JP7526701B2 - Compressor casing, turbocharger, and turbocharger operating method - Google Patents

Description

This disclosure relates to a compressor casing, a turbocharger, and a method for operating a turbocharger.

At engine startup, the amount of exhaust gas flowing from the engine to the turbocharger is small, and the amount of compressed air sent from the turbocharger to the engine is small because of the inertia of the turbocharger's rotor, so black smoke may be emitted from the engine. In order to suppress such black smoke emission and improve the turbocharger's load response (speed-up) at engine startup and thereby improve turbocharger efficiency, there is a method of injecting compressed gas into the impeller blades of the compressor impeller from injection holes provided in the air guide tube of the compressor casing.

Patent Document 1 describes how, when increasing the load on the engine, a target supercharged air pressure is obtained by supplying compressed air (compressed gas) toward the impeller blades of the compressor impeller from a large number of injection holes provided around the entire outer periphery of the compressor impeller in the supercharger.

Japanese Unexamined Patent Publication No. 132721/1986

According to the findings of the present inventors, when compressed gas is injected near the outlet of the compressor impeller (the outer periphery of the compressor impeller) as in the configuration described in Patent Document 1, a large moment for assisting the rotation of the compressor impeller can be obtained when the engine load is relatively small, such as when the engine is started up. However, as the engine load increases (
It became clear that the effect of assisting the rotation of the compressor impeller by the compressed gas tends to be limited as the rotation speed of the turbocharger increases. For this reason, in the configuration described in Patent Document 1, the range of the rotation speed of the turbocharger in which the rotation of the compressor impeller can be assisted by the injection of the compressed gas is limited.

In view of the above circumstances, at least one embodiment of the present disclosure has an object to provide a compressor casing that enables the rotation of a compressor impeller to be effectively assisted by compressed gas over a wide range of rotation speeds of the turbocharger, a turbocharger including the same, and an operating method of the turbocharger.

In order to achieve the above object, a compressor casing according to at least one embodiment of the present disclosure comprises:
A compressor casing that houses a compressor impeller of a turbocharger,
a plurality of injection holes for injecting compressed gas toward the impeller blades of the compressor impeller;
The plurality of injection holes are
At least one first injection hole;
at least one second injection hole having an outlet at a position different from an outlet of the first injection hole in the axial direction of the compressor impeller;
including.

In order to achieve the above object, a turbocharger according to at least one embodiment of the present disclosure includes:
The compressor casing;
a valve control device configured to control the at least one first valve and the at least one second valve in response to an operating state of at least one of the turbocharger and the engine;
Equipped with.

In order to achieve the above object, a method for operating a turbocharger according to at least one embodiment of the present disclosure includes:
a first injection hole injection step of injecting compressed gas from a first injection hole provided in a compressor casing of the turbocharger toward an impeller blade of a compressor impeller;
a second jet hole injection step of injecting compressed gas toward the impeller blades from a second jet hole provided in the compressor casing downstream of the first jet hole in the axial direction of the compressor impeller;
Equipped with
The second jet hole injection step is executed when the rotation speed of the turbocharger is in a first rotation speed range, and the first jet hole injection step is executed when the rotation speed of the turbocharger is in a second rotation speed range that is higher than the first rotation speed range.

According to at least one embodiment of the present disclosure, there is provided a compressor casing that enables the rotation of a compressor impeller to be effectively assisted by compressed gas over a wide range of rotational speeds of the turbocharger, a turbocharger including the same, and an operating method of the turbocharger.

FIG. 1 is a diagram that illustrates a schematic cross section of a turbocharger 2 according to an embodiment. FIG. 2 is a diagram showing an example of a cross-sectional configuration of a centrifugal compressor 4 that can be applied to the turbocharger 2 shown in FIG. 3 is an enlarged view of the vicinity of a jet hole 28 in the centrifugal compressor 4 shown in FIG. 2. 1 is a diagram showing the relationship between the rotation speed of the turbocharger 2 when compressed air is injected and the increase in the rotation speed of the turbocharger 2 due to the injection of compressed air. FIG. 1 is a diagram showing an example of static pressure distribution in the meridian direction distance from a leading edge 18LE to a trailing edge 18TE of an impeller blade 18. FIG. 13 is a diagram showing an example of the circumferential arrangement of outlets 28a2 of a plurality of injection holes 28. FIG. 13 is a diagram showing another example of the circumferential arrangement of outlets 28a2 of a plurality of injection holes 28. FIG. FIG. 2 is a diagram showing an example of a cross-sectional configuration of a centrifugal compressor 4 in a turbocharger 2 equipped with valves 36a to 36c and a valve control device 38, and is an enlarged view of the vicinity of an injection hole 28. FIG. 4 is a diagram showing a determination flow for determining an injection mode to be executed by a valve control device 38. 11 is a diagram showing time series changes in the rotation speed of the turbocharger 2, the opening degree of the valves 36a to 36c, and the injection amount of compressed air. 2 is a diagram for explaining an example of a turbocharger 2 including a blocking member 42. FIG. 11 is a diagram for explaining another example of a turbocharger 2 including a blocking member 42. FIG.

Hereinafter, some embodiments of the present disclosure will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of components described as the embodiments or shown in the drawings are merely illustrative examples and are not intended to limit the scope of the invention.
For example, "in a certain direction,""along a certain direction,""parallel,""orthogonal,""center,"
Expressions expressing relative or absolute configuration, such as "concentric" or "coaxial", do not only express such a configuration strictly, but also express a state in which there is a relative displacement with a tolerance or an angle or distance to the extent that the same function is obtained.
For example, expressions indicating that things are in an equal state, such as "identical,""equal," and "homogeneous," not only indicate a state of strict equality, but also indicate a state in which there is a tolerance or a difference to the extent that the same function is obtained.
For example, expressions describing shapes such as a rectangular shape or a cylindrical shape do not only refer to rectangular shapes, cylindrical shapes, etc. in the strict geometric sense, but also refer to shapes that include uneven portions, chamfered portions, etc., to the extent that the same effect is obtained.
On the other hand, the expressions "comprise,""include,""have,""includes," or "have" of one element are not exclusive expressions excluding the presence of other elements.

