JPH0656215B2 - Dry gas seal device - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a shaft rotating through a casing wall,
A dry gas sealing device configured as an axial sliding ring packing, comprising a shaft bushing configured as a carrier for a sealing surface that rotates together with the shaft, and a sliding surface that is pressed against the sealing surface by gas. In order to lubricate the sealing surface and the sliding surface by the pressure increase, the sealing surface and / or the sliding surface are provided with a plurality of grooves extending obliquely to the radial direction from the outer peripheral edge as a starting point. Regarding things.

[Conventional technology]

Such an axial shaft seal device is disclosed, for example, in European Patent No. 1
No. 3678, a casing inner chamber of a turbomachine, for example a turbocompressor or turbine, which is under pressure, is sealed at the shaft penetration to the outside or to the intermediate chamber. It is used to prevent the flow of pressure medium out of. This outflow prevention is a blocking medium,
For example, with a sealing gas, the blocking medium presses the sliding surface of the sliding ring against the sealing surface of the shaft bushing, thus minimizing the outflow of gas from the casing interior, in which case the leakage of the sealing device is prevented. It is kept at the minimum possible value by means of a corresponding packing ring. At the same time, a gear for the contactless relative movement of the sealing device is formed.

In known shaft sealing devices, aerodynamic sealing devices are utilized, in which case the gas used as lubricant is externally supplied via inclined, for example oblique or spiral grooves or sealing surfaces or Supply to the sliding surface, whereby lubricant and thus gas leaks are significantly less than with known aerostatic sealing devices. By the groove extending obliquely to the radial direction, in this case, when the shaft rotates, the lubricant is automatically distributed from the outside to the inside on the sealing surface or the sliding surface by the pump action, and A purposeful pressure build-up occurs at the temperature, which results in a low-friction sealing device. However, a disadvantage of such a sealing device is that it cannot adequately distribute the lubricant on the sliding surface when moving in the opposite direction, e.g. when reversing the turbomachine, and therefore bites and locks and thus breaks. It is to be.

[Problems to be Solved by the Invention]

The object of the present invention is to eliminate the above-mentioned drawbacks of the prior art and to improve the dry gas seal device of the type mentioned at the outset to a shaft seal device when the shaft rotates in the direction opposite to the predetermined rotation direction. Avoid rocks and damage.

[Means for Solving the Problems]

The constituent means of the present invention for solving the above-mentioned problems is a load that generates a force in the direction opposite to the crimping direction of the sliding ring with respect to the sealing surface when reversing the rotation direction of the shaft or when the sealing surface and the sliding surface are relatively rotated. A release device is provided.

[Action]

With the unloading device of the present invention, friction is reduced to a non-hazardous degree when the shaft is reversed or relative movement between the sliding surface and the sealing surface, or the sliding ring is completely separated from the sealing surface, A force opposite to the crimping direction is generated.

[Advantageous configuration]

An unloading device according to the invention comprises an outer rim of a sliding ring,
It is particularly advantageous to have an oblique guide on the inner surface of the packing holder facing the outer rim. Due to the friction between the sealing surface and the sliding surface, a torque is applied to the sliding ring, which exerts a circumferential force on the sliding ring in a given direction of rotation, but in the opposite direction of rotation. , A force component opposite to the direction in which the sliding ring is pressed against the shaft bush is additionally generated. Such an oblique guide has one or more sliding surfaces distributed over the entire circumference of the slide ring and oblique to the axis of rotation and cooperating with corresponding elements of the other member. Is advantageous.

〔Example〕

 Next, an embodiment of the present invention will be described in detail with reference to the drawings.

In the example shown in FIG. 1, the shaft 1 is hermetically guided from the high-pressure region Pi to the low-pressure region Pa, for example through a casing wall 2 of the turbomachine. The sealing device comprises a shaft bushing 3 mounted on the shaft 1, said shaft bushing holding the shaft 1 in the radial gear box 4.
The sleeve-shaped end 3'of the shaft bushing is spring-elastically supported on the shaft 1 toward the outside. Axis bush 3
Supports a seal body 5 on the outer peripheral surface thereof, and the seal body has an annular seal surface 6 formed on the outer peripheral surface thereof.

