CN111765247B - Combined bearing for hydroelectric generating set - Google Patents

Abstract

The invention relates to the field of hydroelectric power generation equipment, and discloses a combined bearing for a hydroelectric power generator set, which comprises a thrust bearing and an oil groove, wherein an oil groove cover is arranged above the oil groove, the oil groove cover comprises an annular plate and a vertical sleeve, the annular plate is fixedly arranged on the top wall surface of the oil groove, and the vertical sleeve is positioned below the annular plate and fixedly connected with the inner ring side of the annular plate; the thrust bearing comprises a thrust head, the thrust head is arranged in the vertical sleeve in a penetrating way, and a sealing cover is arranged between the top of the thrust head and the oil groove cover; the thrust head is equipped with oil mist conveying mechanism on being located the inside lateral wall of sealed lid to be equipped with oil mist clearance mechanism on the oil groove and cover, oil mist conveying mechanism flows the oil mist that the thrust head was rotatory to clearance mechanism in through wind-force, and oil mist clearance mechanism is collected in turn to the oil mist, discharges the lubricating oil after collecting into the oil groove again. The invention can effectively prevent the oil mist from being brought into the wind path of the generator due to the negative pressure area formed between the bearing and the generator rotor hub.

Description

Combined bearing for hydroelectric generating set

Technical Field

The invention relates to the field of hydroelectric power generation equipment, in particular to a combined bearing for a hydroelectric generating set.

Background

The hydraulic generator is a generator which uses a hydraulic turbine as a prime motor to convert water energy into electric energy, when water flows through the hydraulic turbine, the water energy is converted into mechanical energy, and a rotating shaft of the hydraulic turbine drives a rotor of the generator to convert the mechanical energy into electric energy for output. The hydraulic generator mainly comprises main components such as a rotor, a stator, an oil groove, a thrust bearing, a guide bearing, a cooler, a brake and the like, wherein the thrust bearing and the guide bearing can be used for bearing circumferential load and radial load of a rotating part of the hydraulic generator set respectively, the thrust bearing and the guide bearing have the problem of oil throwing in the running process of the hydraulic generator set, and the problem of oil mist of the hydraulic generator set brings great hidden danger and harm to safe and stable running of the hydraulic generator set.

The main reason for the oil slinging is: in the process of high-speed rotation of the generator, under the action of centrifugal force and stirring of a main shaft, lubricating oil in an oil groove of the bearing can do irregular parabolic motion, and can be collided vigorously when encountering obstruction, so that a large amount of oil mist is formed at the upper part of the oil groove; in the high-speed rotation process of the generator rotor, a negative pressure area is formed between the bearing and the generator rotor hub, and oil mist is immediately brought to the wind path of the generator under the action of negative pressure, so that large-area oil mist pollution is caused.

Aiming at the problems, the prior art is often treated by improving a sealing structure, such as an oil mist sealing structure of a hydraulic generator disclosed in China patent application No. CN201610056202.7, wherein the sealing structure on a sealing cover consists of a gapless sealing part and a magnetic liquid sealing part, the sealing structure belongs to rotary combined sealing, the gapless sealing has the effect of follow-up compensation, so that the sealing is more effective and reliable, and the magnetic liquid sealing is a non-contact sealing, and the sealing performance is improved. However, the sealing structure has the following problems in practical application: when the hydraulic generator operates at a high speed, the negative pressure of the negative pressure area is larger, the generated oil mist is larger, and although the sealing performance is enhanced on the sealing cover, the sealing cover and the thrust head are in running fit, and the oil mist can leak out from the space between the thrust head and the sealing cover under the action of the negative pressure and is brought to a wind path of the generator. Therefore, the sealing performance is increased but the problem of oil mist leakage cannot be fundamentally solved.

Disclosure of Invention

The invention aims to provide a combined bearing for a hydroelectric generating set, which can effectively prevent oil mist from being brought into a wind path of a generator due to a negative pressure area formed between the bearing and a generator rotor hub.

