will collide and rebound on the wall of the annular groove, thereby further mitigating the vibration generated by the water film.

[0048] The liquid film vibration damping device 14 described in Example 3, as follows: Figure 6 As shown, based on Embodiment 1, two sets of liquid film vibration damping devices 14 are installed in the second gap 17. The first set of liquid film vibration damping devices 14 includes a first stationary ring 14-2 and a first moving ring 14-1. One end of the first stationary ring 14-2 is mounted on a protective ring A7; one end of the first moving ring 14-1 is mounted on a protective ring B8; a gap is provided between the first stationary ring 14-2 and the first moving ring 14-1 for forming a first water film at the gap. The second set of liquid film vibration damping devices 14 is above the first set of liquid film vibration damping devices 14. The second set of liquid film vibration damping devices 14 includes a second stationary ring 14-4 and a second moving ring 14-3. One end of the second stationary ring 14-4 is mounted on a protective ring A7; one end of the second moving ring 14-3 is mounted on a protective ring B8; a gap is provided between the second stationary ring 14-4 and the second moving ring 14-3 for forming a second water film at the gap.

[0049] Because the water film will be lost during use, a liquid replenishment device is provided based on Example 1 or Example 2, such as... Figure 4 and Figure 5 As shown, the liquid replenishment device includes a water film replenishment channel 7-1. The protective ring A7 contains the water film replenishment channel 7-1, one end of which is connected to an external dripping system. The other end of the water film replenishment channel 7-1 has its outlet located directly above the gap, replenishing the liquid film through dripping. In this embodiment, a through hole is provided on the reinforcing plate 12 and the shaft head housing 1, through which one end of the water film replenishment channel 7-1 is connected to an external dripping system.

[0050] Based on Example 3, a liquid replenishment device was provided, such as... Figure 6 As shown, the liquid replenishment device includes a water film replenishment channel 7-1. The protective ring A7 contains the water film replenishment channel 7-1. One end of the water film replenishment channel 7-1 is connected to an external dripping system. One outlet of the other end of the water film replenishment channel 7-1 is located directly above the gap of the second set of liquid film vibration damping devices 14, replenishing the liquid film by dripping. The other outlet of the water film replenishment channel 7-1 is located between the two sets of liquid film vibration damping devices 14, replenishing the liquid film of the first set of liquid film vibration damping devices 14 by dripping.

[0051] The aforementioned liquid replenishment device also has the function of replenishing the water film used to form a seal in the third gap 18. The outlet of the other end of the water film replenishment channel 7-1 is located on the inner wall of the step of the protective ring A7, which can replenish the water film used to form a seal in the third gap 18.

[0052] The concrete mixer of this invention is a twin-shaft mixer, with shaft end sealing structures installed at both ends of each mixing shaft. In the shaft end sealing structures at both ends of each mixing shaft, the directions of the first blade 13-1 and the second blade 13-2 are consistent with the rotation direction of the mixing shaft, as shown below. Figure 3 The stirring shaft 15 shown rotates counterclockwise, so the flow-guiding surfaces of the first blade 13-1 and the second blade 13-2 can use centrifugal force to throw out some fine sand.

[0053] like Figure 8 As shown, the concrete mixer of the present invention is a twin-shaft mixer, which has two mixing shafts, and the shaft end seals 19 of the concrete mixer of the present invention are installed at both ends of each mixing shaft 15.

[0054] It should be understood that although this specification is described according to various embodiments, not every embodiment contains only one independent technical solution. This way of describing the specification is only for clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

[0055] The detailed descriptions listed above are merely specific illustrations of feasible embodiments of the present invention and are not intended to limit the scope of protection of the present invention. All equivalent embodiments or modifications made without departing from the spirit of the present invention should be included within the scope of protection of the present invention.

Claims

1. A shaft end seal of a concrete mixer comprising a protector ring A (7) and a protector ring B (8), said protector ring A (7) and said protector ring B (8) are step shoulder fitted, characterized in that, The radial gap between the protective ring A (7) and the protective ring B (8) of the stepped fit includes a first gap (16) and a second gap (17). The first gap (16) is provided with a centrifugal device (13), which pressurizes and discharges impurities in the gap between the protective ring A (7) and the protective ring B (8). The second gap (17) is provided with at least one set of liquid film vibration damping devices (14), which have gaps to form a water film at the gaps to reduce vibration. The centrifugal device (13) includes a first blade (13-1) and a second blade (13-2). Several second blades (13-2) are evenly distributed on one side of the protective ring B (8). The second blades (13-2) have a frontal surface and a backal surface. One end of the frontal surface of the second blade (13-2) extends radially to the edge of the protective ring B (8). At least one first blade (13-1) is provided on the upper surface of each second blade (13-2). The outline of the first blade (13-1) is smaller than the outline of the second blade (13-2). The radius of curvature of the frontal surface of the first blade (13-1) is R1 = (0.4~0.6)R, and the radius of curvature of the backal surface of the first blade (13-1) is R2 = (0.2~0.3)R, where R is the radius of the outer circle of the protective ring B (8); The liquid film vibration damping device (14) includes a stationary ring and a moving ring. One end of the stationary ring is mounted on a protective ring A (7); one end of the moving ring is mounted on a protective ring B (8); a gap is provided between the stationary ring and the moving ring to form a water film at the gap. The gap between the stationary ring and the moving ring is an inclined gap, and the water film formed by the inclined gap is frustoconical.

2. The shaft end seal for a concrete mixer as claimed in claim 1, wherein, The thickness of the second blade (13-2) increases radially, while the thickness of the first blade (13-1) decreases radially. The maximum thickness of the first blade (13-1) does not exceed the maximum thickness of the second blade (13-2). An arc-shaped guide plate (13-3) is provided at the junction of the front and back surfaces of the first blade (13-1).

3. The shaft end seal for a concrete mixer as set forth in claim 1, wherein, The protective ring A (7) is provided with an annular groove, one end of the stationary ring is located in the annular groove, and the gap between the stationary ring and the moving ring is located in the annular groove.

4. The shaft end seal of the concrete mixer according to claim 1, characterized in that, The axial gap between the protective ring A (7) and the protective ring B (8) of the step fit is the third gap (18). A hydrophilic texture is provided on the surface of the third gap (18) to form a hydrophilic surface. The hydrophilic surface is used to form a water film for sealing in the third gap (18).

5. The shaft end seal of the concrete mixer according to claim 1, characterized in that, It also includes a liquid replenishment device, which includes a water film replenishment channel (7-1). The protective ring A (7) is provided with a water film replenishment channel (7-1). One end of the water film replenishment channel (7-1) is connected to the external dripping system, and the outlet of the other end of the water film replenishment channel (7-1) is located directly above the gap, replenishing the liquid film by dripping.

6. A concrete mixer, characterized in that, The shaft end of the mixer is fitted with the shaft end seal of the concrete mixer as described in any one of claims 1-5.

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