FIG. 1 is a diagram that illustrates a schematic cross section of a turbocharger 2 according to one embodiment.
As shown in FIG. 1 , the turbocharger 2 includes a centrifugal compressor 4 and a turbine 6 .
The centrifugal compressor 4 includes a compressor impeller 8 and a compressor casing 10 that houses the compressor impeller 8. The turbine 6 includes a turbine wheel 12 and a turbine casing 14 that houses the turbine wheel 12.

The compressor impeller 8 includes a hub 16 and a plurality of impeller blades 18 spaced apart in the circumferential direction on the outer circumferential surface of the hub 16.
The rotating shaft 20 is connected to the bearing casing 2 and is configured to rotate together. The rotating shaft 20 is rotatably supported by a bearing 22. The bearing 22 is supported by a bearing casing 2.
The bearing casing 24 is housed in the compressor casing 10 at one axial end thereof, and is connected to the turbine casing 14 at the other axial end thereof.

As the turbine wheel 12 rotates due to exhaust gas from an engine (not shown), the compressor impeller 8 connected to the turbine wheel 12 via a rotating shaft 20 rotates and compresses the air, and the compressed air discharged from the centrifugal compressor 4 is supplied to the engine.

In this specification, the axial direction of the compressor impeller 8, i.e., the axial direction of the rotating shaft 20, will be simply referred to as the "axial direction", the radial direction of the compressor impeller 8, i.e., the radial direction of the rotating shaft 20, will be simply referred to as the "radial direction", and the circumferential direction of the compressor impeller 8, i.e., the circumferential direction of the rotating shaft 20, will be simply referred to as the "circumferential direction".

FIG. 2 is a diagram showing an example of a detailed configuration of the centrifugal compressor 4 that can be applied to the turbocharger 2 shown in FIG.
In the exemplary embodiment shown in Fig. 2, the compressor casing 10 includes an air guide tube 30 that guides air to the compressor impeller 8, and a scroll casing 34 that forms a spiral scroll passage 32 on the outer circumferential side of the compressor impeller 8. The air guide tube 30 is configured in a cylindrical shape so as to surround the compressor impeller 8. The inner and outer diameters of the air guide tube 30 expand toward the downstream side in the axial direction on the downstream side in the air flow from the position of the leading edge 18LE of the impeller blade 18. Note that in this specification, the upstream side and the downstream side in the air flow will be simply referred to as the "upstream side" and the "downstream side", respectively.

As shown in Fig. 2, the air guide tube 30 of the compressor casing 10 has a plurality of injection holes 28 for injecting compressed air toward the negative pressure surface 26 (blade surface) of the impeller blade 18 of the compressor impeller 8. Each of the plurality of injection holes 28 is a through hole penetrating from the outer peripheral surface to the inner peripheral surface of the air guide tube 30, and in the illustrated example, penetrates the air guide tube 30 in a straight line. Each of the injection holes 28 may be formed so as to inject compressed air as compressed gas toward the negative pressure surface 26 along a direction perpendicular to the negative pressure surface 26 of the impeller blade 18. That is, the angle between the central axis of each injection hole 28 and the negative pressure surface 26 of the impeller blade 18 may be about 90 degrees.

In addition, in the illustrated example, an annular space 31 through which compressed air passes is formed between the outer peripheral surface of the air guide tube 30 and the scroll casing 34, and the scroll casing 34 includes a compressed air passage 35 extending radially so as to supply compressed air to the annular space 31.
The compressed air passage 35 is connected to a compressed air tank 46 as a compressed air supply source through a compressed air line 44.
The compressed air line 44 is provided with a valve 45 for controlling the supply of compressed air from a compressed air tank 46. The compressed air that passes from the compressed air tank 46 through the compressed air line 44, the compressed air passage 35, and the space 31 in this order is injected from the injection holes 28 toward the negative pressure surface 26 of the impeller blade 18, and functions as assist air that assists the rotation of the compressor impeller 8.

The plurality of injection holes 28 are, as described in detail below, a plurality of injection holes 28a and a plurality of injection holes 2
8b and a plurality of injection holes 28c.

FIG. 3 is an enlarged view of the vicinity of the injection hole 28 in the centrifugal compressor 4 shown in FIG.
As shown in FIG. 3 , among the multiple injection holes 28 , the multiple injection holes 28 a are formed at a position closest to the leading edge 18 LE of the impeller blade 18 .

The outlet 28a2 of the injection hole 28a is located between the blade tip 18LE1 of the leading edge 18LE of the impeller blade 18 and the outlet 28b2 of the injection hole 28b in the axial direction.
2. In other words, the outlet 28a2 of the injection hole 28a is located radially inward relative to the outlet 28b2 of the injection hole 28b and the outlet 28c2 of the injection hole 28c. The injection hole 28a is configured to inject compressed air into the inlet side portion of the compressor impeller 8 (the inner peripheral portion of the compressor impeller 8), i.e., the portion 18i of the impeller blade 18 on the leading edge 18LE side. The multiple injection holes 28a are provided at the same position in the axial direction and spaced apart in the circumferential direction. The inlets 28a1 of the multiple injection holes 28a are provided at the same position in the axial direction and spaced apart in the circumferential direction. The outlets 28a2 of the multiple injection holes 28a are provided at the same position in the axial direction and spaced apart in the circumferential direction.

The multiple injection holes 28b are formed at positions between the multiple injection holes 28a and the multiple injection holes 28c in the axial direction.

