Source: https://patents.justia.com/patent/20150014939
Timestamp: 2017-12-13 14:59:21
Document Index: 616693372

Matched Legal Cases: ['arts 8', 'arts 8', 'art 2', 'arts 8', 'art 8', 'art 8', 'art 2', 'art 8', 'art 2']

US Patent Application for BRUSH SEAL Patent Application (Application #20150014939 issued January 15, 2015) - Justia Patents Search
Justia Patents Brush SealUS Patent Application for BRUSH SEAL Patent Application (Application #20150014939)
A brush seal includes a bristle part formed by multiple bristles attached to a stationary part between the stationary part and a rotational part that undergo relative motion by maintaining a space in between and a back plate to restrict the movement of the bristle part. Such brush seal for sealing a fluid between the stationary part and the rotational part includes the bristle part formed by the multiple bristles such that the multiple bristles arranged in a direction of pressure difference between the high-pressure side and the low-pressure side are mutually fixed between a base end and a free end to form planar bristles, and these planar bristles are arranged continuously in layers in a circumferential direction to form a circular bristle part, wherein circumferential grooves are formed on the sliding surface of the bristle part on its free end side.
To solve the problems of the solution described in Patent Literature 2, solutions are proposed that involve providing restraining bristles having just enough elasticity not to prevent the deformation of the bristle part upon contact, in place of a braking plate on the high-pressure side of bristles. (Refer to Patent Literature 3, for example.)
The brush seal described in Patent Literature 3 absorbs any change in the interval between the stationary part and the rotational part by the deflection of the bristle part, and because the movement of the bristle part is suppressed by the back plate on the low-pressure side, these bristles deflect in the direction of the restraining bristles; since the restraining bristles have just enough elasticity not to prevent the deformation of the bristle part upon contact; the restraining bristles undergo elastic deformation and thereby absorb the deformation of the bristle part, and consequently any increase in wear can be prevented in a steady state without increasing the contact friction force as the interval between the stationary part and rotational part changes.
{Patent Literature 1} Japanese Patent Laid-open No. 2003-14128 (FIG. 8 on Page 10)
{Patent Literature 2} Japanese Patent Laid-open No. 2001-73708
{Patent Literature 3} Japanese Patent Laid-open No. 2008-121512
To achieve the aforementioned object, firstly, the brush seal proposed by the present invention is a brush seal having: a bristle part formed by multiple bristles attached to a stationary part between the stationary part and a rotational part that undergo relative motion by maintaining a space in between; and a back plate attached adjacent to the bristle part on a low-pressure side to restrict the movement of the bristle part, wherein such brush seal of sealing fluid flowing between the stationary part and the rotational part is characterized in that the bristle part formed by multiple bristles is such that the multiple bristles arranged in the direction of pressure difference between the high-pressure side and low-pressure side are mutually fixed between the base end and free end to form planar bristles and these planar bristles are arranged continuously in layers in the circumferential direction to form the circular bristle part, and that circumferential grooves are formed on the sliding surface on the free end side of the bristle part.
In addition, since circumferential grooves are formed on the sliding surface to create a labyrinth seal structure, fluid leaking from the high-pressure side toward the low-pressure side undergoes sequential pressure drops to eventually become low-pressured, and consequently the amount of fluid leaking from the high-pressure side toward the low-pressure side is suppressed.
Secondly, the brush seal proposed by the present invention is characterized in that, in the first characteristics, the circumferential grooves are formed by arranging, among the multiple bristles arranged in the direction of pressure difference between the high-pressure side and low-pressure side, bristles whose height is shorter on the free end side on the interior side in locations not facing the high-pressure side or low-pressure side, and then arranging the resulting planar bristles continuously in layers in the circumferential direction.
According to these characteristics, the circumferential grooves can be formed with ease by arranging bristles of different heights.
Thirdly, the brush seal proposed by the present invention is characterized in that, in addition to the first or second characteristics, dams are formed in the middle of the circumferential grooves in the circumferential direction.