In order to achieve the aim of the invention, the invention adopts the following technical scheme: the combined bearing for the hydroelectric generating set comprises a thrust bearing and an oil groove for installing the thrust bearing, wherein the oil groove is U-shaped and filled with lubricating oil, an oil groove cover is arranged above the oil groove, the oil groove cover comprises an annular plate and a vertical sleeve, the annular plate is fixedly installed on the top wall surface of the oil groove, and the vertical sleeve is positioned below the annular plate and fixedly connected with the inner ring side of the annular plate; the thrust bearing comprises a thrust head, the thrust head is arranged in the vertical sleeve in a penetrating manner, and a sealing cover is arranged between the top of the thrust head and the oil groove cover; the oil mist cleaning device is characterized in that an oil mist conveying mechanism is arranged on the side wall of the inside of the sealing cover, an oil mist cleaning mechanism is arranged on the oil groove cover, oil mist generated by rotation of the thrust head flows into the cleaning mechanism through wind power, the oil mist cleaning mechanism alternately collects the oil mist, and then the collected lubricating oil is discharged into the oil groove.

Preferably, the oil mist conveying mechanism comprises a mounting ring sleeved on the outer wall of the upper part of the thrust head, a plurality of fan blades are arranged on the mounting ring, the fan blades synchronously rotate along with the thrust head, negative pressure is generated on the inner side of a sealing cover above the fan blades, a plurality of air inlets are arranged on the sealing cover above the fan blades, and a one-way air valve is arranged on the outer side of each air inlet.

Preferably, the one-way air valves are connected with air pipes, one ends of the air pipes, which are far away from the one-way air valves, are connected with refrigerators, and the refrigerators refrigerate and cool air input into the sealing covers.

Preferably, the oil mist cleaning mechanism comprises a plurality of pairs of mounting sleeves arranged on the annular plate, two mounting sleeves of each pair are symmetrical along the circle center of the oil tank cover, a first through hole is formed in the annular plate in the mounting sleeve, the inner diameter of the first through hole is smaller than that of the mounting sleeve, a supporting plate is arranged below the annular plate, a plurality of pairs of connecting rods are arranged at the edge of the supporting plate, the tops of the connecting rods are fixed on the lower surface of the annular plate, a cylindrical oil absorption sponge in a honeycomb shape is arranged on the supporting plate, and the tops of the oil absorption sponges extend into the first through hole; the installation sleeves are provided with extrusion assemblies for extruding the oil absorption sponge, the extrusion assemblies in each pair of installation sleeves alternately carry out extrusion operation, each extrusion assembly comprises a pressure plate arranged above a first through hole, the top of each installation sleeve is provided with a telescopic piece, and a push rod of each telescopic piece is connected with each pressure plate;

an exhaust window is arranged on the side wall of the upper part of the mounting sleeve, and a detector for detecting air pressure is arranged in the oil groove.

Preferably, a guide rod is arranged in the middle of the supporting disc, the guide rod penetrates through the oil absorption sponge, the push rod is tubular, and the top end of the guide rod penetrates through the pressure plate and extends into the push rod.

Preferably, the extrusion assembly further comprises a sealing disc arranged above the pressure disc, a section of annular groove is formed in the outer wall of the push rod, the sealing disc is sleeved in the annular groove, the outer diameter of the sealing disc is larger than the inner diameter of the first through hole and smaller than the inner diameter of the mounting sleeve, sealing rings are arranged on the edge of the lower surface of the sealing disc, far away from the push rod, of the sealing disc, on the side wall, opposite to the push rod, of the sealing disc, a limiting disc is arranged on the outer wall of the push rod, located above the annular groove, and a spring is sleeved on the push rod between the limiting disc and the sealing disc.

Preferably, the lower part cover of thrust head is equipped with the guide bearing, the outer wall fixed connection of guide bearing is on the lateral wall of vertical cover lower part, the lubrication oil in the oil groove is immersed to the lower part of vertical cover, be equipped with annular last oil baffle disc and lower oil baffle disc between vertical cover and the oil groove inner wall, the outer rampart of going up the oil baffle disc links to each other with the oil groove inner wall, and goes up the internal diameter of oil baffle disc and be greater than the external diameter of vertical cover, on the inner rampart of lower oil baffle disc and the another lateral wall of vertical cover, and the external diameter of oil baffle disc is less than the internal diameter of oil groove down.

Preferably, the upper portion of vertical cover is equipped with a plurality of second through-holes, the second through-hole is used for communicating guide bearing upper portion region and last oil baffle disc upper portion region, and every second through-hole is close to last oil baffle disc one side and is equipped with the air guide cover, the lower part opening of air guide cover, be equipped with first swash plate and second swash plate on two relative lateral walls of air guide cover and vertical cover respectively, first swash plate and the crisscross distribution of second swash plate constitute the gas-supply passageway of buckling in succession.

