JPH0519742U - Shaft seal device - Google Patents

Abstract

(57) [Summary] [Purpose] No seizure occurs even under operating conditions of high surface pressure and high peripheral speed, and good sealing action can be performed and free maintenance is possible. Aim for [Structure] On the inner peripheral surface of the fixed body 26, a right-hand thread 27 having a length 1 on the pressure fluid 23 side and a left-hand thread 28 having a length 2l, which is twice the length, are provided along the flow direction of the pressure fluid 23. Are installed in series to form a screw seal. The fixed body 26 is provided with a passage 32 that communicates the portion 30 between these screw seals and the atmosphere side chamber 31, and a valve 33 that is opened and closed by the pressure between these screw seals is provided in this passage 32. A bearing 34 is provided on a part of the inner circumference of the fixed body 26 so as to keep the fixed body 26 in a perfect circle with respect to the sleeve 25 attached to the main shaft (rotating body) 21.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a shaft sealing device suitable for being applied to a shaft penetrating portion of a rotary fluid machine such as a water turbine or a pump.

[0002]

[Prior Art]

 As an example of the prior art, as shown in FIG. 5, a gland packing is used as the shaft sealing device 4 so that the pressure fluid 3 containing foreign matter does not flow out between the main shaft 1 which is a rotating body and the casing 2 of the rotating machine. 5 is mounted between a seal box 7 attached to the flange 6 and a sleeve 8 attached to the spindle 1. The packing retainer 9 arranged above the gland packing 5 is fixed to the seal box 7 by bolts 10 and nuts 11. A seal surface 12 is formed on the inner peripheral surface side of the gland packing 5 to seal the pressure fluid 3.

However, since the sealing surface 12 of the gland packing 5 heats up when tightened, resulting in insufficient lubrication, it is necessary to flow fresh water through the fresh water supply pipe 13 from a complicated and large fresh water supply auxiliary machine (not shown). Is. Further, in order to always maintain the sealing property, it is necessary to frequently adjust the gland packing 5.

[0004]

[Problems to be solved by the device]

 However, in such a conventional example, there were various problems as follows. That is, the conventional gland packing 5 reaches the limit of causing seizure under operating conditions on a high-pressure surface and a high peripheral speed, which hinders the operation of the mother machine.

Further, since the conventional gland packing 5 needs to be frequently adjusted in order to always maintain the sealing property as described above, maintenance of the shaft sealing device is not easy.

Further, the foreign matter contained in the pressure fluid 3 causes severe wear of the gland packing 5 and the sleeve 8, which shortens the life of the shaft sealing device.

In addition, since the gland packing 5 has a structure in which the gland packing 5 is tightened and sealed on the circumference of the sleeve 8 by a multi-step packing, seizure easily occurs, and it is necessary to supply fresh water as described above. Therefore, a complicated fresh water supply auxiliary device is required, and the shaft sealing device becomes large.

Further, since the tightening force is large and the water mixed with the foreign matter is sealed, the seal surface 12 is severely worn, and the wear is compensated for. Therefore, it is necessary to constantly tighten the gland packing 5. Not easy to manage.

The present invention has been made in order to solve the problems of the prior art as described above, and does not cause seizure even under the operating conditions of high surface pressure and high peripheral speed, and can perform a good sealing action. It is an object of the present invention to provide a shaft sealing device that is capable of achieving free maintenance as well as having a long life and compactness.

[0010]

[Means for Solving the Problems]

 In order to solve the above-mentioned problems, the present invention provides a shaft sealing device arranged between a fixed body and a rotating body rotating in the forward and reverse directions, wherein the rotating body is provided in a part of an inner circumference of the fixed body and the rotating body The bearing that supports the body, the thread seals of the right-hand thread and the left-hand thread that are provided in series on the inner peripheral side of the fixed body along the flow direction of the pressure fluid, and the portion between these thread seals and the atmosphere side are provided. It is provided with a communicating passage and a valve arranged in this passage and opened and closed by the pressure between the screw seals, and the left-hand or right-hand screw seal on the atmosphere side is the right-hand screw or right-hand screw on the pressure fluid side. It has twice the length of the left-hand thread seal.

[0011]

[Action]

In the above means, when the rotating body rotates to the right and the thread seal on the pressure fluid side is a right thread, and the screw length is 1 on the pressure fluid side, 2l on the atmosphere side, and the fluid pressure is P ₀ , the right thread A pushing action acts on the seal portion, and a pushing pressure P ₀ having the same pressure as the fluid pressure is generated. Then, the pressure between the screw seals is P ₀ + P ₀ , and the valve closes the passage communicating with the atmosphere side to prevent the outflow of fluid. At this time, the screw seal on the atmosphere side has a left-hand thread having a length that is twice as long, so that double the drawing pressure of P ₀ acts and the pressure fluid does not flow out to the atmosphere side.