According to these characteristics, the hydrodynamic force generated by the swirling flows that in turn are generated by the rotation of the rotational part contacts the side faces of the bristles constituting the dams to generate buoyancy in the bristles, thereby reducing the amount of wear of bristles further.
Furthermore, the hydrodynamic force generated by the swirling flows that in turn are generated by the rotation of the rotational part contacts the side faces of the bristles constituting the dams to generate buoyancy in the bristles, thereby reducing the amount of wear of bristles further.
FIG. 4 is a perspective view explaining the circumferential grooves provided on the sliding surface of a bristle part pertaining to Embodiment 1 of the present invention
FIG. 5 is a perspective view explaining the circumferential grooves provided on the sliding surface of a bristle part pertaining to Embodiment 2 of the present invention
Modes for carrying out a brush seal pertaining to the present invention are explained in detail by referring to the drawings, but it should be noted that the present invention is not at all restricted to these interpretations and various changes, modifications and improvements can be added according to the knowledge of those skilled in the art so long as they do not deviate from the scope of the present invention.
Also, the inner periphery side of the brush seal device 1 is provided in a manner opposingly contacting or positioned close to the outer periphery surface of a rotor 60 which is a component of the other section, and the brush seal device 1 seals the leakage of the sealed fluid to the low-pressure side from the high-pressure side.
The wire diameter of bristles 5 is generally 0.02 mm to 0.5 mm. For the material of bristles 5, steel, stainless steel or nickel alloy, heat-resistant cobalt alloy, or the like, is used. Additionally, the cross-section shape of bristles 5 may be oval, triangle, square, or other polygon, in addition to circle.
FIG. 3 is a perspective view explaining the process of forming a bristle part pertaining to an embodiment of the present invention, where circumferential grooves are not formed on the sliding surface of the bristle part in (a) and (b), while circumferential grooves are formed on the sliding surface of the bristle part in (c).
In FIG. 3, for the purpose of illustration, the number of bristles arranged in the direction of pressure difference between the high-pressure side and low-pressure side is less than the actual number, but in reality hundreds of bristles are arranged to form a specified width.
In FIG. 3 (b), three fixed parts 8 are provided in the diameter direction between the base end 6 and free end 7. However, the number of fixed parts 8 in the diameter direction is not at all restricted to three, as long as at least one fixed part is provided, and any location (s) and number of fixed part (s) can be set according to the required rigidity of the bristle part 2. Among the fixed parts 8, the position of the fixed part 8 close to the free end 7 is important in determining the rigidity at the free end of bristles 5.
The planar bristles 10 shown in FIG. 3 (c) are such that, among the multiple bristles 5 forming a specified width, bristles 50 whose height is short on the free end side are arranged on the interior side in locations not contacting the high-pressure side or low-pressure side. FIG. 3 (c) shows two independent locations, in the direction of pressure difference between the high-pressure side and low-pressure side, where short bristles 50 are arranged over a specified width. The number of locations where short bristles 50 are arranged is not at all restricted to two, and it can be one or three or more.
Additionally, the planar bristles 10 are such that, since degrees of freedom of the tips of individual bristles 5, or specifically degrees of freedom of the tips of individual bristles 5 in the direction orthogonal to the direction of pressure difference (=circumferential direction) between the fixed part 8 close to the free end 7 and the free end 7, are ensured, their rigidity is low in the direction orthogonal to the direction of pressure difference and therefore the free end 7 can separate from the outer periphery surface of the rotor 60 due to the dynamic pressure of the rotor 60 even when it is rotating at low speed, resulting in such advantages as reduced wear and improved wear resistance.
Next, the circumferential grooves provided on the sliding surface of a bristle part pertaining to Embodiment 1 of the present invention is explained by referring to FIG. 4. In FIG. 4, the top side of the drawing represents the free end side of bristles that slide with the rotational part, while the bottom side represents the base end side (stationary part side). Also note that the direction connecting the front left and rear right of the drawing represents the circumferential direction. Furthermore, the right side of the drawing represents the high-pressure side, while the left side represents the low-pressure side.
