Abstract:
A rotating assembly of a mechanical seal includes a retainer, a pair of compression rings, a shaft sleeve, a first rotating seal ring and a second rotating seal ring. The retainer includes a plurality of spring members and a plurality of slide legs longitudinally extended in opposite directions to define limiting spaces where the compression rings are correspondingly restricted. The compression rings are located at opposite sides of the retainer between which the spring members are arranged. In assembling, the retainer, the compression rings, the first rotating seal ring and the second rotating seal ring are assembled on the shaft sleeve. Spring forces of the spring members can actuate the compression rings to push the first rotating seal ring and the second rotating seal ring in the opposite directions.

Description:
This is a continuation-in-part application of U.S. patent application Ser. No. 11/380,123 filed on Apr. 25, 2006 now abandoned. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a mechanical seal, and, particularly, to a mechanical seal with a retainer holding two compression rings by engaging blocks and engaging with two rotating seal rings by a plurality of slide legs. 
     2. Description of the Related Art 
     Referring initially to  FIG. 1 , a conventional rotary machine such as a pump system has a shaft  9 , which may be used to stir liquids contained in a housing such as a liquid tank. In rotating operation, the rotary machine functions as a stirring apparatus of the housing for example. The rotary machine generally includes a mechanical seal for keeping the stirred liquids within the housing. 
     Typically, the mechanical seal includes a gland  7  and a rotating assembly  8 . The gland  7  permits extension of the shaft  9  and mounts the shaft  9  on equipments such as the said housing. The rotating assembly  8  is securely mounted on and rotated with the shaft  9  while being received in the gland  7 . The gland  7  includes a shaft bore  70 , a fluid inlet  71 , and a fluid outlet  72 . The shaft bore  70  longitudinally extends through the body of the gland  7  for the rotating assembly  8  and shaft  9  to pass through. The fluid inlet  71  and fluid outlet  72  both communicate the outside of the gland  7  and the shaft bore  70  for gas or a coolant to be guided into and out of the shaft bore  70  through the fluid inlet  71  and the fluid outlet  72 . Besides, two stationary seal rings  73  are oppositely received in the shaft bore  70  at two ends thereof, and longitudinally sandwiched between the gland  7  and rotating assembly  8 , with both of the stationary seal rings  73  being able to move longitudinally. 
     The rotating assembly  8  includes a retainer  81 , a pair of compression rings  82 , a pair of O-rings  83 , a pair of rotating seal rings  84  and a shaft sleeve  85 . The retainer  81 , the compression rings  82 , the O-rings  83  and the rotating seal rings  84  are mounted and assembled on an outer periphery of the shaft sleeve  85 . There are a series of spring members  810  provided on each of two longitudinally opposite sides of the retainer  81  for bias forces of the spring members  810  to oppositely push the two compression rings  82  outwards relative to the retainer  81 . Besides, a plurality of pins  811  are also sandwiched between the retainer  81  and the compression rings  82  for preventing the compression rings  82  from revolving about the shaft  9 . Two side surfaces of each compression rings  82  are respectively in contact with the corresponding spring members  810  and the corresponding rotating seal ring  84 . The O-rings  83  are disposed between the compression rings  82  and the rotating seal rings  84  for providing sealing effects therebetween. Each of the rotating seal rings  84  closely abuts one of the stationary seal rings  73 . Furthermore, the shaft sleeve  85  is mounted on the shaft  9  and rotated therewith. 
     When the shaft  9  rotates, the stationary seal rings  73  in the shaft bore  70  of the gland  7  elastically abut against the rotating seal rings  84  of the rotating assembly  8 . In long-term use, there are abrasions occurring between the stationary seal rings  73  and the rotating seal rings  84  of the rotating assembly  8 . The bias forces of the spring members  810  ensure no gap existing between the stationary seal rings  73  and the rotating seal rings  84  by successively pushing the rotating seal rings  84  through the corresponding compression rings  82 . Consequently, the bias forces of the spring members  810  can reduce the possibilities of liquid leakage in the interior of the mechanical seal. 