The outlet 28b2 of the injection hole 28b is located between the outlet 28a2 of the injection hole 28a and the outlet 28c2 of the injection hole 28c in the axial direction.
In the axial direction, downstream of the outlet 28a2 of the injection hole 28a and downstream of the outlet 28a of the injection hole 28c
Therefore, the outlet 28b2 of the injection hole 28b is located upstream of the outlet 28c2 of the injection hole 28
The outlet 28b2 of the injection hole 28b is located radially outward of the outlet 28a2 of the injection hole 28a and radially inward of the outlet 28c2 of the injection hole 28c.
The injection hole 28b is located on the outer periphery side of the outlet 28a2 of the impeller 18a and on the inner periphery side of the outlet 28c2 of the injection hole 28b. The injection hole 28b is located in an intermediate portion between the inlet side portion (the inner periphery of the compressor impeller 8) and the outlet side portion (the outer periphery of the compressor impeller 8) of the compressor impeller 8, i.e., between the portion 18i on the leading edge 18LE side and the portion 18o on the trailing edge 18TE side of the impeller blade 18.
The plurality of injection holes 28 are configured to inject compressed air into the intermediate portion 18m between the
The inlets 28b1 of the multiple injection holes 28b are spaced apart in the circumferential direction at the same axial position. The outlets 28b2 of the multiple injection holes 28b are spaced apart in the circumferential direction at the same axial position.

Among the multiple injection holes 28, the multiple injection holes 28c are closest to the trailing edge 18T of the impeller blade 18.
It is formed at a position close to E.

The outlet 28c2 of the injection hole 28c is located between the outlet 28b2 of the injection hole 28b and the blade tip 18TE1 of the trailing edge 18TE of the impeller blade 18 in the axial direction. Therefore, the outlet 28c2 of the injection hole 28c is located downstream of the outlet 28a2 of the injection hole 28a and downstream of the outlet 28b2 of the injection hole 28b in the axial direction.
The outlet 28c2 of the injection hole 28c is located radially outward from the outlet 28a2 of the injection hole 28a and the outlet 28b2 of the injection hole 28b. In other words, the outlet 28c2 of the injection hole 28c is located radially outward from the outlet 28a2 of the injection hole 28a and the outlet 28b2 of the injection hole 28b.
The nozzles 28c are configured to inject compressed air into an outlet side portion of the compressor impeller 8 (the outer periphery of the compressor impeller 8), i.e., into a portion 18o of the impeller blade 18 on the trailing edge 18TE side. The multiple injection holes 28c are provided at the same axial position and spaced apart in the circumferential direction. The inlets 28c1 of the multiple injection holes 28c are provided at the same axial position and spaced apart in the circumferential direction. The outlets 28c2 of the multiple injection holes 28c are provided at the same axial position and spaced apart in the circumferential direction.

As described above, the outlets 28a2, 28b2, and 28c2 are located at different positions in the axial direction.
The technical significance of providing the compressor casing 10 with the injection holes 28a, 28b, and 8c, each having the above-mentioned features, will now be described.

According to the knowledge of the present inventors, when tests were conducted on a conventional turbocharger, the higher the turbocharger speed when compressed air was injected (when compressed air was injected from the injection hole to the impeller blades), the smaller the effect of increasing the turbocharger speed by compressed air, and this tendency remained the same even when the input pressure of compressed air was changed, as shown in Fig. 4. In this way, when compressed air is injected into the outlet side of the compressor impeller, a large moment for assisting the rotation of the compressor impeller can be obtained when the engine load is relatively small, such as when the engine is started (not shown), but as the engine load increases (as the turbocharger speed increases), the effect of assisting the rotation of the compressor impeller by compressed air tends to become limited.

This is believed to be because as the engine load increases, the turbocharger speed increases, and the amount of compressed air that can be introduced decreases because the pressure increases near the outlet of the compressor impeller as shown in Figure 5. On the other hand, as can be seen from Figure 5, the pressure is low near the inlet of the compressor impeller even during operation of the turbocharger, so if compressed air is introduced from the inlet side, it is possible to effectively assist the rotation of the compressor impeller and increase the turbocharger speed.

Therefore, by providing the compressor casing 10 with the injection holes 28a, 28b, and 28c having outlets 28a2, 28b2, and 28c2 at different positions in the axial direction, for example, when the rotation speed of the turbocharger 2 is in a low rotation speed range (when the pressure on the outlet side of the compressor impeller 8 is relatively low), compressed air is injected from the injection hole 28c2 located relatively downstream in the axial direction, when the rotation speed of the turbocharger 2 is in a medium rotation speed range, compressed air is injected from the injection hole 28b2 located in the middle in the axial direction, and when the rotation speed of the turbocharger is in a high rotation speed range (when the pressure on the outlet side of the compressor impeller 8 is relatively high), compressed air is injected from the injection hole 28a located relatively upstream in the axial direction. In this way, it becomes possible to appropriately use the injection of compressed air from the injection holes 28a to 28c depending on the operating state of the turbocharger 2 (for example, the rotation speed of the turbocharger 2 or the discharge pressure of the turbocharger 2).
Therefore, it is possible to satisfactorily assist the rotation of the compressor impeller 8 by the compressed air over a wide range of rotation speeds of the turbocharger 2.

In some embodiments, the outlets 28a2 of the multiple injection holes 28a may have equal intervals d in the circumferential direction, as shown in FIG. 6, or may have unequal intervals d (d1, d2, d3) in the circumferential direction, as shown in FIG. 7. In the example shown in FIG. 6, the outlets 28a2 of the six injection holes 28a are provided at intervals of 60 degrees in the circumferential direction. In the example shown in FIG. 7, the six intervals in the circumferential direction of the six injection holes 28a include four equal intervals d1, an interval d2 smaller than the interval d1, and an interval d3 larger than the interval d1. Note that when the outlets 28a2 of the multiple injection holes 28a have unequal intervals (unequal pitch) in the circumferential direction,
The intervals between the outlets 28a2 of the multiple injection holes 28a may be different from each other, or may include three or more different intervals as shown in FIG.

The number of the plurality of injection holes 28a and the intervals between the plurality of injection holes 28a are determined based on the compressor impeller 8.
This affects the blade vibration of the impeller blades 18. If the outlets of the multiple injection holes 28a are arranged at equal intervals (the same pitch), it is considered that the harmonics corresponding to the number of the multiple injection holes 28a will increase. In contrast, if the outlets 28a2 of the multiple injection holes 28a are unevenly spaced in the circumferential direction, the harmonics of the injection holes 28a will be increased compared to when the outlets are uniformly spaced in the circumferential direction.
Since the harmonics corresponding to the number of a are dispersed to other harmonics, the impeller blade 1
The blade vibration of the compressor impeller 8 can be reduced. The hole diameter, number and intervals of the multiple injection holes 28a may be determined taking into consideration the effect of assisting the rotation of the compressor impeller 8 and the strength of the rotor including the compressor impeller 8 and the turbine wheel 12. For example, when the hole diameter of the multiple injection holes 28a is reduced, it is expected that the flow speed of the compressed air will increase and the effect of assisting the rotation of the compressor impeller 8 will increase, but the load on the rotor will increase.

