CN114207287A

CN114207287A - Blower fan

Info

Publication number: CN114207287A
Application number: CN202180003259.XA
Authority: CN
Inventors: 坂田和夫; 奥野薫; 木下龙男
Original assignee: Osaka Forced Draft Fan Manufacturing Co ltd
Current assignee: Osaka Forced Draft Fan Manufacturing Co ltd
Priority date: 2020-06-04
Filing date: 2021-03-23
Publication date: 2022-03-18
Anticipated expiration: 2041-03-23
Also published as: JPWO2021246029A1; JP7319636B2; WO2021246029A1; CN114207287B; KR20210151860A; KR102653737B1

Abstract

A blower is provided with: a rotating shaft (21) inserted into a shaft hole (12) of a housing (10) in which a gas passage (11) is formed, an impeller (22) supported by the rotating shaft (21), and a sealing device (30) for sealing the shaft hole (12), wherein the sealing device (30) comprises: a first seal ring (31) and a second seal ring (32) that surround the rotating shaft (21) in the vicinity of the shaft hole (12); a shaft seal case (33) that surrounds the first seal ring (31) and the second seal ring (32); a static pressure gas seal means (40) which forms a main seal chamber (42) for introducing seal air higher than the pressure in the gas passage (11) in the shaft seal box (33) and prevents the exhaust gas from leaking from the gas passage (11) to the atmosphere; and a backup seal unit (60) which has an annular third seal ring (61) surrounding the rotating shaft (21) on the outside in the axial direction of the shaft seal box (33), and which forms an auxiliary seal chamber (62) that restricts leakage of seal air from the atmosphere side of the main seal chamber (42).

Description

Blower fan

Technical Field

The present invention relates to a blower, and more particularly to a blower suitable for an exhaust gas recirculation system of a large engine.

Background

As a blower for sucking and pressurizing air to be blown, there are known: a recirculation blower that boosts pressure of exhaust gas discharged from a system that outputs power or motive power and recirculates it to the system, an auxiliary blower that boosts pressure of supply gas (containing low-pressure recirculated gas) supplied to the system, and the like.

For example, as one of exhaust emission reduction technologies for engines such as marine diesel engines, an EGR system (exhaust gas recirculation system) is widely used which recirculates a part of exhaust gas of an engine to the intake side (the intake side when scavenging is performed) of the engine to reduce NOx (nitrogen oxides) in the exhaust gas, and in such an EGR system, an EGR blower which boosts a part of the exhaust gas to a pressure at which recirculation is possible is described in, for example, patent document 1 and patent document 2.

Further, for example, patent document 3 describes the following blower: the flow rate of the recirculated exhaust gas can be controlled according to the blower rotation speed of the blower itself, and a rotation sensor that measures the blower rotation speed is mounted.

Patent document 4 describes a centrifugal blower in which an impeller and a rotary shaft are integrally molded with each other by a resin material and accommodated in a casing, wherein a first seal ring and a second seal ring made of a fluororesin are provided at a plurality of locations in the casing in the axial direction of the rotary shaft, the first seal ring and the second seal ring having inner peripheral surfaces with a diameter substantially equal to that of the outer peripheral surface of the rotary shaft, and seal air is supplied to a space in the casing between the first seal ring and the second seal ring.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2011-157959

Patent document 2: japanese patent laid-open publication No. 2012-172647

Patent document 3: japanese patent laid-open publication No. 2002-332919

Patent document 4: japanese patent laid-open publication No. 2016-89671

Disclosure of Invention

Problems to be solved by the invention

However, in the conventional blower of the type described above, if the pressure of the seal air supplied to the impeller-side space inside the casing is set sufficiently higher than the pressure inside the impeller housing in order to suppress the EGR gas, which is pressurized inside the impeller housing and is to be recirculated to the engine, from intruding into the internal space side of the casing through the shaft hole of the impeller rotating shaft, there are problems as follows: the amount of seal air leaking from the impeller-side space to the motor-side space communicating with the outside (atmosphere side) of the housing increases.

Therefore, the conventional blower has the following problems: a problem of an increase in power consumption of a driving motor for driving the sealed air supply source, and a problem of difficulty in use of an EGR blower for a marine engine installed in a ship.

The present invention has been made to solve the above-described conventional problems, and an object thereof is to provide a blower capable of suppressing power consumption of a seal air supply source, and an object thereof is to provide a blower suitable for an EGR blower of a marine engine.

Means for solving the problems

(1) To achieve the above object, a blower according to the present invention includes: a housing formed with a gas passage and a shaft hole communicating with the gas passage; a rotating shaft rotatably inserted through the shaft hole of the housing; an impeller supported by the rotary shaft and housed in the housing; and a sealing device that seals the shaft hole, the blower being characterized in that the sealing device includes: a first seal ring and a second seal ring having a ring shape and surrounding the rotary shaft in the vicinity of the shaft hole; an annular shaft seal case having an annular wall portion surrounding the first seal ring and the second seal ring, and a pair of inner side wall portions integrally joined to the annular wall portion on both sides in the axial direction of the rotary shaft; a static pressure gas seal unit that forms a main seal chamber in the shaft seal case to prevent the exhaust gas from leaking from the gas passage to the atmosphere, the main seal chamber being introduced with seal air having a pressure higher than a pressure in the gas passage and bringing the first seal ring and the second seal ring into close contact with the pair of inner side wall portions; and a backup seal unit having an annular third seal ring and forming an auxiliary seal chamber for restricting leakage of seal air from the main seal chamber to the atmosphere, the third seal ring surrounding the rotary shaft on an axially outer side isolated from the gas passage with respect to the shaft seal case.