     The conventional mechanical seal has several drawbacks in manufacture. In the installing process, the spring members  810  must be disposed between each side of the retainer  81  and the corresponding rotating seal rings  84  without any positioning member before the whole rotating assembly  8  is completely fixed on the shaft  9 . The primary problem in such a structure is the difficulty in assembling or maintaining due to the fact that the spring members  810  may be easily fallen off from the retainer  81 . Disadvantageously, this may result in a low efficiency in assembly of the above-mentioned elements of the mechanical seal. Moreover, convenience in assembly is especially important for repair or replacement of the rotating seal rings  84  due to the said abrasions thereof. 
     Another problem naturally occurring during use of such a mechanical seal is due to the fact that liquids contained in the housing may permeate through a clearance existing between the compression ring  82  and the rotating seal rings  84 . With the structure shown in  FIG. 1 , because the spring members  810  for pushing the rotating seal rings  84  at two sides of the retainer  81  are isolated, there is no assistant effect provided by the spring members  810  to prevent the compression rings  82  from revolving about the shaft  9 . In this circumstance, the liquid pressure can press the O-ring  83  and the compression ring  82  to be moved backward to the retainer  81 , and thus can further compress the spring members  810  to be retracted. Consequently, the rotating seal rings  84  cannot exactly abut against the corresponding stationary seal rings  73 . Disadvantageously, the possibility of leakage in such a mechanical seal is increased. 
     Another conventional mechanical seal in U.S. Pat. No. 5,375,853 and titled “SECONDARY CONTAINMENT SEAL” discloses a retainer with a cylindrical outer circumferential and an inner wall, and an annular disk element with several apertures is arranged along a central portion of the inner wall. Therefore, a plurality of springs can be inserted in the apertures and sandwiched between a pair of discs disposed on two sides of the annular disk element, with the said springs oppositely pushing two rotating seal rings to respectively abut two stationary seal rings through the said pair of discs. However, in order to retain the discs and rotating seal rings within the retainer, there should be an internal groove adjacent to each end of the retainer for receiving a snap ring with a radially extending wall. As a result, the invention disclosed in the said cited patent provides a complex structure and an assembly process that are still inconvenient for processing the repair or replacement of the rotating seal rings. Furthermore, in operation, the retainer of this cited structure has to suffer a large torque and a revolving movement of the discs. Besides, still another conventional mechanical seal disclosed by U.S. Pat. No. 3,888,495, titled “DUAL-COOLED SLIDE RING SEAL,” provides a structure similar to the last cited patent and also has the same problem of inconvenience in assembly. 
     Another US patent titled “SELF-CONTAINED ROTARY MECHANICAL SEALS” and U.S. Pat. No. 4,213,618 shows another conventional mechanical seal mounted on a shaft for rotating therewith and including a lug holder, a plurality of lugs, a plurality of belleville washers, a contact washer, and a carbon seal washer. The lug holder is radially fixed around the shaft, with the lugs extending from the lug holder and parallel to the shaft. The belleville washers are radially surrounded by the lugs and axially compressed between the lug holder and the contact washer to create a spring force urging the carbon seal washer forwards into abutting against a seal seat. Regarding to this conventional invention, what is characterized is that a plurality of tines extending from the lugs in a direction perpendicular to the lugs and concentric to the shaft is provided while several shoulders radially extend from the carbon seal washer. Besides, the shoulders are dimensioned for engagement with the lugs and tines. In detail, a distance of a gap between two adjacent tines of two different lugs is not smaller than a length of the shoulder, so that the shoulder can pass through the gap and received between the said two different lugs. Although convenience in assembly for mechanical seal is improved by this conventional invention, the belleville washers and contact washer are still easy to fall out of the space defined by the lugs once the carbon seal washer is removed. And this is inconvenient for repair or replacement of the carbon seal washer as well. Furthermore, because the carbon seal washer directly abuts against the tines, the shoulders may be easily damaged due to axially pushing force of the belleville washers. Hence, there is a need for a further improvement over the conventional mechanical seal. 
     SUMMARY OF THE INVENTION 
     The primary objective of this invention is to provide a mechanical seal with a retainer and two compression rings for easily maintaining a plurality of spring members between the two compression rings and in a plurality of spring holes of the retainer while two rotating seal rings are axially released from the retainer, with the retainer further providing a plurality of engaging blocks for retaining the compression rings and spring members in the retainer. And, the mechanical seal is used as a dual cartridge seal with two-way-pushing spring members to provide a balanced structure. As a result, the release of the rotating seal rings are completed without disengagement between the spring members, retainer, and compression rings, and only stationary seal rings and rotating seal rings have to be routinely replaced. 
