JPH0518533Y2 - - Google Patents

Description

[Detailed description of the invention] (Industrial application field) The present invention is a mechanical seal useful as a shaft sealing device for rotating equipment such as a pump, and in particular, a mechanical seal that circulates a cooling liquid in a seal housing and has a sliding seal. This product relates to a mechanical seal with a cooling function that prevents frictional heat generation.

(Prior Art) In general, a mechanical seal is configured such that a fixed ring on the seal housing side and a rotating ring on the rotating shaft side are brought into pressure contact with each other by a spring force, and a seal is formed between the relatively rotating sliding contact surfaces of both rings. However, in order to prevent sealing failures caused by burning and deterioration due to frictional heat generation on the sliding contact surface, a cooling liquid is circulated within the seal housing to cool and lubricate the sliding contact surface. is known.

As a method of circulating the coolant in such a mechanical seal with a cooling function, there is a method of forced circulation using the rotation of the rotating shaft without using external power. A blade is provided on the seal housing, and a groove is formed on the inner surface of the seal housing along the outer periphery of the blade, and the coolant flowing from the inlet toward the sliding surface is rotated by the rotational force of the blade. Forcibly discharging from the outlet located at the end of the direction (such as Utility Model Application No. 59-68866), with an inlet at one end of the seal housing and an outlet at the other end, and from the inlet at the middle part. An expeller having inclined blades that generate an axial flow of cooling flow toward the outlet side is fixed to a rotating shaft, and the inlet and outlet are formed separately at both ends of the seal housing as described above, and the The inner diameter of the outlet side of the housing is increased, and instead of the above-mentioned expeller, the inside of the housing is divided into an inflow side and an outflow side by a partition wall part, and a circumferential wall part extending from the partition wall part to the outflow side. A type of pumping ring is fixed, and the pumping action is performed by the difference in centrifugal force due to the difference in radial position between the liquid passage hole formed in the partition wall and the liquid passage hole formed in the peripheral wall opposite the outlet. It has been adopted.

(Problems to be Solved by the Invention) However, in the conventional rotary ring itself in which blades are provided, an inlet and an inlet, a groove, and a blade are provided on both side sealing portions of the seal housing, resulting in structural problems. The drawback was that it was complicated and the manufacturing cost was high. In addition, in the conventional expeller and pumping ring fixed to the rotating shaft, the circulating fluid volume is usually 0.5 to 2/min.
Because of the relatively small diameter, there was a problem in that the cooling capacity was insufficient when the diameter of the rotating shaft was large or when the rotational speed was high.

The present invention was made to solve the above-mentioned conventional problems, and aims to provide a mechanical seal that is structurally simple, dramatically increases the amount of circulating fluid, and has a large cooling effect. .

(Means for Solving the Problems) In order to achieve the above object, the mechanical seal of the present invention has two ends of the seal housing 7, a fixed ring 10 on the seal housing side and a rotating shaft, which are pressed against each other by spring force. The housing 7 is sealed at the sliding contact portion 20 with the rotating ring 14 on the 6 side.
A mechanical seal having a coolant inflow hole 11 formed at one end and a coolant outflow hole 13 formed at the other end is fixed to the rotating shaft 6 and flows through the housing 7 to the inflow side space 22a. side space 2
2b and an annular partition wall 21a forming a booth _t1 with the inner circumferential surface of the housing; A plurality of blades 21e are fixed at predetermined intervals along the edge of the opening of the cylindrical portion 21b located near the outflow hole, and form a booth _t2 between the surrounding cylindrical portion 21b and the inner end surface of the housing.
A pumping impeller 21 is provided, and the annular partition wall 21 of the impeller 21 is
In a, a structure is adopted in which liquid passage holes 23 are bored at predetermined intervals in the circumferential direction to communicate both the spaces 22a and 22b.

(Example) Hereinafter, the present invention will be explained based on illustrated examples.

In Fig. 1, 1 is a centrifugal pump installed on a base 2, and 3 is a coolant tank supported and fixed via a bracket 4 on the upper part of a mounting frame 2a erected at the rear of the base 2. A coolant inlet pipe 5a and a coolant outlet pipe 5b are installed between the tank 3 and the shaft sealing device portion of the pump 1.