In FIG. 4, multiple planar bristles 10 of the same shape, having multiple independently formed grooves comprising short bristles 50 arranged over a specified width in the direction of pressure difference between the high-pressure side and low-pressure side, are provided in locations on the interior side not contacting the high-pressure side or low-pressure side and arranged in the circumferential direction.
Here, the circumferential grooves 15 are formed by continuously arranging in layers in the circumferential direction the planar bristles 10 that have, among the multiple bristles 5 arranged in the direction of pressure difference between the high-pressure side and low-pressure side, bristles 50 whose height is short over a specified width in the direction of pressure difference between the high-pressure side and low-pressure side, and in FIG. 4, circumferential grooves 15 are formed independently at four locations in the direction of pressure difference between the high-pressure side and low-pressure side, as indicated by 15-1 to 15-4. These circumferential grooves 15-1 to 15-4 are formed along the rotating direction of the rotor 60 in locations on the interior side not contacting the high-pressure side or low-pressure side. Herein, the aforementioned “specified width” refers to the width needed by the fluid leaking from the high-pressure side toward the low-pressure side as it undergoes adiabatic expansion.
The sliding surface on which the circumferential grooves 15-1 to 15-4 are formed has a labyrinth seal structure having multiple constrictions, and the fluid F, indicated by arrows, that leaks from the high-pressure side toward the low-pressure side is constricted at a first constriction S1 on the high-pressure side and receives resistance, after which it undergoes adiabatic expansion at the circumferential groove 15-1 and drops in pressure and then is constricted at a second constriction S2 and receives resistance, after which it undergoes adiabatic expansion at the circumferential groove 15-2, and after going through repeated pressure drops until at a constriction S5 in the same manner, the fluid eventually becomes low-pressured. As a result, the amount of fluid leaking from the high-pressure side toward the low-pressure side is suppressed.
The number of circumferential grooves 15 provided in the direction of pressure difference between the high-pressure side and low-pressure side is set as deemed appropriate according to the pressurization condition, type of sealed fluid, and so on.
Next, the circumferential grooves provided on the sliding surface of a bristle part pertaining to Embodiment 2 of the present invention are explained by referring to FIG. 5. In FIG. 5, the top side of the drawing represents the free end side of bristles that slide with the rotational part, while the bottom side represents the base end side (stationary part side). Also note that the direction connecting the front left and rear right of the drawing represents the circumferential direction. Furthermore, the right side of the drawing represents the high-pressure side, while the left side represents the low-pressure side.
Embodiment 2 in FIG. 5 is different from Embodiment 1 in FIG. 4 in that circumferential grooves are provided at two locations and that dams are formed in the middle of the circumferential grooves in the circumferential direction, but since the remainder of the configuration is the same as with Embodiment 1 in FIG. 4, the same symbols are used for those members identical to the corresponding members in FIG. 4 and redundant explanations are omitted.
In FIG. 5, multiple planar bristles 10 of the same shape, having multiple independently formed grooves comprising short bristles 50 arranged over a specified width in the direction of pressure difference between the high-pressure side and low-pressure side, are provided in locations on the interior side not contacting the high-pressure side or low-pressure side and arranged in the circumferential direction, where planar bristles 100 of the same shape, having tall bristles 5 arranged over the entire width in the direction of pressure difference between the high-pressure side and low-pressure side, are placed in the middle in the circumferential direction over a specified length in the circumferential direction. Here, the “specified length in the circumferential direction” refers to the length needed to holdback the flow of fluid in the circumferential direction being generated by the rotation of the rotor 60.