     The secondary objective of this invention is to provide the mechanical seal, which has a shaft sleeve with a positioning flange disposed at an outer periphery thereof to limit an axial movement of an O-ring or one of the rotating seal rings. Accordingly, the positioning flange of the shaft sleeve can enhance the sealing effect of the rotating assembly. 
     Another objective of this invention is to provide the mechanical seal with a reduced area of the said interface. Accordingly, the mechanical seal is suitable for use in viscous liquid stir. 
     Further another objective of this invention is to provide the mechanical seal with a stirring unit that forms an end of the shaft sleeve and faces the said interface. Consequently, suspended impurities in the liquid are unable to accumulate in the said interface. 
     The mechanical seal in accordance with an aspect of the present invention includes an gland for being mounted on a housing, a rotating assembly for being passed through by a shaft, and two stationary seal rings separately installed on the gland, with the rotating assembly being arranged between the gland and the stationary seal rings. An inner wall of the gland defines a shaft bore for the rotating assembly as well as the shaft to pass through. And the rotating assembly comprises a retainer, a first compression ring, a second compression ring, a plurality of spring members, a first rotating seal ring, a second rotating seal ring, an a shaft sleeve. The retainer has a primary ring, a plurality of first slide legs, and a plurality of second slide legs. The primary ring is coaxial with the shaft bore and defines a first axial surface and a second axial surface at two axial ends thereof, and a plurality of spring holes communicate the said first and second axial surfaces. The first slide legs are formed on the first axial surface and axially extend outwards while an free end of each first slide leg has a first engaging block protruding to an axial line of the shaft bore. The second slide legs are formed on the second axial surface and axially extend outwards while an free end of each second slide leg has a second engaging block protruding to the said axial line. The first compression ring is coaxial with the shaft bore and formed with at least one cutaway portion at an outer periphery thereof. And the first compression ring is movably positioned between the first axial surface and the first engaging block in axial direction and is radially surrounded by the first slide legs. The second compression ring is also coaxial with the shaft bore and formed with at least one cutaway portion at an outer periphery thereof. And the second compression ring is movably positioned between the second axial surface and the second engaging block in axial direction and is radially surrounded by the second slide legs. The spring members are separately received in the spring holes and oppositely abut against the first and second compression rings with two ends. The first rotating seal ring has one end being abutted by the first compression ring, and a plurality of first notches are formed in a outer periphery of the first rotating seal ring. And an amount of the first notches is not less than an amount of the first slide legs for each first slide leg to be received in and engaged with one of the first notches. The second rotating seal ring has one end being abutted by the second compression ring, and a plurality of second notches are formed in a outer periphery of the second rotating seal ring. And an amount of the second notches is not less than an amount of the second slide legs for each second slide leg to be received in and engaged with one of the second notches. The shaft sleeve for mounted on the shaft sequentially passes through one of the stationary seal rings, the first rotating seal ring, first compression ring, primary ring of the retainer, second compression ring, second rotating seal ring, and the other stationary seal ring. The spring members oppositely push the first and second rotating seal rings through the first and second compression rings. And thus the first and second rotating seal rings respectively abut against the two stationary seal rings to form an interface between the first rotating seal ring and one of the stationary seal rings and another interface between the second rotating seal ring and the other stationary seal ring. A smallest distance form the axial line of the shaft bore to each cutaway portion is not larger than a distance from the said axial line to each first or second engaging block, and radiuses of the outer peripheries of the two compression rings out of the at least one cutaway portion are larger than the said distance between the said axial line and each first or second engaging block, but are not larger than a smallest distance form the said axial line to each slide leg excluded the engaging blocks. The at least one cutaway portion of the first compression ring is mis-aligned with each first slide leg for the first compression ring to be limited between the first engaging blocks and the first axial surface, and the at least one cutaway portion of the second compression ring is mis-aligned with each second slide leg for the second compression ring to be limited between the second engaging blocks and the second axial surface. 
     In a separate aspect of the present invention, an end of the shaft sleeve adjacent to the first rotating seal ring forms at least one helical groove facing the said interface between the first rotating seal ring and the corresponding stationary seal ring, with a circular extending direction of each helical groove or helical blade being opposite to a rotating direction of the shaft. 
