JP7251528B2 - Bearing Rust Prevention Device for Variable Displacement Turbocharger - Google Patents

Description

The present disclosure relates to a bearing anticorrosion device for a variable displacement turbocharger.

Generally, in a variable displacement turbocharger, a plurality of movable nozzle vanes provided in a nozzle of a turbine are opened and closed by rotating an operating shaft projecting out of the turbine. The operating shaft is rotatably supported by bearings provided in the turbine housing.

JP 2012-47090 A

However, rust may enter the contact portion between the bearing and the operating shaft. If such rust infiltration occurs, the friction during rotation of the operating shaft increases, possibly resulting in poor rotation.

Accordingly, the present disclosure was created in view of such circumstances, and its object is to provide a bearing rust prevention device for a variable displacement turbocharger that can suppress the infiltration of rust at the contact portion between the bearing and the operating shaft. .

According to one aspect of the present disclosure,
a plurality of nozzle vanes provided openable and closable on the nozzle of the turbine;
a link mechanism coupled to the plurality of nozzle vanes;
a mechanism chamber formed in the turbine housing and accommodating the link mechanism;
a bearing provided in the turbine housing and communicating between the mechanism chamber and the outside;
an operating shaft rotatably provided in the bearing and having one end connected to the link mechanism;
A bearing rust prevention device for a variable displacement turbocharger comprising
There is provided a bearing rust preventive device for a variable displacement turbocharger, comprising a gas supply device configured to supply pressure gas from outside the turbine to a contact portion between the bearing and the operating shaft. be.

Preferably, the operating shaft includes a first contact surface formed on the mechanism chamber side and brought into contact with the bearing, a second contact surface formed on the outside side and brought into contact with the bearing, the first contact surface and a reduced diameter portion formed between the second contact surfaces and spaced from the bearing;
The gas supply device supplies pressurized gas into the bearing at an axial location of the reduced diameter portion.

Preferably, the gas supply device supplies pressurized gas higher than the pressure in the mechanism chamber.

Preferably, said pressurized gas is compressed air produced by a compressor of said turbocharger.

Preferably, the pressurized gas is compressed air stored in an air tank.

Preferably, the gas supply device comprises a check valve for preventing reverse flow in the direction opposite to the direction of pressure gas supply.

Preferably, the gas supply device includes a nozzle provided in the bearing for supplying pressurized gas into the bearing, a gas supply source, and a pipe connecting the nozzle and the gas supply source.

According to the present disclosure, it is possible to suppress entry of rust into the contact portion between the bearing and the operating shaft.

1 is a schematic longitudinal side view of a variable displacement turbocharger; FIG. FIG. 2 is an enlarged view of a main portion of FIG. 1; 2 is a schematic front view when viewed from line III-III of FIG. 1; FIG. It is a schematic longitudinal side view showing a state before pressure gas is supplied. It is a schematic longitudinal side view showing a state after pressure gas is supplied. It is a schematic vertical side view which shows a modification.

Embodiments of the present disclosure will be described below with reference to the accompanying drawings. Note that the present disclosure is not limited to the following embodiments.

FIG. 1 is a schematic longitudinal side view of a variable displacement turbocharger according to this embodiment. FIG. 2 is an enlarged view of the essential parts of FIG. 1, and FIG. 3 is a schematic front view of FIG. 1 with a housing cover removed, as seen from line III-III of FIG. For ease of understanding, FIG. 3 is shown in a transparent view.

An internal combustion engine (also referred to as an engine) to which the turbocharger of the present embodiment is applied is a vehicle diesel engine. The vehicle is a large vehicle such as a truck. However, there are no particular restrictions on the type, type, application, etc. of the internal combustion engine, and the engine may be, for example, a gasoline engine.

For convenience, the front, back, left, right, up and down directions are defined as shown in the figure. However, it should be noted that these directions are merely defined for convenience of explanation.

The central axis of the turbine, or turbine axis, is indicated by letter C. Hereinafter, unless otherwise specified, the axial direction, radial direction, and circumferential direction relative to the turbine axis C are simply referred to as the axial direction, radial direction, and circumferential direction.

