JP2000081034A - Pad type ceramic bearing device and water turbine equipped with pad type ceramic bearing device - Google Patents

Abstract

(57) [Problem] To provide a pad-type ceramic bearing device in which generation of shaft vibration is sufficiently prevented and stable bearing performance is obtained over a long period of time. The pad type bearing is provided on the outer periphery of a rotating shaft and has a ceramic layer on a sliding contact surface, and a load supporting member for supporting the pad type bearing. In the pad-type ceramic bearing device using the above, a foreign matter intrusion preventing means for preventing foreign matter from intruding between the pad-type bearing and the bearing load supporting member is provided on or around the pad-type bearing 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pad type ceramic bearing device, and more particularly to a pad type ceramic bearing device which supports a rotating shaft using river water as a lubricant.

[0002]

2. Description of the Related Art Conventionally, a bearing device that supports a rotating shaft by lubricating with river water generally uses resin, rubber, carbon, or the like as a bearing material. If these materials are lubricated with water containing hard particles such as earth and sand, such as river water, they will wear out in a short time and become unusable. Had to be lubricated.

[0003] In recent years, however, bearing devices using a combination of cemented carbide and ceramic materials as sliding materials have been developed, and some of them have been used for main bearings such as rainwater drainage pumps. As described above, such a bearing device uses river water as a lubricant, and since the hardness of cemented carbide and ceramics is higher than that of earth and sand, lubricating with water containing hard particles such as earth and sand. Hardly wears. Therefore, as compared to bearing devices using resin, rubber, etc., not only is lubrication with fresh water unnecessary, but also a water supply means is not necessary. It is extremely effective as a bearing material in terms of cost and the like.

However, since this ceramic material does not have sufficient impact resistance, there is a tendency that during operation, the earth and sand particles are caught in the sliding surface, and when subjected to an impact load, the ceramic itself is cracked and breaks. In addition, if the bearing is constrained and one-sided contact occurs, damage may occur. For this reason, Japanese Patent Application Laid-Open No. 8-338-428 discloses a pad-type ceramic bearing device capable of preventing hard particles such as earth and sand from entering the bearing sliding surface and preventing the bearing from colliding.

FIG. 7 schematically shows this bearing device, in which a sleeve 2 is divided into two parts along the circumference of a rotating shaft 1.
Both ends of the divided axial direction are fastened by bolts 13 and cover the periphery of the rotating shaft 1. Note that a cemented carbide layer 3 is provided on the outer periphery of the sleeve 2.

A plurality of pad-type bearings 5 are arranged along the periphery between the sleeve 2 and the bearing case 9, and a ceramic portion 4 is provided on the sliding surface of the sleeve 2 with the cemented carbide portion 3. Is provided. The bearing case 9 has a cylindrical shape, and a coil spring 7a is attached to the lower end in the axial direction, and a plate 8 is attached to the upper end. That is, each of the bearings 5 has an elastic support mechanism provided with the coil spring 7a and the plate 8 in order to prevent one-side contact. Also, when the rotating shaft is stopped, the respective bearings 5 are mounted on the ceramic portions 4 of the respective bearings.
Pressure adjusting mechanism 1 for bringing oil into contact with cemented carbide part 3 of sleeve
0s.

In the pressure adjusting mechanism 10 s, opposing walls 14 project from each other at the axially and circumferentially central portions of the outer peripheral surface of the bearing 5, and have an appropriate depth between the opposing walls 14. A groove 15 is formed, and the coil spring 7 mounted in the groove 15, the leaf spring 6 interposed between the coil spring 7 and the spherical portion 10 a of the adjusting body between the opposing walls 14, and moves in the radial direction. It comprises a possible adjustment body 10.

In this configuration, the spherical portion 10 a of the adjusting body screwed into the bearing case 9 presses the coil spring 7 via the leaf spring 6, and the ceramic portion 4 of the bearing 5 is elastically moved by the coil spring 7. The sleeve 2 is brought into contact with the sleeve 2, whereby the contact pressure of each bearing 5 with the sleeve 2 is adjusted.

The adjusting body 10 is constituted by a bolt having a spherical portion 10a at the tip, a threaded portion 10c on the outer periphery of the other end, and a groove 10b for rotating the end surface. The bearing 5 is formed so as to move in the radial direction by screwing 10 into a screw hole 9 a provided in the bearing case 9.