According to this configuration, in the present invention, the static pressure gas seal means introduces the seal air having a pressure higher than the pressure in the gas duct into the main seal chamber formed between the first seal ring and the second seal ring, thereby reliably preventing the exhaust gas in the blower from leaking from the gas duct side to the atmosphere side. Further, when the front-rear differential pressure of the second seal ring is suppressed by the third seal ring of the backup seal unit, the front-rear differential pressure of the third seal ring is also suppressed, and therefore, the reduction of the leakage flow rate of the seal air to the atmosphere side according to the front-rear differential pressure of each seal ring can be effectively suppressed.

(2) In a preferred embodiment of the present invention, the casing may be formed with the gas passage through which a part of exhaust gas of an engine can be introduced and the shaft hole communicating with the gas passage, and the impeller may recirculate the exhaust gas, which is introduced into the gas passage and is pressurized, to the engine.

In this case, the EGR blower is suitable for recirculating exhaust gas of the engine to reduce NOx and the like.

(3) In a preferred embodiment of the present invention, at least the second seal ring on the atmosphere side of the first seal ring and the second seal ring may be formed of a plurality of arcuate segment seal members adjacent in the circumferential direction, the plurality of segment seal members having a first opposing surface and a second opposing surface, the first opposing surface extending in the axial direction and the radial direction and opposing in the circumferential direction, and the second opposing surface extending in the circumferential direction and the radial direction and opposing in the axial direction.

With this configuration, the shape of the small gap between the plurality of segment seal members can be appropriately set according to the inner peripheral surface shape and the end portion shape of the segment seal members, and the flow rate of the seal air passing through the small gap of the second seal ring and the differential pressure between the front and rear of the second seal ring can be stably ensured.

(4) In a preferred embodiment of the present invention, the backup seal unit may further include an outer annular member that covers the third seal ring from a radially outer side and an axially outer side with respect to an axial direction outside the shaft seal case from the gas passage, and an elastic member that urges the third seal ring in an axial direction of the rotary shaft so that the third seal ring is in close contact with the outer annular member.

In this case, the auxiliary seal chamber can be easily formed by the third seal ring and the outer annular member, and the stable sealing posture of the third seal ring can be set, so that the leakage of the seal air to the atmosphere during operation can be more effectively reduced.

(5) In a preferred embodiment of the present invention, the outer annular member may be fixed to an axially outer side of the shaft seal case, the outer annular member being isolated from the gas passage.

With this configuration, the third seal ring and the outer annular member can be easily added to the conventional blower.

(6) In a preferred embodiment of the present invention, the blower is provided with a motor for rotating the rotary shaft, and the housing is integrally connected to the motor.

In this case, a compact blower can be manufactured.

(7) In a preferred embodiment of the present invention, a spin-off plate having a circular ring plate shape and a diameter larger than an inner circumferential diameter of the outer annular member may be disposed on the rotating shaft on the axially outer side than the outer annular member.

According to this configuration, the seal air leaking out of the auxiliary seal chamber in the axial direction can be thrown off in the radial outward direction together with the surrounding dust and the like by the throwing-off plate, and the dust can be effectively prevented from entering the motor side.

(8) In a preferred embodiment of the present invention, there is provided a sealing device for an EGR blower, which is attached to a blower and seals a shaft hole, the blower including: a housing formed with a gas passage through which a part of exhaust gas of an engine can be introduced and the shaft hole communicating with the gas passage; a rotating shaft rotatably inserted through the shaft hole of the housing; and an impeller supported by the rotary shaft and housed in the housing, the impeller recirculating the EGR gas, which is introduced into the gas passage and pressurized, to the engine, the sealing device for the EGR blower including: a first seal ring and a second seal ring having a ring shape and surrounding the rotary shaft in the vicinity of the shaft hole; an annular shaft seal case having an annular wall portion surrounding the first seal ring and the second seal ring, and a pair of inner side wall portions integrally joined to the annular wall portion on both sides in the axial direction of the rotary shaft; a static pressure gas seal unit that forms a main seal chamber in the shaft seal case to prevent the exhaust gas from leaking from the gas passage to the atmosphere, the main seal chamber being introduced with seal air having a pressure higher than a pressure in the gas passage and bringing the first seal ring and the second seal ring into close contact with the pair of inner side wall portions; and a backup seal unit having an annular third seal ring and forming an auxiliary seal chamber for restricting leakage of seal air from the main seal chamber to the atmosphere, the third seal ring surrounding the rotary shaft on an axially outer side isolated from the gas passage with respect to the shaft seal case.

According to this configuration, leakage of the exhaust gas in the blower from the gas passage side to the atmosphere side in the ship can be effectively suppressed by the pressurized sealing air of the static pressure gas sealing means, and the amount of leakage of the sealing air to the atmosphere side can be sufficiently reduced by cooperation of the static pressure gas sealing means and the backup sealing means.

Effects of the invention

According to the present invention, it is possible to provide a blower capable of suppressing power consumption of a seal air supply source, and a blower suitable for an EGR blower of a marine engine.