Similarly, with respect to the injection holes 28b, the outlets 28b2 of the multiple injection holes 28b may be spaced equally in the circumferential direction, or may be spaced unevenly in the circumferential direction.
In the case where the outlets 28b2 of the multiple injection holes 28b are unevenly spaced (unequal pitch) in the circumferential direction, the intervals between the outlets 28b2 of the multiple injection holes 28b may be different by only one or by three.
In the case where the outlets 28b2 of the multiple injection holes 28b are unevenly spaced in the circumferential direction, the number of injection holes 28b is smaller than that in the case where the outlets 28b2 are uniformly spaced in the circumferential direction.
The harmonics corresponding to the number of injection holes 28b are dispersed to other harmonics. This reduces the blade vibration of the impeller blades 18. The hole diameter, number and interval of the injection holes 28b may be determined taking into consideration the effect of assisting the rotation of the compressor impeller 8 and the strength of the rotor including the compressor impeller 8 and the turbine wheel 12.

Similarly, with respect to the injection holes 28c, the outlets 28c2 of the multiple injection holes 28c may be spaced equally in the circumferential direction, or may be spaced unevenly in the circumferential direction.
In the case where the outlets 28c2 of the multiple injection holes 28c are unevenly spaced (unequal pitch) in the circumferential direction, the intervals between the outlets 28c2 of the multiple injection holes 28c may be different by only one or by three.
In the case where the outlets 28c2 of the multiple injection holes 28c are unevenly spaced in the circumferential direction, the number of injection holes 28c is smaller than that in the case where the outlets 28c2 are uniformly spaced in the circumferential direction.
The harmonics corresponding to the number of injection holes 28c are dispersed to other harmonics. This reduces the blade vibration of the impeller blades 18. The hole diameter, number and intervals of the injection holes 28c may be determined taking into consideration the effect of assisting the rotation of the compressor impeller 8 and the strength of the rotor including the compressor impeller 8 and the turbine wheel 12.

In some embodiments, the centrifugal compressor 4 of the turbocharger 2 described with reference to FIGS. 1 to 7 may be configured as shown in FIG.
2, the turbocharger 2 may further include a valve 36a for controlling the injection of compressed air from the injection hole 28a, a valve 36b for controlling the injection of compressed air from the injection hole 28b, a valve 36c for controlling the injection of compressed air from the injection hole 28c, a valve control device 38 configured to control each of the valves 36a, 36b, and 36c and a valve 45 according to the operating state of the turbocharger 2, and a revolution counter 40 for measuring the rotation speed of the turbocharger 2 (the rotation speed of the rotating shaft 20). The valve 36a may be provided for each of the multiple injection holes 28a provided at intervals in the circumferential direction, the valve 36b may be provided for each of the multiple injection holes 28b provided at intervals in the circumferential direction, and the valve 36c may be provided for each of the multiple injection holes 28c provided at intervals in the circumferential direction.

The valve control device 38 may be configured by an electric circuit or a computer. When the valve control device 38 is configured by a computer, the RAM (
Random Access Memory), ROM (Read Only Memo)
The computer system includes a storage device such as a central processing unit (CPU) and a processor such as a central processing unit (CPU), and the processor executes a program stored in the storage device to realize its functions.

The valve control device 38 is configured to be able to execute an injection mode for the injection hole 28a, an injection mode for the injection hole 28b, and an injection mode for the injection hole 28c.

The jet hole 28a jet mode is a mode in which compressed air is jetted from the multiple jet holes 28a toward the negative pressure surface 26 of the impeller vane 18, and compressed air is not jetted from the multiple jet holes 28b and the multiple jet holes 28c.
a is controlled to an open state, while the valves 36b and 36c are controlled to a closed state.

The jet hole 28b injection mode is a mode in which compressed air is injected from the multiple jet holes 28b toward the negative pressure surface 26 of the impeller vane 18, and compressed air is not injected from the multiple jet holes 28a and the multiple jet holes 28c.
b is controlled to an open state, while the valves 36a and 36c are controlled to a closed state.

The jet hole 28c injection mode is a mode in which compressed air is injected from the multiple jet holes 28c toward the negative pressure surface 26 of the impeller vane 18, and compressed air is not injected from the multiple jet holes 28a and the multiple jet holes 28b. In the jet hole 28c injection mode, the valve control device 38 controls the valve 36
The valve control device 38 controls the valves 36a and 36b to be in a closed state while controlling the valves 36a and 36c to be in an open state.
During execution of each of the injection modes, the valve 45 is controlled to be open.

The valve control device 38 executes the injection hole 28c injection mode when the rotation speed of the turbocharger 2 measured by the rotation speed meter 40 is in a low rotation speed range (a rotation speed range corresponding to engine startup or engine idling, not shown). The valve control device 38 executes the injection hole 28b injection mode when the rotation speed of the turbocharger 2 measured by the rotation speed meter 40 is in a medium rotation speed range that is higher than the low rotation speed range. The valve control device 38 executes the injection hole 28a injection mode when the rotation speed of the turbocharger 2 measured by the rotation speed meter 40 is in a high rotation speed range that is higher than the medium rotation speed range. The low rotation speed range, the medium rotation speed range, and the high rotation speed range may be, for example, a rotation speed range of the turbocharger 2 corresponding to a case where the engine is operating at a load of 30% or less of the rated load, a rotation speed range of the turbocharger 2 corresponding to a case where the engine is operating at a load of 30% to 60% of the rated load, and a rotation speed range of the turbocharger 2 corresponding to a case where the engine is operating at a load of 60% or more of the rated load, respectively.