In this case, the adjustment body 10 is moved by the adjustment body 1
This is performed by inserting a tool such as a hexagonal rod into the groove 10b of the No. 0 and turning it. The leaf spring 6 is mounted between opposing walls (movement preventing protrusions) 14 formed on the outer periphery of each bearing 5, and is interposed between the coil spring 7 and the spherical portion 10 a of the adjusting body 10. The leaf springs 6 are formed so as to engage with pivots 11 attached to both ends in the axial direction of the outer periphery of each bearing 5.

That is, when the leaf spring 6 is pressed by the adjusting body 10, each bearing 5 is formed to move in the radial direction together with the coil spring 7. Also, pivot 1
The member 1 is screwed or inserted and fixed to the bearing 5, and at the same time, is sufficiently prevented from loosening.

[0012]

As described above, the ceramic bearing device formed as described above uses river water containing soil and the like as a lubricant as described above. The water supply means is not required, and it is also advantageous in terms of maintenance.However, in this bearing device, shaft vibration is more likely to occur earlier than a bearing lubricated with fresh water during long-term operation, It has been clarified as a result of this detailed experiment that stable bearing performance cannot be obtained over a long period of time.

SUMMARY OF THE INVENTION The present invention has been made in view of the foregoing, and it is an object of the present invention to provide a pad-type ceramic bearing device of this kind which can sufficiently prevent the occurrence of shaft vibration and obtain stable bearing performance over a long period of time. To be.

[0014]

Means for Solving the Problems First of all, as a result of pursuing the cause of the vibration generation based on the result of the experiment, it became clear that the structure is formed as described above with reference to FIG. In the pad-type ceramic bearing device, at the time of a stop, any one of between the pivot 11 and the leaf spring 6 or between the spherical portion 10a of the adjustment body and the leaf spring 6 is in a non-contact state. On the other hand, when driving, the pivot 1
1 and the leaf spring 6 are in contact with each other, and the spherical portion 10a of the adjusting body and the leaf spring 6 are in contact with each other to support a bearing load. In this manner, contact and non-contact between the pivot 11 and the leaf spring 6 or between the spherical portion 10a of the adjusting body 10 and the leaf spring 6 are repeated.

Since the river water, which is a lubricant, contains foreign matters such as hard earth and sand, if used for a long period of time, the pivot 1
Foreign matter is caught between the plate spring 1 and the leaf spring 6 or between the spherical portion 10a of the adjusting body 10 and the leaf spring 6, and the pivot 11 or the spherical portion 10a is damaged. As a result, the bearing clearance is increased accordingly. As a result, the vibration damping effect was reduced, which led to the occurrence of vibration.

The present invention has successfully solved this reduction in vibration damping effect without greatly changing the bearing configuration.
That is, the present invention includes a pad-type bearing disposed on the outer periphery of a rotating shaft and having a ceramic layer on a sliding contact surface, and a load supporting member for supporting the pad-type bearing. In the pad-type ceramic bearing device, a foreign object intrusion preventing means for preventing foreign matter from intruding between the pad-type bearing and the bearing load supporting member is provided at or around the pad-type bearing to achieve the intended purpose. It is something to do.

Also, a pad-type bearing disposed on the outer periphery of the rotating shaft and having a ceramic layer on a sliding contact surface, and a load supporting member for supporting the pad-type bearing are provided, and a bearing supporting side end surface of the load supporting member. Is formed into a spherical surface, and river water is used as the lubricant of the bearing. In the pad-type ceramic bearing device, the pad-type bearing and the bearing load are provided between the vicinity of the outer periphery of the spherical portion of the load supporting member and the back surface of the bearing. A ring-shaped elastic member is interposed so that foreign matter in the lubricant does not enter the joint with the support member.

A pad-type bearing which is disposed on the outer periphery of the rotating shaft and has a ceramic layer on a sliding contact surface, and a load supporting member for supporting the pad-type bearing, and a bearing supporting side end face of the load supporting member. Is formed in a spherical surface, and in a pad-type ceramic bearing device in which river water is used as a lubricant of the bearing, a bag-shaped back surface of the pad-shaped bearing has a bag-like shape that covers a bearing back surface and a spherical portion of the load supporting member. An elastic member is provided.

The present invention also provides a pad-type ceramic bearing device in which river water is used as a lubricant. The pad-type ceramic bearing device includes a pad-type bearing having a ceramic layer on a sliding surface, and a pad-type bearing. In a water turbine having a load supporting member for supporting, a foreign matter intrusion preventing means for preventing foreign matter from intruding between the pad type bearing and the bearing load supporting member is provided on or around the pad type bearing.

In this case, the foreign matter intrusion prevention means is formed on the back surface of the pad-type bearing by a bag-shaped elastic member that covers the back surface of the bearing and the spherical surface of the load supporting member. It is. Further, the foreign matter intrusion preventing means is formed at a joint between the pad-type bearing and the bearing load supporting member by interposing a ring-shaped elastic member so as to surround the joint.

That is, in the pad-type ceramic bearing device formed as described above and in the water turbine provided with the bearing, since the load supporting portion of the bearing is provided with the foreign matter intrusion prevention means, the river is provided on the load supporting portion. Hard particles such as earth and sand contained in the water are no longer caught, and damage to the load supporting portion is prevented, that is, the bearing gap based on the damage to the load supporting portion does not increase. This is sufficiently prevented, and stable bearing performance is maintained for a long period of time. In addition, a highly reliable water turbine that requires no maintenance for a long period of time can be obtained.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the illustrated embodiments. FIG. 1 shows a cross section of the pad-type ceramic bearing device and a water wheel provided with the bearing device. In the figure, 1 is a rotating shaft, 41 is a water turbine runner, 48 is a guide vane, and 20 is a ceramic bearing device. Reference numeral 42 denotes a fixed body, and reference numeral 50 denotes a servomotor that drives the guide vanes 48.

The rotating shaft 1 is provided through a fixed body 42, and a runner 41 is fixed below the rotating body 1. Ceramic bearing device 20 for rotatably supporting this rotating shaft 1
Are supported by the fixed body 42. The fixed body 42 has a hollow shape, supports the bearing 20 at the top plate 43, and has a shaft sealing device 45 between the upper cover 44 and the rotary shaft 1.

A casing 47 is formed by the upper cover 44 and the lower cover 46 of the fixed body 42, and the flow rate of water flowing from the casing 47 into the runner 41 is adjusted by guide vanes 48. The guide vane 48 is connected to a guide ring 49 provided on the top plate 43, and is driven by a servomotor 50.

As shown in FIGS. 1 and 2, the sleeve 2 provided on the rotating shaft is divided into two parts along the periphery of the rotating shaft 1, and the two divided ends of the sleeve in the axial direction are separated from each other. Are formed so as to cover the periphery of the rotating shaft 1 by being fastened by bolts 13. A cemented carbide layer 3 is provided on an outer peripheral portion of the sleeve 2, that is, on a surface on which the sleeve 5 slides.

The ceramic bearing device 20 is mainly composed of a bearing case 9, a pad type bearing 5 having a ceramic layer on a sliding surface, a pressure adjusting mechanism 10s as a bearing load supporting member, and an elastic supporting mechanism 7s. Case 9
As shown in FIG. 2, it has a cylindrical shape, and a coil spring 7 as shown in FIG.
a, a plate 8 is attached to the upper part so as to surround the bearing 5. Among them, the coil spring 7a arranged at the lower part
Are provided two or more for the purpose of stabilization. Since the coil spring 7a can be easily deformed in the radial direction with a small force, the movement of the coil spring 7a is stable for a long period of time and can sufficiently follow the movement of the rotating shaft 1.

Since the sleeve 2 and the ceramic bearing portion 4 provided on the rotating shaft are always kept in contact with each other, hard particles such as earth and sand contained in river water are hardened by the sleeve 2 and each of them. It does not enter between the ceramic bearings 4.

The pressure adjusting mechanism 10 s is provided at the center of the outer peripheral surface of the bearing 5 in the axial direction and the circumferential direction.
4 is projected, and a groove 15 having an appropriate depth is formed between the opposing walls 14. The coil spring 7 mounted in the groove 15 and the coil spring 7 and the adjusting body 10 between the opposing walls 14 are formed.
And a regulating body 10 movable in the radial direction.

In this configuration, the spherical portion 10 a of the adjusting body 10 screwed into the bearing case 9 presses the coil spring 7 via the leaf spring 6, and the elastic force of the coil spring 7 causes the ceramic portion 4 of the bearing 5. Is brought into contact with the sleeve 2,
Thereby, the contact pressure of each bearing 5 with respect to the sleeve 2 is adjusted.

Each of the bearings 5 has a
This elastic support mechanism 7s is provided. Elastic support mechanism 7s
Is mainly composed of a coil spring 7a and a plate 8. Since the pad-type bearing 5 is elastically supported by the coil spring 7a and the plate 8, one-side contact is prevented.

On the other hand, an adjusting body 10 is mounted on the bearing case 9 at a position corresponding to the coil spring 7 of the bearing 5 so as to be movable in the radial direction. The adjusting body 10 is generally formed in a bolt shape. That is, the tip is a spherical part 1
0a, and a screw portion 10c is engraved on the outer periphery of the other end. A groove 10b for rotation is provided on the other end face. This adjusting body 10 moves the bearing 5 in the radial direction by being screwed into a screw hole 9 a provided in the bearing case 9. In this case, the adjustment body 10 is moved by inserting a tool such as a hexagonal rod into the groove 10b of the adjustment body 10 and turning it.

The leaf spring 6 is interposed between the coil spring 7 and the spherical portion 10a of the adjusting body 10 between the bearings 5 and the bearing case 9 between the opposing walls 14 of the bearings 5, and in the axial direction. It is engaged between pivots 11 attached to both ends of the outer periphery of the bearing 5. When pressed by the adjusting body 10, each bearing 5 is moved in the radial direction together with the coil spring 7 located at the center between the opposing walls 14 and between the pivots 11.

The member having the pivot 11 is a bearing 5
Although it is screwed or inserted and fixed, it also prevents loosening at the same time. The head of the pivot 11 has a spherical shape.

Further, this bearing device is provided with foreign matter intrusion prevention means so that foreign matter of river water does not intrude into the load supporting portion of the bearing. That is, between the pivot 11 which is a load supporting portion and the leaf spring 6, or the spherical portion 1 of the adjusting body 10
Elastic rings 16a, 16c and 16d are mounted on the pivot 11 and the spherical body 10a side of the adjusting body 10 in order to prevent foreign matter from being caught between the spring 0a and the leaf spring 6.

As described above, the pivot 11 and the adjusting body 1
Elastic rings 16a, 16c, 1
6d, the gap between the pivot 11 and the leaf spring 6 and the gap between the adjusting body 10 and the leaf spring 6 are covered with this elastic ring. When these gaps are formed, hard space such as earth and sand contained in river water is formed in these gaps. No particles can penetrate, i.e. damage to the load bearing by hard particles is prevented and therefore
Stable bearing performance can be obtained over a long period.

The elastic rings 16a, 16c, 16d
The area covered with is not invaded by river water,
It has excellent corrosion resistance and has the effect of preventing corrosion and abrasion. Furthermore, since the adhesion of scale or the like can be eliminated, the contact state of the load supporting portion can be maintained without change for a long time, and a stable load supporting function can be obtained. The elastic rings 16a,
16c and 16d are the contact surfaces, that is, the pivot 1
1. The surface of the spherical portion 10a of the adjustment body and the leaf spring 6 may be fixed using an adhesive or the like.

As described above, in this ceramic bearing device, since the foreign matter intrusion prevention means is provided in the load supporting portion of the bearing, hard particles such as earth and sand contained in river water are caught in the load supporting portion. And damage is prevented. In addition, there is no adhesion of scale or the like on the load supporting portion. As a result, stable bearing performance is maintained over a long period.

In the water turbine of the present invention, the rotating shaft 1
, A cemented carbide part 3 provided on the outer peripheral surface, and a plurality of divided sleeves 2, a bearing case 9 disposed at an outer peripheral position of the sleeve 2, and a circumferential direction between the bearing case 9 and the sleeve 2. And a plurality of bearings 5 each having a ceramic portion 4 provided on a sliding contact surface with the sleeve 2, and each of the bearings 5 is biased in a centripetal direction so that when the rotation shaft is stopped, each bearing 5 Replace the ceramic part 4 with the cemented carbide part 3 of the sleeve 2
A pad-type ceramic bearing device comprising: a pressure adjusting mechanism for contacting the bearing; an elastic supporting mechanism that does not hinder the movement of the bearing; and a means for preventing foreign matter from entering the load supporting portion of the bearing. Therefore, damage to the load supporting portion of the bearing is improved, and a bearing device exhibiting stable bearing performance over a long period of time can be obtained. By applying this bearing device to a water turbine, high reliability as a water turbine can be obtained.

