JP2010230032A - End face contacting type mechanical seal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an end face contacting type mechanical seal which can excellently clean and sterilize sealing end face by a structure unchanged with respect to a general mechanical seal. <P>SOLUTION: The end face contacting type mechanical seal, which seals in shielding a device inside region A, or inner circumferential side region of relatively rotating slide section and its device outside region B, or peripheral side region of it by a relatively rotating sliding action between a statically sealing ring 3 fixed in a seal case 2 and rotary sealing ring 5 movably held in interfit to a rotary shaft 4 through an O-ring 6, wherein: a closing force, pushing the rotary sealing ring 5 to the statically sealing ring 3 when the device inside region A is made to be lower in pressure than the device outside region B, acts by making the O-ring 6 held in engagement to an annular recessed groove 12 formed in an inner circumferential section of the rotary sealing ring 5; and opening force, being separated from the statically sealing ring 3, acts by resisting a biasing force of spring member 7 pushing the rotary sealing ring 5 to the statically sealing ring 3 when the device inside region A is made to be higher in pressure than the device outside region B. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention is a rotating device that is used in the fields of foods, pharmaceuticals, etc. and needs to be cleaned or sterilized regularly or irregularly, and keeps the in-machine region A at a lower pressure than the out-of-machine region B during operation. In addition, the present invention relates to an end-face contact type mechanical seal used as a shaft sealing means of a rotating device (for example, a vacuum emulsifying device or the like) that is held at a higher pressure than the outside region B during cleaning or sterilization in the machine.

  In this type of rotating equipment, cleaning or sterilization treatment is performed by injecting a cleaning fluid such as steam or sterilizing fluid periodically or irregularly for hygiene management or quality control. Yes. In this case, it is necessary to clean and sterilize the shaft sealing means for sealing the inside and outside of the machine.

  However, when an end-face contact type mechanical seal in which the sealing end faces, which are the opposite end faces of both sealing rings, are in contact with each other as a shaft sealing means, cleaning fluid and sterilization fluid cannot pass between the sealing end faces. The sealed end face cannot be sufficiently cleaned and sterilized.

  Therefore, in general, the mechanical seal is cleaned and sterilized by disassembling the mechanical seal at the time of cleaning and sterilization or by directly injecting a cleaning and sterilizing fluid from the outside of the machine toward the sealed end face.

  However, in the former case, cleaning and sterilization operations are extremely troublesome and work efficiency is poor. In the latter case, since the sealed end surfaces are in close contact with each other, even if cleaning and sterilizing fluid are sprayed onto the sealed end surfaces, the sealed end surfaces cannot be sufficiently cleaned. There is a risk that the wear powder generated by the above will intrude into the machine due to cleaning and sterilizing fluid injection.

  Therefore, the cleaning and sterilization fluid injected into the machine has been conventionally made by allowing one of the sealing rings to be advanced and retracted by a cylinder and separating the sealing ring from the other sealing ring and opening the sealed end surfaces during cleaning and sterilization. Has been proposed (see Patent Document 1, for example).

Japanese Patent Laid-Open No. 2001-21045

  However, such a mechanical seal requires a cylinder and a member associated therewith, and the mechanical seal configuration becomes unnecessarily complicated and large, and the original function of the mechanical seal becomes unstable.

  The present invention has been made in view of the above points, and is an end face contact type that can satisfactorily clean and sterilize a sealed end face with a structure that is not different from a general mechanical seal without impairing the original function of the mechanical seal. The object is to provide a mechanical seal.

  INDUSTRIAL APPLICABILITY The present invention is used as a shaft sealing means for a rotating device that keeps the in-machine region at a lower pressure than the outside region during operation and at a higher pressure than the outside region during cleaning or sterilization. It is a mechanical seal, and a seal case is attached to the shaft seal portion of the rotary device, a stationary seal ring is fixed to the seal case, and the rotary seal ring is attached to the rotary shaft of the rotary device concentrically penetrating the stationary seal ring. It is fitted and held so that it can move in the axial direction in a secondary seal state via an O-ring, and the rotary seal ring is pressed and urged to the stationary seal ring by a spring member interposed between the rotary seal ring and the rotary seal ring. By the relative rotational sliding contact action of the sealing end surface that is the opposite end surface of the sealing ring, the inner region that is the inner peripheral region of the relative rotational sliding contact portion and the outer region that is the outer peripheral region are sealed and sealed. Configured to In the end face contact type mechanical seal, in order to achieve the above-mentioned purpose, in particular, the in-machine region is externally connected by engaging and holding the O-ring in an annular concave groove formed in the inner peripheral portion of the rotary seal ring. When the pressure is lower than the region, a closing force is applied to the rotary seal ring to press it against the stationary seal ring, and when the inner region is higher than the outer region, the rotary seal ring is attached to the rotary seal ring. It is proposed that an opening force acting against the force is separated from the stationary sealing ring.