Drawings

Fig. 1 is a schematic configuration diagram of an EGR blower and an EGR system of a marine engine including the EGR blower according to an embodiment of the present invention.

Fig. 2 is an enlarged cross-sectional view of a portion near an axial hole of an EGR blower according to an embodiment of the present invention.

Fig. 3 is a partially enlarged sectional view showing a portion M encircled by a two-dot chain line in fig. 2 in a further enlarged manner.

Fig. 4A is a front view of a segment seal type seal ring in an EGR blower according to an embodiment of the present invention.

Fig. 4B is a structural diagram of a segment seal type seal ring in the EGR blower according to the embodiment of the present invention, and is a view from the B direction in fig. 4A.

Fig. 5 is an enlarged cross-sectional view of a portion near an axial hole of an EGR blower according to another embodiment of the present invention.

Detailed Description

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

(one embodiment)

Fig. 1 to 4B show a case where a blower of one embodiment of the present invention is provided in a power system with an EGR device as an EGR blower.

First, the structure thereof will be explained.

As shown in fig. 1, a power system 100 according to the present embodiment includes an engine 110, a turbocharger 120, and an EGR device 130, where the engine 110 is a multi-cylinder large two-stroke diesel engine, and the engine 110, the turbocharger 120, and the EGR device 130 are all mounted in a cabin of a ship, not shown.

The engine 110 is, for example, an electronically controlled high-output engine that can be used as a main engine of an ocean-going vessel, and has the following structure: a fuel supply unit 102, an air supply receiver 103, an exhaust receiver 104, and the like are mounted on the multi-cylinder engine main body 101. Although the present embodiment is for a ship, the engine 110 may be used as a stationary engine for operating a generator of a power plant, for example, in a case other than for a ship.

A plurality of cylinders 111 are provided in the multi-cylinder engine main body 101. The plurality of cylinders 111 are connected to the intake receiver 1033 through the scavenging ports 113, respectively, and can discharge air into the exhaust receiver 104 when the corresponding exhaust valves 114 are opened. In each cylinder 111, when air that is compressed by the piston 112 to a point equal to or higher than the ignition point after being taken in by scavenging and fuel injected into the air are combusted, the combustion gas expands, and the piston 112 is driven to generate exhaust gas. Then, the exhaust gas from each cylinder 111 is intermittently sent out into the exhaust receiver 104.

The fuel supply unit 102 pumps and pressurizes the marine diesel fuel purified by the fuel purifier, and when the fuel valve of each cylinder is opened at a predetermined timing, the fuel can be injected and supplied into each cylinder 111 of the engine main body 101.

The air supply receiver 103 is a compressed air accumulator (scavenging receiver) for performing a scavenging action of discharging the combustion gas in each cylinder 111 of the engine main body 101 and filling it with new air, and the exhaust receiver 104 is an exhaust accumulator capable of accumulating and storing the exhaust gas from each cylinder of the engine main body 101 and supplying most of it to the turbocharger 120 side.

The turbocharger 120 has: a turbine 121 driven by exhaust gas supplied from the exhaust receiver 104 side; and a compressor 122 that introduces and compresses outside air when driven by the turbine 121, and supplies it into the air supply receiver 103.

The EGR device 130 includes: a wet scrubbing unit 131 that takes in and purifies a part of the exhaust gas from the exhaust gas receiver 104 to a recirculation path Le leading to the side of the supply gas receiver 103; an EGR cooler 132 that cools the exhaust gas (hereinafter referred to as EGR gas) purified by the scrubber 131 by heat exchange; and an EGR blower 133 that boosts the EGR gas cooled by the EGR cooler 132 to a pressure level that can be supplied from the compressor 122 of the turbocharger 120 into the boost passage Lc leading to the air-supply receiver 103.

Wet scrubbing unit 131 includes: a scrubber which, for example, sprays droplets capable of neutralizing sulfur oxides introduced into the exhaust gas of the recirculation path Le, or which becomes a size suitable for absorbing soot particles in the exhaust gas or primarily cooling the recirculated exhaust gas in the recirculation path Le; and a mist trap that collects droplets purified by the returned exhaust gas on the inner bottom side of the scrubber.

Although not shown in detail, the EGR cooler 132 is constituted by a heat exchanger having an EGR gas passage through which the EGR gas passing through the scrubbing unit 131 and purified and primarily cooled passes and a cooling water passage through which cooling water from the outside passes, that is, a heat exchanger capable of cooling the EGR gas (secondary cooling) by heat exchange between fluids passing through the two passages.

EGR blower 133 includes: a housing 10 having a gas passage 11 into which EGR gas having passed through the EGR cooler 132 is introduced and a shaft hole 12 communicating with the gas passage 11; a rotating shaft 21 rotatably inserted through the shaft hole 12 of the housing 10; an impeller 22 supported by the rotary shaft 21 and housed in the casing 10; and a sealing device 30 for sealing the shaft hole 12.

As shown in fig. 1, a motor 70 is disposed on an outer surface side (right side in fig. 1) of the shaft seal case 33 which is isolated from the gas passage 11 of the housing 10, and the motor 70 has an output shaft 71 which rotationally drives the rotary shaft 21.