The beneficial effects of the invention are concentrated in that: the invention can effectively prevent the oil mist from being brought into the wind path of the generator from the thrust bearing to the sealing cover due to the negative pressure area formed between the bearing and the generator rotor hub, thereby further polluting the unit and reducing the waste of lubricating oil. Specifically, the oil mist conveying mechanism utilizes the power of the thrust head to enable the fan blades to synchronously rotate along with the thrust head, negative pressure is generated on the upper parts of the fan blades when the fan blades rotate, cold air is input through the air inlet holes, and oil mist on the upper parts of the oil tanks is brought into the oil mist cleaning mechanism for collection through air flow; negative pressure areas are generated on the outer side and the inner side of the sealing cover and are mutually offset to form air pressure balance or internal negative pressure intensity is larger than the external negative pressure intensity, and oil mist cannot leak out from between the sealing cover and the thrust bearing in the running process of the unit.

Drawings

FIG. 1 is a schematic view of the overall structure of a combination bearing of the present invention;

FIG. 2 is an enlarged view of portion A of the structure shown in FIG. 1;

FIG. 3 is an enlarged view of portion B of the structure of FIG. 1;

fig. 4 is an enlarged view of a portion C of the structure shown in fig. 1.

Detailed Description

In order to make the technical solution of the present invention better understood by those skilled in the art, the present invention will be further described in detail with reference to the accompanying drawings and specific embodiments.

As shown in fig. 1-4, a combined bearing for a hydroelectric generating set comprises a thrust bearing and an oil groove 1 for installing the thrust bearing, wherein the thrust bearing comprises a thrust head 4, a thrust tile, a mirror plate and other parts and a main shaft penetrating through the combined bearing, the specific connection structure is not excessively detailed in the embodiment, the oil groove 1 is in a U shape and is filled with lubricating oil, an oil groove cover is arranged above the oil groove 1, the oil groove cover comprises an annular plate 2 and a vertical sleeve 3, the annular plate 2 is fixedly installed on the top wall surface of the oil groove 1 through bolts, the vertical sleeve 3 is positioned below the annular plate 2 and is fixedly connected with the inner ring side of the annular plate 2, and the annular plate 2 and the vertical sleeve 3 can be integrally formed; the thrust head 4 is arranged in the vertical sleeve 3 in a penetrating way, a sealing cover 5 is arranged between the top of the thrust head 4 and the oil groove cover, and the sealing cover 5 is used for sealing the combined bearing; in order to prevent oil mist from leaking out of the combined bearing, an oil mist conveying mechanism is arranged on the side wall of the thrust head 4, which is positioned in the sealing cover 5, and an oil mist cleaning mechanism is arranged on the oil groove cover, wherein the oil mist conveying mechanism enables oil mist generated by rotation of the thrust head 4 to flow into the cleaning mechanism through wind force, the oil mist cleaning mechanism alternately collects the oil mist, and then the collected lubricating oil is discharged into the oil groove 1.

For the oil mist conveying mechanism, specifically, as shown in fig. 2, the oil mist conveying mechanism comprises a mounting ring 6 sleeved on the outer wall of the upper part of a thrust head 4, a plurality of fan blades 7 are arranged on the mounting ring 6, the fan blades 7 synchronously rotate along with the thrust head 4, a negative pressure area is generated on the inner side of a sealing cover 5 above the fan blades 7, the negative pressure area on the inner side of the sealing cover 5 and the negative pressure area on the outer side can be mutually offset to form a balanced state, or the negative pressure intensity on the inner side is larger than the negative pressure intensity on the outer side, so that oil mist cannot leak out from between the sealing cover 5 and the thrust head 4, a plurality of air inlets 8 are arranged on the sealing cover 5 above the fan blades 7, one-way air valves 9 are respectively arranged on the outer sides of the air inlets 8 to supplement air into a bearing, the air pressure balance in the combined bearing is kept, and meanwhile, air flows are formed to facilitate collection of the oil mist.

Further, all be connected with gas-supply pipe 10 on the one-way pneumatic valve 9, the one end that gas-supply pipe 10 kept away from one-way pneumatic valve 9 is connected with refrigerator 11, refrigerator 11 carries out refrigeration cooling to the air of input in sealed lid 5, because the oil mist has higher temperature, through in inputting the cold air to the combination bearing, can carry out quick cooling to inside oil mist, the oil mist of being convenient for condenses into fluid.