The turbocharger 1 includes a turbine 2 driven by exhaust gas, and a compressor 3 driven by the turbine 2 to compress or supercharge intake air. The turbine 2 includes a turbine housing 4 and a turbine wheel 5 rotatably provided within the turbine housing 4 . The compressor 3 includes a compressor housing 6 and an impeller 7 rotatably provided within the compressor housing 6 . Turbine wheel 5 and impeller 7 are coaxially coupled to each other by turbine shaft 8 . Turbine housing 4 and compressor housing 6 are coupled to a center housing 9 positioned therebetween. A turbine shaft 8 is rotatably supported coaxially with the turbine axis C by a center bearing 10 in the center housing 9 . As a result, the turbine wheel 5, turbine shaft 8 and impeller 7 are integrally arranged coaxially with the turbine axis C and rotatable around the turbine axis C. As shown in FIG.

The turbine housing 4 has a housing body 11 that accommodates the turbine wheel 5 and a housing cover 12 fixed to the front end of the housing body 11 . Inside the housing body 11 are nozzles 13 that supply exhaust gas to the turbine wheel 5 from the radially outer side, and turbine scroll chambers 14 that supply the exhaust gas introduced from a turbine inlet (not shown) to the nozzles 13 at all circumferential positions. is formed.

Inside the compressor housing 6, there are provided a diffuser 15 for guiding the compressed air discharged from the impeller 7 radially outward, and a diffuser 15 for guiding the compressed air discharged from the diffuser 15 toward a compressor outlet (not shown) in a circumferential direction. A compressor scroll chamber 16 is formed which leads to the .

The turbocharger 1 also includes a plurality of nozzle vanes 21 that are openable and closable on the nozzle 13, a link mechanism 22 connected to the plurality of nozzle vanes 21, and a mechanism chamber 23 that is formed in the turbine housing 4 and accommodates the link mechanism 22. , a bearing 24 provided in the turbine housing 4 and communicating with the mechanism chamber 23 and the outside, and an operation shaft 25 rotatably provided in the bearing 24 and having one end (front end) connected to the link mechanism 22 .

Bearing 24 is formed as a plain bearing. The bearing 24 is formed of a metal tube, such as a steel tube, having a predetermined length and constant inner and outer diameters, and is arranged to extend in the longitudinal direction parallel to the turbine axis C. As shown in FIG. The bearing 24 penetrates through the housing body 11 and is fixed to the housing body 11 . Its front end (inner end) is positioned inside the mechanism chamber 23 and its rear end (outer end) is outside the turbine housing 4 . be located.

An operating shaft 25 is coaxially and rotatably provided in the bearing 24 . The operating shaft 25 is rotatable around its central axis C1. A front end and a rear end of the operating shaft 25 protrude from the bearing 24 . A driving plate 26 of the link mechanism 22 is fixed to the front end of the operating shaft 25 . An operation lever 27 is fixed to the rear end of the operation shaft 25 . The operating lever 27 is connected to an actuator (not shown) via a link 28 and driven to rotate about the central axis C1 by the actuator. The driving force of the actuator is finally transmitted to the nozzle vanes 21 via the link mechanism 22 . The actuators are formed, for example, by servomotors.

The operating shaft 25 has an inner contact surface 29 that is a first contact surface, an outer contact surface 30 that is a second contact surface, and a reduced diameter portion 31 formed between the inner contact surface 29 and the outer contact surface 30 . Prepare. The inner contact surface 29 is formed on the mechanism chamber 23 side in the direction of the central axis C<b>1 and contacts the inner peripheral surface of the bearing 24 . The outer contact surface 30 is formed on the outer side in the direction of the central axis C<b>1 and contacts the inner peripheral surface of the bearing 24 . The reduced diameter portion 31 is formed to have a smaller diameter than the inner contact surface 29 and the outer contact surface 30 and is separated from the inner peripheral surface of the bearing 24 . Thereby, a gap 32 is formed between the bearing 24 and the reduced diameter portion 31 .