Further, the sealing device is arranged in the packing holder 2'inserted into the casing wall 2 in the circumferential direction, that is, non-rotatably, but has a slight play in the circumferential direction and is slidable in the axial direction. It has a movable sliding ring 7, which is centered on the inner peripheral surface side 7 ′ with respect to the additional part 8 of the packing holder 2 ′. The sliding rings 7 are arranged on both sides of the inner side and have sliding surfaces 9'facing the annular sealing surface 6.
Holding a sliding body 9 with a material of good sliding properties.

The shaft sealing device is supplied with the sealing gas at pressure Ps through the casing wall 2 via the conduit 10, which pressure may be slightly higher than the high pressure Pi to be sealed in the turbomachine. The pressure Ps may then be taken from the turbomachine itself or supplied as external gas. The sealing gas presses the rear surface of the sliding ring 7 and presses the sliding ring onto the shaft bush 3, so that the annular sealing surface 6 abuts on the sliding surface 9'of the sliding body 9 and thus the gas flows out from the inside of the casing. Is sufficiently prevented. Nevertheless, the trace amount of gas flowing out is discharged via the conduit 13.

In the present embodiment, in addition to the sealing device, a sliding ring sealing device 14 having substantially the same structure is provided to further improve the sealing effect or as an emergency sealing device. It can be omitted in some cases.

As shown in FIG. 2, the annular sealing surface 6 or the sliding surface 9 ′ is provided with a plurality of spiral grooves 18 starting from the outer peripheral edge 17 as a starting point. The groove 18 is in the radial direction R
With respect to the sealing surface 6 by means of a pressure buildup, by which gas is pumped from the outside by pumping into the groove in a predetermined normal rotational direction. Sufficient gas lubrication of the sliding surface 9'is guaranteed.

In the case of the reverse rotation direction, the pressure buildup in the gear is insufficient and the sealing surface and the sliding surface are in contact with each other, so that the lubrication is not sufficiently performed, and there is a risk of biting or sticking of the packing. As a result, the sealing device will be damaged and damaged. In order to avoid this, as reverse rotation prevention means,
A load release device 19 is provided on the outer rim 11 of the slide ring 7 and the corresponding inner surface 20 of the packing holder 2 ′. The load releasing device 19 automatically applies a reaction force to the sliding ring 7 when the rotational direction is reversed, and the sliding ring 7 releases the load of the sliding surface 9 ′ from the annular sealing surface 6 and the sealing surface 6 Pull back the sliding surface 9'completely.

The load release device 19 can consist of a plurality of wedges 21 provided on the outer rim 11 of the sliding ring 7, which wedges have a plurality of wedge-shaped projections 22 provided on the corresponding inner surface 20 of the packing holder 2 '. Will work together. The wedge portion 21 and the wedge-shaped convex portion 2
2 is a sliding surface that is oblique to the axial direction A on one side
21 ', 22' and on the other side axial stop surface 2
It has 1 ″ and 22 ″.

FIG. 3a shows the load release device during normal operation, i.e. during a predetermined forward rotation of the shaft 1. Since the sliding ring 7 is frictionally linked by the annular sealing surface 6,
In this case, the stopper surfaces 21 ″ and 22 ″ are in contact with each other. Since both stopper surfaces are oriented in the axial direction,
Substantially only the force in the circumferential direction P is produced. Therefore, the stopper surfaces 21 "and 22" act as anti-rotation means for the sliding ring 7.

When the direction of rotation of the shaft 1 is reversed, the sliding ring 7 is also frictionally moved by the sealing body 5 of the rotating shaft bush 3 and the sliding surfaces 21 'and 22' are in contact with each other as shown in FIG. 3b. They press each other with a predetermined force. However, since the two sliding surfaces 21 'and 22' are inclined with respect to the axis of the shaft 1, a force component in the axial direction A is generated, and the force component is generated.
When the load on the sliding ring 7 is released and the sufficient force is applied, the sliding ring 7 is separated from the sealing surface 6. Therefore, there is little or no dry friction that can wear or damage the sealing device.

As shown in FIG. 4, instead of the wedge portion 21, it is possible to provide another type of member such as a pin or a roller 23.
However, the prerequisite in that case is that this corresponding member can slide or roll on the inclined sliding surface 22 '.

It should be noted that the stop surface 22 ″ may also be constructed in another way, for example as a roller 23 ′ and / or as a surface which is inclined in the opposite direction to the sliding surface 22 ′. Often, this results in an additional crimping or unloading force of the sliding ring 7 against the annular sealing surface 6 during normal operation.