Further, as shown in fig. 3, the oil mist cleaning mechanism includes a plurality of pairs of installation sleeves 12 disposed on the annular plate 2, two installation sleeves 12 of each pair are symmetrical along the center of the oil groove cover, a first through hole 13 is disposed on the annular plate 2 located in the installation sleeve 12, the inner diameter of the first through hole 13 is smaller than the inner diameter of the installation sleeve 12, a supporting disc 28 is disposed below the annular plate 2, a plurality of pairs of connecting rods 14 are disposed at the edge of the supporting disc 28, the top of the connecting rods 14 is fixed on the lower surface of the annular plate 2 through bolts, a cylindrical oil absorption sponge 15 in a honeycomb shape is disposed on the supporting disc 28, when the air flow passes through the oil absorption sponge 15, oil mist is absorbed in the oil absorption sponge 15, when the oil in the sponge is saturated, an extrusion assembly for extruding lubricating oil in the oil absorption sponge 15 is required to be disposed on the installation sleeve 12, the extrusion assembly comprises a pressure disc 16 disposed above the first through hole 13, the top of the pressure disc 12 is provided with a cylindrical oil absorption sponge 15, the top of the pressure disc is mounted with a telescopic rod 16 in the installation sleeve 16 or a telescopic rod 17 in the telescopic part is arranged on the telescopic rod 16, and the telescopic rod is arranged on the telescopic rod 16, when the telescopic rod is pushed by the telescopic rod 16 is pushed down along the telescopic rod 16, and the telescopic rod is arranged in the telescopic rod 16;

In this embodiment, when the oil absorbing sponge 15 is saturated by adsorption, the oil absorbing sponge 15 is equivalent to blocking the first through hole 13, the air pressure in the oil groove 1 is increased, and by providing the detector 19 for detecting the air pressure in the oil groove 1, when the detector 19 detects the air pressure increase, the extrusion operation is alternately performed by the extrusion assembly in each pair of the installation sleeves 12, that is, if four oil mist cleaning mechanisms are adopted, that is, four water absorbing sponges are adopted, wherein two oil absorbing sponges 15 are in a natural state, the other two oil absorbing sponges are in an extrusion state, when two oil absorbing sponges 15 in a natural state are saturated by adsorption, the pressure plates 16 on the other two oil absorbing sponges 15 are controlled to be upward, the oil absorbing sponges 15 are restored to the natural state, then the oil mist on the oil absorbing sponge 15 in the saturated state is downward, and the oil mist is extruded, so that the continuous operation of the cleaning mechanism can be ensured.

Further, in order to ensure that the oil absorbing sponge 15 is smoothly inserted into the first through hole 13 when being restored to the natural state from the compressed state, a guide rod 29 is arranged in the middle of the supporting disc 28, the guide rod 29 is arranged in the oil absorbing sponge 15 in a penetrating manner, the push rod 17 is tubular, and the top end of the guide rod 29 penetrates through the pressure plate 16 and extends into the push rod 17.

Further, since the pressure plate 16 and the first through hole 13 are in clearance fit, in the pressing process, lubricating oil flows onto the pressure plate 16, in order to enable the lubricating oil to flow into the oil groove 1 completely, the pressure plate 16 is moved down to the lower side of the first through hole 13, in order to ensure sealing of the mounting sleeve 12, therefore, the extrusion assembly further comprises a sealing disc 20 arranged above the pressure plate 16, a section of annular groove 21 is arranged on the outer wall of the push rod 17, the sealing disc 20 is sleeved in the annular groove 21, the outer diameter of the sealing disc 20 is larger than the inner diameter of the first through hole 13 and smaller than the inner diameter of the mounting sleeve 12, a sealing ring 22 is arranged on the edge of the lower surface of the sealing disc 20, which is far away from the push rod 17, on the side wall of the sealing disc 20, which is opposite to the push rod 17, a limiting disc 23 is arranged on the outer wall of the push rod 17, which is positioned above the annular groove 21, a spring 24 is sleeved on the push rod 17, when the pressure plate 16 is positioned at the upper position of the first through hole 13, the spring 24 is in a compressed state, the sealing disc 20 is positioned below the pressure plate 21, and when the pressure plate 20 is positioned at the lowest pressure plate 21, the pressure plate 21 is positioned at the annular groove 21, and the first through hole 13 is further moved down, and the sealing disc 13 can be moved down to the first through hole 13, and the sealing disc 13 is further conveniently, and the lubricating oil can be moved down to the first through hole 13.

Further, the lower part cover of thrust head 4 is equipped with guide bearing 25, guide bearing 25's outer wall fixed connection is on the lateral wall of vertical cover 3 lower part, the lubrication oil in the oil groove 1 is immersed to the lower part of vertical cover 3, be equipped with annular last oil retaining tray 26 and lower oil retaining tray 27 between vertical cover 3 and the oil groove 1 inner wall, go up the outer annular wall of oil retaining tray 26 and link to each other with oil groove 1 inner wall, and go up the internal diameter of oil retaining tray 26 and be greater than the external diameter of vertical cover 3, on the inner annular wall of lower oil retaining tray 27 and the another lateral wall of vertical cover 3, and the external diameter of lower oil retaining tray 27 is less than the internal diameter of oil groove 1, go up oil retaining tray 26 and the setting of lower oil retaining tray 27, can avoid thrust bearing to drive the lubricating oil and rotate together when rotating, and spill lubricating oil to oil mist clearance mechanism on, influence the normal work of oil absorption sponge 15.

Further, as shown in fig. 4, the upper portion of the vertical sleeve 3 is provided with a plurality of second through holes 30, the second through holes 30 are used for communicating the upper region of the guide bearing 25 with the upper region of the upper oil baffle disc 26, each second through hole 30 is provided with a gas guide cover 31 on one side close to the upper oil baffle disc 26, the lower portion of the gas guide cover 31 is opened, two opposite side walls of the gas guide cover 31 and the vertical sleeve 3 are respectively provided with a first inclined plate 32 and a second inclined plate 33, the first inclined plates 32 and the second inclined plates 33 are distributed in a staggered manner to form a continuously bent gas transmission channel, and as the refrigerator 11 mixes and cools the gas temperature input into the combined bearing with the oil mist at a higher temperature inside, when passing through the continuously bent gas transmission channel, the oil mist and cold air are sufficiently mixed, so that the oil mist is condensed into oil, part of the oil mist in the gas stream can be collected first, the oil mist is treated through a plurality of links, the gas discharged from the installation sleeve 12 is ensured to be almost free of lubricating oil, and the treatment quality is high.

It should be noted that, for simplicity of description, the foregoing method embodiments are all expressed as a series of action combinations, but it should be understood by those skilled in the art that the present application is not limited by the order of action described, as some steps may be performed in other order or simultaneously according to the present application. Further, it should be understood by those skilled in the art that the embodiments described in the specification are all preferred embodiments, and the acts and elements referred to are not necessarily required for the present application.

Claims (5)

1. The combined bearing for the hydroelectric generating set comprises a thrust bearing and an oil groove (1) for installing the thrust bearing, wherein the oil groove (1) is U-shaped and filled with lubricating oil, an oil groove cover is arranged above the oil groove (1), the oil groove cover comprises an annular plate (2) and a vertical sleeve (3), the annular plate (2) is fixedly installed on the top wall surface of the oil groove (1), and the vertical sleeve (3) is positioned below the annular plate (2) and fixedly connected with the inner ring side of the annular plate (2); the thrust bearing comprises a thrust head (4), the thrust head (4) is arranged in the vertical sleeve (3) in a penetrating manner, and a sealing cover (5) is arranged between the top of the thrust head (4) and the oil groove cover; the method is characterized in that: the oil mist cleaning device is characterized in that an oil mist conveying mechanism is arranged on the side wall of the thrust head (4) positioned in the sealing cover (5), an oil mist cleaning mechanism is arranged on the oil groove cover, the oil mist conveying mechanism enables oil mist generated by rotation of the thrust head (4) to flow into the cleaning mechanism through wind force, the oil mist cleaning mechanism alternately collects the oil mist, and then the collected lubricating oil is discharged into the oil groove (1);