Here, an example of a control flow of the valve control device 38 will be described with reference to FIGS.
For example, as shown in FIG. 9 , in S11, the valve control device 38 determines whether or not the rotation speed of the turbocharger 2 measured by the tachometer 40 is equal to or lower than a first threshold value N1 (for example, the rotation speed of the turbocharger 2 corresponding to the case where the engine is operating at a load of 30% of the rated load).

In S11, when the rotation speed of the turbocharger 2 is equal to or lower than the first threshold value N1 (when the rotation speed of the turbocharger 2 is in the low rotation speed range), in S12, the valve control device 38 controls the valve 36c to be in the open state and controls the valves 36a and 36b to be in the closed state as shown in FIG. 10, and controls the valve 45 to be in the open state when the rotation speed of the turbocharger 2 increases, thereby
8c Injection mode is executed.

If the rotation speed of the turbocharger 2 is not equal to or less than the first threshold value N1 in S11, then in S13 it is determined whether the rotation speed of the turbocharger 2 measured by the tachometer 40 is equal to or less than a second threshold value N2 (for example, the rotation speed of the turbocharger 2 corresponding to when the engine is operating at a load of 60% of the rated load).

In S13, when the rotation speed of the turbocharger 2 is equal to or lower than the second threshold value N2 (when the rotation speed of the turbocharger 2 is in the medium rotation speed range), in S14, the valve control device 38 controls the valve 36b to an open state and controls the valves 36a and 36c to a closed state as shown in FIG. 10, and controls the valve 45 to an open state when the rotation speed of the turbocharger 2 increases, thereby reducing the injection hole 28.
b) Execute injection mode.

In S13, when the rotation speed of the turbocharger 2 is not equal to or lower than the second threshold value N2 (when the rotation speed of the turbocharger 2 is in the high rotation speed range), in S15, the valve control device 38 controls the valve 36a to be in the open state and the valves 36b and 36c to be in the closed state as shown in FIG. 10, and controls the valve 45 to be in the open state when the rotation speed of the turbocharger 2 increases, thereby reducing the injection hole 28.
a) Execute injection mode.

By performing such valve control, when the rotation speed of the turbocharger 2 is in the low rotation speed range (
When the pressure on the outlet side of the compressor impeller 8 is relatively low, compressed air is injected from the outlet 28c2 of the injection hole 28c which is the most downstream in the axial direction among the outlets 28a2, 28b2, 28c2 of the multiple injection holes 28, and therefore a large moment can be obtained to assist the rotation of the compressor impeller 8. Therefore, it is possible to improve the turbocharger efficiency and suppress the generation of black smoke when the rotation speed of the turbocharger 2 is in the low rotation speed range.

In addition, when the rotation speed of the turbocharger 2 is in the medium rotation speed range, the outlets 28a of the multiple injection holes 28
The outlet 28b of the injection hole 28b located at the middle in the axial direction among the injection holes 28b2, 28c2
Compressed air is injected from the compressor impeller 8. This assists the rotation of the compressor impeller 8, thereby improving the turbocharger efficiency when the rotation speed of the turbocharger 2 is in the medium rotation speed range.

In addition, when the rotation speed of the turbocharger 2 is in a high rotation speed range (when the pressure on the outlet side of the compressor impeller 8 is high), the outlets 28a2, 28b2, 28c of the multiple injection holes 28
Since compressed air is injected from the outlet 28a2 of the injection hole 28a that is located most upstream in the axial direction among the two, even if the pressure in the vicinity of the outlet of the compressor impeller 8 is high, the compressed air can be appropriately injected onto the negative pressure surface 26 of the impeller blade 18 to effectively assist the rotation of the compressor impeller 8.

In this way, it is possible to satisfactorily assist the rotation of the compressor impeller 8 by using compressed air over a wide range of rotation speeds of the turbocharger 2 from low rotation speeds to high rotation speeds.
Therefore, it is possible to suppress the generation of black smoke when the rotation speed of the turbocharger 2 is in the low rotation speed range, while realizing high turbocharger efficiency over the entire rotation speed range of the turbocharger 2.

In the example shown in Fig. 8 etc., it is determined which of the injection hole 28a injection mode, the injection hole 28b injection mode, and the injection hole 28c injection mode is to be executed based on the rotation speed of the turbocharger 2 measured by the rotation speed meter 40, but in other embodiments, the rotation speed meter 40 is not necessarily required. For example, the relationship between the load or rotation speed of the engine and the rotation speed of the turbocharger 2 may be obtained in advance, and the load or rotation speed of the engine may be converted to the rotation speed of the turbocharger 2 using that relationship, and the flow shown in Fig. 9 may be executed using the result. In other words, the valve control device 38 controls the operation of these valves 36a, 36b according to the operating state of the engine (for example, the load or rotation speed of the engine).
, 36c and the valve 45, and these valves 36a, 36b, 36c and 45 may be controlled in response to at least one of the operating state of the turbocharger and the operating state of the engine.
It may be configured to control each of valves 36 b , 36 c and valve 45 .

Further, the first threshold value N1 and the second threshold value N2 described with reference to FIG. 9 do not necessarily need to be fixed values, and may be adjusted based on the operating state of the turbocharger 2, environmental conditions, and the like.

The present disclosure is not limited to the above-described embodiments, and includes modifications to the above-described embodiments and appropriate combinations of these modifications.
For example, in the example shown in FIG. 8, the valve control device 38 automatically changes the opening degrees of the valves 36a to 36c, but the valves 36a to 36c may be manually changed.

In some embodiments, the turbocharger 2 may include a blocking member 42 that blocks at least one of the multiple injection holes 28, as shown in FIGS. 11 and 12, instead of the valves 36a to 36c and the valve control device 38 shown in FIG. 8.

In the exemplary embodiment shown in each of Figures 11 and 12, the turbocharger 2 includes a plurality of closing members 42a that close the plurality of jet holes 28a and a plurality of closing members 42b that close the plurality of jet holes 28b.