  In the end-face contact type mechanical seal of the present invention, since the in-machine area becomes higher than the out-of-machine area by injecting cleaning fluid such as steam or sterilizing fluid into the machine, the sealed end face is opened in the machine. The cleaning fluid and sterilization fluid supplied to the region can effectively clean and sterilize the sealed end surface, and can be suitably used as a shaft seal means for a rotating device that requires high-level cleaning and sterilization. That is, according to the present invention, since the sealing end face is closed only by making a very simple improvement such as engaging and holding the O-ring in the annular groove formed in the inner peripheral portion of the rotary sealing ring, the sealing end face is closed. The end face contact type mechanical seal that cannot be sufficiently cleaned and sterilized can solve the fatal and unavoidable problems.

FIG. 1 is a longitudinal front view showing an example of an end-face contact mechanical seal according to the present invention. FIG. 2 is a longitudinal side view of the mechanical seal. FIG. 3 is an enlarged detailed view showing the main part of FIG. 1 and shows a state during operation in which the in-machine region is held at a lower pressure than the out-of-machine region. FIG. 4 is a longitudinal front view corresponding to FIG. 3 and shows a state during cleaning and sterilization in which the in-machine region is held at a higher pressure than the out-of-machine region. FIG. 5 is a longitudinal front view of the main part showing a modification of the end face contact type mechanical seal according to the present invention. FIG. 6 is a longitudinal front view of the main part showing another modification of the end surface contact type mechanical seal according to the present invention.

  Hereinafter, embodiments of the present invention will be specifically described with reference to FIGS. FIG. 1 is a longitudinal front view showing an embodiment of an end face contact type mechanical seal according to the present invention, FIG. 2 is a longitudinal side view of the mechanical seal, and FIGS. 3 and 4 are main parts of FIG. FIG. 3 is an enlarged detail view, and FIG. 3 shows a state during operation in which the in-machine region is held at a lower pressure than the out-of-machine region, and FIG. 4 shows the in-machine region held at a higher pressure than the out-of-machine region. This indicates the state during cleaning and sterilization.

  The end-face contact mechanical seal in this embodiment performs stirring (emulsification processing, etc.) of food, medicines, etc. in a state in which the in-machine region A is vacuumed and maintained at a lower pressure than the air region which is the out-of-machine region B during operation. A vertical rotation that cleans or sterilizes the interior of the machine while maintaining the in-machine area A at a higher pressure than the atmospheric area (external area) B by injecting a cleaning fluid such as steam or a sterilizing fluid into the machine when the operation is stopped. It is used as a shaft sealing means for equipment (such as a vacuum emulsifier) and is configured as follows according to the present invention. In the following description, “upper and lower” means the upper and lower sides in FIGS.

  That is, as shown in FIGS. 1 and 2, the end-face contact type mechanical seal has a seal case 2 attached to a shaft seal portion 1 a that is an upper end portion of the housing 1 of the rotating device, and a stationary seal ring 3 is attached to the seal case 2. The rotary seal ring 5 is fitted and held so as to be movable in the axial direction in a secondary sealed state via an O-ring 6 on the rotary shaft (stirring shaft or the like) 4 of the rotary device that is fixed and passes through the stationary seal ring 3 concentrically. Then, the rotary seal ring 5 is pressed against the stationary seal ring 3 by a spring member 7 interposed between the rotary seal ring 5 and the rotary shaft 4 so as to be opposed end faces of the seal rings 3 and 5 during operation. By the relative rotational sliding contact action of the sealing end faces 3a and 5a, the in-machine region A that is the inner peripheral side region of the relative rotational sliding contact part and the outer peripheral region B that is the outer peripheral side region are shielded and sealed. It is configured.