In the link mechanism 22 , the drive plate 26 rotates integrally with the operation shaft 25 . The drive plate 26 is formed in the shape of a two-forked fork facing downward, and a square joint plate 33 is slidably sandwiched between the fork portions. A rear end portion of a pin 34 is rotatably attached to the joint plate 33 . The front end of pin 34 is rotatably attached to input arm portion 36 of unison ring 35 . The unison ring 35 is formed in a ring plate shape that makes one turn around the turbine axis C, and is rotatably supported around the turbine axis C by the housing body 11 .

The unison ring 35 is connected to a plurality of (15 in this embodiment) nozzle vanes 21 arranged at regular intervals in the circumferential direction as follows. First, the nozzle vane 21 integrally has a vane shaft 37 as its rotation axis. The vane shaft 37 is slidably and rotatably inserted through the bearing hole 38 of the housing body 11 and protrudes into the mechanism chamber 23 . A vane arm 39 is fixed to the front end of the projected vane shaft 37 .

The vane arm 39 is formed in the shape of a bifurcated fork facing radially outward. A substantially rectangular joint plate 40 is slidably sandwiched between the fork portions. A rear end portion of a pin 41 is rotatably attached to the joint plate 40 . The front end of pin 41 is rotatably attached to unison ring 35 .

Thereby, the rotation of the operating shaft 25 is transmitted to the nozzle vanes 21 through the link mechanism 22, and the nozzle vanes 21 are rotated. As shown in FIG. 3, when the operating shaft 25 is rotated in the A1 direction, the unison ring 35 is rotated in the B1 direction, and the nozzle vanes 21 are rotated in the V1 direction, that is, the valve closing direction. Conversely, when the operating shaft 25 is rotated in the A2 direction, the unison ring 35 is rotated in the B2 direction, and the nozzle vanes 21 are rotated in the V2 direction, that is, the valve opening direction.

Reference numeral 42 in FIG. 3 denotes a plurality of female screw holes used when bolting the housing cover 12 to the housing body 11 . Numeral 43 indicates an elongated hole provided in the unison ring 35 to avoid interference with the vane shaft 37 .

When the housing cover 12 is attached to the housing body 11, a sealed mechanism chamber 23 is formed therebetween. The link mechanism 22 is arranged in this mechanism chamber 23 .

In such a turbocharger 1, rust may enter the contact portion between the bearing 24 and the operating shaft 25, which may increase friction during rotation of the operating shaft 25 and cause rotation failure.

Therefore, in the present embodiment, a bearing rust preventive device is provided in order to suppress the infiltration of such rust. The bearing rust prevention device includes a gas supply device 50 configured to supply pressure gas from outside the turbine 2 toward the contact portion between the bearing 24 and the operating shaft 25 .

The gas supply device 50 includes a nozzle 51 provided in the bearing 24 for supplying pressure gas into the bearing 24 , the compressor 3 as a gas supply source, and a pipe 52 connecting the nozzle 51 and the compressor 3 . In this embodiment, the compressor 3 is used as the gas supply source, and the compressed air generated by the compressor 3 is used as the pressure gas.

The nozzle 51 is formed by a pipe joint (for example, a nipple) fixed to the bearing 24 through the inside and outside of the bearing 24 . The nozzle 51 is arranged perpendicularly to the central axis C<b>1 at a position in the direction of the central axis C<b>1 where the diameter-reduced portion 31 is located, and is positioned outside the turbine housing 4 . The nozzle 51 discharges high pressure compressed air into the gap 32 between the bearing 24 and the reduced diameter portion 31 . Thus, the gas supply device 50 supplies pressurized gas into the bearing 24 at the axial position of the reduced diameter portion 31 .

The piping 52 includes an outlet pipe 53 attached to the compressor housing 6 and a connecting pipe 54 connecting the nozzle 51 and the outlet pipe 53 . Like the nozzle 51 , the outlet pipe 53 is formed by a pipe joint (for example, a nipple) that passes through the inside and outside of the compressor housing 6 and is fixed to the compressor housing 6 . The outlet pipe 53 communicates with the compressor scroll chamber 16 on the downstream side of the impeller 7 and extracts compressed air from the compressor scroll chamber 16 .

The connecting pipe 54 is formed by a rubber hose or tube. However, the material of the connecting pipe 54 is arbitrary, and may be metal or resin. The upstream end of the connecting pipe 54 is connected to the outlet pipe 53 and the downstream end is connected to the nozzle 51 .

The gas supply device 50 also includes a check valve 55 for preventing reverse flow in the direction opposite to the supply direction of the pressure gas. The check valve 55 is provided in the pipe 52 in this embodiment, and is provided in the middle of the connecting pipe 54 . However, its installation position is arbitrary, and for example, it may be integrally incorporated into the nozzle 51 or the outlet pipe 53 . The check valve 55 allows only the flow from the compressor 3 side to the bearing 24 side, and prohibits the flow in the opposite direction.

Now, as described above, rust may enter the contact portion between the bearing 24 and the operating shaft 25, resulting in so-called rust rust. The contact portions are a contact portion (referred to as an inner contact portion) 43 between the inner contact surface 29 and the bearing 24 and a contact portion (referred to as an outer contact portion) 44 between the outer contact surface 30 and the bearing 24 .

There are various causes of rust, but the main cause is rust generated within the mechanism room 23 of the turbine housing 4 . Exhaust gas passing through the nozzle 13 leaks into the mechanism chamber 23 through a small gap between the vane shaft 37 and the bearing hole 38, although the amount is very small. Rust occurs in the mechanism chamber 23 due to this exhaust.

Especially when the engine is running at low load and low temperature, and in an environment where the outside air temperature is low, the exhaust temperature is low, so the water vapor contained in the exhaust may condense below the dew point and condense water may be generated. . The condensed water contains sulfuric acid, nitric acid, organic acids, etc. generated during the combustion process of the fuel dissolved in the condensed water, so the condensed water is highly corrosive acidic water. Therefore, when condensed water adheres to the inside of the mechanism chamber 23, rust is likely to occur.

Since the exhaust gas leaks into the mechanism chamber 23 while the engine is running, the pressure in the mechanism chamber 23 becomes higher than the atmospheric pressure outside. Therefore, a flow of exhaust gas is generated from the mechanism chamber 23, passing between the bearing 24 and the operating shaft 25 and leaking to the outside. The rust in the mechanism chamber 23 also moves along with this flow.

The rust generated in the mechanism chamber 23 is partly exfoliated, moves in the chamber, passes through the gap between the drive plate 26 and the front end surface of the bearing 24, and enters the inner contact portion 43. After that, it moves outward in the direction of the central axis C1, sequentially passes through the gap 32 and the outer contact portion 44, and is finally discharged to the outside. In addition, other foreign matter may enter and move mixed with the rust.

On the other hand, another cause is rust generated on the outer surface of the turbocharger 1 , especially near the outer contact portion 44 . In winter, salt (rock salt or snow-melting agents such as calcium chloride) is sometimes sprinkled on the road surface as an anti-freezing agent. This salt mixes with rainwater and condensed water adhering to the outer surface of the turbocharger 1, and produces highly corrosive salt water. The salt water rusts the outer surface of the turbocharger 1 .

Part of the rust peels off and approaches the outer contact portion 44 . This rust enters the outer contact portion 44 after passing through the gap between the operating lever 27 and the rear end face of the bearing 24 . After that, it may move further inward in the direction of the central axis C1 and enter the gap 32 and the inner contact portion 43 successively.

In the process of moving the rust described above, the rust stops at the inner contact portion 43 and the outer contact portion 44 and accumulates. Rust may be discharged from the contact portions 43 and 44 by the rotation of the operating shaft 25, but when the deposition speed exceeds the discharge speed, the deposition amount gradually increases.

If rust adheres and accumulates on the contact portions 43 and 44, the friction during rotation of the operating shaft 25 increases, and in the worst case, the operating shaft 25 sticks to the bearing 24 and does not move. As a result, there is a possibility that the operating shaft 25 will not rotate properly, and the rotating operation of the operating shaft 25 and the opening/closing operation of the nozzle vanes 21 will not be performed normally.

Therefore, in this embodiment, compressed air is supplied into the bearing 24 by the gas supply device 50 in order to suppress adhesion of rust to the contact portions 43 and 44 . The operation at this time will be described with reference to FIGS. 4 and 5. FIG.

FIG. 4 shows a state where rust R adheres before compressed air is supplied. The rust R adheres not only to the inner contact portion 43 and the outer contact portion 44 but also everywhere.

In this state, when the pressure in the compressor scroll chamber 16 becomes higher than the pressure in the mechanism chamber 23, the check valve 55 opens, and as indicated by the arrow in FIG. It is supplied from the nozzle 51 into the gap 32 through the pipe 53 and the connecting pipe 54 in this order.

Compressed air is divided into a flow F1 toward the inside of the turbine housing 4 and a flow F2 toward the outside. The inward flow F<b>1 pushes out the rust R adhering to the inner contact portion 43 and discharges it into the mechanism chamber 23 . The outward flow F2 pushes out the rust R adhering to the outer contact portion 44 and discharges it to the outside. In this way, rust adhering to the inner contact portion 43 and the outer contact portion 44 can be removed. At this time, the rust adhering to the gap 32 can also be removed at the same time.

Further, when the pressure in the compressor scroll chamber 16 is higher than the pressure in the mechanism chamber 23, compressed air is constantly supplied, so that new rust R on the inner contact portion 43 and the outer contact portion 44 is caused by the flows F1 and F2. intrusion can be suppressed. Therefore, adhesion of rust R can be prevented.

In this manner, the gas supply device 50 supplies pressure gas higher than the pressure inside the mechanism chamber 23 .

On the other hand, when the pressure in the compressor scroll chamber 16 is lower than the pressure in the mechanism chamber 23, the check valve 55 is closed. Therefore, exhaust gas in the mechanism chamber 23 can be prevented from flowing back into the compressor scroll chamber 16 .

As described above, according to the present embodiment, since the gas supply device 50 is provided, it is possible to prevent rust R from entering the contact portions 43 and 44 between the bearing 24 and the operating shaft 25 .

Further, according to the present embodiment, even when two contact portions, that is, the inner contact portion 43 and the outer contact portion 44 are provided, it is possible to effectively suppress the penetration of rust R into both contact portions.

Further, according to this embodiment, since compressed air having a higher pressure than the pressure in the mechanism chamber 23 is supplied, the rust R that has entered the inner contact portion 43 can be reliably discharged into the mechanism chamber 23 .

Further, according to the present embodiment, since the compressed air generated by the compressor 3 of the turbocharger 1 is used as the pressure gas, there is no need to provide a separate gas supply source, and the configuration can be simplified. Moreover, the distance from the gas supply source to the gas supply position (nozzle 51) can be shortened, and the pressure loss can be reduced.

Further, according to this embodiment, since the pressure gas is supplied from the outside of the turbine 2, it is advantageous in suppressing the adhesion of rust to the contact portion. That is, if the pressurized gas from inside the turbine 2, that is, the exhaust gas, is supplied to the contact portion, the contact portion will further rust due to the acidic water resulting from the condensation of the exhaust gas, as described above. However, in this embodiment, since the pressure gas is supplied from outside the turbine 2, such rusting can be avoided and the rust prevention effect can be enhanced.

Although the embodiments of the present disclosure have been described in detail above, various other embodiments and modifications of the present disclosure are conceivable.

(1) For example, as shown in FIG. 6, an air tank 61 provided separately from the turbocharger 1 may be used as a pressure gas supply source, and compressed air stored in the air tank 61 may be used as the pressure gas. In the case of the vehicle of the present embodiment, since the air tank 61 is provided for the operation of the brakes and the like, the use of the air tank 61 eliminates the need to provide a separate gas supply source.

(2) As the pressure gas, a gas other than air, for example, a nonflammable gas such as nitrogen or argon may be used.

(3) There may be one contact portion between the bearing and the operating shaft. In this case, it is preferable to directly supply the pressurized gas to the contact portion.

(4) A solenoid valve may be provided instead of the check valve, and the solenoid valve may be controlled by the control unit. In this case, the bearing anticorrosion device includes a gas supply device including an electromagnetic valve, a control unit, a first pressure sensor that detects the pressure in the mechanism chamber, and a second pressure sensor that detects the gas pressure of the gas supply source. Prepare. The control unit opens the electromagnetic valve when the gas pressure detected by the second pressure sensor is higher than the mechanism chamber pressure detected by the first pressure sensor, and otherwise closes the electromagnetic valve. As the control unit, for example, an electronic control unit (ECU) mounted on the vehicle for engine control can be used.

Embodiments of the present disclosure are not limited to the above-described embodiments, and include all modifications, applications, and equivalents encompassed by the concept of the present disclosure defined by the claims. Accordingly, the present disclosure should not be construed in a restrictive manner, and can be applied to any other technology that falls within the spirit of the present disclosure.

1 turbocharger 2 turbine 3 compressor 4 turbine housing 13 nozzle 21 nozzle vane 22 link mechanism 23 mechanism chamber 24 bearing 25 operating shaft 29 inner contact surface 30 outer contact surface 31 reduced diameter portion 43 inner contact portion 44 outer contact portion 50 gas supply device 51 Nozzle 52 Piping 55 Check valve 61 Air tank

Claims (7)

a plurality of nozzle vanes provided openable and closable on the nozzle of the turbine;
a link mechanism coupled to the plurality of nozzle vanes;
a mechanism chamber formed in the turbine housing and accommodating the link mechanism;
a bearing provided in the turbine housing and communicating between the mechanism chamber and the outside;
an operating shaft rotatably provided in the bearing and having one end connected to the link mechanism;
A bearing rust prevention device for a variable displacement turbocharger comprising
a gas supply device configured to supply pressure gas from outside the turbine toward the contact portion between the bearing and the operating shaft ;
The gas supply device is configured to supply pressurized gas into the bearing, push out rust adhering to the contact portion with the pressurized gas, and discharge the rust to the outside of the bearing.
A bearing rust preventive device for a variable displacement turbocharger characterized by: The operating shaft includes a first contact surface formed on the mechanism chamber side and brought into contact with the bearing, a second contact surface formed on the outside side and brought into contact with the bearing, the first contact surface and the second contact surface. a reduced diameter portion formed between the contact surfaces and spaced from the bearing;
2. A bearing rust prevention device for a variable displacement turbocharger according to claim 1, wherein said gas supply device supplies pressurized gas into said bearing at a position in the axial direction of said reduced diameter portion. 3. The bearing rust preventive device for a variable displacement turbocharger according to claim 1, wherein said gas supply device supplies pressure gas having a higher pressure than the pressure in said mechanism chamber. The bearing rust prevention device for a variable displacement turbocharger according to any one of claims 1 to 3, wherein the pressure gas is compressed air generated by a compressor of the turbocharger. The bearing rust prevention device for a variable displacement turbocharger according to any one of claims 1 to 3, wherein the pressure gas is compressed air stored in an air tank. The bearing rust preventive device for a variable displacement turbocharger according to any one of claims 1 to 5, wherein the gas supply device includes a check valve for preventing reverse flow in a direction opposite to the pressure gas supply direction. 7. The gas supply device according to any one of claims 1 to 6, comprising: a nozzle provided in the bearing for supplying pressure gas into the bearing; a gas supply source; and a pipe connecting the nozzle and the gas supply source. 1. A bearing anticorrosion device for a variable displacement turbocharger according to claim 1.

Images