In the example shown in Fig. 11, each of the blocking members 42a and 42b is configured as a flange-shaped cover member, and is fixed to the outer circumferential surface of the air guide cylinder 30 by means of a fastener such as a bolt (not shown). In the example shown in Fig. 12, the inner circumferential surface of each of the jet holes 28 is machined to have a female thread, the blocking member 42a is machined to have a male thread so that it can be screwed into the female thread on the inner circumferential surface of the jet hole 28a, and the blocking member 42b is machined to have a male thread so that it can be screwed into the female thread on the inner circumferential surface of the jet hole 28b. In this case, the blocking members 42a and 42b are machined to have a male thread so that it can be screwed into the female thread on the inner circumferential surface of the jet hole 28a and 28b, respectively.
8b.

With such a configuration including the blocking member 42, it is possible to select the jet hole 28 to be used (jet hole 28c in the illustrated example) according to the usage environment and specifications of the turbocharger 2, and block the jet holes 28 other than the jet hole 28 to be used. This makes it possible to change the position at which the blocking member 42 is provided after the shipment of the turbocharger 2, and therefore it becomes possible to satisfactorily assist the rotation of the compressor impeller 8 using the compressed gas according to the usage environment and specifications of the turbocharger 2.

In addition, in the above-described embodiment, a plurality of injection holes 28 are provided at three positions of the air guide tube 30 in the axial direction, spaced apart in the circumferential direction, but only one injection hole 28 may be provided in the circumferential direction at each of the three positions of the air guide tube 30 in the axial direction.

In addition, the air guide tube 30 may be provided with at least one injection hole 28 at each of two positions in the axial direction, or at least one injection hole 28 at each of four or more positions.
may be provided.

In addition, in the turbocharger 2 shown in FIG. 1, a radial turbine is exemplified as the turbine 6.
The turbine 6 may be an axial flow turbine.

In the above-described embodiment, compressed air is used as the compressed gas injected from the injection holes 28. However, in other embodiments, a compressed gas other than compressed air may be used.

In addition, the valve 36a may be provided for each of the multiple injection holes 28a, or one valve 36a may be provided for each of the multiple injection holes 28a. The valve 36b may be provided for each of the multiple injection holes 28b, or
One valve 36b may be provided for multiple injection holes 28b.
A valve 36a may be provided for each of the multiple injection holes 28c, or one valve 36a may be provided for each of the multiple injection holes 28c. When a valve 36a is provided for each of the multiple injection holes 28a, the valves 36a
When a valve 36b is provided for each of the multiple injection holes 28b among the multiple injection holes 28b, the opening and closing timings of the multiple valves 36b may be the same. When a valve 36c is provided for each of the multiple injection holes 28c among the multiple injection holes 28c, the opening and closing timings of the multiple valves 36c may be the same.

The contents described in each of the above embodiments can be understood, for example, as follows:

(1) A compressor casing according to at least one embodiment of the present disclosure (e.g., the compressor casing 10 described above) has
A compressor casing that houses a compressor impeller (e.g., the above-mentioned compressor impeller 8) of a turbocharger (e.g., the above-mentioned turbocharger 2),
A plurality of injection holes (e.g., the above-mentioned injection holes 28) for injecting compressed gas (e.g., the above-mentioned compressed air) toward the impeller blades (e.g., the above-mentioned impeller blades 18) of the compressor impeller.
(28a to 28c),
The plurality of injection holes are
At least one first injection hole (e.g., the above-mentioned plurality of injection holes 28a, the plurality of injection holes 28
b or a plurality of injection holes 28c);
At least one second injection hole (e.g., the above-mentioned plurality of injection holes 28) having an outlet (e.g., any of the above-mentioned outlets 28a2, 28b2, and 28c2 other than the outlet corresponding to the outlet of the first injection hole) at a position different from the outlet of the first injection hole (e.g., the above-mentioned outlet 28a2, outlet 28b2, or outlet 28c2) in the axial direction of the compressor impeller.
a, any one of the plurality of jet holes 28b and the plurality of jet holes 28c other than the jet hole corresponding to the first jet hole;
including.

When a test was performed on a conventional turbocharger, it was found that the greater the turbocharger speed when compressed air was injected (when compressed air was injected from the injection hole to the impeller blade), the smaller the effect of increasing the turbocharger speed by compressed air, and this tendency remained the same even when the input pressure of compressed air was changed. Thus, when compressed air is injected into the outlet side (trailing edge side of the impeller blade) of the compressor impeller, a large moment for assisting the rotation of the compressor impeller can be obtained when starting an engine (not shown) or when the engine load is relatively small, but as the engine load increases (as the turbocharger speed increases), the effect of assisting the rotation of the compressor impeller by compressed air tends to become limited.
This is thought to be because as the engine load increases, the turbocharger speed increases, and the pressure increases near the outlet of the compressor impeller, reducing the amount of compressed air that can be introduced. On the other hand, even when the turbocharger is operating, the pressure is low near the inlet of the compressor impeller, so if compressed air is introduced from the inlet side, it is possible to effectively assist the rotation of the compressor impeller and increase the turbocharger speed.
Therefore, the compressor casing described in (1) above includes, as injection holes for injecting compressed gas to the impeller blades, at least one first injection hole and at least one second injection hole having an outlet at a position different from the outlet of the first injection hole in the axial direction of the compressor impeller. Since the inner diameter of the compressor casing of the turbocharger increases toward the downstream side in the axial direction of the compressor impeller, the outlet of the first injection hole and the outlet of the second injection hole are also at different radial positions.
As a result, for example, when the rotation speed of the turbocharger is relatively low (when the pressure near the outlet of the compressor impeller is relatively low), the compressed gas is injected from the outlet of the first injection hole or the outlet of the second injection hole which is the downstream one in the axial direction, and when the rotation speed of the turbocharger is relatively high (when the pressure near the outlet of the compressor impeller is high), the compressed gas is injected from the outlet of the first injection hole or the outlet of the second injection hole which is the upstream one in the axial direction. In this way, it is possible to appropriately use the injection of compressed gas from the first injection hole and the injection of compressed gas from the second injection hole depending on the operating state of the turbocharger.
Therefore, it is possible to satisfactorily assist the rotation of the compressor impeller by using the compressed gas over a wide range of rotation speeds of the turbocharger.