  As shown in FIGS. 1 and 2, the seal case 2 is a cylindrical body separated into a main body portion 2a that abuts on the shaft seal portion 1a and a flange portion 2b that abuts on the outer periphery of the upper end thereof. It is comprised with metal materials (for example, SUS304 etc.).

  As shown in FIGS. 1 and 2, the stationary seal ring 3 is an annular body made of a hard material such as ceramics (for example, silicon carbide), and the inner peripheral portion (more precisely, the flange portion) of the seal case 2 The inner periphery of 2b is concentrically fitted and fixed via O-rings (or sheet-like gaskets) 8 and 8. The upper end surface, which is the distal end surface of the stationary seal ring 3, is configured as a sealed end surface (hereinafter referred to as "stationary side sealed end surface") 3a which is an annular smooth plane orthogonal to the axis. The inner peripheral surface on the lower end side of the stationary seal ring 3 is a conical surface that expands downward.

  The rotary shaft 4 extends vertically from the shaft seal portion 1a and passes through the seal case 2 and the stationary seal ring 3 concentrically. As shown in FIGS. A spring retainer 9 made of a metal material (for example, SUS316 or the like) such as stainless steel is fitted and fixed above the ring 3. That is, the spring retainer 9 is a cylindrical body having an L-shaped cross section composed of a cylindrical sealing ring holding portion 9 a and an annular spring holding portion 9 b integrally formed at the upper end portion thereof. As shown in FIG. 2, the O-ring 10 is interposed between the rotating shaft 4 and an appropriate number of set screws 11.

  As shown in FIGS. 1 to 4, the rotary seal ring 5 includes an O-ring 6 engaged with a seal ring holding portion 9 a of a spring retainer 9 and an annular groove 12 formed in the inner peripheral portion of the seal ring 5. Are fitted and held so as to be movable in the axial direction (vertical direction).

  That is, the rotary seal ring 5 is fitted to the main body portion 5b, a sealed end surface forming portion 5c projecting from the distal end (lower end), and the main body portion 5b in a state of being in contact with the base end surface (upper end surface) and the outer peripheral surface. It is comprised by the annular body which consists of the reinforcement part 5d fixed together. The reinforcing portion 5d is made of a metal material such as stainless steel (for example, SUS316), and the main body portion 5b and the sealing end surface forming portion 5c are softer than the constituent material of the stationary sealing ring 3 (for example, polytetrafluorocarbon). A composite material mainly composed of ethylene (PTFE) or carbon).

  Thus, as shown in FIG. 3, an annular groove 12 for engaging and holding the O-ring 6 in a compressed state is formed in the inner peripheral portion of the main body 5b. The diameter D1 of the bottom surface (groove bottom surface) 12a of the recessed groove 12 allows axial rotation of the rotary seal ring 5 between the groove bottom surface 12a and the outer peripheral surface of the seal ring holding portion 9a of the spring retainer 9, and is rotationally sealed. The O-ring 6 is set in a compressed state in which the space between the ring 5 and the spring retainer 9 is sealed (secondary seal). The shape (groove depth) of the concave groove 12 is set in the in-machine region A. Regardless of whether the pressure is negative (vacuum) or positive, the O-ring 6 does not jump out of the concave groove 12, and the movement of the O-ring 6 in the axial direction is restricted by the groove side surfaces 12b and 12c. Is set to The inner diameter D2 of the rotary seal ring 5 is constant and is set slightly larger than the outer diameter (diameter of the sliding surface of the O-ring 6) D3 of the seal ring holding portion 9b of the spring retainer 9. The outer diameter D3 of the sealing ring holding portion 9b is constant. Further, as shown in FIG. 2, the rotary seal ring 5 allows the drive pin 13 fixed to the holding portion 5d to be inserted into the through hole 9c formed in the spring holding portion 9b of the spring retainer 9, thereby moving the axial direction within a predetermined range. Thus, relative rotation with respect to the rotating shaft 4 is prevented.