FIG. 2 shows a radial end face of the shaft sealing device portion of the centrifugal pump 1. As shown in FIG. In the figure, reference numeral 6 denotes a rotating shaft, and a stainless steel sleeve 6a is fitted and fixed on the outside of the rotating shaft, the outer diameter of both ends being slightly smaller than that of the middle part. Reference numeral 7 denotes a seal housing forming the outer shell of the mechanical seal, and from the pump main body side, that is, from the left side in the figure, a pump casing cover part 7a, a cylindrical seal part cover 7b having flanges at both ends, an annular spacer 7c, and an annular end plate. 7d, each made of stainless steel, are sequentially joined at their stepped end faces via O-rings 8 made of tetrafluoride resin, etc., and then tightened with connecting bolts 9a, 9b, and 9c to integrate them. It is configured. Therefore, at both ends of the seal housing 7,
Silicon carbide, etc. are applied to annular recesses 7e and 7e formed on the inner peripheral surface side between the casing cover portion 7a and the seal portion cover 7b, and on the inner peripheral surface side between the annular spacer 7c and the annular end plate 7d, respectively. A fixing ring 10 made of high-hardness ceramics is fitted with an annular convex portion 10a on the outer peripheral surface of the fixing ring 10, and the rotating shaft 6 is fixed.
It is fixed in a non-contact state.

Further, at one end side of the seal housing 7, a coolant inlet hole 11 connecting the introduction pipe 5a is bored in the annular spacer 7c along the radial direction, and at the other end side, an annular groove is formed on the inner surface of the seal part cover 7b. 12
At the same time, a coolant flow hole 13 connected to the outlet pipe 5b is opened at the bottom of the groove and is bored along a tangential direction to the inside of the groove, as shown in FIG. It is set up. Note that the opening position of the inflow hole 11 is set closer to the axis of the rotating shaft 6 than the opening position of the outflow hole 13.

Reference numeral 14 denotes a rotating ring made of carbon and formed in three stages, with the inner circumferential surface becoming smaller in diameter toward the outer end. The sleeve 6a is positioned and externally fitted on the stepped portion of the sleeve 6a, and an annular groove 14a that opens toward the center of the seal housing is formed between the inner end surface and the rotary shaft 6.

Reference numeral 15 denotes a stainless steel pressing ring whose outer peripheral surface is formed in a two-stage shape with a smaller diameter on the outer end side. , small diameter portion 15
a is fitted into the annular groove 14a of the rotary ring 14 via the O-ring 16. An engaging pin 15b is screwed into the small diameter portion 15a at a key point, and by engaging the engaging pin 15b with a U-shaped notch 14b formed in the rotating ring 14, both rings 14 and 15 are set to rotate together.

Reference numeral 17 denotes a spring retaining ring made of stainless steel, and as shown in FIG. Two bottomed spring holding holes 17b which are parallel to the axial direction and open to the outer end surface are equally spaced. This spring retaining ring 17
is located further toward the center of the seal housing than the press ring 15 with the coil spring 18 fitted in each spring holding hole 17b, and is fitted onto the rotating shaft 6, and the rotation is controlled by the set screws 17c, 17c. axis 6
is fixed to. Therefore, each pin insertion hole 17a
A screw-shaped drive pin 19 is inserted from the inner end side, and the threaded end of the pin 19 is inserted into the press ring 15.
It is screwed on. This drive pin 19 has a screw head located in a notch 17d formed on the inner end side of the insertion hole 17a, and allows the press ring 15 to rotate integrally with the spring retaining ring 17, and also allows the press ring to rotate when assembling the seal. It functions to prevent the pressure ring from coming off.

Therefore, the pressing ring 15 is the spring retaining ring 17
The rotating ring is always pressed against the fixed ring 10 via the O-ring 16 by being pressed by a coil spring 18, and when the rotating shaft 6 is driven, the pressing ring 1
5 and the rotating ring 14 rotate together with the spring retaining ring 17 via the drive pin 19 and the engagement pin 15b, and the rotating ring 14 and the fixed ring are in relative rotational sliding contact, and at this sliding contact portion 20, the inside and outside of the seal housing are always connected. sealed. Note that this sealing structure is provided at both ends of the seal housing 7, respectively.

21 is a pumping impeller, as shown in Fig. 5,
As shown in FIG. 6, in the center of the seal housing 7, the interior of the housing 7 is
and an annular partition wall 21a that partitions into an outflow side space 22b, a cylindrical part 21b surrounding the rotating shaft 6 and having one end welded and fixed to the peripheral edge of the side surface of the outflow hole of the partition wall 21a, and the cylindrical part 21b. The impeller 21c is welded to the other end of the impeller 21b. Thus, the annular partition wall 21a has an inflow side space 22a and an outflow side space 22 at an inner position than the cylindrical part 21b.
Liquid passage holes 23 are equally spaced along the circumferential direction and are fixed to the rotating shaft 6 via a set pin 21d, and in this fixed state, the outer circumferential surface and the inner circumferential surface of the seal housing 7 The booth is set to form a booth 〓t. Also, the impeller 21c
As shown in FIG. 5, a plurality of inclined blades 21e are protruded from the side surface thereof so as to be equally distributed along the circumferential direction. The outer periphery of the cooling liquid outlet hole 13 is set so as to face the annular groove 12 in which the coolant outlet hole 13 is opened.