(2) In some embodiments, in the compressor casing described in (1) above,
at least one first valve (e.g., valve 36a, valve 36b or valve 36c described above) for controlling the injection of the compressed gas from the at least one first injection hole;
At least one second valve (e.g., one of the valves 36a, 36b, and 36c described above) for controlling the injection of the compressed gas from the at least one second injection hole.
any valve other than the valve corresponding to the first valve).

According to the compressor casing described in (2) above, for example, when the rotation speed of the turbocharger is relatively low (when the pressure near the outlet of the compressor impeller is relatively low), the valve corresponding to the outlet of the first injection hole or the outlet of the second injection hole which is the downstream one in the axial direction is opened to inject compressed gas, and when the rotation speed of the turbocharger is relatively high (when the pressure near the outlet of the compressor impeller is high), the valve corresponding to the outlet of the first injection hole or the outlet of the second injection hole which is the upstream one in the axial direction is opened to inject compressed gas. In this manner, by controlling the first valve and the second valve in accordance with the operating state of the turbocharger, it becomes possible to appropriately use the injection of compressed gas from the first injection hole and the injection of compressed gas from the second injection hole in accordance with the operating state of the turbocharger.
This makes it possible to satisfactorily assist the rotation of the compressor impeller by using compressed gas over a wide range of rotation speeds of the turbocharger.

(3) In some embodiments, in the compressor casing described in (1) above,
The nozzle further includes a blocking member that blocks the first injection hole or the second injection hole.

According to the compressor casing described in (3) above, by blocking the first injection hole or the second injection hole with a blocking member, it is possible to select the injection hole to be used according to the operating environment and specifications of the turbocharger. This makes it possible to satisfactorily assist the rotation of the compressor impeller using compressed gas according to the operating environment and specifications of the turbocharger.

(4) In some embodiments, in the compressor casing described in any one of (1) to (3),
the at least one first injection hole includes a plurality of first injection holes (e.g., the above-mentioned plurality of injection holes 28a, the plurality of injection holes 28b, or the plurality of injection holes 28c) spaced apart in the circumferential direction;
The outlets of the plurality of first injection holes are non-uniformly spaced in the circumferential direction.

According to the compressor casing described in (4) above, compared to a case where the outlets of the multiple first injection holes are spaced evenly in the circumferential direction, harmonics corresponding to the number of first injection holes are dispersed to other harmonics, thereby reducing blade vibration of the impeller blades.

(5) In some embodiments, in the compressor casing according to any one of (1) to (4),
The plurality of injection holes are formed to inject compressed gas into the impeller blade along a direction perpendicular to a blade surface of the impeller blade.

According to the compressor casing described in (5) above, the energy of the compressed gas can be efficiently converted into the rotational energy of the compressor impeller, and the rotation of the compressor impeller can be effectively assisted.

(6) A turbocharger according to at least one embodiment of the present disclosure,
The compressor casing according to (2) above;
A valve control device (e.g., the valve control device described above) configured to control the at least one first valve and the at least one second valve in response to an operating state of at least one of the turbocharger and the engine;
Equipped with.

According to the turbocharger described in (6) above, by appropriately opening and closing the first valve and the second valve by the valve control device according to the operating state of the turbocharger, it is possible to appropriately control the injection of compressed gas from the first injection hole and the injection of compressed gas from the second injection hole according to the operating state of the turbocharger, thereby effectively assisting the rotation of the compressor impeller.

(7) In some embodiments, in the turbocharger described in (6) above,
an outlet of the second injection hole is located downstream in the axial direction of an outlet of the first injection hole,
The valve control device is configured to be able to execute a first jet hole injection mode (e.g., the above-mentioned jet hole 28b injection mode or the jet hole 28c injection mode) in which compressed gas is injected from the first jet hole toward the impeller blade of the compressor impeller, and a second jet hole injection mode (e.g., any of the above-mentioned jet hole 28a injection mode and the jet hole 28b injection mode other than the injection mode corresponding to the first jet hole mode) in which compressed gas is injected from the second jet hole toward the impeller blade of the compressor impeller,
The valve control device is configured to execute the second jet hole injection mode when the rotation speed of the turbocharger is in a first rotation speed range (e.g., the above-mentioned low rotation speed range or medium rotation speed range), and to execute the first jet hole injection mode when the rotation speed of the turbocharger is in a second rotation speed range that is higher than the first rotation speed range (e.g., the above-mentioned medium rotation speed range or high rotation speed range that does not correspond to the first rotation speed range).

According to the turbocharger described in (7) above, when the turbocharger speed is in a first speed range where the speed is relatively low (when the pressure near the outlet of the compressor impeller is relatively low), compressed gas is injected from the outlet of the second jet hole which is on the downstream side (high pressure side) in the axial direction out of the outlets of the first jet hole and the second jet hole, and a large moment for assisting the rotation of the compressor impeller can be obtained. Therefore, it is possible to improve the turbocharger efficiency and suppress the generation of black smoke when the turbocharger speed is in the first speed range where the speed is relatively low.
Furthermore, when the rotation speed of the turbocharger is in a relatively high second rotation speed range (when the pressure near the outlet of the compressor impeller is high), the compressed gas is injected from the outlet of the first jet hole which is located upstream in the axial direction out of the outlets of the first jet holes and the second jet holes. Therefore, even when the pressure near the outlet of the compressor impeller is high, the compressed gas can be injected to the impeller blades from the outlet of the first jet hole which is located relatively more inward (low pressure side) than the outlet of the second jet hole, so that the compressed gas can be appropriately injected to the impeller blades to assist the rotation of the compressor impeller.
In this manner, it becomes possible to satisfactorily assist the rotation of the compressor impeller by using compressed gas over a wide range of rotational speeds of the turbocharger.

(8) A method for operating a turbocharger according to at least one embodiment of the present disclosure,
a first jet hole injection step (e.g., S12 or S14 described above) of injecting compressed gas (e.g., the above-mentioned compressed air) from a first jet hole (e.g., the above-mentioned jet hole 28a or jet hole 28b) provided in a compressor casing (e.g., the above-mentioned compressor casing 10) of the turbocharger toward an impeller blade (e.g., the above-mentioned impeller blade 18) of a compressor impeller (e.g., the above-mentioned compressor impeller 8);
A second injection hole (for example, the above-mentioned injection hole 28b or injection hole 28) provided in the compressor casing downstream of the first injection hole in the axial direction of the compressor impeller.
c) a second injection hole injection step (e.g., S14 or S15 described above) of injecting compressed gas toward the impeller blade;
Equipped with
The second jet hole injection step is executed when the rotation speed of the turbocharger is in a first rotation speed range (e.g., the low rotation speed range or medium rotation speed range described above), and the first jet hole injection step is executed when the rotation speed of the turbocharger is in a second rotation speed range (e.g., the medium rotation speed range or high rotation speed range described above) which is a rotation speed range higher than the first rotation speed range.

According to the method for operating a turbocharger described in (8) above, when the rotation speed of the turbocharger is in a first rotation speed range that is relatively low (when the pressure near the outlet of the compressor impeller is relatively low),
Compressed gas is injected from the outlet of the second injection hole, which is located downstream (high pressure side) in the axial direction out of the outlets of the injection hole and the second injection hole, and a large moment for assisting the rotation of the compressor impeller can be obtained. Therefore, it is possible to improve the turbocharger efficiency and suppress the generation of black smoke when the turbocharger rotation speed is in the first rotation speed range where the rotation speed is relatively low.
In addition, when the rotation speed of the turbocharger is in a relatively high second rotation speed range (when the pressure near the outlet of the compressor impeller is high), the compressed gas is injected from the outlet of the first injection hole, which is located on the upstream side (low pressure side) in the axial direction out of the outlets of the first injection hole and the second injection hole. Therefore, even when the pressure on the outlet side of the compressor impeller is high,
Since compressed gas can be injected into the impeller blades from the outlet of the first injection hole, which is located relatively more inward than the outlet of the second injection hole, the compressed gas can be appropriately injected into the impeller blades to assist the rotation of the compressor impeller.
In this manner, it becomes possible to satisfactorily assist the rotation of the compressor impeller by using compressed gas over a wide range of rotational speeds of the turbocharger.

2 Turbocharger 4 Centrifugal compressor 6 Turbine 8 Compressor impeller 10 Compressor casing 12 Turbine wheel 14 Turbine casing 16 Hub 18 Impeller blade 18LE Leading edge 18LE1 Blade tip 18TE Trailing edge 18TE1 Blade tip 18i Leading edge side portion 18m Intermediate portion 18o Trailing edge side portion 20 Rotating shaft 22 Bearing 24 Bearing casing 26 Negative pressure surface 28, 28a, 28b, 28c Injection holes 28a1, 28b1, 28c1 Inlet 28a2, 28b2, 28c2 Outlet 30 Air guide tube 31 Space 32 Scroll flow passage 34 Scroll casing 35 Compressed air passage 36a, 36b, 36c Valve 38 Valve control device 40 Tachometer 42, 42a, 42b Blocking member 44 Compressed air line 45 Valve 46 Compressed air tank

Claims (7)

A compressor casing that houses a compressor impeller of a turbocharger,
a plurality of injection holes for injecting compressed gas toward the impeller blades of the compressor impeller;
The plurality of injection holes are
At least one first injection hole;
at least one second injection hole having an outlet at a position different from an outlet of the first injection hole in the axial direction of the compressor impeller;
The compressor casing comprises:
the compressor casing further comprising at least one first valve for controlling injection of the compressed gas from the at least one first injection hole and at least one second valve for controlling injection of the compressed gas from the at least one second injection hole. A compressor casing that houses a compressor impeller of a turbocharger,
a plurality of injection holes for injecting compressed gas toward the impeller blades of the compressor impeller;
The plurality of injection holes are
At least one first injection hole;
at least one second injection hole having an outlet at a position different from an outlet of the first injection hole in the axial direction of the compressor impeller;
The compressor casing comprises:
The compressor casing further comprises a blocking member that blocks one of the first injection hole and the second injection hole. A compressor casing that houses a compressor impeller of a turbocharger,
a plurality of injection holes for injecting compressed gas toward the impeller blades of the compressor impeller;
The plurality of injection holes are
At least one first injection hole;
at least one second injection hole having an outlet at a position different from an outlet of the first injection hole in the axial direction of the compressor impeller;
the at least one first injection hole includes a plurality of circumferentially spaced first injection holes;
The outlets of the plurality of first injection holes are unevenly spaced in the circumferential direction of the compressor casing. The compressor casing according to claim 1 , wherein the plurality of injection holes are formed so as to inject compressed gas into the impeller blade along a direction perpendicular to a blade surface of the impeller blade. A compressor casing according to claim 1 ;
a valve control device configured to control the at least one first valve and the at least one second valve in response to an operating state of at least one of the turbocharger and the engine;
A turbocharger. an outlet of the second injection hole is located downstream in the axial direction of an outlet of the first injection hole,
the valve control device is configured to be able to execute a first jet hole injection mode in which compressed gas is injected from the first jet hole toward the impeller blade of the compressor impeller, and a second jet hole injection mode in which compressed gas is injected from the second jet hole toward the impeller blade of the compressor impeller,
6. The turbocharger according to claim 5, wherein the valve control device is configured to execute the second jet hole injection mode when a rotation speed of the turbocharger is in a first rotation speed range, and to execute the first jet hole injection mode when a rotation speed of the turbocharger is in a second rotation speed range that is a rotation speed range higher than the first rotation speed range. a first injection hole injection step of injecting compressed gas from a first injection hole provided in a compressor casing of the turbocharger toward an impeller blade of a compressor impeller;
a second jet hole injection step of injecting compressed gas toward the impeller blades from a second jet hole provided in the compressor casing downstream of the first jet hole in the axial direction of the compressor impeller;
Equipped with
A method for operating a turbocharger, comprising the steps of: executing the second jet hole injection step when a rotation speed of the turbocharger is in a first rotation speed range; and executing the first jet hole injection step when the rotation speed of the turbocharger is in a second rotation speed range that is a higher rotation speed range than the first rotation speed range.

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