     In a further separate aspect of the present invention, at least one untaken notch is inclined relative to the first or second slide leg when the number of the notches of the first or second rotating seal ring is larger than the number of the first or second slide leg. 
     Further scope of the applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various will become apparent to those skilled in the art from this detailed description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will become more fully understood from the detailed description given hereinafter and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention, and wherein: 
         FIG. 1  is a cross-sectional view of a conventional mechanical seal in accordance with the prior art; 
         FIG. 2  is an exploded, perspective view of a rotating assembly and a fluid guiding member of a mechanical seal in accordance with a first embodiment of the present invention; 
         FIG. 3  is an assembled, cross-sectional view of the mechanical seal in accordance with the first embodiment of the present invention; 
         FIG. 4  is a cross-sectional view, taken along line  4 - 4  in  FIG. 3 , of a gland of the mechanical seal in accordance with the first embodiment of the present invention; 
         FIG. 5  is a partial, perspective view of a primary ring, slide legs, and compression rings before a fore-step in assembly is processed; 
         FIG. 6  is a partial, cross-sectional view of the primary ring, slide legs, and compression rings before the fore-step in assembly is processed; 
         FIG. 7  is a partial, perspective view of the primary ring, slide legs, and compression rings after a later step in assembly is processed; 
         FIG. 8  is a partial, cross-sectional view of the primary ring, slide legs, and compression rings after the later step in assembly is processed; 
         FIG. 9  is an exploded, perspective view of a rotating assembly and a fluid guiding member of a mechanical seal in accordance with a second embodiment of the present invention; 
         FIG. 10  is an assembled, cross-sectional view of the mechanical seal in accordance with the second embodiment of the present invention; 
         FIG. 11   a  is a partial, perspective view of a blade-formed stirring unit of the mechanical seal in accordance with the second embodiment of the present invention; 
         FIG. 11   b  is a partial, perspective view of a groove-formed stirring unit of the mechanical seal in accordance with the second embodiment of the present invention; 
         FIG. 12  is a perspective view of a blade-formed helical guiding unit of the mechanical seal in accordance with the second embodiment of the present invention; 
         FIG. 13  is an assembled, cross-sectional view of a mechanical seal in accordance with a third embodiment of the present invention; and 
         FIG. 14  is a perspective view of a fluid guiding member of the mechanical seal in accordance with the third embodiment of the present invention. 
     
    
    
     In the various figures of the drawings, the same numerals designate the same or similar parts. Furthermore, when the term “first”, “second”, “inner”, “outer” “axial”, “radial” and similar terms are used hereinafter, it should be understood that these terms are reference only to the structure shown in the drawings as it would appear to a person viewing the drawings and are utilized only to facilitate describing the invention. 
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to  FIGS. 2 through 4 , views of a mechanical seal in accordance with a first embodiment of the present invention are shown, which includes a gland designated numeral  1 , a rotating assembly designated numeral  2  and a fluid guiding member designated numeral  3 . In the illustrated embodiment, the mechanical seal is installed between a rotary machine and a housing such as a liquid tank or the like for mechanically linking them. 
     Still referring to  FIG. 3 , construction of the gland  1  shall be described in detail. In the first embodiment, the gland  1  is firmly mounted on the housing and includes a shaft bore  10 , a fluid inlet  11 , and a fluid outlet  12 . The shaft bore  10 , through which the rotating assembly  2  and a shaft  9  extends, is penetratingly arranged along an axial direction of the gland  1  and defined by an inner wall of the gland  1 . The fluid inlet  11  and fluid outlet  12  both communicate the outside of the gland  1  and the shaft bore  10 , so that a fluid such as gas or a coolant can be guided into and out of the shaft bore  10  through the fluid inlet  11  and the fluid outlet  12 . Preferably, the said fluid inlet  11  and fluid outlet  12  radially extend in the same axial level relative to the shaft bore  10 . In operation, the fluid provides a heat exchange function, such as heat dissipation or heat absorption, to maintain a suitable operational temperature of the gland  1  and the rotating assembly  2 . Besides, two stationary seal rings  13  are received in the shaft bore  10  at two opposite ends thereof, and axially compressed between the gland  1  and rotating assembly  2 , with both of the stationary seal rings  13  being able to move along an axial direction of the gland  1 . 