A plurality of load releasing devices 19 are provided along the circumference of the sliding ring 7.
In particular in a symmetrical arrangement on the outer rim 11, eg two load release devices are arranged diametrically opposite one another in order to even the introduction of forces and avoid tilting moments, or a relatively large number of load release devices. Are advantageously arranged in a star arrangement.

[Brief description of drawings]

1 is a cross-sectional view of the shaft seal device along the axis, FIG. 2 is a plan view of a sealing surface or a sliding surface, FIG. 3a is a plan view of an annulus of a sliding ring at a specified forward rotation, and 3b.
The figure is a plan view of the ring part of the sliding ring during reverse rotation,
FIG. 4 is a plan view of a ring portion according to another embodiment. Pi ... High pressure part, Pa ... Low pressure part, Ps ... Seal gas pressure,
1 ... Shaft, 2 ... Casing wall, 2 '... Packing holder,
3 ... Shaft bush, 3 '... Sleeve end, 4 ... Radial gear, 5 ... Sealing body, 6 ... Annular sealing surface, 7 ... Sliding ring, 7' ... Inner peripheral surface side, 8 ... Additional portion, 9 … Sliding body,
9 '... Sliding surface, 10 ... Conduit, 11 ... Outer rim, 13 ... Conduit, 14 ... Sliding ring seal device, 17 ... Outer peripheral edge, 18
... Spiral groove, R ... Radial direction, 19 ... Load releasing device, 20 ... Corresponding inner surface, A ... Axial direction, 21 ... Wedge part, 22
... Wedge-shaped projections, 21 ', 22' ... Sliding surface, 21 ", 22" ... Stopper surface, 23,23 '... Roller

Claims (7)

[Claims] 1. A dry gas sealing device in the form of an axial sliding ring packing for a shaft (1) rotating through a casing wall (2), said sealing surface rotating with said shaft (1). A shaft bush (3) configured as a carrier of (6), and a sliding surface (9 ') that is pressed against the sealing surface by gas, and the sealing surface (6) is formed by pressure increase. And a plurality of sliding surfaces (9 ') extending obliquely to the sealing surface (6) and / or the sliding surface (9') with respect to the radial direction (R) starting from the outer peripheral edge (17). In which the groove (18) is provided, the sliding ring with respect to the sealing surface (6) when the rotation direction of the shaft (1) is reversed or when the sealing surface (6) and the sliding surface (9 ') are relatively rotated. (9 ′)
A dry gas seal device, characterized in that a load releasing device (19) for generating a force in the direction opposite to the crimping direction is provided. 2. An oblique load release device (19) provided on the outer rim (11) of the sliding ring (7) or on the inner surface (20) of the packing skin holder (7) facing the outer rim. Having directional guides (21 ', 22'),
Due to the torque applied to the sliding ring (7) by the friction between the sealing surface (6) and the sliding surface (9 ') when the shaft (1) rotates in the direction opposite to the predetermined rotational direction, The dry gas seal device according to claim 1, wherein the dry gas seal device is configured to generate a force component in a direction opposite to a direction in which the sliding ring (7) is pressed against the sealing surface (6). 3. The oblique guides are distributed over the circumference (11) of the sliding ring (7) or on the casing wall (20) facing it, obliquely with respect to the axis of rotation and on the other hand. 3. A dry gas sealing device according to claim 2, characterized in that it has one or more sliding surfaces (21 ', 22') cooperating with corresponding elements of said member. 4. The sliding surface is the outer rim (1) of the sliding ring (7).
1) or the opposite inner surface (2) of the packing holder (2 ')
0) comprising at least one surface (21 ') oblique to the axial direction and corresponding elements (22', 23) of the other member cooperating with said surface. The dry gas seal device described. 5. The corresponding element has an inclined sliding surface (2
5. A dry gas sealing device according to claim 4, characterized in that it has an oblique facing surface (22 ') corresponding to 1'). 6. The corresponding element has an inclined sliding surface (2
5. The dry gas sealing device according to claim 4, comprising rollers (23) cooperating with 1 '). 7. A plurality of load release devices (19) symmetrically distributed over the entire circumference (11) of the sliding ring (7) are provided. The dry gas seal device described.