The circumferential grooves 15 are formed by continuously arranging in layers in the circumferential direction the planar bristles 10 that have, among the multiple bristles 5 arranged in the direction of pressure difference between the high-pressure side and low-pressure side, bristles 50 whose height is short over a specified width in the direction of pressure difference between the high-pressure side and low-pressure side, and in FIG. 5, circumferential grooves 15 are formed independently at two locations in the direction of pressure difference between the high-pressure side and low-pressure side, as indicated by 15-1 and 15-2. These circumferential grooves 15-1, 15-2 are formed along the rotating direction of the rotor 60 in locations on the interior side not contacting the high-pressure side or low-pressure side. Additionally, dams, 16, 16 are formed in the middle of the respective circumferential grooves 15-1, 15-2 in the circumferential direction as a result of planar bristles 100 being placed over a specified length in the circumferential direction. At least one dam 16 is provided in each of the circumferential grooves 15-1, 15-2 in the circumferential direction, and normally multiple dams are provided at equal distributions. Also in FIG. 5, dams 16, 16 are provided in the two circumferential grooves 15, 15 at the same positions in the circumferential direction. However, the positions of dams are not at all restricted to the foregoing, and they may be provided at positions offset in the circumferential direction.
The sliding surface on which the circumferential grooves 15-1, 15-2 are formed have a labyrinth seal structure having multiple constrictions, and the fluid, indicated by arrows F, that leaks from the high-pressure side toward the low-pressure side is constricted at a first constriction S1 on the high-pressure side and receives resistance, after which it undergoes adiabatic expansion at the circumferential groove 15-1 and drops in pressure and then is constricted at a second constriction S2 and receives resistance, after which it undergoes adiabatic expansion at the circumferential groove 15-2, and after going through repeated pressure drops until at a constriction S3 in the same manner, the fluid eventually becomes low-pressured. As a result, the amount of fluid leaking from the high-pressure side toward the low-pressure side is suppressed.
In addition, the dams 16, 16 provided in the middle of the circumferential grooves 15-1, 15-2 are such that the hydrodynamic force generated by the swirling flows indicated by arrows FS that in turn are generated by the rotation of the rotor 60 contacts the side faces 17, 17 of the bristles 5 constituting the dams 16, 16 to generate buoyancy in the bristles 5, thereby reducing the amount of wear of bristles 5.
The brush seal 1 is such that, as the rotor 60 turns and contacts the free end 7 of bristle 5 as a result of vibration, shaking, etc., the bristle 5 tilts more while being pressed against the rotor 60. Here, since degrees of freedom of the tip of individual bristle 5 are ensured in the direction orthogonal to the direction of pressure difference, their rigidity is low in the direction orthogonal to the direction of pressure difference and therefore the free end 7 can separate from the outer periphery surface of the rotor 60 due to the dynamic pressure of the rotor 60 even when it is rotating at low speed, resulting in such advantages as reduced wear and improved wear resistance. Furthermore, the ability of the individual bristles 5, 15 to move independently of the conical vibration of the rotor 60 also helps to reduce wear and improve wear resistance.
Furthermore, since the sliding surface on the free end 7 side of the circular bristle part 2 has circumferential grooves 15 formed on it in locations on the interior side not contacting the high-pressure side or low-pressure side to create a labyrinth seal structure, and therefore the fluid F that leaks from the high-pressure side toward the low-pressure side undergoes repeated pressure drops and eventually becomes low-pressured, the amount of fluid leaking from the high-pressure side toward the low-pressure side is suppressed as a result.
Furthermore, the dam 16 provided in the middle of the circumferential groove 15 is such that the hydrodynamic force generated by the swirling flows FS that in turn are generated by the rotation of the rotor 60 contacts the side faces of the bristles 5 constituting the dams 16 to generate buoyancy in the bristles 5, thereby reducing the amount of wear of bristles 5 further.
The operations and effects of brush seals pertaining to the embodiments of the present invention are summarized as follows.
Since multiple bristles arranged in the direction of pressure difference between the high-pressure side and low-pressure side are mutually fixed between the base end and free end to be formed into planar bristles, rigidity is higher in the direction of pressure difference between the high-pressure side and low-pressure side (=axial direction of the rotor) compared to when conventionally known brush seal bristles are used, and consequently application to steam turbines and other high-pressure equipment becomes possible.