     Referring again to  FIGS. 2 and 3 , the construction of the rotating assembly  2  is described in detail as the following. In the first embodiment, the rotating assembly  2  is connected with the shaft  9  and includes a retainer  21 , a pair of compression rings  22 , a shaft sleeve  23 , a first rotating seal ring  24 , a second rotating seal ring  25  and a collar  26 . Extending through the retainer  21  are a series of spring holes to receive spring members identified as “a”. The compression rings  22  are located at either side of the retainer  21  and are in contact with ends of the spring members “a” received in the spring holes. In assembling, each of the compression rings  22  pushes the corresponding rotating seal ring  24  or  25  by spring forces of the spring members “a”. The retainer  21 , the compression rings  22 , the first rotating seal ring  24  and the second rotating seal ring  25  are assembled on the shaft sleeve  23 . The collar  26  securely connects with the shaft sleeve  23  on the shaft  9  such that the rotating assembly  2  may rotate with the shaft  9 . 
     Preferably, the rotating seal rings  24 ,  25  may be made of wear resisting silicon carbide, carbon steel for example, and closely abut against the stationary seal rings  13  mounted in the gland  1 . Besides, the first rotating seal ring  24  is at a side of the mechanical seal facing the inner of the housing, and the second rotating seal ring  25  is at another side of the mechanical seal adjacent to the atmospheric side. Constructions of the retainer  21 , the compression rings  22 , the shaft sleeve  23 , the first rotating seal ring  24  and the second rotating seal ring  25  will be further described in greater detail below. 
     The construction of the fluid guiding member  3  shall be described in detail, still referring to  FIGS. 2 through 4 . In the first embodiment, the fluid guiding member  3  is mounted on the inner wall of the gland  1 , adjacent to at least one of the fluid inlet and outlet  11 ,  12 , and provided with an axial hole  30 , a stepped portion  31  and a channel  32 . Preferably, the fluid guiding member  3  is in a ring shape and coaxial with the shaft bore  10  of the gland  1 . A diameter of the axial hole  30  allows the passage of any section of the rotating assembly  2  passed through by the shaft  9 , as best shown in  FIG. 3 . An O-ring identified as “b 1 ” rests on a side of the stepped portion  31  to seal a clearance existing between the inner wall of the gland  1  and the fluid guiding member  3  such that any possible leakage of liquid is prevented. The channel  32  is radially extended, connects an outer periphery and an inner periphery of the fluid guiding member  3 , and aligns with both of the fluid inlet  11  and fluid outlet  12 . Preferably, each of two opposite edges defining the channel  32  provides a guiding surface  321 , and the two guiding surfaces  321  are adjacent to and obliquely face the fluid inlet  11  and fluid outlet  12  as best shown in  FIG. 4 . Therefore, each of the guiding surface  321  guides the incoming fluid from a direction along the fluid inlet  11  into a peripheral direction of the shaft bore  10 , or guides the outgoing fluid from the peripheral direction of the shaft bore  10  into a direction along the fluid outlet  12 . 
     Preferably, the retainer  21  is a monolithic one-piece member provided with a primary ring  211 , a plurality of first slide legs  212 , and a plurality of second slide legs  213 . The primary ring  211  is coaxial with the shaft bore  10  and has a first axial surface  214 , a second axial surface  215 , and the series of spring holes, which are previously described and used for receiving the spring members “a”, identified as “ 216 .” The first and second axial surfaces  214 ,  215  respectively form two axial ends of the primary ring  210  while the spring holes  215  communicate the two axial surfaces  213 ,  214 . Furthermore, in assembly, the primary ring  210  radially surrounds the shaft sleeve  23 . The first slide legs  211  are formed on the first axial surface  214  and axially extend outwards, and an free end of each first slide leg  211  has a first engaging block  217  protruding to an axial line of the shaft bore  1  of the gland  1 . Similarly, The second slide legs  213  are formed on the second axial surface  215  and axially extend outwards, and an free end of each second slide leg  213  has a second engaging block  218  protruding to the axial line of the shaft bore  1 . Preferably, the first and second engaging blocks  217 ,  218  are formed on inner surfaces of the first and second slide legs  212 ,  213 , which directly face the axial line of the shaft bore  1 . 