The oil mist conveying mechanism comprises a mounting ring (6) sleeved on the outer wall of the upper part of the thrust head (4), a plurality of fan blades (7) are arranged on the mounting ring (6), the fan blades (7) synchronously rotate along with the thrust head (4), negative pressure is generated on the inner side of a sealing cover (5) above the fan blades (7), a plurality of air inlet holes (8) are formed in the sealing cover (5) above the fan blades (7), and a one-way air valve (9) is arranged on the outer side of each air inlet hole (8);

the one-way air valves (9) are connected with air pipes (10), one ends of the air pipes (10) far away from the one-way air valves (9) are connected with refrigerators (11), and the refrigerators (11) cool air input into the sealing covers (5);

The oil mist cleaning mechanism comprises a plurality of pairs of mounting sleeves (12) arranged on an annular plate (2), two mounting sleeves (12) of each pair are symmetrical along the circle center of an oil tank cover, a first through hole (13) is formed in the annular plate (2) positioned in the mounting sleeve (12), the inner diameter of the first through hole (13) is smaller than that of the mounting sleeve (12), a supporting disc (28) is arranged below the annular plate (2), a plurality of pairs of connecting rods (14) are arranged at the edge of the supporting disc (28), the top of each connecting rod (14) is fixed on the lower surface of the annular plate (2), a cylindrical oil absorption sponge (15) which is in a honeycomb shape is arranged on the supporting disc (28), and the top of the oil absorption sponge (15) extends into the first through hole (13); the oil absorption device is characterized in that the mounting sleeves (12) are provided with extrusion assemblies for extruding the oil absorption sponge (15), the extrusion assemblies in each pair of the mounting sleeves (12) alternately perform extrusion operation, each extrusion assembly comprises a pressure plate (16) arranged above the first through hole (13), the top of each mounting sleeve (12) is provided with a telescopic piece, and a push rod (17) of each telescopic piece is connected with each pressure plate (16);

An exhaust window (18) is arranged on the side wall of the upper part of the mounting sleeve (12), and a detector (19) for detecting air pressure is arranged in the oil groove (1).

2. The combination bearing for a hydroelectric generating set according to claim 1, wherein: the middle part of supporting disk (28) is equipped with guide bar (29), guide bar (29) wear to establish in oil absorption sponge (15), push rod (17) are the tubulose, the top of guide bar (29) runs through pressure disk (16) and extends to in push rod (17).

3. The combination bearing for a hydroelectric generating set according to claim 2, wherein: the extrusion assembly further comprises a sealing disc (20) arranged above the pressure disc (16), a section of annular groove (21) is formed in the outer wall of the push rod (17), the sealing disc (20) is sleeved in the annular groove (21), the outer diameter of the sealing disc (20) is larger than the inner diameter of the first through hole (13) and smaller than the inner diameter of the installation sleeve (12), sealing rings (22) are arranged on the edge, away from the push rod (17), of the lower surface of the sealing disc (20) and on the side wall, opposite to the push rod (17), of the sealing disc (20), a limiting disc (23) is arranged on the outer wall of the push rod (17) above the annular groove (21), and a spring (24) is sleeved on the push rod (17) between the limiting disc (23) and the sealing disc (20).

4. A composite bearing for a hydroelectric generating set according to claim 3, wherein: the lower part cover of thrust collar (4) is equipped with guide bearing (25), the outer wall fixed connection of guide bearing (25) is on a lateral wall of vertical cover (3) lower part, the lubrication oil in oil groove (1) is immersed to the lower part of vertical cover (3), be equipped with annular last oil retaining disc (26) and lower oil retaining disc (27) between vertical cover (3) and oil groove (1) inner wall, the outer annular wall of last oil retaining disc (26) links to each other with oil groove (1) inner wall, and go up the internal diameter of oil retaining disc (26) and be greater than the external diameter of vertical cover (3), the internal annular wall of lower oil retaining disc (27) is less than the internal diameter of oil groove (1) with the another lateral wall of vertical cover (3).

5. The combination bearing for a hydroelectric generating set according to claim 1, wherein: the upper portion of vertical cover (3) is equipped with a plurality of second through-holes (30), second through-hole (30) are used for with guide bearing (25) upper portion region and last oil baffle dish (26) upper portion regional intercommunication, and every second through-hole (30) are close to last oil baffle dish (26) one side and are equipped with air guide cover (31), the lower part opening of air guide cover (31), be equipped with first swash plate (32) and second swash plate (33) on two lateral walls that air guide cover (31) and vertical cover (3) are relative respectively, first swash plate (32) and second swash plate (33) staggered distribution constitute the gas transmission passageway of buckling in succession.