As shown in fig. 1 and 2, the gas passage 11 of the casing 10 includes an introduction passage 11a and a scroll passage 11b, the introduction passage 11a is opened with a large diameter on the outer end side of the casing 10, that is, the left end side in fig. 1, and extends in the axial direction of the rotary shaft 21 toward the right side (inner side) in the drawing while being reduced in diameter on the inner side, and the scroll passage 11b surrounds the inner end portion of the introduction passage 11 a. The casing 10 has an inlet 11c and an outlet 11d, the inlet 11c is open on the outer end side of the inlet 11a with a large diameter, and the outlet 11d projects the downstream end of the scroll passage 11b radially outward of the inlet 11 c.

The housing 10 is composed of a main body 13, a motor mounting plate 14, and a plurality of bolts 15, wherein the main body 13 forms the gas passage 11 and opens a motor mounting surface side, the motor mounting plate 14 is substantially disc-shaped to close the motor mounting surface side of the main body 13, and a shaft hole 12 is formed in a central portion thereof, and the plurality of bolts 15 detachably fix the motor mounting plate 14 to the main body 13. A mounting bracket 73 for mounting the motor 70 is attached to the motor mounting plate 14 of the housing 10, and a support bracket 74 for supporting the motor 70 from below is attached to the rear surface side of the housing 10. The housing 10 and the case 72 of the motor 70 are integrally connected by the mounting bracket 73 and the support bracket 74.

Further, the rotary shaft 21 includes: a substantially cylindrical stepped body 23 which is a cylindrical body with a cover connected to the output shaft 71 of the motor 70 so as to be integrally rotatable and which is fitted to the output shaft 71 of the motor 70 with a predetermined fitting pressure; a lid 24 that is fitted concentrically with one end of the substantially cylindrical body 23 in the impeller 22 and closes the one end; an annular spacer 25 interposed between the cover 24 and the output shaft 71 of the motor 70, the annular spacer being capable of positioning the substantially cylindrical body 23 and the cover 24 at a predetermined position in the axial direction with respect to the output shaft 71 of the motor 70; and a bolt 26 that fastens the substantially cylindrical body 23, the lid 24, and the spacer 25 to the output shaft 71 of the motor 70.

The impeller 22 supported by the rotary shaft 21 in the housing 10 includes: an inlet portion 22a close to the inner end portion of the introduction passage 11a in the gas passage 11, an outlet portion 22b opening in the radial outward direction in the scroll passage 11b, and a plurality of vane portions 22c extending from the inlet portion 22a to the outlet portion 22b and spaced apart from each other at equal angular intervals. The impeller 22 constitutes a centrifugal blower together with the housing 10 and the rotary shaft 21, and when the motor 70 is driven to rotate via the rotary shaft 21, the EGR gas introduced into the gas passage 11 of the housing 10 is pressurized to be recirculated to the engine 110.

As shown in fig. 2, the sealing device 30 is installed between the housing 10 and the rotary shaft 21 and closes the gap G around the rotary shaft 21 in the shaft hole 12.

The sealing device 30 includes: a first seal ring 31 and a second seal ring 32 in annular shapes surrounding the rotary shaft 21 near one end of the shaft hole 12, and an annular shaft seal box 33 accommodating the first seal ring 31 and the second seal ring 32. As shown in fig. 2 and 3, the sealing device 30 includes a static pressure gas seal unit 40 and a backup seal unit 60.

The shaft seal case 33 has an annular wall portion 33a having an annular inner peripheral surface shape, the annular wall portion 33a surrounding the first seal ring 31 and the second seal ring 32, and a pair of inner

side wall portions

33b, 33c integrally joined to the annular wall portion 33a at both sides in the axial direction of the rotary shaft 21 so as to be substantially orthogonal to the annular wall portion 33 a.

Specifically, the shaft seal box 33 is constituted by a first annular body 34, a second annular body 35, and a third annular body 36, wherein the first annular body 34 is fixed on the outer surface side around the shaft hole 12 of the housing 10 by a plurality of bolts 33g, the second annular body 35 forms an inner wall portion 33b on one of the pair of inner wall portions and is fixed on the inner surface side (left end surface side in fig. 2) of the first annular body 34 by bolts, and the third annular body 36 is integrally formed on the outer surface side of the first annular body 34, and forms an inner wall portion 33c on the other side so as to face the inner wall portion 33b on one of the pair of inner wall portions.

The static pressure gas seal unit 40 is configured such that a plurality of compression coil springs 41 are arranged in the shaft seal case 33 so as to be compressed at equal intervals (equal angular intervals) in the circumferential direction between the first seal ring 31 and the second seal ring 32, and the first seal ring 31 and the second seal ring 32 are urged to be brought into close contact with the pair of

inner side walls

33b, 33c of the shaft seal case 33, thereby forming an annular main seal chamber 42 in the shaft seal case 33. The sealing air having a pressure higher than the pressure in the gas passage 11 and the axial hole 12 of the housing 10 is introduced into the main seal chamber 42 from the sealing air (air for sealing) supply circuit 45 shown in fig. 3, and leakage of the exhaust gas from the gas passage 11 in the housing 10 to the atmosphere can be suppressed.

As shown in fig. 3, the seal air supply circuit 45 has, in an air supply passage 45h communicating with the seal air passage 34h formed in the first annular body 34 of the shaft seal tank 33: a check valve 46, a pressure regulating unit 47 including a pressure gauge, a flow meter, a safety valve, a filter, and the like, which are not shown, an on-off valve 48, and an air supply source 49 such as an air pump.

