JPH0615172Y2 - mechanical seal - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention relates to a mechanical seal for both forward and reverse pressure and for forward and reverse rotation.

[Prior Art] Conventionally, a mechanical seal is relatively small and has an O-ring (6) on the outer peripheral surface of the rotating shaft (2) as shown in FIG. 5, for example.
The seal ring (5) attached and rotated through the non-rotating mating ring (3) attached through the O-ring (4) on the inner peripheral surface of the housing (1) has a single coil spring. It is a "one coil spring type" that is pressed by (7) and engages with both the collar (8) that supports the rear end of the coil spring (7) and the seal ring (5) in the circumferential direction. There is a "clutch type" structure in which a clutch portion (9) is provided to transmit the rotational force from the rotary shaft (2) to the seal ring (5).

[Problems to be solved by the device]

However, although the above mechanical seal can be used for both forward and reverse rotations, the pressure relationship between the spaces (A) and (B) partitioned by the mechanical seal is the reverse pressure, that is, the space (A) pressure is greater than the space (A) pressure. If the pressure in (B) is large, the pressure difference is the sealing sliding surface between the mating ring (3) and the seal ring (5).
Since it acts to open (S), it cannot be used for both forward and reverse pressure, and it is a small one-coil spring type, and the mechanical seal for both forward and reverse rotation and forward and reverse pressure is It did not exist.

From this point of view, the present invention intends to provide a compact and inexpensive mechanical seal for both forward and reverse rotation and forward and reverse pressure.

[Means for Solving the Problems]

The mechanical seal of the present invention includes a case having a protrusion that engages with a groove that extends axially from the outer diameter step portion of the rotating shaft to the outer peripheral surface on the large diameter side, and the case that is retained in the case and extends in the circumferential direction. A seal ring that engages with the non-rotating mating ring and is in sliding contact with the non-rotating mating ring, and a packing that is axially movably mounted in an annular space surrounded by the inner diameter step of the seal ring and the outer diameter step of the rotating shaft A washer interposed between the packing and the outer diameter step portion of the rotating shaft is provided.

[Action]

According to the configuration of the present invention, since the seal ring is rotated integrally with the rotary shaft by transmitting the rotational force through the case engaged with the seal ring and the groove on the outer peripheral surface of the rotary shaft,
It can be applied to both reverse rotations.

In addition, the axial component of the fluid pressure (positive pressure) on the sliding surface between the seal ring and the mating ring that flows inward is balanced on the outer peripheral side of the packing installed in the annular space inside the seal ring. , Acting as a pressing force to the mating ring side by acting on the inner diameter step portion of the seal ring via the packing, and an axial component of the fluid pressure (reverse pressure) on the side that makes an outward flow on the sliding surface. Acts between the inner diameter step and the packing,
After all, it becomes the pressing force to the mating ring side. In this back pressure state, the packing moves under pressure to move to the outer diameter step portion side of the rotating shaft in the annular space and press-contacts with the washer, so that it protrudes into the groove extending from the outer diameter step portion. , There is no bite.

〔Example〕

Hereinafter, the mechanical seal of the present invention will be described with reference to FIGS.
Description will be given with reference to an embodiment shown in the drawing.

In the figure, (10) is the housing and (20) is this housing.
The rotary shaft inserted in the inner circumference of (10), and (30) is a mechanical seal.

The mechanical seal (30) has a non-rotating mating ring (301) fitted in the housing (10) with an O-ring (302) interposed, and an O-ring (304) on the outer peripheral surface of the rotating shaft (20). Seal ring that is fitted through and rotates integrally with the rotating shaft (20)
It has (303).

On the inner peripheral surface of the seal ring (303), an inner diameter step portion (305) whose inner diameter is large on the side opposite to the mating ring is formed, while on the other hand, on the rotating shaft (20), the inner diameter step portion is formed.
An outer diameter step portion (201) is formed so as to face the (305) in the axial direction, and the O-ring (304) for maintaining airtightness between the rotary shaft (20) and the seal ring (303) is Both steps (201)
It is slightly movable in the axial direction in the annular space (40) surrounded by (305). Furthermore, the annular space (40) is located between the outer diameter step (201) and the O-ring (304),
A metal washer (306) is inserted.

(307) is a metal ring-shaped case holding the seal ring (303), the depression (309) formed in the outer periphery (307a)
Engages with the notch (308) formed on the outer peripheral surface of the seal ring (303), and extends on the back surface of the case (307) so as to cover the end surface of the seal ring (303) on the side opposite to the mating ring. The protrusion (310) formed on the inner diameter end of (307b) is
It engages with a groove (203) extending in the axial direction from the outer diameter stepped portion (201) of 0) to the outer peripheral surface (202) on the large diameter side of the rotating shaft (20).

(311) is a single coil spring that spirally surrounds the outer circumference of the rotary shaft (20), and one end (311a) of the coil spring abuts the back surface (307b) of the case (307), and the other end (311b). Is the axis of rotation
A collar made of a metal plate fitted into a second outer diameter step portion (205) formed on the outer diameter side of the outer diameter step portion (201) of (20).
It abuts (312) and is properly compressed. That is, the seal ring (303) is a rotary shaft (20) with the seal ring (303).
Via the case (307) engaged with both sides of the case (30) to rotate by receiving the torque from the rotating shaft (20).
It is pressed in the axial direction by the coil spring (311) via 7) and comes into close contact with the non-rotating mating ring (301) to form a sealed sliding surface (30S).

Further, the inner diameter (D2) of the O-ring (302) interposed between the housing (10) and the opposing end surface of the mating ring (301), and between the rotating shaft (20) and the opposing peripheral surface of the seal ring (303). The outer diameter (D3) of the O-ring (304) is set to be substantially the same as the outer diameter (D1) of the sealing sliding surface (30S).

The mechanical seal (30) of the present embodiment having the above configuration,
Since the seal ring (303) is circumferentially engaged with the rotary shaft (20) via the case (307), it can be used for both forward and reverse rotation.

Regarding the pressure relationship between the spaces (A) and (B) on both sides of the mechanical seal (30), for example, the pressure in the space (A) on the sealing sliding surface (30S), which is the inward flow, is Considering the case of a positive pressure relationship that is larger than the pressure in the space (B) on the surface (30S) side that faces outward flow, the outer diameter (D1) of the sealing sliding surface (30S) and the O-ring (304) Since the outer diameter (D3) is almost the same, the axial component of the differential pressure applied to the seal ring (303) from the space (A) side is sealed and slid as shown by many arrows in FIG. The surface (30S) and the O-ring (304) are more balanced on the outer peripheral side than the O-ring (304), and the O-ring (304) is located in the inner peripheral annular space (40).
The seal ring (303) acts as a load to press the seal ring (303) against the mating ring (301) via the inner diameter stepped portion (305).
On the contrary, when considering the case where the pressure in the space (A) is smaller than the pressure in the space (B), as shown in FIG. 4, the seal ring (303) is applied from the space (B) side. The axial component of the differential pressure acts as a load that presses the seal ring (303) against the mating ring (301) against the inner diameter stepped portion (305) in the annular space (40) on the inner circumference of the seal ring (303), and the sealing slide It does not open to the moving surface (30S). Where the O-ring
(304) is a rotating shaft (2
0) is pressed to the outer diameter step (201) side, but the O-ring
(304) and the outer diameter step (201) between the washer (306)
Since the O-ring (304) is provided, the O-ring (304) is prevented from being pushed out into the groove (203) which is an engaging portion with the protrusion (310) of the case (307) and protruding and being damaged. Also, O-ring
Since the inner diameter (D2) of (302) is almost the same as the outer diameter (D1) of the sealing sliding surface (30S), the mating ring (301) and seal ring
The axial component of the pressure acting on (303) is balanced.

Further, according to the structure of the above embodiment, the coil spring (7) is provided on the outer peripheral side of the seal ring (5) and the clutch portion (9) of the collar (8) as in the conventional example shown in FIG. Since it is not wound, the radial width of the seal ring (303) does not become large even though it was used for both forward and reverse rotation and forward and reverse pressure, and the washer (306) Since the case (307) and the collar (312) are metal press-molded products, they have the advantage of being inexpensive.

[Effect of device]

As described above, according to the present invention, a small one-coil spring type mechanical seal can be used for both forward and reverse rotation and for forward and reverse pressure.

[Brief description of drawings]

FIG. 1 is a half sectional view showing an embodiment of the present invention, FIG. 2 is a partially enlarged perspective view of the same, FIGS. 3 and 4 are operation explanatory views, and FIG. 5 is a half sectional view showing a conventional example. is there. (10) …… Housing, (20) …… Rotary shaft (30) …… Mechanical seal, (40) …… annular space (201) …… Outer diameter step, (202) …… Large diameter side outer peripheral surface (203) …… Groove, (301) …… Mating ring (302) (304) …… O-ring (packing) (303) …… Seal ring, (305) …… Inner diameter step (306) …… Washer , (307) …… Case, (310) …… Protrusion (311) …… Coil spring

Claims (1)

[Scope of utility model registration request] 1. A case having a projection engaging with a groove axially extending from an outer diameter step portion of a rotary shaft to an outer peripheral surface on the large diameter side thereof, and a case held in the case and engaged in the circumferential direction. And a seal ring that slides on the non-rotating mating ring,
A packing mounted in an annular space surrounded by the inner diameter step portion of the seal ring and the outer diameter step portion of the rotating shaft so as to be free to move in the axial direction, and a washer interposed between the packing and the outer diameter step portion of the rotating shaft. Mechanical seal characterized by comprising and.