On the contrary, when the rotating body rotates counterclockwise, the right screw on the pressure fluid side acts to seal the pressure fluid P ₀ . Between the screw seals, the screw seal on the atmosphere side is a left-hand thread, so the fluid is pushed out to the atmosphere side, and a negative pressure is set.At this time, the valve opens the passage and communicates with the atmosphere side. To work. For this reason, the pressure fluid is completely sealed because the pressure between the screw seals is equalized with the atmospheric pressure.

[0013]

【Example】

 Hereinafter, embodiments of the present invention will be described in detail with reference to FIGS.

FIG. 1 is a vertical sectional view showing a shaft sealing device according to a first embodiment of the present invention. In this embodiment, between the main shaft 21 which is a rotating body and the casing 22 of the rotary machine, between the main shaft 21 and the sleeve 25 which is fixed by the fixing pin 24 so that the pressure fluid 23 containing the foreign matter does not flow out. On the inner peripheral surface of the fixed body 26 where is the minimum clearance, the pressure-fluid side screw 27 of length l and the atmosphere-side left-hand screw 28 of length 2 l, which is twice the length, are arranged along the flow direction of the pressure fluid 23. They are arranged in series to form a screw seal.

A plurality of O-rings 29 are provided on the outer peripheral surface of the fixed body 26 to seal the pressure fluid 23 from between the outer peripheral surface of the fixed body 26 and the casing 22 and to elastically support the fixed body 26. Is installed. Further, the fixed body 26 is provided with a passage 32 that communicates the portion 30 between the screw seals and the atmosphere side chamber 31, and a valve 33 having both a sealing action and a pressure equalizing action is provided in the passage 32. It is provided.

Further, on a part of the inner periphery of the fixed body 26, the right screw 27 having a length 1 and the left screw 28 having a length 2l which is twice as long as that of the right screw 27 are prevented from coming into contact with the sleeve 25 during rotation. , A bearing 34 having an inner diameter smaller than the inner diameters of the left-handed screws 27, 28 and having a function of keeping the fixed body 26 in a perfect circle with respect to the sleeve 25. The fixed body 26 is fixed to the casing 22 by a rotation stop pin 35.

Next, the operation will be described. In the above configuration, when the main shaft 21 rotates clockwise, the pressure fluid 23 having the fluid pressure P ₀ flowing through the gap 60 between the inner peripheral surface of the fixed body 26 and the sleeve 25 is on the pressure fluid side of the fixed body 26. The pushing action is exerted by the right screw 27 having the length l cut in the direction L, and the pushing pressure P ₀ is generated, and the pressure of the portion 30 between the screw seals becomes the pressure of P ₀ + P ₀ . At this time, the valve 33 is pressed against the passage 32 by the pressure to close the passage 32 and prevent the pressure fluid 23 from flowing out. Then, since the double sealing pressure P ₀ acts on the thread seal of the left screw 28 having a length of 2l cut to the other atmosphere side, the pressure fluid 23 does not flow into the atmosphere side chamber 32.

On the contrary, when the main shaft 21 rotates counterclockwise, the pressure fluid 23 having the fluid pressure P ₀ flowing through the gap 60 between the inner peripheral surface of the fixed body 26 and the sleeve 25 is cut into the fixed body 26. Due to the right-hand thread 27 having a length of 1 on the pressure fluid side, the sealing pressure P ₀ acts and the pressure fluid 23 does not flow out to the portion 30 between the screw seals. However, since the left side screw 28 of double length 2l is cut on the atmosphere side, the fluid is pushed out to the atmosphere side, and the portion 30 between the screw seals tends to become a negative pressure. At this time, the valve 33 opens the passage 32, and the portion 30 between the atmosphere side chamber 31 and the screw seal is pressure-equalized, so that the atmosphere is always maintained, so that the fluid pressure 23 does not flow out.

The fluid accumulated in the atmosphere-side chamber 31 flows out through a drain hole 36 provided in the fixed body 26, a drain hole 37 provided in the casing 22, and a drain pipe 38. In addition, with respect to external leakage from between the sleeve 25 and the seal box 39, a simple gland packing 40 seals. Reference numeral 41 is a packing presser, and 42 is a bolt for fixing the packing presser 41 to the seal box 39.