In addition, the planar bristles 10 are ensured of degrees of freedom in the direction orthogonal to the direction of pressure difference (=circumferential direction) at the tips of individual bristles 5, or specifically at the tips of individual bristles 5 between the fixed part 8 close to the free end 7 and the free end 7, and thus have low rigidity in the direction orthogonal to the direction of pressure difference, and therefore the free end 7 can separate from the outer periphery surface of the rotor 60 due to the dynamic pressure of the rotor 60 even when it is rotating at low speed, which provides such benefits as reduced wear and improved wear resistance.
Moreover, since circumferential grooves 15 are formed on the sliding surface on the free end 7 side of the circular bristle part 2 to create a labyrinth seal structure, the fluid F that leaks from the high-pressure side toward the low-pressure side undergoes repeated pressure drops and eventually becomes low-pressured, thereby suppressing the amount of fluid leaking from the high-pressure side toward the low-pressure side.
Also, the circumferential grooves 15 are formed by continuously arranging in layers in the circumferential direction the planar bristles 10 that have, among the multiple bristles 5 arranged in the direction of pressure difference between the high-pressure side and low-pressure side, bristles 50 whose height is short on the free end side in locations on the interior side not contacting the high-pressure side or low-pressure side, which means that the circumferential grooves can be formed with ease by arranging bristles of different heights.
Furthermore, the dam 16 provided in the middle of the circumferential groove 15 is such that the hydrodynamic force generated by the swirling flows FS that in turn are generated by the rotation of the rotor 60 contacts the side faces 17 of the bristles 5 constituting the dams 16 to generate buoyancy in the bristles 5, thereby further reducing the amount of wear of bristles 5.
For instance, the embodiments explained bristles having a circular or square cross-section shape, but the bristles are not at all restricted to the foregoing and bristles having a triangle, polygonal, oval, or other cross-section shape can also be used.
Also, the embodiments explained a method to form circumferential grooves by continuously arranging in layers in the circumferential direction the planar bristles that have, among the multiple bristles arranged in the direction of pressure difference between the high-pressure side and low-pressure side, bristles whose height is short over a specified width in the direction of pressure difference between the high-pressure side and low-pressure side, for instance, but the method to form circumferential grooves is not at all limited to the foregoing and circumferential grooves can be formed by forming a circular bristle part and then irradiating laser onto the sliding surface, or the like.
In addition, Embodiment 2 explained a method to form dams by inserting over a specified length in the circumferential direction those planar bristles of the same shape having higher bristles arranged in the middle in the circumferential direction over the entire width in the direction of pressure difference between the high-pressure side and low-pressure side, for instance, but the method to form dams is not at all restricted to the foregoing and dams can be formed simultaneously when circumferential grooves are formed by forming a circular bristle part and then irradiating laser onto the sliding surface, or the like.
17 Side face of the bristle
F Leaking fluid
FS Swirling flow
S1 to S5 Constriction
1. A brush seal having:
a bristle part formed by multiple bristles attached to a stationary part between the stationary part and a rotational part that undergo relative motion by maintaining a space in between; and
a back plate attached adjacent to the bristle part on its low-pressure side to restrict movement of the bristle part,
said brush seal for sealing fluid flowing between the stationary part and the rotational part being characterized in that the bristle part formed by multiple bristles is such that the multiple bristles arranged in a direction of pressure difference between the high-pressure side and the low-pressure side are mutually fixed between a base end and a free end to form planar bristles, and these planar bristles are arranged continuously in layers in a circumferential direction to form a circular bristle part, wherein circumferential grooves are formed on a sliding surface of the bristle part on its free end side.
2. A brush seal according to claim 1, characterized in that the circumferential grooves are formed by continuously arranging in layers in the circumferential direction the planar bristles that have, among the multiple bristles arranged in the direction of pressure difference between the high-pressure side and low-pressure side, bristles whose height is short on the free end side in locations on an interior side not facing the high-pressure side or low-pressure side.
3. A brush seal according to claim 1, characterized in that dams are formed in the middle of the circumferential grooves in the circumferential direction.
4. A brush seal according to claim 2, characterized in that dams are formed in the middle of the circumferential grooves in the circumferential direction.
Applicant: EAGLE INDUSTRY CO., LTD. (Minato-ku, Tokyo)
Application Number: 14/380,904