For example, the pressure adjusting means 47 and the on-off valve 48 are controlled in accordance with the rotation speed [ rpm ] of the engine 110, the load, the pressure in the gas passage 11, and the like, and the seal air supply circuit 45 constantly supplies seal air into the main seal chamber 42 at a supply pressure higher than the pressure of the gap G in the shaft hole 12 communicating with the gas passage 11, thereby constantly suppressing the EGR gas from leaking from the gas passage 11 in the housing 10 to the atmosphere through the shaft hole 12. Therefore, the supply pressure of the seal air is always higher than the atmospheric pressure, and when the pressure in the gas passage 11 (the pressure on the back surface side of the impeller 22) increases in accordance with any of the outlet-side pressure of the exhaust gas receiver 104, the back pressure from the turbine 121 side of the turbocharger 120, the inlet-side pressure of the supply air receiver 103, the boost pressure from the compressor 122 side of the turbocharger 120, the rotation speed [ rpm ] of the motor 70, and the like, the supply pressure of the seal air can be adjusted to a pressure higher than the pressure in the gas passage 11. The supply pressure of the sealing air may be increased or decreased in stages.

The second seal ring 32 on the atmosphere side of the first seal ring 31 and the second seal ring 32 of the static pressure gas seal unit 40 has a split seal structure including a plurality of arc-shaped segment seal members 51 adjacent in the circumferential direction, and a garter spring 52 that elastically and integrally regulates the plurality of segment seal members 51 by applying a force to the rotary shaft 21 side against the plurality of segment seal members 51.

In the present embodiment, not only the second seal ring 32 but also the first seal ring 31 adjacent to the shaft hole 12 of the housing 10 has a split seal structure including a plurality of arcuate segment seal members 51 adjacent in the circumferential direction and a garter spring 52 that elastically and integrally regulates the plurality of segment seal members 51 while applying a force to the rotary shaft 21 side against the plurality of segment seal members 51.

The plurality of segment seal members 51 of the first and second seal rings 31, 32 have a pair of dowel pin holes 51k spaced apart by a predetermined angular interval on one surface side thereof, and a plurality of recessed holding holes 51n capable of holding end portions of the plurality of compression coil springs 41 on the other surface side thereof. The first seal ring 31 and the second seal ring 32 are provided in opposite directions so that the concave holding holes 51n and the dowel pin holes 51k open in opposite directions in the axial direction of the rotary shaft 21.

The segment seal members 51 are arranged on the same circumference so as to have a first opposing surface 51a and a second opposing surface 51b, the first opposing surface 51a is expanded in the axial direction and the radial direction and opposed to each other with a slight gap Ec in the circumferential direction, the second opposing surface 51b is expanded in the circumferential direction and the radial direction and opposed to each other with a sliding gap Ed in the axial direction, the segment seal members 51 are guided to the rotary shaft 21 by the

positioning pins

33j and 33k fitted to the shaft seal housing 33 side of the positioning pin holes 51k, and are pressed against the outer circumferential surface of the rotary shaft 21 with a predetermined contact pressure by the chucking spring 52 on the outer circumferential side.

Here, the minute gap Ec extending in the axial direction of the rotary shaft 21 is not covered with anything on the outer peripheral surface sides of the first and second seal rings 31, 32 and on the mutually opposite sides (the recessed holding hole 51n sides), but is covered with the pair of inner

side wall portions

33b, 33c and narrowed on the close contact surface side (the registration pin hole 51k side) where the first and second seal rings 31, 32 and the pair of inner

side wall portions

33b, 33c are in close contact with each other.

On both axial surfaces of the first seal ring 31 and the second seal ring 32, the positions of the minute gaps Ec extending in the axial direction of the rotary shaft 21 are shifted in the circumferential direction, and as shown in fig. 4B, the sliding gap Ed extending in the circumferential direction is curved in opposite directions between the minute gaps Ec on both axial surfaces of the first seal ring 31 and the second seal ring 32, and is narrower than the minute gaps Ec on both axial surfaces. These small clearance Ec and the small clearance Ec constitute a small hole-like leak passage 51e having a large pressure loss.

The backup seal unit 60 includes: an annular third seal ring 61 that is disposed on the outer surface side (right end side in fig. 2) of the shaft seal case 33 that is isolated from the gas passage 11 of the housing 10 and surrounds the rotary shaft 21; an outer annular member 63 which is provided to cover the third seal ring 61 from the outside in the radial direction and the outside in the axial direction, and is detachably fixed to the first annular body 34 of the shaft seal case 33 by a bolt 66; an elastic member 64 such as a compression coil spring that biases the third seal ring 61 outward in the axial direction of the rotary shaft 21 so as to be in close contact with the inner wall portion 63a of the outer annular member 63; and an airtight seal 65 made of a rubber elastic ring and attached between the first annular body 34 of the shaft seal box 33 and the outer annular member 63.

The backup seal unit 60 forms an auxiliary seal chamber 62 that restricts leakage of seal air from the main seal chamber 42 of the static pressure gas seal unit 40 to the atmosphere between the shaft seal case 33 and the outer annular member 63.