  As shown in FIG. 3, the front end surface (lower end surface) of the sealed end surface forming portion 5c is configured as a sealed end surface (hereinafter referred to as “rotation side sealed end surface”) 5a which is an annular smooth plane orthogonal to the axis. The inner diameter D4 of the rotation-side sealing end surface 5a is the sliding surface of the O-ring 6 engaged and held in the concave groove 12 (the outer peripheral surface of the rotating shaft portion in contact with the O-ring 6, that is, the sealing ring holding portion 9b of the spring retainer 9). The diameter D3 of the outer peripheral surface) and the diameter D1 of the groove bottom surface 12a of the groove 12 are set to be larger by a predetermined amount. The inner diameter D4 of the rotary side sealing end surface 5a is set larger than the inner diameter of the stationary side sealing end surface 3a, and the outer diameter D5 is the outer diameter of the stationary side sealing end surface 3a and the outer diameter of the reinforcing portion 5d of the rotary sealing ring 5. It is set smaller than D6. In other words, in this example, the inner and outer diameters of the sealing surfaces (the annular surfaces on which the both sealing rings 3 and 5 are in sliding contact) with both the sealing rings 3 and 5 are the same as the inner diameter D4 and the outer diameter D5 of the rotation-side sealing end surface 5a. It has become.

  As shown in FIG. 1, the spring member 7 is composed of a plurality of coil springs 7a loaded at equal intervals in the circumferential direction between the reinforcing portion 5d of the rotary seal ring 5 and the spring holding portion 9b of the spring retainer 9. The rotary seal ring 5 is pressed and urged to the stationary seal ring 3.

  By the way, in the end face contact type mechanical seal having the above-described configuration, the O-ring 6 is engaged and held in the annular groove 12 formed in the inner peripheral portion of the rotary seal ring 5 as described above. Due to the differential pressure P (= | Pa−Pb |) between the pressure of A (hereinafter referred to as “in-machine pressure”) Pa and the pressure in the outside region B (hereinafter referred to as “external pressure”) Pb, The thrust (acting force in the axial direction) as shown in FIG. In the following description, each pressure P, Pa, Pb is an absolute pressure.

That is, during operation of the rotating device, the in-machine pressure Pa becomes a vacuum (the in-machine pressure Pa is lower than the out-of-machine pressure Pb), so that the rotary seal ring 5 has a differential pressure P as shown in FIG. Thrusts F1, F2, F3, F4 and F5 act. Here, thrusts F1, F2, and F3 are separation forces that act in a direction to separate the rotary seal ring 5 from the stationary seal ring 3, and are opening forces that open between the sealed end faces 3a and 5a, and the thrusts F4 and F5 are rotations. This is a pressing force acting in the direction in which the sealing ring 5 is brought into contact with the stationary sealing ring 3, and is a closing force that closes between the sealing end faces 3a and 5a. That is, the opening force F1 is generated between the sealing end faces 3a and 3b by the relative rotation of the sealing rings 3 and 5, and F1 = (P / 2) · (π / 4) · ((D5) ² − (D4) ² ). The opening force F2 acts on the front end surfaces of the main body portion 5a and the holding portion 5b on the outer peripheral side of the sealed end surface forming portion 5b, and F2 = P · (π / 4) · ((D6) ² − (D5) ² ). The thrust F3 acts on the upper groove side surface 12b and is given by F3 = P · (π / 4) · ((D1) ² − (D2) ² ). The closing force F4 is due to the back pressure acting on the back surface of the rotary seal ring 5 (the back surface of the holding portion 5b), and F4 = P · (π / 4) · ((D6) ² − (D2) ² ) = P (Π / 4) (((D6) ² − (D5) ² ) + ((D5) ² − (D4) ² ) + ((D4) ² − (D1) ² ) + ((D1) ² − (D2) ² )). The closing force F5 acts to press the O-ring 6 toward the lower groove side surface 12c, and is given by F5 = P · (π / 4) · ((D1) ² − (D3) ² ). From these, F4 + F5- (F1 + F2 + F3) = P · (π / 4) · ((((D5) ² − (D4) ² ) / 2) + ((D4) ² − (D3) ² ))> 0 Thus, during the operation of the rotating device, the closing force Fc (= F4 + F5− (F1 + F2 + F3)) that presses the rotating seal ring 5 toward the stationary seal ring 3 acts on the rotary seal ring 5 due to the differential pressure P. Therefore, the sealing end surfaces 3a and 5a are always in relative sliding contact with each other without setting the pressing biasing force, that is, the closing force S spring force 7 by the spring member 7, so that a good end surface contact type mechanical seal function is exhibited. Is done.