In the mechanical seal having the above configuration, when the rotary shaft 6 is rotated with the inside of the seal housing 7 filled with coolant, the coolant in the seal housing 7 rotates with the rotation of the rotary shaft 6 and exerts centrifugal force. However, the outer peripheral side of the inflow side space 22a is formed by the inner peripheral surface of the seal housing 7, which is a non-rotating body, and the outflow side space 22b is mostly formed by the annular partition wall 21b and the cylindrical part 21.
Since the pumping impeller 21 is integral with the rotating shaft 6 and consists of Much greater than force. Moreover, the opening area of the opening on the side end of the outflow hole 13 in the cylindrical portion 21b is sufficiently larger than the total opening area of the liquid passage hole 23 provided in the annular partition wall 21a.

Therefore, the coolant in the cylindrical portion 21b receives velocity energy due to a large centrifugal force, and flows from the opening at the end of the cylindrical portion 21b on the side of the outflow hole 1 to the outflow hole 1.
As a result, the coolant in the inflow side space 22a flows into the cylindrical portion 21b from the liquid passage hole 23, and the coolant in the inflow side space 22a flows into the cylindrical portion 21b. The liquid passage hole 23 on one end side
A pumping action occurs in which the liquid is sucked in more and discharged from the opening at the other end. Moreover, an inclined blade 21e is provided in the vicinity of the outflow hole 13 at the end of the cylindrical portion 21b on the side of the outflow hole 13 through which the coolant in the cylindrical portion 21b is discharged. A strong pumping action is exerted by the rotation of 21e, and the coolant discharged from inside the cylindrical portion 21b receives even greater velocity energy and reaches the outflow hole 13.

In this way, since the pumping impeller 21 exerts a pumping action on the inside of the cylindrical portion 21b and the vicinity of the outflow hole 13, the synergistic effect of the two pumping actions causes the flow from the outflow hole 13 to the outlet pipe 5b to the coolant tank. 3→Introduction pipe 5a→Inflow hole 11→Inside of seal housing 7 The flow rate of the coolant circulation becomes very large, and as a result, the flow rate of the coolant circulation becomes very large.
The sealing portions at both ends, that is, the sliding contact portions 20, 20 are efficiently and strongly cooled. Therefore, the rotating shaft 6
Even when the shaft diameter is large or the rotational speed is high, a sufficient cooling effect can be obtained and temperature rise due to frictional heat generation can be avoided. In this circulation process, the cooling liquid returns from the outflow side space 22b to the inflow side space 22a through the space between the outer peripheral surface of the partition wall 21a of the pumping impeller 21 and the inner peripheral surface of the seal housing 7. Since the above distance is set to t ₁ , the pressure loss will be negligible.
Furthermore, the pumping action of the pumping impeller 21 can be further enhanced by making the space t ₂ between the inner end surface of the casing 7 and the opposing blade 21e as small as possible.

In particular, in the above embodiment, the annular groove 12 is formed on the inner circumferential surface of the seal housing where the outflow hole 13 opens.
Since a spiral chamber is formed in the groove 12, the pumping action becomes stronger, and the outflow hole 13 is formed tangentially to the inner circumferential surface, which improves the cooling efficiency. It has the advantage that the liquid discharge resistance is small, smooth flow occurs, and the pumping action is increased.

Incidentally, the coolant circulation flow rate of the mechanical seal configured in the above example is about 10/min when a mixture of glycerin and water (viscosity at room temperature 30 cp) is used as the coolant on a normal scale, which is different from that of the conventional mechanical seal described above. The circulating fluid volume is 5 to 20 times larger than that of similar scale models using an expeller or pumping ring, which is about 0.5 to 2/min.

In addition, in this invention, the detailed configurations of the shape of the rotating ring and fixed ring that make up the sealing part, the elastic pressure structure, etc. can be variously designed in addition to the above-mentioned embodiments, and the rotating equipment to which the mechanical seal is applied can be various rotating equipment, not limited to pumps such as centrifugal pumps.

(Operations and effects of the invention) According to the invention, the following effects can be achieved.