     Particularly referring to the  FIGS. 2 and 5  through  8 , a structure of each compression ring  22  and a relationship between the retainer  21  and the compression rings  22  are illustrated as the following. Each of the compression rings  22  is formed with at least one cutaway portion  221  at an outer periphery thereof. Besides, both of the compression rings  22  are also coaxial with the shaft bore  1 . In order to clearly describe the precise relationship between the retainer  21  and the compression rings  22 , the compression ring  22  faced by the first axial surface  214  of the retainer  21  is renamed and designated as “first compression ring  22   a ,” and the compression ring  22  faced by the second axial surface  215  of the retainer  21  is renamed and designated as “second compression ring  22   b .” The first compression ring  22   a  is movably positioned between the first axial surface  214  and the first engaging blocks  217  in axial direction, and radially surrounded by the first slide legs  212 . Similarly, The second compression ring  22   b  is movably positioned between the second axial surface  215  and the second engaging blocks  218  in axial direction, and radially surrounded by the second slide legs  213 . 
     Specifically, please refer to  FIGS. 5 and 6 , which show schematic, partial views of the retainer  21  and the first and second compression rings  22   a ,  22   b  before the two compression rings  22   a ,  22   b  being assembled into the retainer  21 . The two compression rings  22   a ,  22   b  with the at least one cutaway portion  221  are characterized in that a smallest distance D 1  form the axial line of the shaft bore  1  to each cutaway portion  221  is not larger than a distance D 2  from the said axial line to each first or second engaging block  217  or  218 . Besides, if there are plural cutaway portions  221  utilized in the compression rings  22   a ,  22   b , each of the plural cutaway portions  221  corresponds to one of the slide legs  212 ,  213 . Therefore, regarding to a fore-step in assembly, taking the first engaging block  217  and the first compression ring  22   a  for example, the at least one cutaway portion  221  initially aligns with at least one of the first slide legs  212  for the first compression rings  22   a  to be pressed into a space between the first engaging blocks  217  and the first axial surface  214  of the retainer  21 . Please be noted that the pressing of the first compression ring  22   a  can be completed with the first compression ring  22   a  being parallel to the first axial surface  214  when the numbers of the first slide legs  212  and the at least one cutaway portion  221  are the same. Alternatively, the insertion of the first compression ring  22   a  is completed with the first compression ring  22   a  being inclined relative to the first axial surface  214  for passing the first engaging blocks  217 . The insertion of the second compression ring  22   b  is complete in the same way to place the second compression ring  22   b  in a space between the second engaging blocks  218  and the second axial surface  215  of the retainer  21 . 
     Please further refer to  FIGS. 7 and 8 , which show schematic, partial views of the retainer  21  and the first and second compression rings  22   a ,  22   b  after the said fore-step in assembly is finished. The two compression rings  22   a ,  22   b  with the at least one cutaway portion  221  are further characterized in that radiuses R of the outer peripheries of the two compression rings  22   a ,  22   b  out of the at least one cutaway portion  221  are larger than the said distance D 2  but not larger than a smallest distance D 3  form the axial line of the shaft bore  1  to each slide leg  212  or  213  excluded the engaging blocks  217  or  218 . Therefore, regarding to a later step in assembly, taking the first slide leg  212  and the first compression ring  22   a  for example, the first compression ring  22   a  is turned about the said axial line for the at least one cutaway portion  221  of the first compression ring  22   a  to be mis-aligned with each first slide leg  212 . And thus the first compression ring  22   a  is exactly limited in the space between the first engaging blocks  217  and the first axial surface  214 . Alternatively, the second compression ring  22   b  is also turned for being exactly limited in the space between the second engaging blocks  218  and the second axial surface  215  of the retainer  21 . Therefore, an assembly of the retainer  21  and compression rings  22   a ,  22   b  can be easily completed by the following steps: firstly pressing or inserting the first compression ring  22   a  into the space between the first engaging blocks  217  and the first axial surface  214  through the said fore-step; turning the first compression ring  22   a  about the said axial line to complete the misalignment between the at least one cutaway portion  221  of the first compression ring  22   a  and each first slide leg  212  through the later step; placing the spring members “a” into the spring holes  216  of the retainer  21 ; pressing or inserting the second compression ring  22   b  into the space between the second engaging blocks  218  and the second axial surface  215  through the said fore-step; and turning the second compression ring  22   b  about the said axial line to complete the misalignment between the at least one cutaway portion  221  of the second compression ring  22   b  and each second slide leg  213  through the later step at last. As a result, the spring members “a” can be always maintained between the two compression rings  22   a ,  22   b  and in the spring holes  216 . 
     Referring again to  FIGS. 2 and 3 , the shaft sleeve  23  is a monolithic body and includes a shaft-assembling hole  230 , a positioning flange  231 , and an annular groove  232 . The shaft-assembling hole  230  is penetratingly arranged along an axial direction of the shaft sleeve  23  and coaxial with the gland  1  for the shaft  9  to extend through. The positioning flange  231  is disposed at an outer periphery of the shaft sleeve  23 , and used to limit an axial movement of an O-ring identified as “b 2 ” rested on the outer periphery of the shaft sleeve  23 , as best shown in  FIG. 3 , so as to provide a greater sealing effect. Alternatively, the positioning flange  231  can also be used to limit an axial movement of the first rotating seal ring. In rotating operation, the O-ring “b 2 ” functions to prevent any possible leakage of liquids contained in the housing via a clearance existing between the shaft sleeve  23  and the first rotating seal ring  24 . Provided on an inner periphery of the shaft sleeve  23  is the annular groove  232  in which receives another O-ring identified as “b 3 ”. Similarly, the O-ring “b 3 ” functions to prevent any possible leakage of liquids contained in the housing via a clearance existing between the shaft sleeve  23  and the shaft  9 . Besides, the retainer  21  is firmly mounted around the shaft sleeve  23 , preferably, by means of screw connection as shown in  FIGS. 2 and 3 . 
     Still referring to  FIGS. 2 and 3 , the first rotating seal ring  24  is provided with an axial hole  240 , a first stepped portion  241 , a second stepped portion  242  and a plurality of notches  243 , and is abutted by the first compression ring  22   a  and pushed by the spring members “a” through the first compression ring  22   a . The axial hole  240  connects between two opposite sides of the first rotating seal ring  24 . In assembling, the axial hole  240  permits the shaft sleeve  23  to extend through. The first stepped portion  241  and the second stepped portion  242  are formed on an inner periphery of the first rotating seal ring  24 . Formed between the first stepped portion  241  and the positioning flange  231  is a space to receive the O-ring “b 2 ”. Formed on an outer periphery of the first rotating seal ring  24  are the notches  243  arranged on an annular flange (unlabeled), extending in a direction parallel to the first slide legs  212 , and preferably being spaced out evenly. The number of the notches  243  is not less than that of the first slide legs  212  for the first slide legs  212  to be received in and engage with the notches  243 . 
     Still referring to  FIGS. 2 and 3 , the second rotating seal ring  25  is provided with an axial hole  250 , a stepped portion  251  and a plurality of notches  252 , and is arranged to face the second axial surface  215  and pushed by the spring members “a” through the second compression ring  22   a . The axial hole  250  connects between two opposite sides of the second rotating seal ring  25 . In assembling, the axial hole  250  also permits the shaft sleeve  23  to extend through. The stepped portion  251  is formed on an inner periphery of the second rotating seal ring  25 . An O-ring identified as “b 4 ” is received in the stepped portion  251 . Formed on an outer periphery of the second rotating seal ring  25  are the notches  252 , which are also arranged on an annular flange (unlabeled). The number of the notches  252  is not less than that of the second slide legs  213  for the slide legs  211  to be received in and engage with the notches  252 . 
     Accordingly, the first rotating seal ring  24 , the retainer  21  and the second rotating seal ring  25  are mounted on the shaft sleeve  23  in order. And the repair or replacement of the rotating seal rings  24 ,  25  can surely be simply completed by axially taking off the rotating seal rings  24 ,  25  from the retainer  21  without a disengagement between the spring members “a,” retainer  21 , and compression rings  22 . Please be noted that, when the number of the notches  243  or  252  is larger than that of the slide legs  212  or  213 , those of the notches  243  or  252  that are untaken by the slide legs  212 ,  213  function as an impeller to drive the fluid in the gland  1  when the shaft  9  is rotated. Moreover, the first and second rotating seal rings  24 ,  25  are oppositely pushed by the spring members “a” to closely abut against the two stationary seal rings  13 . Furthermore, a limiting member  14  may firmly engaged on the inner wall of the gland  1 , adjacent to the stationary seal ring  13  abutted by the first rotating seal ring  24 , and radially protruding inwards, so as to prevent failure of sealing due to a large axial movement of the said stationary seal ring  13 . And the limiting member  14  is preferably formed in a ring shape and coaxial with the shaft bore  10  of the gland  1 , with a plurality of through holes  141  extending between two axial faces of the limiting member  14 . 
     Now further referring to  FIGS. 9 and 10 , views of a mechanical seal in accordance with a second embodiment of the present invention are shown. Differences between the mechanical seals of the first and second embodiments are that a stirring unit  233  forms an end of the shaft sleeve  23  and an auxiliary guiding unit  219  is formed on an outer periphery of the primary ring  211 . Regarding the stirring unit  233 , the end of the shaft sleeve  23  provides the stirring unit  233  is adjacent to the first rotating seal ring  24  and also facing the inner of the housing. Particularly, the stirring unit  233  radially faces the said interface between the first rotating seal ring  24  and the corresponding stationary seal ring  13  outwards. Specifically, please further referring to  FIGS. 11   a  and  11   b , the stirring unit  233  can be formed by at least one helical groove  233   a , or by at least one helical blade  233   b . Preferably, form a middle part of the shaft sleeve  23  to the said end thereof, a circular extending direction of each helical groove  233   a  or helical blade  233   b  is opposite to a rotating direction of the shaft  9 . Thereby, when the shaft  9  turns, the stirring unit  233  can drive the liquid received and stirred in the housing to flow beside the said interface, so as to prevent suspended impurities in the liquid from accumulating in the said interface. 
     Regarding the auxiliary guiding unit  219 , referring to  FIG. 12 , the auxiliary guiding unit  219  is preferably provided with at least one radially outwards formed helical blade  219   a . Therefore, the auxiliary guiding unit  219  can assist the flowing of the fluid received in the shaft bore  10 . 
     Moreover, please refer to  FIG. 9  again. In order to further enhancing efficiency in driving of the fluid, those untaken ones of the notches  243  or  252  can be inclined relative to the slide legs  212  or  213 . 
     Now, please refer to  FIGS. 13 and 14 . Views of a mechanical seal in accordance with a third embodiment of the present invention are shown. Differences between the mechanical seals of the second and third embodiments are that the fluid inlet  11  and fluid outlet  12  radially extend in different axial levels relative to the shaft bore  10 . Besides, the said fluid guiding member  3  is arranged adjacent to the fluid outlet  12 , with the channel  32  aligning with the fluid outlet  12 . Furthermore, another fluid guiding member  3 ′ is also mounted on the inner wall of the gland  1  but adjacent to the fluid inlet  11 . The fluid guiding member  3 ′ is in a tube shape that is coaxial with the shaft bore  1  and has a first axial end providing a plurality of radial grooves  33  and a second axial end providing a radial extended annular protrusion  34 . Particularly, an inner opening of each radial groove  33  faces first rotating seal ring  24 , preferably the interface between the first rotating seal ring  24  and the stationary seal ring  13 , inwards. The annular protrusion  34  connects with the inner wall of the gland  1  by an outer periphery thereof, and provides a curved surface  341  smoothly linking a surface of the fluid inlet  11  and an outer periphery of the fluid guiding member  3 ′ out of the annular protrusion  34 . Accordingly, the fluid guiding member  3 ′ smoothly guides the fluid inputted from the fluid inlet  11  to pass through the radial grooves  33  and directly cooling down or heating up the first rotating seal ring  24  and stationary seal ring  13  close to the said interface. 
     As has been discussed above, base on the design of the retainer  21  and the compression rings  22 , assembly and repair of the mechanical seal of the present invention without a disengagement of the spring members “a” is easy to be completed, which is absolutely unachievable for those sited prior arts. 
     Although the invention has been described in detail with reference to its presently preferred embodiment, it will be understood by one of ordinary skill in the art that various modifications can be made without departing from the spirit and the scope of the invention, as set forth in the appended claims.