Next, FIG. 2 shows a second embodiment of the present invention. The same parts as those in FIG. 1 are designated by the same reference numerals, and the duplicated description will be omitted. In this embodiment, with respect to external leakage from between the sleeve 25 and the fixed body 26, a lip seal 43 is provided at the upper end of the fixed body 26 to prevent the pressure fluid 23 from flowing out.

FIG. 3 shows a third embodiment of the present invention. The same parts as those in FIG. 1 are designated by the same reference numerals, and the duplicated description will be omitted. In this embodiment, a right-hand screw 45 having a length 1 and a left-hand screw 46 having a length 2l, which is twice as long as the right-hand screw 45, are cut in a fixed body 44 corresponding to the fixed body 26 in FIG. The first embodiment shown in FIG. 1 is formed by inserting a cylindrical skirt portion 48 extending parallel to the axis of the sleeve 47 fixed to the main shaft 21 between the opposed portions and forming a gap 49 in each of them. The pressure fluid 23 is sealed by the same action as described above.

Finally, FIG. 4 shows a fourth embodiment of the present invention, in which the same parts as those shown in FIG. 3 are designated by the same reference numerals, and a duplicate description will be omitted. According to this embodiment, one end of the inner surface of the fixed body 50 corresponding to the fixed body 44 in FIG. 3 parallel to the main shaft 21, the right screw 51 having a length 1 on the pressure fluid 23 side and the A left-hand thread 52 of double length 2l is cut back to back. Then, these screws 51 and 52 are attached so as to cover the cylindrical skirt portion 54 extending in parallel with the axis of the sleeve 53, and the gap 55 is formed in each of them, whereby the first embodiment shown in FIG. The pressure fluid 23 is sealed by the same action as described above.

Although not shown, as a modification of each of the above-described embodiments, a left screw having a length of 1 is provided on the pressure fluid side, and a right screw having a length of 2 l, which is twice the length, is provided on the atmosphere side. You can also

[0024]

[Effect of the device]

 As described above, according to the present invention, the right or left screw having a length 1 on the pressure fluid side and the left or right screw on the atmosphere side having a length 2 l, which is twice that, are arranged in series. Since it has a non-contact seal structure for both forward and reverse rotation, seizure does not occur even under high surface pressure and high peripheral speed operating conditions, and a good sealing effect is achieved. Moreover, since the sealing property is always maintained, no adjustment is required, and the shaft sealing device can be maintained free. Furthermore, since the wear resistance can be improved without the wear of the seal due to foreign matter water, etc., the life of the shaft sealing device can be extended. In addition, since no complicated fresh water supply auxiliary equipment is required, the shaft sealing device can be made compact.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing a shaft sealing device according to a first embodiment of the present invention.

FIG. 2 is a vertical sectional view showing a shaft sealing device according to a second embodiment of the present invention.

FIG. 3 is a vertical sectional view showing a shaft sealing device according to a third embodiment of the present invention.

FIG. 4 is a longitudinal sectional view showing a shaft sealing device according to a fourth embodiment of the present invention.

FIG. 5 is a vertical sectional view showing a conventional shaft sealing device.

[Explanation of symbols]

 21 main shaft (rotating body) 23 pressure fluid 26 fixed body 27 right-hand screw 28 left-hand screw 30 screw seal part 31 atmosphere side chamber 32 passage 33 valve 34 bearing 44 fixed body 45 right-hand screw 46 left-hand screw 50 fixed body 51 right-hand screw 52 left screw

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takanobu Komuro 1-1-1, Niihama, Arai-cho, Takasago, Hyogo Prefecture Mitsubishi Heavy Industries, Ltd. Takasago Plant (72) Inventor Takeshi Tanaka 2-chome, Niihama, Arai-cho, Takasago, Hyogo Prefecture No.25 Takahishi Engineering Co., Ltd.

Claims (1)

[Scope of utility model registration request] 1. A shaft sealing device arranged between a fixed body and a rotating body rotating in the forward and reverse directions, wherein a bearing is provided on a part of an inner circumference of the fixed body and supports the rotating body. Right and left threaded screw seals provided in series on the inner circumference side of the fixed body along the flow direction of the pressure fluid, a passage communicating between the screw seal and the atmosphere side, and in this passage. And a valve that opens and closes depending on the pressure between the screw seals, and the left-hand or right-hand thread seal on the atmosphere side has a length twice that of the right-hand or left-hand thread seal on the pressure fluid side. A shaft sealing device having.