FIG. 3 shows another embodiment of the pad type ceramic bearing device according to the present invention. This embodiment is different from the above-mentioned embodiment in that the foreign matter intrusion prevention means of the load supporting portion of the bearing is provided with a groove 17 on the surface of the leaf spring 6 facing the spherical portion 10a of the adjusting body 10. .

In this embodiment, the same operation and effect as those of the above-described embodiment can be basically achieved, and the outer peripheral portion of the elastic ring 16b can be mounted on the leaf spring 6 by providing the groove 17. Since it is fixed, the reliability can be further improved.

FIG. 4 shows a third embodiment of the pad type ceramic bearing device according to the present invention. This embodiment is different from the above-described embodiment in that the foreign matter intrusion prevention means of the load support portion of the bearing is configured by covering the load support portion and the leaf spring 6 with a rubber mold 18 or the like.

According to this embodiment, basically the same functions and effects as those of the above-described embodiment can be obtained. In addition, since the rubber bushes 18a, 18b and 18c are formed on the leaf spring 6 side, assembly is possible. Secure and easy mounting at the time.
Further, since the inner diameters of the rubber bushes 18a, 18b, 18c are slightly smaller than the outer diameter of the mating side to be mounted, the rubber bushes 18a, 18b, 18c are securely fixed to the mating side. Further, since the leaf spring 6 is formed by the rubber mold 18, the corrosion resistance of the leaf spring 6 is improved.

FIG. 5 shows a fourth embodiment of the pad type ceramic bearing device according to the present invention. This embodiment is different from the above embodiment in that the bag 19 is attached so that the foreign matter intrusion prevention means of the load support portion of the bearing wraps around the outer peripheral surface of the bearing and the inner peripheral side of the bearing case of the adjusting body. That is the point. The material of the bag 19 is preferably rubber or vinyl. Further, in this embodiment, a hole 21 for dropping foreign matter is provided at the mounting position of the coil spring 7a. Therefore, accumulation of foreign matter is prevented, and the coil spring 7a
Is eliminated and stable performance can be obtained for a long period of time.

According to this embodiment, basically the same functions and effects as those of the first embodiment can be obtained.
Since the intrusion of river water into the coil spring 7 can be prevented, the contact pressure can be kept constant. Further, the corrosion resistance of the pivot 11, the leaf spring 6 adjuster and the like is improved.

FIG. 6 shows a fifth embodiment of the pad type ceramic bearing device according to the present invention. This embodiment differs from the first embodiment in that the foreign matter intrusion prevention means of the load support portion of the bearing is configured by attaching a bag 19a so as to wrap the outer peripheral surface of the bearing and the spherical portion 10a of the adjusting body. It is. Even in this embodiment, basically the same effects as in the above-described embodiment can be obtained.

As described above, in the case of the pad-type ceramic bearing device formed as described above, since the load supporting portion of the bearing is provided with the foreign matter intrusion preventing means, the load supporting portion is provided with river water. Hard particles such as earth and sand contained therein are no longer caught, and damage to the load supporting portion is prevented, that is, the bearing gap due to damage to the load supporting portion does not increase, so that shaft vibration is sufficiently generated. Thus, stable bearing performance is maintained over a long period of time.

Further, by applying this bearing device to a water turbine, a highly reliable water turbine that does not require maintenance for a long period of time can be obtained.

[0048]

As described above, according to the present invention, it is possible to obtain a pad-type ceramic bearing device of this kind, in which generation of shaft vibration is sufficiently prevented and stable bearing performance is obtained over a long period of time.

[Brief description of the drawings]

FIG. 1 is a vertical sectional side view showing an embodiment of a water turbine provided with a pad-type ceramic bearing device of the present invention, and a vertical sectional side view showing an embodiment of a pad-type ceramic bearing device.

FIG. 2 is a sectional view taken along line BB of FIG.

FIG. 3 is a longitudinal sectional side view showing another embodiment of the pad-type ceramic bearing device of the present invention.