Although not shown in detail, the third seal ring 61 of the backup seal unit 60 is substantially identical to the second seal ring 32 on the atmosphere side of the static pressure gas seal unit 40, and has a split seal structure including a plurality of arc-shaped segment seal members (corresponding to the segment seal members 51) adjacent in the circumferential direction, and a garter spring (corresponding to the garter spring 52) that elastically and integrally regulates the plurality of segment seal members while applying a force to the rotary shaft 21 side.

The plurality of segment seal members of the third seal ring 61 also have small-hole-shaped leakage passages (indicated by reference numeral 61e with parenthesis in the figure) having a large pressure loss due to the plurality of segment seal members, similarly to the plurality of arc-shaped segment seal members 51 of the second seal ring 32 shown in fig. 4A and 4B.

In the sealing device 30 of the present embodiment, when the supply pressure of the sealing air supplied to the main seal chamber 42 is a pressure P1[ MPa ] sufficiently higher than the atmospheric pressure, a condition ((P2+0.1)/(P1+0.1) being a critical pressure ratio b or less) can be established that the sealing air leaking from the leak passage 51e of the second seal ring 32 becomes a so-called blocked flow. In this case, when the seal air leaks from the main seal chamber 42 to the auxiliary seal chamber 62 side, a large pressure loss corresponding to the upstream pressure P1 is generated by the second seal ring 32, and the mass flow rate of the seal air leaking from the main seal chamber 42 to the auxiliary seal chamber 62 side is effectively limited.

In this case, the pressure P2 in the auxiliary seal chamber 62 is equal to or higher than atmospheric pressure but equal to or lower than a predetermined pressure sufficiently lower than the pressure P1 of the seal air in the main seal chamber 42, and the atmospheric pressure P3[ MPa ] as the downstream pressure is higher than the pressure P2 in the auxiliary seal chamber 62 as the upstream pressure of the third seal 61. Therefore, a condition ((P3+0.1)/(P2+0.1) being greater than the critical pressure ratio b) is satisfied that the seal air leaking from the small-hole-shaped leak passage 61e of the third seal ring 61 becomes a so-called subsonic flow. Therefore, the mass flow rate of the seal air leaking out to the atmosphere side from the auxiliary seal chamber 62 depends on both the pressure P2 in the auxiliary seal chamber 62 and the atmospheric pressure P3, and is sufficiently limited by the third seal ring 61 (the flow rate in the auxiliary seal chamber 62 is smaller than the flow rate in the case where the flow becomes a choke flow at a high pressure of about pressure P1).

On the other hand, when the supply pressure of the seal air supplied to the main seal chamber 42 is higher than the atmospheric pressure but not so high, or when the supply pressure of the seal air supplied to the main seal chamber 42 is a pressure P1 sufficiently higher than the atmospheric pressure but the pressure P2 in the auxiliary seal chamber 62 is high, a condition ((P2+0.1)/(P1+0.1) that the seal air leaking from the small-hole-shaped leak passage 51e of the second seal ring 32 becomes subsonic flow is established as being higher than the critical pressure ratio b).

In this case, the mass flow rate of the seal air leaking from the main seal chamber 42 to the auxiliary seal chamber 62 side is limited by the second seal ring 32 sufficiently (a flow rate smaller than that in the case of the blocked flow) depending on both the pressure P1 in the main seal chamber 42 and the pressure P2 in the auxiliary seal chamber 62.

In this way, the EGR blower 133 having the sealing device 30 of the present embodiment sufficiently reduces the amount of leakage of the sealing air that leaks to the atmosphere side through the shaft hole 12 of the housing 10 by cooperating the static pressure gas sealing means 40 and the backup sealing means 60 of the sealing device 30.

As shown in fig. 2, an annular plate-shaped throwing plate 81 having a diameter larger than the inner peripheral diameter of the outer annular member 63 is disposed on the rotating shaft 21 located axially outward of the outer casing member 63 with respect to the housing 10. The throwing-off plate 81 projects in a baffle shape substantially perpendicular to the outer peripheral surface of the rotary shaft 21, and throws off the seal air leaking from the auxiliary seal chamber 62 in the axial direction of the rotary shaft 21 in the radial outward direction together with surrounding dust and the like, thereby suppressing the dust from entering the motor 70 side.

However, in the turbocharger 120, when the turbine 121 is driven to rotate by the energy of the exhaust gas from the exhaust gas receiver 104 of the engine 110, the fresh air (air from the outside) and the EGR gas sucked into the compressor 122 are pressurized to be supercharged to the air supply receiver 103 side of the engine 110 at a predetermined supercharging pressure. The turbocharger 120 may be configured to control the intake of the exhaust gas into the turbine 121 by the variable nozzle function or to bypass the exhaust gas and control the bypass flow rate thereof in accordance with a preset operating condition. In this case, the energy of the exhaust gas from the exhaust receiver 104 may be changed according to the operating state of the engine 110, and the boost pressure of the turbocharger 120 may be appropriately controlled.

Further, the EGR apparatus 130 can selectively restrict its operation by narrowing or blocking the recirculation path Le according to the rotation speed [ rpm ] of the engine or according to a preset operation condition. In this way, the discharge of NOx can be selectively restricted according to the rotational speed [ rpm ] of the engine or the sailing sea area of the ship.

Next, the operation will be explained.