In other words, in the mechanical seal of the present invention, when the rotary shaft is rotated with the seal housing filled with cold liquid, the coolant inside the seal housing also rotates with the rotation of the rotary shaft and is subject to centrifugal force. However, the inflow side space, which is separated from the outflow side space through the annular partition wall of the pumping impeller, has an outer peripheral side formed by the inner peripheral surface of the seal housing, which is a non-rotating body, and an outflow side space on the opposite side. Most of the area is occupied by the pumping impeller integrated with the rotating shaft, which consists of the partition wall and a cylindrical part fixed to the peripheral edge of the side surface of the partition wall on the outflow hole side. The centrifugal force acting on the coolant in the side space is much larger than the centrifugal force acting on the coolant in the inflow side space. Moreover, the opening area of the end of the cylindrical portion on the outflow hole side is sufficiently larger than the opening area of the liquid passage hole provided in the partition wall.

Therefore, the cooling liquid in the cylindrical part receives velocity energy due to a large centrifugal force and flows out from the opening at the end of the cylindrical part on the outflow hole side to the outflow hole, thereby causing the cooling liquid in the inflow side space to The liquid flows into the cylindrical part through the liquid passage hole, and the cylindrical part has a pump action that sucks the coolant in the inflow side space through the liquid passage hole at one end and discharges it from the opening at the other end. works. Moreover, an inclined vane is provided near the outflow hole at the end of the cylindrical part on the side of the outflow hole through which the coolant inside the cylindrical part is discharged, and a strong pumping action is generated near the outflow hole by the rotation of the inclined vane. works, and the coolant discharged from the cylindrical portion receives even greater velocity energy and reaches the outflow hole.

In this way, since the pumping impeller exerts a pumping action on the inside of the cylindrical portion and in the vicinity of the outflow hole, the amount of circulating coolant becomes extremely large due to the synergistic effect of both pumping actions.
The sealing part due to the relative rotational sliding contact between the fixed ring and the rotating ring is extremely efficiently and powerfully cooled, and even when the rotating shaft diameter is large or the rotation speed is high, a sufficient cooling effect can be obtained and the frictional heat generation is prevented. Temperature rise is prevented. Furthermore, since the mechanical seal of the present invention has a very simple structure, manufacturing costs are low and it is easy to assemble and disassemble.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention,
Figure 1 is a side view of a centrifugal pump to which the present invention is applied.
Fig. 2 is a longitudinal sectional front view taken from the shaft sealing device portion of the pump, Fig. 3 is a sectional view taken along the - line in Fig. 2, Fig. 4 is a sectional view taken along the - line in Fig. 2, and Fig. 5 is a sectional view taken along the - line in Fig. 2. A front view of the pumping impeller, FIG. 6 is a sectional view taken along the - line in FIG. 5. 6...Rotating shaft, 7...Seal housing, 10
...Fixing ring, 11...Cooling liquid inflow hole, 12...
...Annular groove, 13...Cooling liquid flow, 14...Rotating ring, 18...Coil spring, 20...Sliding contact part, 2
DESCRIPTION OF SYMBOLS 1... Pumping impeller, 21a... Annular partition wall part, 21b... Cylindrical part, 21e... Inclined vane, 22a... Inflow side space, 22b... Outflow side space, 23... Liquid passage hole, _t1 , t ₂ ...booth〓.

Claims (1)

[Claims for Utility Model Registration] 1. Both ends of the seal housing are sealed at sliding contact portions between a fixed ring on the seal housing side and a rotating ring on the rotating shaft side, which are pressed against each other by spring force, and one end of the housing A mechanical seal having a coolant inflow hole and a coolant outflow hole formed at the other end thereof, the mechanical seal being fixed to a rotating shaft to partition the inside of the housing into an inflow side space and an outflow side space; an annular partition wall that forms a booth with an inner circumferential surface; a cylindrical part that is fixed to the peripheral edge of the side surface of the partition wall on the outflow hole side and surrounds the rotating shaft; and the outflow hole of the cylindrical part. A pumping impeller configured with a plurality of blades fixed at predetermined intervals along the edge of the opening located nearby and forming a space with the inner end surface of the housing is disposed, and an annular partition of the impeller. A mechanical seal characterized in that the wall portion has liquid passage holes formed at predetermined intervals in the circumferential direction to communicate the two spaces. 2. The mechanical seal according to claim 1, wherein the coolant outflow hole is formed tangentially to the inner periphery of the seal housing. 3. A utility model according to claim 1 or 2, wherein an annular groove is formed on the inner surface of the end of the seal housing on the coolant outlet side, and the coolant outlet hole is opened at the bottom of the groove. mechanical seal.