FIG. 4 is a longitudinal sectional side view showing another embodiment of the pad-type ceramic bearing device of the present invention.

FIG. 5 is a longitudinal sectional side view showing another embodiment of the pad-type ceramic bearing device of the present invention.

FIG. 6 is a longitudinal sectional side view showing another embodiment of the pad-type ceramic bearing device of the present invention.

FIG. 7 is a vertical sectional side view showing a conventional pad-type ceramic bearing device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Rotating shaft, 2 ... Split sleeve, 3 ... Carbide part, 4 ...
Ceramic part, 5: pad type bearing, 6: leaf spring, 7, 7
a: coil spring, 8: plate, 9: bearing case, 10
... Adjusting body, 10a ... Spherical part, 10s ... Pressure adjusting mechanism (bearing load supporting part), 11 ... Pivot, 16a, 16b, 1
6c: elastic ring, 18a, 18b, 18c: rubber bush, 19, 19a: bag.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tetsuo Fujiwara 3-1-1 Sachimachi, Hitachi-shi, Ibaraki Prefecture Inside Hitachi, Ltd. Hitachi Plant (72) Inventor Junichi Tamura Ichibancho, Aoba-ku, Sendai-shi, Miyagi 2-4-1, Hitachi, Ltd. Tohoku Branch (72) Inventor Yoshinobu Sasakawa 3-7-1, Ichibancho, Aoba-ku, Sendai, Miyagi Prefecture Tohoku Electric Power Co., Inc. (72) Inventor Haruhito Chiba Sendai, Miyagi Prefecture 3-7-1, Ichibancho, Aoba-ku, Aichi-shi F-term in Tohoku Electric Power Co., Inc. (reference) 3J011 AA01 AA12 BA17 JA02 KA02 LA06 MA12 QA04 RA01 SD01

Claims (6)

[Claims] 1. A pad-type bearing which is disposed around a rotating shaft and has a ceramic layer on a sliding surface, and a load supporting member for supporting the pad-type bearing, wherein river water is contained in a lubricant of the bearing. A pad-type ceramic bearing device comprising: a pad-type ceramic bearing device provided with foreign matter intrusion prevention means for preventing foreign matter from entering between the pad-type bearing and the bearing load supporting member, at or around the pad-type bearing. apparatus. 2. A pad-type bearing which is disposed around a rotating shaft and has a ceramic layer on a sliding contact surface, and a load supporting member for supporting the pad-type bearing, and a bearing-support-side end surface of the load supporting member. Is formed into a spherical surface, and river water is used as the lubricant of the bearing. In the pad-type ceramic bearing device, the pad-type bearing and the bearing load are provided between the vicinity of the outer periphery of the spherical portion of the load supporting member and the back surface of the bearing. A pad-type ceramic bearing device, wherein a ring-shaped elastic member is interposed so that foreign matter in a lubricant does not enter into a joint with a support member. 3. A pad-type bearing which is disposed around a rotating shaft and has a ceramic layer on a sliding surface, and a load supporting member for supporting the pad-type bearing, and a bearing-support-side end surface of the load supporting member. Is formed into a spherical surface, and river water is used as a lubricant for the bearing. In the pad-type ceramic bearing device, a bag-shaped back surface portion of the pad-type bearing has a back surface of a bearing and a spherical portion of the load supporting member. A pad-type ceramic bearing device comprising an elastic member. 4. A pad-type ceramic bearing device in which river water is used as a lubricant. The pad-type ceramic bearing device has a pad-type bearing having a ceramic layer on a sliding surface, and elastically supports the pad-type bearing. A water turbine having a load supporting member, wherein pad-type ceramic bearings are provided with or at the periphery of the pad-type bearing, foreign matter intrusion prevention means for preventing foreign matter from entering between the pad-type bearing and the bearing load supporting member. Water wheel with equipment. 5. The foreign matter intrusion prevention means is formed on a back surface of the pad-type bearing by a bag-shaped elastic member that covers the back surface of the bearing and the spherical portion of the load support member. A water turbine comprising the pad-type ceramic bearing device according to the above. 6. The foreign matter intrusion preventing means is formed by interposing a ring-shaped elastic member at a joint between the pad type bearing and the bearing load supporting member so as to surround the joint. A water turbine comprising the pad-type ceramic bearing device according to claim 4.