JPH11324884A - Shaft seal device for hydraulic machine, and hydraulic machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a shaft seal device for a hydraulic machine and the hydraulic machine, which leaks less water during a positive pressure operation, and can stably perform a long time operation without supplying lubricating water during a negative pressure operation. SOLUTION: A shaft seal device 100 which seals a gap between a sleeve 102 provided on the outer periphery of a pump rotation shaft 101 and a seal casing 108 has seal materials 103A, 103B (103) which abut slidably, radially to the outer periphery of the sleeve 102, a seal case 105 and a cover 106 which form a pressure chamber 104 on the outer peripheral side of this seal material 103 and store the seal material 103, and a radial groove 103b and a cercumferential groove 103a for communicating the pressure chamber 104 with a pump sealing side P, and an O-ring 112 for shutting off the pressure chamber 104 from the atmospheric side Po.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shaft sealing device for sealing a gap between, for example, a pump rotating shaft and a casing penetrating portion of the rotating shaft, and more particularly to a shaft of a hydraulic machine suitable for performing a negative pressure operation. It relates to a sealing device.

[0002]

2. Description of the Related Art There are various types of shaft sealing devices for sealing a gap between a rotary shaft of a hydraulic machine and a penetrating portion through which the rotary shaft passes through a casing, depending on the application. For example, a shaft sealing device of a vertical shaft drain pump for draining river water (water containing hard particles such as earth and sand) generally includes a shaft having a gland packing structure using a string-shaped packing as a sealing material. A sealing device is used. This shaft sealing device can be used for both positive pressure operation (when the sealed side inside the hydraulic machine is higher than the outside atmosphere side) and negative pressure operation (when the sealed side is lower than the atmosphere side). Thus, the lubricating water is supplied to the sliding surface. Normally, the supply pressure of the lubricating water is about 0.1 MPa higher than the pressure on the sealed side.

On the other hand, as another type of shaft sealing device, for example, a ring-shaped rotating sliding member is connected to a rotating shaft, and a fixed sliding member is also connected to a casing. There is a shaft sealing device provided with a so-called mechanical seal that mechanically seals by sliding the members together. In recent years, in this shaft sealing device, as described in Mechanical Design Vol. 32, No. 2 (February, 1988), a mechanical seal in which a sliding member is formed of ceramics having excellent wear resistance has been proposed. I have. In a shaft sealing device provided with a mechanical seal, in the case of a positive pressure operation, the pumped liquid from the sealing side is introduced into the seal portion where the two sliding members slide, and is lubricated by the pumped liquid. Water supply is not required. However, in the case of the negative pressure operation, since the temperature of the seal increases due to friction due to the dry state of the seal portion, in order to cope with this, for example, as disclosed in Japanese Patent Application Laid-Open No. 154869/1990, from the outside of the pump. Lubrication is performed by introducing lubricating water.

[0004] Further, as another type of shaft sealing device, for example, as disclosed in Japanese Utility Model Laid-Open Publication No. 62-147766, a gap is previously set between the rotating shaft and the fixed side member so as to prevent the shaft from contacting. There has been proposed a shaft sealing device provided with a so-called bush seal that seals with a shaft.

[0005]

The above prior art has the following problems. That is, in the shaft sealing device having the gland packing structure, it is necessary to always supply the lubricating water regardless of the positive pressure operation or the negative pressure operation. Further, even in a shaft sealing device having a mechanical seal, lubricating water needs to be supplied in the case of a negative pressure operation. Therefore, when the negative pressure operation is performed for a long time, a large amount of lubricating water is required, which increases the cost. In addition, since a lubricating water supply piping system is required, maintenance and management of the piping is required, which increases the work load and further increases the cost. Further, when a trouble occurs in the water supply piping system, there is a possibility that the pump cannot be started, and there is a problem that it is difficult to improve the reliability.

On the other hand, in a shaft sealing device provided with a bush seal, since the rotating shaft and the fixed side member are normally in a non-contact state, a long-time operation can be performed without using lubricating water even in a negative pressure operation. It is. However, during the positive pressure operation, since the pumped liquid leaks from the sealed side through the gap between the rotating shaft and the fixed-side member, a large amount of water leaks and the efficiency is reduced. In addition, in the negative pressure operation, contrary to the positive pressure operation, air from the atmosphere side is sucked through the gap between the rotating shaft and the fixed side member. When the number of the pumps is too large, there is also a problem that the operation of the pump itself becomes difficult.

The present invention has been made in view of the above-mentioned problems of the prior art, and has as its object to reduce the amount of water leakage during positive pressure operation and to provide a long time without supplying lubricating water during negative pressure operation. An object of the present invention is to provide a shaft seal device and a hydraulic machine of a hydraulic machine that can stably operate.