On the other hand, at the time of cleaning or sterilization in which cleaning fluid such as steam or sterilizing fluid is injected into the machine when the operation of the rotating equipment is stopped, the internal pressure Pa is higher than the external pressure (atmospheric pressure) Pb. As shown in FIG. 4, thrusts F 6, F 7, F 8 due to the differential pressure P act on the seal ring 5. Here, the thrust F6 is an opening force acting on the distal end surface of the main body 5a on the inner peripheral side of the sealed end surface forming portion 5b, and F6 = P · (π / 4) · ((D4) ² − (D2) ² ). The thrust F7 is an opening force that acts to press the O-ring 6 toward the upper groove side surface 12b, and is given by F7 = P · (π / 4) · ((D1) ² − (D3) ² ). On the other hand, the thrust F8 is a closing force which acts on the lower groove side 12c, F8 = P · (π / 4) · - is given by ^{((D1) 2 (D2)} 2). From these, F6 + F7−F8 = P · (π / 4) · ((D4) ² − (D3) ² )> 0, and the rotary seal ring 5 is caused by the differential pressure P during cleaning or sterilization. Open force Fo (= F6 + F7−F8) acting in the direction away from the stationary seal ring 3 acts. Therefore, the spring force S of the spring member 7 is smaller than the opening force Fo (= F6 + F7−F8 = P · (π / 4) · ((D4) ² − (D3) ² )) (S <Fo). If set, the space between the sealed end surfaces 3a and 5a will be opened, and the cleaning fluid such as steam injected into the machine and the sterilizing fluid will flow between the sealed end surfaces 3a and 5a and flow out to the outside region B. become. As a result, not only the inside of the machine but also the sealed end surfaces 3a and 5a are cleaned and sterilized by the cleaning fluid and the sterilizing fluid. Moreover, since the cleaning fluid and the sterilizing fluid pass through the sealed end faces 3a and 5a and flow out to the outside area B, the abrasion powder generated by the contact of the sealed end faces 3a and 5a is released to the outside area B, and the in-machine area A Will not pollute. When the cleaning fluid and the sterilizing fluid pass between the sealed end faces 3a and 5a, as shown in FIG. 4, the opening force F9 (= P · (π / 4)) due to the differential pressure P is also applied to the rotating side sealed end face 5a. ((D5) ^2- (D4) ² )) acts, and the sealed end surfaces 3a, 5a are further opened, and the sealed end surfaces 3a, 5a are more effectively cleaned and sterilized. By the way, since the closing force Fc due to the differential pressure P acts during operation as described above, that is, even when the spring force S is set as small as possible, the sealing function of the end surface contact type mechanical seal can be exhibited. Therefore, setting the spring force S of the spring member 7 so that S <Fo can be easily performed without any particular difficulty, and adversely affects the mechanical seal function during operation. Will not affect. Incidentally, the spring force S is given by S = k · x · n (N) from the number n of the coil springs 7a, the spring constant k (N / m), and the compression amount x (m) from the free length.

  According to the end surface contact type mechanical seal configured as described above, when the in-machine region A is at a lower pressure than the out-of-machine region B (during operation), the rotary seal ring 5 is pressed against the stationary seal ring 3. When the closing force Fc is applied and the in-machine region A is at a higher pressure than the out-of-machine region B (during cleaning and sterilization), an opening force Fo is applied to the rotary seal ring 5 to separate it from the stationary seal ring 3. Since the spring force S is set to be smaller than the opening force Fo acting on the rotary seal ring 5 by the differential pressure P between the two regions A and B during cleaning and sterilization, the end face contact during operation is achieved. The sealing end surfaces 3a and 5a as well as the inside of the machine can be cleaned and sterilized without any adverse effect on the sealing function of the mechanical seal.

  The configuration of the end face contact type mechanical seal according to the present invention is not limited to the above-described embodiment, and can be appropriately improved and changed without departing from the basic principle of the present invention.

  For example, in the above embodiment, the inner diameter D4 (the inner diameter of the rotation-side sealing end surface 5a in the above example) D4 of the sealing surface (contact portion of the sealing end surfaces 3a and 5a) is larger than the diameter D1 of the groove bottom surface 12a. <D1 or D4 = D1 may be set, and in any case, the closing force Fc during operation and the opening force Fo during cleaning and sterilization are generated by the differential pressure P, as in the embodiment.

That is, when D4 <D1, when the rotating device is operated, as shown in FIG. 5A, the opening force F1 (= (P) generated between the sealing end faces 3a and 3b by the relative rotation of the sealing rings 3 and 5 is shown. / 2) · (π / 4) · ((D5) ² − (D4) ² )), an opening force F2 acting on the front end surface of the main body portion 5a and the holding portion 5b on the outer peripheral side of the sealed end surface forming portion 5b (= P · (π / 4) · ((D6) ² − (D5) ² )), opening force F3 acting on the upper groove side surface 12b (= P · (π / 4) · ((D1) ² − (D2 ² )) and the closing force F4 (= P · (π / 4) · ((D6) ² − (D2) ² ) = P · (π) acting on the back surface of the rotary seal ring 5 (the back surface of the holding portion 5b)) ^{/ 4) · (((D6} ) 2 - (D5) 2) + ((D5) 2 - (D1) 2) + - and ^{((D1) 2 (D2)} 2)), the O-ring 6 Position of closing force F5 (= P · (π / 4 which acts to push into the groove side surface ^{12c) · ((D1) 2} - (D3) 2) = P · (π / 4) · ((D1) 2 − (D4) ² ) + ((D4) ² − (D3) ² ))), the rotary seal ring 5 has a closing force Fc (= F4 + F5− (F1 + F2 + F3) = P · (π / 4) · ( (((D5) ^2- (D4) ² ) / 2) + ((D4) ^2- (D3) ² ))> 0) will act, and the sealed end face 3a regardless of the magnitude of the spring force S. , 5a are contacted. On the other hand, at the time of cleaning and sterilization, as shown in FIG. 5B, an opening force F6 (= P · (π / 4)) acting on the distal end surface of the main body portion 5a on the inner peripheral side of the sealed end surface forming portion 5b. ((D4) ^2- (D2) ² )), an opening force F7 (= P · (π / 4) · ((D1) ^2- () acting to press the O-ring 6 against the upper groove side surface 12b) D3) ² )) and the resultant force of the closing force F8 (= P · (π / 4) · ((D1) ^2- (D2) ² )) acting on the lower groove side surface 12c is opened to the rotary seal ring 5 The force Fo (= F6 + F7−F8 = P · (π / 4) · ((D4) ² − (D3) ² )> 0) acts. Therefore, by setting the spring force S so that S <Fo, the space between the sealed end faces 3a and 5a is opened.

The case where D4 = D1 is the same as the case where D4 <D1. That is, during operation of the rotating device, as shown in FIG. 6A, the opening force F1 (= (P / 2) · (π /) generated between the sealing end faces 3a and 3b by the relative rotation of the sealing rings 3 and 5 4). ((D5) ^2- (D4) ² )), opening force F2 (= P · (π / 4) acting on the front end surface of the main body 5a and the holding portion 5b on the outer peripheral side of the sealed end surface forming portion 5b ((D6) ^2- (D5) ² )), opening force F3 (= P · (π / 4) · ((D1) ^2- (D2) ² )) acting on the upper groove side surface 12b and rotational sealing Closing force F4 (= P · (π / 4) · ((D6) ² − (D2) ² ) = P · (π / 4) · ((( ^{D6) 2 - (D5) 2} ) + ((D5) 2 - (D1) 2) + ((D1) 2 - and ^{(D2) 2)),} and the O-ring 6 to the lower groove side 12c Closing force acts to push F5 (= P · (π / 4) · ((D1) 2 - (D3) 2) = P · (π / 4) · ((D1) 2 - (D4) 2) + ( ^{(D4) 2 - (D3)} 2)) as a resultant force of), the closing force Fc is the rotary seal ring 5 (= F4 + F5- (F1 + F2 + F3) = P · (π / 4) · ((((D5) 2 - ( D4) ² ) / 2) + ((D4) ² − (D3) ² ))> 0) is applied, and the sealed end faces 3a and 5a are brought into contact regardless of the magnitude of the spring force S. Become. On the other hand, at the time of washing and sterilization, as shown in FIG. 6B, an opening force F6 (= P · (π / 4)) acting on the front end surface of the main body 5a on the inner peripheral side of the sealed end surface forming portion 5b. ((D4) ^2- (D2) ² )), an opening force F7 (= P · (π / 4) · ((D1) ^2- () acting to press the O-ring 6 against the upper groove side surface 12b) D3) ² )) and the resultant force of the closing force F8 (= P · (π / 4) · ((D1) ^2- (D2) ² )) acting on the lower groove side surface 12c is opened to the rotary seal ring 5 The force Fo (= F6 + F7−F8 = P · (π / 4) · ((D4) ² − (D3) ² )> 0) acts. Therefore, by setting the spring force S so that S <Fo, the space between the sealed end faces 3a and 5a is opened.