In the EGR blower 133 including the sealing device 30 of the present embodiment configured as described above, the static pressure gas seal means 40 introduces the seal air having a pressure higher than the pressure in the shaft hole 12 communicating with the gas passage 11 into the main seal chamber 42 formed between the first seal ring 31 and the second seal ring 32, thereby reliably preventing the exhaust gas in the EGR blower 133 from leaking from the gas passage 11 side to the atmosphere side.

Further, since the front-rear differential pressure of the second seal ring 32 is suppressed by the third seal ring 61 of the backup seal unit 60, and the front-rear differential pressure of the third seal ring 61 is also suppressed, the leakage flow rate of the seal air to the atmosphere, which can be changed according to the front-rear differential pressure of the seal rings 32, 61, can be further effectively suppressed by the cooperation of the static pressure gas seal unit 40 and the backup seal unit 60.

In the present embodiment, the blower is configured such that the housing 10 is formed with the gas passage 11 through which a part of the exhaust gas of the engine 110 can be introduced, the rotary shaft 21 is inserted through the shaft hole 12 communicating with the gas passage 11 to support the impeller 22, and the exhaust gas introduced into the gas passage 11 is pressurized to be recirculated to the engine 110, and therefore, the blower is suitable for the EGR blower 133 capable of recirculating the exhaust gas discharged from the engine 110 to reduce the discharge amount of NOx and the like.

In the present embodiment, at least the second seal ring 32 on the atmospheric side of the first seal ring 31 and the second seal ring 32 is formed of the plurality of arcuate segment seal members 51, so that the minute gaps Ec, Ed, and the like between the plurality of segment seal members 51 can be set to appropriate shapes and sizes in accordance with the inner peripheral surface shapes and the end shapes of the segment seal members 51, and the leakage flow rate of the seal air passing through the minute gap of the second seal ring 32 and the differential pressure across the second seal ring 32 can be stably secured.

In addition, in the present embodiment, since the backup seal unit 60 includes the outer annular member 63 that covers the third seal ring 61 from the outside in the radial direction and the outside in the axial direction, and the elastic member 64 that urges the third seal ring 61 in the axial direction of the rotary shaft 21 so that the third seal ring 61 and the outer annular member 63 are in close contact with each other, the auxiliary seal chamber 62 can be easily formed by the third seal ring 61 and the outer annular member 63, and a stable seal posture of the third seal ring 61 can be set, and leakage of seal air to the atmosphere side during operation can be more effectively reduced.

In the present embodiment, the outer annular member 63 is detachably coupled to the shaft seal case 33 on the axial outer side of the shaft seal case 33 isolated from the gas duct 11, and therefore the third seal ring 61 and the outer annular member 63 can be easily added to the conventional blower.

In the preferred embodiment of the present invention, the motor 70 for rotating the rotary shaft 21 is disposed axially outside the gas duct 11 with respect to the shaft seal case 33, and the housing 10 and the case 72 of the motor 70 are integrally connected, so that the compact EGR blower 133 can be manufactured.

In the present embodiment, since the annular plate-shaped spin-off plate 81 having a diameter larger than the inner peripheral diameter (the hole diameter (2R1) corresponding to the radius R1 in fig. 2) of the outer annular member 63 is disposed on the rotating shaft 21 on the outer side in the axial direction than the outer annular member 63, the seal air leaking to the outer side in the axial direction from the auxiliary seal chamber 62 can be spun off in the radially outward direction by the spin-off plate 81 together with the surrounding dust and the like, and the entry of dust into the motor 70 side can be effectively suppressed.

As described above, in the present embodiment, the mechanical seal type sealing device 30 for closing the axial hole 12 of the EGR blower 133 includes: a first seal ring 31 and a second seal ring 32 in the form of rings surrounding the rotary shaft 21 in the vicinity of the shaft hole 12; an annular shaft seal case 33 having an annular wall portion 33a surrounding the first seal ring 31 and the second seal ring 32, and a pair of inner side wall portions 33b, 33c integrally joined to the annular wall portion 33a on both sides in the axial direction of the rotary shaft 21; a static pressure gas seal unit 40 which forms a main seal chamber 42 in the shaft seal box 33 to prevent the exhaust gas from leaking from the gas passage 11 to the atmosphere, and which introduces seal air having a pressure higher than the pressure in the gas passage 11 into the main seal chamber 42 to bring the first seal ring 31 and the second seal ring 32 into close contact with the pair of inner side wall portions 33b, 33 c; and a backup seal unit 60 having an annular third seal 61 and forming an auxiliary seal chamber 62 for restricting leakage of seal air from the main seal chamber 42 to the atmosphere, the third seal 61 surrounding the rotary shaft 21 on the axially outer side with respect to the shaft seal box 33 and isolated from the gas passage 11.

Therefore, leakage of the exhaust gas in the EGR blower 133 from the gas passage 11 side to the atmosphere side in the ship can be effectively suppressed by the pressurized sealing air of the static pressure gas sealing unit 40, and the leakage amount of the sealing air to the atmosphere side can be sufficiently reduced by cooperation of the static pressure gas sealing unit 40 and the backup sealing unit 60.