[0008]

(1) In order to achieve the above object, the present invention provides a seal between a rotating shaft of a hydraulic machine or a sleeve provided on the outer periphery of the rotating shaft and a casing of the hydraulic machine. In the shaft sealing device of a hydraulic machine, a sliding member is disposed so as to radially contact the outer peripheral portion of the rotary shaft or the sleeve and slide, and a pressure chamber is provided on the outer peripheral side of the sliding member. A storage member for storing the sliding member while being formed, communication means for communicating the pressure chamber with the sealed side of the hydraulic machine, and shutoff means for shutting off the pressure chamber and the atmosphere side of the hydraulic machine. Having. During the negative pressure operation, the pressure on the sealed side of the hydraulic machine becomes lower than the atmospheric pressure on the atmosphere side. At this time, the inner peripheral portion of the sliding member contacts the outer peripheral portion of the sleeve (or the rotating shaft) in the radial direction and slides. As a result, the inner peripheral portion of the sliding member has the atmospheric pressure at the atmospheric end, but the pressure is reduced toward the sealed end, so that the pressure at the sealed end is as low as the hydraulic machine sealed side. On the other hand, the pressure chamber located on the outer peripheral side of the sliding member communicates with the hydraulic machine sealed side via the communication means, and is isolated from the hydraulic machine atmosphere side by the isolation means. As a result, the pressure inside the pressure chamber is uniformly reduced to the same pressure as the hydraulic machine sealing side. Therefore, the balance between the force acting on the entire inner peripheral portion of the sliding member and the force acting on the entire outer peripheral portion of the sliding member from the pressure chamber is larger in the former, so that the inner peripheral portion of the sliding member is reduced. A pushing force is generated on the radially outer peripheral side. Thereby, the frictional force between the inner peripheral portion of the sliding member and the sleeve (or the rotating shaft) is reduced, and the temperature is hardly increased. Therefore, the negative pressure operation can be stably performed for a long time without supplying lubricating water.

On the other hand, during positive pressure operation, the pumped liquid from the sealed side of the hydraulic machine is discharged from the inner peripheral portion of the sliding member to the sleeve (or the rotating shaft).
The lubrication is performed with the pumped liquid. At this time, the force that presses the inner peripheral portion of the sliding member toward the radially inner peripheral side by an operation completely opposite to that in the negative pressure operation. Is generated, the leakage amount of the pumped liquid through the sliding surface can be reduced. At this time, the pumped liquid from the hydraulic machine sealed side is also introduced into the pressure chamber through the communication means, but the pressure chamber and the hydraulic machine atmosphere side are shut off by the shutoff means, so that Water leakage of pumped liquid can be prevented. As described above, the leakage amount of the pumped liquid as a whole during the positive pressure operation can be sufficiently reduced.

(2) In the above (1), preferably,
The sliding member has a structure divided into a plurality in the circumferential direction.

(3) In the above (1), preferably, the shutoff means is a resistance means for communicating the pressure chamber with the atmosphere side of the hydraulic machine via a predetermined pressure loss.

(4) In the above (1), preferably, at least the outermost peripheral portion of the rotary shaft or the sleeve is made of a cemented carbide. Since the cemented carbide has a high hardness and is easily oxidized, the sliding surface is stabilized and seizure can be prevented. Therefore, the reliability of the shaft sealing device can be improved.

(5) In the above (4), more preferably, the outer peripheral surface of the cemented carbide is impregnated with an ethylene tetrafluoride resin. As a result, a thin ethylene tetrafluoride resin film of several μm is formed on the sliding surface by the rotation of the rotating shaft. Since this film is easy to slip and has a small friction coefficient, more stable sliding characteristics can be obtained.

(6) In (1) above, preferably, the sliding member is made of ceramics. Since the hardness of ceramics is higher than that of metal materials, it is possible to extend the life and improve the wear resistance.

(7) In the above (6), more preferably, the ceramic is ceramic of silicon carbide or ceramic of silicon carbide impregnated with ethylene tetrafluoride resin.

(8) In the above (1), preferably, a groove not communicating with the sealing side of the hydraulic machine but communicating with the atmosphere side of the hydraulic machine is formed in the inner peripheral portion of the sliding member. Form. At the time of the negative pressure operation, since the pressure up to the groove portion of the inner peripheral portion of the sliding member becomes the atmospheric pressure, it is based on the balance between the force acting on the entire inner peripheral portion of the sliding member and the force acting on the entire outer peripheral portion of the sliding member. The force for pushing up the sliding member to the outer peripheral side becomes larger. Therefore, the frictional force between the inner peripheral portion of the sliding member and the sleeve (or the rotating shaft) is further reduced, and more stable sliding characteristics can be obtained. Further, since the area of the air film on the sliding surface is increased by the groove, the rigidity of the air film is increased, and the non-contact state with the sliding member can be ensured even when the sleeve (or the rotating shaft) vibrates. Therefore, the life of the sliding member can be extended. Furthermore, since the amount of air passing through the sliding surface increases and the cooling performance improves, the operating range of the hydraulic machine can be expanded to the high peripheral speed range side.

(9) In the above (1), preferably, the blocking means is an O-ring provided in a groove provided in the housing member.

(10) In the above (1), preferably, the communication means includes a groove provided in the sliding member or the storage member in a radial direction.

(11) In the above (1), preferably, the communication means includes a communication hole provided in the storage member. Since the storage member does not slide with other members like a sliding member and can be manufactured with a normal metal member,
The cost for creating the communication means can be reduced as compared with the case where a groove is formed in the sliding member.

(12) In order to achieve the above object, the present invention provides a casing, a rotating shaft, and a shaft for sealing between the rotating shaft or a sleeve provided on the outer periphery of the rotating shaft and the casing. In a hydraulic machine having a sealing mechanism,
The shaft sealing mechanism is in contact with the outer peripheral portion of the rotating shaft or the sleeve in the radial direction, and a sliding member disposed so as to slide,
A housing member for housing the sliding member while forming a pressure chamber on the outer peripheral side of the sliding member; communication means for communicating the pressure chamber with the sealing side of the hydraulic machine; the pressure chamber and the hydraulic machine And a blocking means for blocking the air from the atmosphere.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings.

First, a horizontal shaft drainage pump will be described as an example of a hydraulic machine to which the present invention is applied. FIG. 2 is a longitudinal sectional view showing the overall structure of the horizontal axis drainage pump. In FIG. 2, a pump 1 includes a casing 2, a pump main shaft 3 serving as a rotating shaft, an impeller (runner) 4 fixed to a center portion of the pump main shaft 3, and a pump main shaft 3 that penetrates the casing 2. And a shaft sealing mechanism 6a, 6b, 6c, 6d, 6e, 6f for sealing between the casing 5 and the sleeve 5 provided on the outer periphery of the pump main shaft 3. At this time, both ends of the pump main shaft 3 are rotatably supported by rolling bearings 8,
A coupling 9 is fixed to one end (the right end in the figure).

In the pump 1, water (for example, rainwater) sucked from a suction port (not shown) of the casing 2 is
The air is introduced into the suction passage 10 from the suction port. Thereafter, the pressure is increased by the runner 4 rotating together with the pump main shaft 3, discharged to the discharge passage 11, and discharged to the outside of the pump from a discharge port (not shown) of the casing 2.

FIG. 1 shows a shaft sealing device according to an embodiment of the present invention.
This will be described with reference to FIG. FIG. 1 is a longitudinal sectional view showing the entire structure of the pump shaft sealing device 100 according to the present embodiment. FIG.
, The shaft sealing device 100 is applied, for example, as the shaft sealing mechanisms 6a to 6f in FIG.
1 (corresponding to the pump main shaft 3 in FIG. 2) as a sliding member arranged so as to radially contact and slide on the outer peripheral portion of a sleeve 102 (corresponding to the sleeve 5 in FIG. 2). A seal member 103, a seal case 105 and a cover 106 as storage members for storing the seal member 103 while forming a pressure chamber 104 on the outer peripheral side of the seal member 103, a pump casing (not shown, and a casing 2 shown in FIG. 2) Equivalent to)
And a substantially cylindrical seal casing 108 fixed to the casing.

The sleeve 102 is made of metal and is made of, for example, SUS403. Also sleeve 102
Is a set screw with a hexagonal hole on the rotating shaft 101 (not shown)
Alternatively, it is fixed by applying an adhesive or the like.

The seal member 103 has a substantially cylindrical shape and is made of, for example, a carbon material. The seal member 103 has a structure divided into a plurality of segments (two in this embodiment) in a circumferential direction in a segment shape, and is disposed between the seal case 105 and the sleeve 102 along the circumferential direction. ing. FIG. 1 is a cross-sectional view showing a detailed structure of the sealing member 103 in FIG. 1 (however, a rotation preventing pin 111 is excluded).
Is shown in FIG. In FIG. 3, the sealing material 103 is
Seal material segment 1 at seams 109, 109
03A and a sealing material segment 103B. These sealing material segments 103A, 103B
Has a garter spring 110 on its outer peripheral side (see FIG. 1).
, Which are held in a ring shape. The sealing member 103 has one circumferential groove 103a formed in the circumferential direction on the end face on the pump sealing side (indicated by the P side in FIG. 1) and the circumferential groove 10a.
A radial groove 103a formed in the radial direction from the inner circumference to the outer circumference so as to intersect with 3a;
And two detent grooves 103c formed in the radial direction so as to extend from the outer periphery to the outer periphery. Each detent groove 103
The rotation preventing pin 111 inserted and fixed in the concave groove 105a of the seal case 105 is inserted into c.
The seal member 103 is prevented from rotating together with the sleeve 102. As shown in FIG. 3, the anti-rotation groove 103c is formed into two divided sealing material segments 103A,
103B is provided at the center in the circumferential direction. In addition,
A fixing means (not shown) for preventing rotation is also provided between the seal case 105 and the seal casing 108.

Further, at a portion where the end face of the seal material 103 on the atmosphere side (indicated by Po side in FIG. 1) and the cover 106 are in contact, rubber or the like is used as a blocking means for blocking the pressure chamber 104 and the pump atmosphere side Po. Elastic body, for example, O-ring 11
2 are provided. The O-ring 112 covers the cover 1
The sealing member 103 is inserted and arranged in a circumferential groove 106a formed in the circumferential direction on the opposing surface of the sealing member 103 so as to elastically press the sealing member 103.

The seal case 105 is arranged on the outer peripheral side of the sleeve 102 with a gap in the radial direction, and its axial position is determined by the cover 106.

In the above configuration, one circumferential groove 103a and four radiation grooves 103b are formed in the pressure chamber 10
A communication means for connecting the pump 4 to the pump sealing side (P side) is constituted.

The operation of the present embodiment configured as described above will be described below.

(1) Long-time stable operation at the time of negative pressure operation FIG. 4 and FIG.
This will be described with reference to FIG. FIG. 4 shows a circumferential groove 103a and a radiation groove 103b as communication means from the structure of this embodiment.
And a structure in which the O-ring 112 as the blocking means is omitted (first comparative example; see FIG. 5B), and only the circumferential groove 103a and the radiation groove 103b as the communicating means are omitted, and the blocking means is used. The structure provided with the O-ring 112 (second comparative example; see FIG. 5C) and the structure of the present embodiment (FIG. 5C)
FIG. 9A is a diagram showing a comparison of experimental results obtained by measuring the behavior of the temperature of the sealing material 103 during the negative pressure operation with respect to (a). At this time, the horizontal axis represents the elapsed time after the start of operation, and the vertical axis represents the temperature rise of the sealing material 103. The experimental conditions were as follows: the outer diameter of the sleeve 102 was 100 mm, and the inner diameter of the sealing material 103 was 100.08.
mm, and the temperature of the sealing material 103 was measured by embedding a sensor at a position 1 mm from the sliding surface. Further, the temperature rise value of the sealing material is defined by the temperature of the sealing material minus the air temperature.

First, in the first comparative example having no communication means / blocking means, when the negative pressure operation is started, the pump sealing side (P
Side) is lower than the atmospheric pressure on the atmosphere side (Po side) (in FIG. 5, this is represented by a reference value of 0).
The inner peripheral portion 3 is in contact with the outer peripheral portion of the sleeve 102 in the radial direction and slides. Thereby, the sealing material 1 which is a sliding portion
As shown conceptually in the lower part of FIG. 5B, the inner peripheral portion of 03 has an atmospheric pressure of 0 at the atmospheric side end, while the pressure is reduced toward the sealed side end, and the inner side of the sealed side end is -P. Therefore, the sliding surface per unit circumferential length (seal material 1)
The force acting on the seal member 103 radially outward acting on the inner peripheral surface of the seal member 103 is (− ／) LP, where L is the width of the seal member 103 in the axial direction. At this time, since the pressure on the pump sealing side (P side) is lower than that on the atmosphere side (Po side), the sealing material 103 is pressed toward the pump sealing side, and the atmosphere side end face of the sealing material 103 and the cover 106 are closed. A small gap 113 is formed between the pump sealing end face. Therefore, the pressure chamber 104 located on the outer peripheral portion of the sealing material 103 communicates with the atmosphere side (Po side) through the gap 113, and as shown conceptually in the upper part of FIG. Thus, the atmospheric pressure becomes zero. Therefore, the force that presses the seal member 103 radially inward, which acts on the outer peripheral surface of the seal member 103 per unit circumferential length, is zero. As described above, a force for pressing the seal member 103 radially inward with a size of (１ ／) LP per unit circumferential length acts on the seal member 103. Pressed. Therefore, the sealing material 1
Since the frictional force between the sleeve 03 and the sleeve 102 increases and a remarkable temperature rise of 20 ° C. or more occurs in 3 hours as shown in FIG. 4, it is difficult to operate for a long time as it is. Found that lubrication water supply was necessary.

Next, in the second comparative example in which only the shut-off means is provided, when the negative pressure operation is started, it is conceptually shown in the lower part of FIG. 5C according to the same principle as in the first comparative example. As described above, the sliding surface per unit circumferential length (the inner circumferential surface of the sealing material 103)
The force acting on the seal member 103 to lift it outward in the radial direction is (-1/2) LP. On the other hand, like the first comparative example, the pump sealing side (P side) is on the atmosphere side (Po side).
Due to the lower pressure, a minute gap 113 is generated between the atmosphere-side end face of the sealing material 103 and the pump sealing-side end face of the cover 106.
Since the pressure chamber 12 is provided, the pressure chamber 104 is isolated from the atmosphere (Po side). However, since the sealing member 103 is pressed toward the pump sealing side, the gap between the pump sealing side end surface of the sealing member 103 and the atmosphere side end surface of the sealing case 105 is almost eliminated.
The pressure in the pressure chamber 104 is maintained at a pressure close to the atmospheric pressure 0 before the start of operation, as conceptually shown on the upper left side of FIG. As described above, almost in the same manner as in the above-described embodiment, the sealing material 103 has (１ ／) LP per unit circumferential length.
As a result, a temperature rise of about 9 ° C. occurs in less than three hours after the start of operation, as shown in part a of FIG.

When the temperature rises, the sealing material 103 thermally expands, and joints 109 and 10 between the divided sealing material segments 103A and 103B are formed.
9 is opened to form a gap (this is the same in the first comparative example). Here, in the second comparative example, unlike the first comparative example, the air-side end face of the sealing material 103 and the cover 106 are different.
O-ring 1 as a shut-off means between the
Since the pressure chamber 12 is provided, the pressure chamber 104 communicates mainly with the pump sealing side rather than the atmosphere side. As a result, the pressure in the pressure chamber 104 rapidly drops, and as shown conceptually on the upper right side of FIG.
Pressure close to Therefore, the force that presses the seal member 103 radially inward, which acts on the outer peripheral surface of the seal member 103 per unit circumferential length, is-(1/2) LP.
As described above, since a force for lifting the seal member 103 radially outward with a size of (１ ／) LP per unit circumferential length acts on the seal member 103, the frictional force between the seal member 103 and the sleeve 102 is reduced. As shown in FIG. 4A, a sharp temperature drop occurs.

When the temperature decreases, the sealing material 103 contracts from the thermal expansion state, and the joints 109, 109 between the sealing material segments 103A, 103B are closed again. As a result, the state becomes the same as that immediately after the start of operation again, the frictional force between the seal member 103 and the sleeve 102 increases, and a remarkable temperature rise occurs again as described first, and thereafter, as shown in FIG. It was found that the behavior became extremely unstable with repeated rise and fall of temperature.

In contrast to the first and second comparative examples described above, the present embodiment behaves as follows.
That is, the sliding surface per unit circumferential length (seal material 1)
As in the first and second comparative examples, the force acting on the inner peripheral surface of the seal member 103 is changed in the radial direction as shown in the lower part of FIG. The outward lifting force is (-1/2) LP. At this time, the pressure chamber 104 located on the outer peripheral side of the seal material 103
Is the atmosphere side (Po side) by the O-ring 106 as the shutoff means.
On the other hand, the pump is constantly communicated with the pump sealed side (P side) via the circumferential groove 103a and the radiation groove 103b as communication means, so that the pressure is uniformly reduced to -P at the same pressure as the pump sealed side. Is done. Therefore, the force that presses the seal member 103 radially inward, which acts on the outer peripheral surface of the seal member 103 per unit circumferential length, is-(1/2) LP. As described above, the force of lifting the seal member 103 radially outward with a size of (１ ／) LP per unit circumferential length always acts, so that the frictional force between the seal member 103 and the sleeve 102 is generated. Always decreases, as shown in FIG.
The temperature rise is extremely small and gradually decreases with the lapse of time, and reaches a substantially constant value after about 7 hours. The maximum value of the temperature rise was about 3 ° C. after 9 hours, and thereafter remained at a substantially constant value regardless of the time. Therefore, it was found that the negative pressure operation can be stably performed for a long time without supplying the lubricating water.

(2) Reduction of Water Leakage During Positive Pressure Operation On the other hand, during the positive pressure operation, in the present embodiment, pumping liquid (for example, rainwater) from the pump sealing side (P side) is used as the sealing material 103.
It is introduced into the sliding surface between the inner peripheral portion and the sleeve 102, and lubrication is performed by the pumped liquid. At this time, the inner peripheral portion of the seal member 103 is moved in the radial direction by the operation completely opposite to that in the negative pressure operation. Since a pressing force is generated against the inner peripheral side, the leakage amount of the pumped liquid through the sliding surface can be reduced. At this time, the pumped liquid from the sealed side of the pump is also introduced into the pressure chamber 104 through the circumferential groove 103a and the radiation groove 103b, which are communication means. By being blocked by the ring 112, it is possible to prevent the pumped liquid from leaking from the pressure chamber 104. Normally, the leakage from the shaft sealing device of this type is larger at the gap 113 where the O-ring 112 is installed than at the sliding surface between the inner peripheral portion of the sealing material 103 and the sleeve 102. The structure of the embodiment is particularly effective. As described above, the leakage amount of the pumped liquid as a whole during the positive pressure operation can be sufficiently reduced. Therefore, a decrease in pump efficiency can be prevented.

(3) Others In addition to the above two main functions, there are the following functions.

Suppression of Vibration of Sealing Material The O-ring 112 as a blocking means is in contact with the cover 106, so that the vibration of the sealing material 103 in the circumferential direction can be suppressed. Therefore, the reliability of the shaft sealing device can be improved.

Prevention of one-side contact of the seal member The circumferential groove 103a formed in the seal member 103 can evenly maintain the pressure distribution when the seal member 103 is pressed against the sealing-side end face. .

Effective Use of Dynamic Pressure Effect The detent groove 103c is provided at the center in the circumferential direction of each of the two divided sealing material segments 103A and 103B as shown in FIG. 1
03c, for example, sealing material segments 103A, 103B
The dynamic pressure effect by rotation (the water film is formed by utilizing the viscosity of the pumped liquid by rotation,
(The effect of pushing up the sealing material segments 103A and 103B to the radially outer peripheral side) can be effectively used.

As described above, according to the present embodiment, the operation can be stably performed for a long time without supplying the lubricating water during the negative pressure operation, and the shaft with less water leakage during the positive pressure operation can be used. A sealing device can be obtained.

In the above embodiment, the number of seal stages is one.
Although the case of a step structure has been described as an example, the number of sealing steps is determined by the sealing pressure, the amount of water leakage, and the like, and is not particularly limited.

In the above embodiment, the O-ring 112
Is provided on the cover 106 side, but is not limited thereto, and may be provided on the sealing material 103 side. In this case, a similar effect is obtained.

Further, in the above-described embodiment, the O-ring 112 is provided as the shut-off means. However, the present invention is not limited to this. Resistance means for communicating the pressure chamber 104 with the atmosphere (Po side) through a predetermined pressure loss, For example, an elastic ring having a rectangular cross section or a labyrinth seal may be used. In this case, a similar effect is obtained.

In the above embodiment, the sleeve 102 is provided on the outer periphery of the rotating shaft 101, and the shaft sealing device 100 seals the sleeve 102 and the seal casing 108. However, the present invention is not limited to this. Absent. That is,
When a wear-resistant film is formed on the rotating shaft 101,
The sleeve 102 may be omitted by forming itself 1 from a wear-resistant material, and the shaft sealing device 100 may perform sealing between the rotating shaft 101 and the seal casing 108. In these cases, a similar effect is obtained.

Further, in the above embodiment, the horizontal axis drainage pump is shown as an example of an application object, but the invention is not limited to this.
It may be applied to other pumps, for example, a vertical drainage pump.
FIG. 6 is a longitudinal sectional view showing the structure of this pump. 6, a pump 51 includes a casing 52, a pump main shaft 53 serving as a rotating shaft, a runner 54 fixed to the lower portion of the pump main shaft 53 (impeller), and a through portion 52a through which the pump main shaft 53 penetrates the casing 52. , The sleeve 57 provided on the outer periphery of the pump main shaft 53 and the casing penetrating portion 5
Shaft sealing mechanisms 56a and 56b for sealing between the seal casing 55 and the seal casing 55 connected to 2a. The shaft sealing device 100 of the above embodiment can also be applied to the pump 51. Further, the present invention is not limited to a pump, and can be applied to other hydraulic machines, for example, a water wheel. In these cases, it is needless to say that the same effect as when applied to the pump of FIG. 2 is obtained.

The above embodiment can be variously modified without departing from the spirit of the present invention. The modifications will be sequentially described below.

(A) Use of Cemented Carbide FIG. 7 is a longitudinal sectional view showing the entire structure of a pump shaft sealing device 100A according to this modification. In FIG. 7, the difference from the shaft sealing device 100 of the embodiment is that the sleeve 102A
To the metal ring 102Aa and the metal ring 102A.
(a) a cylindrical member made of a cemented carbide film 102Ab provided on the outer peripheral surface;
AA and 103AB are made of ceramics of cylindrical silicon carbide (or silicon carbide impregnated with ethylene tetrafluoride resin) divided into two in the circumferential direction. The sleeve 102A is made of a metal ring 102Aa (for example, material: SU).
S304) is formed on the outer peripheral surface of the cemented carbide film 102Ab by, for example, thermal spraying, and then impregnated with ethylene tetrafluoride resin into the pores of the cemented carbide film 102Ab. ing. Note that the binder of the cemented carbide coating 102Ab is preferably nickel based from the viewpoint of corrosion resistance. In this modified example, the tetrafluoroethylene resin impregnated in the sleeve cemented carbide film 102Ab forms a thin microfluoroethylene resin film of several microns on the sleeve sliding surface with the rotation of the rotating shaft 101.
Since the formed ethylene tetrafluoride resin film is easy to slip and has a small friction coefficient, there is an effect that more stable sliding characteristics can be obtained. In addition, since the silicon carbide ceramics forming the seal material segments 103AA and the seal material segments 103AB have higher hardness than carbon, they also have the effect of extending the life of the seal material and improving the wear resistance. The cemented carbide coating 102Ab has a high hardness and is easily oxidized even without being impregnated with the tetrafluoroethylene resin, and can stabilize the sliding surface. The impregnation of the ethylene fluoride resin may be omitted. Also in this case, seizure is prevented, and the reliability of the shaft sealing device can be improved. Further, a coating 1 made of cemented carbide is applied to the metal ring 102Aa.
Instead of providing the 02Ab, the sleeve 102A itself may be formed of a cylindrical solid material made of cemented carbide. The sleeve 102A made of a hard metal made of a solid material is manufactured by, for example, manufacturing in the order of powder-molding-sintering, and then impregnating a hole portion opened on the surface with an ethylene tetrafluoride resin.

(B) Increasing the Number of Seal Stages FIG. 8 is a longitudinal sectional view showing the overall structure of a pump shaft sealing device 100B according to this modification. In FIG. 8, the shaft sealing device 10
Reference numeral 0B shows the shaft sealing device 100A of the modified example (A) having a two-stage sealing structure. That is, the shaft sealing device 100
A are arranged side by side (however, case 10
6B and the seal casing 108B are shared).

According to this modification, the two-stage seal structure is employed, so that the differential pressure between the stages is equal to that of the first embodiment.
As a result, the total leak amount during negative pressure operation and the entire leak amount during positive pressure operation can be reduced, and more stable sealing performance can be obtained. Further, as described in the above-described embodiment, since the single-stage structure has sufficient performance, the single-stage structure can function as a spare seal. it can. Therefore, the reliability of the entire shaft sealing device is improved.

(C) Forming Atmospheric Pressure Introducing Groove on Sliding Surface FIG. 9 is a longitudinal sectional view showing the entire structure of a pump shaft sealing device 100C according to this modification. In FIG. 9, the shaft sealing device 10
In the shaft sealing device 100A of the modified example (A), 0C communicates with the inner peripheral portions of the sealing material segments 103AA and 103AB without communicating with the sealing side (P side) and with the atmosphere side (Po side). That is, the air pressure introduction groove 114 is formed.

In this modified example, at the time of the negative pressure operation, as shown in FIG. 10 corresponding to FIG.
Since the pressure up to the groove portion of the inner peripheral portion of 03AA and 103AB is set to the atmospheric pressure, the force for pushing up the sealing material to the outer peripheral side becomes larger. Therefore, the inner peripheral portion of the sealing material and the sleeve 1
02A is further reduced, and more stable sliding characteristics can be obtained. The atmospheric pressure introduction groove 11
4, the area of the air film on the sliding surface increases, so that the rigidity of the air film increases, and even when the sleeve 102A vibrates, the non-contact state with the seal material segments 103AA and 103AB can be secured. Therefore, the life of the sealing material can be extended. Further, since the amount of air passing through the sliding surface is increased and the cooling performance is improved, the operating range of the pump can be expanded toward the high peripheral speed range.

(D) Forming Radiation Grooves in Seal Case FIG. 11 is a longitudinal sectional view showing the entire structure of a pump shaft sealing device 100D according to this modification. In FIG. 11, the difference from the shaft sealing device 100 of the above-described embodiment is that a radiation groove 105 b is formed in the seal case 105 instead of the radiation groove 103 b of the seal member 103 constituting a part of the communication means. . The radiation groove 105 b is formed so as to communicate with the circumferential groove 103 a of the seal material 103 and the seal case 105.
Is formed so as to reach the inner circumference.

In this modification, the seal case 105 does not slide with other members like the seal member 103 and can be made of a normal metal member. Is also easy to process,
There is an effect that the manufacturing cost for disposing the communication means can be reduced.

(E) Forming a communication hole in the seal case FIG. 12 is a longitudinal sectional view showing the entire structure of a pump shaft sealing device 100E according to this modification. In FIG. 12, the difference from the shaft sealing device 100 of the above embodiment is a communication hole 115 formed in the seal case 105 instead of the communication means being configured by the circumferential groove 103 a and the radiation groove 103 b of the seal material 103. That is the configuration. One end of the communication hole 115 is open to the pressure chamber 104, and the other end is open to the inner periphery of the seal case 105, and is formed so as to communicate the pressure chamber 104 with the pump sealing side (P side). ing.

Also in this modification, similarly to the above modification (D), the seal case 105 can be made of a metal member, and the communication hole 115 is more processed than when the circumferential groove 103a and the radiation groove 103b are formed in the seal member 103. Is easier, the manufacturing cost for the arrangement of the communication means can be reduced. The location, size, number, and the like of the communication holes 115 can be determined by the size and dimensions of the shaft sealing device, and are not particularly limited.

[0058]

According to the present invention, during negative pressure operation, the force acting on the entire inner peripheral portion of the sliding member is greater than the force acting on the entire outer peripheral portion of the sliding member from the pressure chamber. As a result, a force is generated that pushes the inner peripheral portion of the sliding member radially outward. Therefore, the frictional force between the inner peripheral portion of the sliding member and the sleeve or the rotating shaft is reduced, and the temperature hardly rises, so that long-time operation can be stably performed without supplying lubricating water. In addition, during the positive pressure operation, a force is generated that presses the inner peripheral portion of the sliding member toward the radially inner peripheral side, and the pressure chamber and the hydraulic machine atmosphere side are shut off by the shutoff means. The total amount of water leakage can be reduced.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view illustrating an entire structure of a shaft sealing device according to an embodiment of the present invention.

FIG. 2 is a longitudinal sectional view showing the overall structure of a horizontal shaft drainage pump as an example of a hydraulic machine to which the present invention is applied.

FIG. 3 shows a detailed structure of the sealing material shown in FIG. 1;
It is I-III sectional drawing.

FIG. 4 is a diagram comparing experimental results obtained by measuring the behavior of the temperature of a sealing material during a negative pressure operation for a first comparative example, a second comparative example, and three embodiments. .

FIG. 5 is a diagram showing a pressure distribution of a pressure chamber and a sliding portion in a first comparative example, a second comparative example, and the embodiment.

FIG. 6 is a longitudinal sectional view showing the entire structure of a vertical shaft drain pump as another example of the hydraulic machine to which the present invention is applied.

FIG. 7 is a longitudinal sectional view illustrating an overall structure of a shaft sealing device according to a modification using a cemented carbide.

FIG. 8 is a longitudinal sectional view showing the overall structure of a shaft sealing device according to a modification in which the number of seal stages is increased.

FIG. 9 is a vertical cross-sectional view illustrating an entire structure of a shaft sealing device according to a modification in which an atmospheric pressure introducing groove is formed on a sliding surface.

FIG. 10 is a diagram showing a pressure distribution in a pressure chamber and a sliding portion in a modification of FIG. 9;

FIG. 11 is a longitudinal sectional view showing the entire structure of a shaft sealing device according to a modified example in which a radiation groove is formed in a seal case.

FIG. 12 is a longitudinal sectional view illustrating the entire structure of a shaft sealing device according to a modified example in which a communication hole is formed in a seal case.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Horizontal axis drainage pump 2 Casing 3 Pump main shaft 6a-f Shaft sealing mechanism 9 Coupling 10 Suction passage 11 Suction passage 51 Vertical shaft drainage pump 52 Casing 53 Pump main shaft 56a, b Shaft sealing mechanism 100 Shaft sealing device 100A-E Shaft sealing device 101 rotating shaft 102 sleeve 102A sleeve 102Aa metal ring 102Ab cemented carbide coating 103 sealing material (sliding member) 103A sealing material segment 103B sealing material segment 103AA sealing material segment 103AB sealing material segment 103a circumferential groove (communicating means) 103b radiation Groove (groove provided in radial direction, communication means) 104 Pressure chamber 105 Seal case (storage member) 105a Recessed groove 105b Radiation groove (groove provided in radial direction, communication means) 106 Cover (storage member) 108 See 114 Casing joint 112 O-ring (blocking means) 114 Atmospheric pressure introduction groove (groove communicating with atmosphere side) 115 Communication hole (communication means) P Sealing side Po Atmospheric side

Claims (12)

[Claims] 1. A shaft sealing device for a hydraulic machine for sealing between a rotating shaft of a hydraulic machine or a sleeve provided on the outer periphery of the rotating shaft and a casing of the hydraulic machine. A sliding member that is disposed so as to contact and slide in the radial direction; a storage member that stores the sliding member while forming a pressure chamber on the outer peripheral side of the sliding member; A shaft sealing device for a hydraulic machine, comprising: a communication unit that communicates with a sealed side of the hydraulic machine; and a shutoff unit that shuts off the pressure chamber and the atmosphere side of the hydraulic machine. 2. The shaft sealing device for a hydraulic machine according to claim 1, wherein the sliding member has a structure divided into a plurality of pieces in a circumferential direction. 3. The shaft sealing device for a hydraulic machine according to claim 1, wherein the shut-off means is a resistance means for communicating the pressure chamber with the atmosphere side of the hydraulic machine through a predetermined pressure loss. A shaft sealing device for hydraulic machinery. 4. The shaft sealing device for a hydraulic machine according to claim 1, wherein at least the outermost peripheral portion of said rotary shaft or sleeve is made of a cemented carbide. 5. The shaft sealing device for a hydraulic machine according to claim 4, wherein an outer peripheral surface of said cemented carbide is impregnated with ethylene tetrafluoride resin. 6. The shaft sealing device for a hydraulic machine according to claim 1, wherein said sliding member is made of ceramics. 7. The shaft sealing device for a hydraulic machine according to claim 6, wherein said ceramics is ceramics of silicon carbide or ceramics of silicon carbide impregnated with ethylene tetrafluoride resin. Sealing device. 8. The shaft sealing device for a hydraulic machine according to claim 1, wherein a groove is formed in an inner peripheral portion of the sliding member, the groove not communicating with a sealing side of the hydraulic machine but communicating with an atmosphere side of the hydraulic machine. A shaft sealing device for a hydraulic machine, characterized in that: 9. The shaft sealing device for a hydraulic machine according to claim 1, wherein said blocking means is an O-ring disposed in a groove provided in said housing member. . 10. A hydraulic machine according to claim 1, wherein said communication means includes a groove formed in said sliding member or said storage member in a radial direction. Shaft sealing device. 11. The shaft sealing device for a hydraulic machine according to claim 1, wherein said communication means includes a communication hole provided in said storage member. 12. A hydraulic machine comprising a casing, a rotating shaft, and a shaft sealing mechanism for sealing between the rotating shaft or a sleeve provided on the outer periphery of the rotating shaft and the casing. Is a sliding member disposed radially in contact with the outer peripheral portion of the rotating shaft or the sleeve and slidably,
A housing member for housing the sliding member while forming a pressure chamber on the outer peripheral side of the sliding member; communication means for communicating the pressure chamber with the sealing side of the hydraulic machine; the pressure chamber and the hydraulic machine And a shut-off means for shutting off the air from the atmosphere.