Further, in the above-described embodiment, the present invention is applied to the shaft sealing means of a rotating device in which the external pressure Pb is atmospheric pressure and the internal pressure Pa is negative (vacuum) during operation. If the rotating device is Pa <Pb at the time and Pa> Pb at the time of cleaning and sterilization, the external pressure Pb is not an atmospheric pressure, or the internal pressure Pa is a positive pressure (high) both during operation and during cleaning and sterilization. Even when the pressure includes an atmospheric pressure), the end face contact type mechanical seal of the present invention can be used as a shaft sealing means of the rotating device. When cleaning and sterilization are performed in the operation stop state where the rotating shaft 4 is not driven, the opening force Fo (= P ···) is used in any of the cases of FIGS. 4, 5B and 6B. In order for (π / 4) · ((D4) ^2- (D3) ² )) to occur, that is, Fo> 0, the diameter of the surface on which the O-ring 6 slides (in each of the above embodiments) In this case, the outer diameter of the sealing ring holding portion 9b of the spring retainer 9)) D3 is the inner diameter of the sealing surface (the inner diameter of the annular surface in which both the sealing rings 3 and 5 are in sliding contact. Is smaller than the inner diameter (D4) of the rotation-side sealing end face 5a (D3 <D4). However, when the rotary shaft 4 is rotationally driven at the time of cleaning or sterilization, the opening force Fx (= (P / 2) · () between the sealing end faces 3a and 3b due to the relative rotation of the sealing rings 3 and 5 due to the in-machine fluid. π / 4) · ((D5) ² − (D4) ² )), this opening force Fx and the opening force Fo (= P · (π / 4) · ((D4) ² − (D3) ^{As long} as the spring force S can be set to be smaller than the opening force (S <Fx + Fo) on the condition that the total force with ² )) becomes the opening force (Fx + Fo> 0), the mechanical seal of the present invention. It is also possible to make the structure D3 ≧ D4, and the object of the present invention can be achieved.

DESCRIPTION OF SYMBOLS 1 Housing of rotating equipment 1a Shaft seal part 2 Seal case 3 Stationary sealing ring 3a Stationary side sealing end surface 4 Rotating shaft 5 Rotating sealing ring 5a Rotation side sealing end surface 6 O-ring 7 Spring member 9 Spring retainer 12 Groove A Machine area B Machine Outside area

Claims (1)

A mechanical seal used as a shaft seal for a rotating device that keeps the in-machine region at a lower pressure than the outside region during operation and at a higher pressure than the outside region during cleaning or sterilization. And
A seal case is attached to the shaft seal of the rotating device, a stationary sealing ring is fixed to the seal case, and the rotating sealing ring is inserted into the rotating shaft of the rotating device concentrically through the stationary sealing ring via an O-ring. In the next seal state, it is fitted and held so as to be movable in the axial direction, and the rotary seal ring is pressed and urged to the stationary seal ring by a spring member interposed between the rotary seal ring and the rotary seal ring, which is the opposite end face of both seal rings. End surface contact configured to shield and seal the in-machine area, which is the inner peripheral area of the relative rotational sliding contact portion, and the outer area, which is the outer peripheral area, by the relative rotational sliding action of the sealing end surface. In the mechanical seal,
By engaging and holding the O-ring in an annular groove formed in the inner periphery of the rotary seal ring, when the in-machine region is at a lower pressure than the out-of-machine region, the O-ring is turned into a stationary seal ring. When the pressing closing force is applied and the in-machine region is at a higher pressure than the out-of-machine region, an opening force is applied to the rotary seal ring against the urging force of the spring member to separate it from the stationary seal ring. An end face contact type mechanical seal characterized by the above.

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