Further, in the EGR blower 133 according to the above-described embodiment, the rotary shaft 21 is fastened to the output shaft 71 of the motor 70, but as shown in fig. 5, it is also possible to provide a dedicated seal rotary sleeve 27 fixed to the outer peripheral surface of the substantially cylindrical body 23 in addition to the substantially cylindrical body 23 of the rotary shaft 21 fastened to the output shaft 71 of the motor 70, and to provide a surface-treated portion 27a in the rotary sleeve 27, and the surface-treated portion 27a forms a sliding surface having a small frictional resistance against sliding with the seal rings 31, 32, 61 and having excellent wear resistance.

In the above-described embodiment, the

seals

31, 32, and 61 all have the same split seal structure, but it is obvious that the first seal 31 or the third seal 61 may have a seal structure different from that of the second seal 32. Further, although the engine 110 is provided for a ship in one embodiment, the present invention is also applicable to a large engine other than a ship, for example, a fixed engine for operating a generator, and the generator and the fixed engine are provided in a relatively narrow space.

As described above, the present invention can provide a blower capable of suppressing power consumption of a seal air supply source, and can provide a blower suitable for an EGR blower of a marine engine, and suitable for all blowers of an exhaust gas recirculation system of a large engine.

Description of reference numerals:

10 outer casing

11 gas channel

12 axle hole

21 rotating shaft

22 impeller

30 sealing device

31 first seal ring

32 second seal ring

33 shaft seal box

33a annular wall

33b, 33c pair of inner wall parts

34h sealed air channel

40 static pressure gas seal unit

42 primary seal chamber

45 sealing air supply circuit

51 segmented seal member

51a first opposite surface

51b second opposite side

51e, 61e leakage path

60 backup seal unit

61 third seal ring

62 auxiliary sealing chamber

63 outer covering ring member

63a inner wall part

64 elastic component

65 gas-tight seal

70 electric motor

71 output shaft

81 throwing plate

100 power system

103 gas supply receiver

104 exhaust receiver

110 engine

120 turbo charger

130 EGR device

133 EGR blower

Ec small gap

Ed sliding clearance

Lc supercharging channel

Le Recirculation Path

P1 pressure (pressure in the main seal chamber)

P2 pressure (pressure in auxiliary seal chamber)

P3 atmospheric pressure.

Claims

1. A blower is provided with:

a housing formed with a gas passage and a shaft hole communicating with the gas passage;

a rotating shaft rotatably inserted through the shaft hole of the housing;

an impeller supported by the rotary shaft and housed in the housing; and

a sealing device for sealing the shaft hole,

the blower is characterized in that,

the sealing device includes:

a first seal ring and a second seal ring having a ring shape and surrounding the rotary shaft in the vicinity of the shaft hole;

an annular shaft seal case having an annular wall portion surrounding the first seal ring and the second seal ring, and a pair of inner side wall portions integrally joined to the annular wall portion on both sides in the axial direction of the rotary shaft;

a static pressure gas seal unit that forms a main seal chamber in the shaft seal case to prevent the exhaust gas from leaking from the gas passage to the atmosphere, the main seal chamber being introduced with seal air having a pressure higher than a pressure in the gas passage and bringing the first seal ring and the second seal ring into close contact with the pair of inner side wall portions;

and a backup seal unit having an annular third seal ring and forming an auxiliary seal chamber for restricting leakage of seal air from the main seal chamber to the atmosphere, the third seal ring surrounding the rotary shaft on an axially outer side isolated from the gas passage with respect to the shaft seal case.

2. The blower according to claim 1,

the housing is formed with the gas passage into which a part of exhaust gas of the engine can be introduced, and the shaft hole communicating with the gas passage,

the impeller recirculates the exhaust gas, which is introduced into the gas passage and is pressurized, to the engine.

3. The blower according to claim 1 or 2,

at least the second seal ring on the atmospheric side of the first seal ring and the second seal ring is formed of a plurality of arc-shaped segment seal members adjacent in the circumferential direction,

the plurality of segment seal members have first opposing faces that expand in the axial direction and the radial direction and oppose in the circumferential direction and second opposing faces that expand in the circumferential direction and the radial direction and oppose in the axial direction with respect to each other.

4. The blower according to any one of claims 1 to 3,

the backup seal unit further includes an outer annular member that covers the third seal ring from a radial outer side and an axial outer side on an axial outer side of the shaft seal case that is separated from the gas passage, and an elastic member that urges the third seal ring in an axial direction of the rotary shaft so that the third seal ring is in close contact with the outer annular member.

5. The blower according to claim 4,

the outer annular member is fixed to an axially outer side of the shaft seal case, which is isolated from the gas passage.

6. The blower according to claim 5,

the blower is provided with a motor that drives the rotary shaft to rotate,

the housing is integrally connected with the motor.

7. The blower according to claim 6,

an annular plate-shaped spin-off plate having a diameter larger than an inner circumferential diameter of the outer annular member is disposed on the rotating shaft on the axially outer side than the outer annular member.

8. A sealing device for an EGR blower, which is attached to a blower and seals a shaft hole, the blower comprising:

a housing formed with a gas passage through which a part of exhaust gas of an engine can be introduced and the shaft hole communicating with the gas passage;

a rotating shaft rotatably inserted through the shaft hole of the housing; and

an impeller supported by the rotary shaft and housed in the housing, the impeller recirculating EGR gas, which is introduced into the gas passage and is pressurized, to the engine,

the sealing device for an EGR blower is characterized by comprising: