JPS6056125A - Turbine scrol in turbo-charger - Google Patents

Abstract

PURPOSE:To enhance the efficiency of a turbine, by providing a spiral type main exhaust passage opened toward the inlet of a turbine rotor and a spiral type auxiliary exhaust passage which is parallel arranged with the main exhaust passage through the intermediary of a partition wall, and as well by forming, in the partition wall, a communication hole which extends over the entire periphery of the rotor. CONSTITUTION:This turbine scrol 13 has a main exhaust passage 13A having it opening 14 directed to the inlet 1A of a rotor 1 and an auxiliary exhaust passage 13B formed in parallel with the passage 13A through the intermediary of a partition wall 5B formed therein with a communication hole 15. With this arrangement the communication hole 15 is formed in a ring-like shape concentrical with the rotor 1, and is inclined in the direction approaching the center axis O of the rotor 1 extending from the passage 13A to the passage 13B, having a constant width B. Further, a shut-off valve is provided upstream of the throat section of the auxiliary exhaust passage 13B to make it possible to adjust the flow rate of auxiliary exhaust gas. With this arrangement, the effective utilization of exhaust gas energy may be made over a range from a low speed to a high speed to enhance the efficiency of the turbine.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a turbine scroll for a turbocharger, and more particularly to a turbine scroll in which the exhaust capacity supplied to the exhaust turbine is made variable at the scroll inlet depending on the operating state of the engine.

FIG. 1 shows an example of a conventional turbine scroll with variable capacity of this type, and this example is disclosed in Japanese Utility Model Application No. 57-11233. Here, l is a turbine rotor that is directly connected to a compressor impeller (not shown) by a rotor shaft 2. A spiral passage turbine scroll 3 is provided on the outer periphery of the turbine rotor 1, and this scroll 3 is connected to the engine. Exhaust gas from the exhaust passage 4 is guided.

Further, in the turbine scroll 3 of this example, the housing 5 is divided by the protruding wall 5A from the diagonal direction with respect to the shaft 2, so that the large exhaust passage section 3A and the small exhaust passage section 3B form a spiral chamber. The inlet portion 6 of the rotor 1 is connected to the inlet portion 3C of the scroll 3 through these passage portions 3A and 3B.
This is an on-off valve provided on the large exhaust passage 3A side at a portion of the exhaust passage 4 connected to the large exhaust passage 3A, and this on-off valve 6 can change the volume of exhaust gas flowing into the large exhaust passage 3A. 7 is an exhaust gas outlet.

In the turbine scroll 3 configured in this way, when the engine is in a low speed rotation region, the gas passage area must be reduced in order to maintain compatibility between the turbocharger and the engine and obtain good supercharging characteristics at low speeds. Since it is necessary to throttle the gas, the opening/closing valve 6 can be operated by a control mechanism (not shown) using, for example, supercharging pressure to adjust the gas volume passing through the large exhaust passage 3A. Furthermore, when the engine is in a high speed rotation region, gas is supplied to the rotor l from both the large exhaust passage 3A and the small exhaust passage 3B.

However, in the turbine scroll 3 in which the gas capacity supplied to the rotor 1 is made variable as described above, both the large exhaust passage 3^ and the small exhaust passage 3B are shaped to open toward the rotor inlet portion 1A, and further, Since the gas flow rate of the large exhaust passage 3A is configured to be throttled by the on-off valve 6, when the gas supply to the large exhaust passage 3A is cut off by the on-off valve 6 in the low speed rotation region of the engine, this large exhaust passage A dead water area occurs at 3A.

However, in such a state, gas flows into the small exhaust passage 3B.
The gas is supplied from the rotor inlet IA to the rotor 1 via the rotor inlet IA, and a swirling flow 10 as shown in FIG. The fluid will have centrifugal force. A part of the gas fluid is then dispersed into the gas body which is a dead water region of the large exhaust passage 3A, and a circulating flow 11 as shown in FIG. 2(B) is generated there. As this circulating Fe1l flows along the wall surface of the large exhaust passage 3A, it loses energy due to frictional loss, and as it merges with the swirling flow lO again, the energy loss within the turbine scroll 3 is large, reducing the turbine efficiency. Incur consequences.

Furthermore, FIG. 3 shows the first scroll 3 of the commonly used double entry housing, in which the housing 5 is divided in the axial direction by a wall 5A projecting from the outer circumference.

However, even if such a double entry housing type scroll 3 is provided with an on-off valve (not shown) that opens and closes either one of the exhaust passages 3D, a similar phenomenon may occur. , the efficiency is lower than in the case of a single-entry turbine scroll, making it difficult to build up turbocharging pressure at low speeds.

The purpose of the present invention is to focus on the above-mentioned problems, and to effectively utilize exhaust energy from low speed to high speed engine speeds, reduce loss, maintain good turbine efficiency, and further reduce engine backlash. An object of the present invention is to provide a turbine scroll for a turbocharger that contributes to maintaining sufficient high-speed output through the effect of lowering pressure.

In order to achieve this object, the present invention includes a spiral main exhaust passage that opens toward the turbine rotor inlet and a spiral auxiliary exhaust passage that is attached to the main exhaust passage and does not directly open to the rotor inlet. None.In the partition wall between these two exhaust passages, a communication hole with a constant width defined by two concentric circles centered on the rotor axis is provided almost all around the rotor, and this communication hole is connected from the main exhaust passage side. The exhaust volume is increased by 5 (
A variable valve is provided to close the valve during low speed ranges of the engine so that exhaust gas is supplied directly to the rotor inlet only from the main exhaust passage.

The present invention will be described in detail below based on the drawings.

FIG. 4 shows an embodiment of the present invention, where 13 is a turbine scroll, and 13A is a main exhaust passage of the scroll 13. The main exhaust passage 13A has an opening 14 facing the inlet l^ of the rotor 1, and
A communication portion 15 is provided between the main exhaust passage 13A and the auxiliary exhaust passage 13B provided in parallel with each other via the partition wall 5B.

As mentioned above, this communication part 15 is formed concentrically, but when forming the slit, it is necessary to connect the auxiliary exhaust passage from the main exhaust passage 13A side as shown in this figure. 13B in a direction closer to the axis 0 of the rotor 1 so as to maintain a constant width B.

Furthermore, although the communication portion 15 is formed with an inclination, at the same time, the overlap (overlap amount) L of the partition wall 5B is made between the main exhaust passage 13A and the auxiliary exhaust passage 13B as shown in FIG. However, it is desirable that the main exhaust passage 1 of the partition wall 5B is
The sharp edge portions 15A and 15B formed on the surfaces on the 3A side and the auxiliary exhaust passage 13B side may be finished smoothly within a range where overlap measurement can be obtained.

Further, as shown in FIG. 6, the communication portion 15 is connected to the rotor axis O
The communication part 15 is provided in a concentric shape around the communication part 15, but the wider the circumferential range, the more desirable it is.
By minimizing the range in which this is not provided, an increase in fluid energy loss due to non-uniformity of flow at the inlet portion IA of the turbine rotor 1 is suppressed.

In this example, it is formed from the smallest passage on the rotor 1 side in the tongue portion 18 of the scroll 13 to a position as close as possible to the throttle portion formed by the tongue portion 18 and the housing 5, that is, the throat portion 17.

Furthermore, in FIG. 6, 25 is an on-off valve (rotary valve in this example) provided on the upstream side of the throat portion 17 of the auxiliary exhaust passage 138, and this on-off valve 25 controls the flow rate on the auxiliary exhaust passage 13B side to tAt! B. As shown in FIG. 7, the on-off valve 25 includes a cover 2B attached to the scroll 5 by means such as bolts, a bushing 27 press-fitted into the cover 2B, and a shaft 28 rotatably supported by the bushing 27. The valve main body 25A has a lever 28 that rotates a shaft 28, and is controlled to open and close by a control means (not shown). Note that FIG. 6 shows the on-off valve 25 in a closed state.

Further, in this example, the on-off valve 25 is provided in the housing 5 upstream from the throat portion 17, but instead of this, the on-off valve 25 is installed in an auxiliary exhaust passage (not shown) upstream from the inlet portion 13C of the scroll 13. It may also be provided. However,
The on-off valve 25 is closed by the control means in the low speed rotation region of the engine.

Next, the setting of the width B of the communication portion 15 in the turbine scroll configured as described above will be described. When setting width B, it is necessary to consider the effect on supercharging characteristics.
The conditional expression that provides the best supercharging characteristics confirmed by the inventor is shown below.

However, in equation (1), AAT: Throat part of main exhaust passage 13^! Area ABT at 7A: Area R^ of the auxiliary exhaust passage 13B at the throat portion 17B: Distance R8 from the rotor axis 0 to the center of gravity of the throat portion 17A Distance H from the rotor axis 0 to the center of gravity of the throat portion 17B: Turbine rotor It is desirable to set the width B of the communicating portion 15 by the blade width at the inlet portion IA of No. 1, that is, the equation (1). However, if the width B is made narrower than this for design reasons, the above conditions should be kept in mind. care must be taken to minimize losses.

Next, the operation of the fluid during the operation of the turbine scroll 13 configured as described above will be described, and the effect of providing the communication portion 15 will also be described.

When the on-off valve 25 is closed in the low speed rotation range of the engine, a dead water area is generated in the auxiliary exhaust passage 13B, but the auxiliary exhaust passage 13B is separated from the main exhaust passage 13A by the partition wall 5B, and the inlet of the rotor 1 Since it is not opened toward IA, the flow described in FIGS. 2(A) and 2(B) does not occur.

Furthermore, the flow velocity distribution on the +3A side of the main exhaust passage of the turbine scroll 13 is a freeportionx flow expressed by VXr = constant, where r is the distance from the axis 0 to the fluid position and V is the flow velocity at that position. Therefore, the flow velocity V changes in inverse proportion to the radius r. That is, the flow velocity becomes slower closer to the outer circumference of the scroll 13, and the flow velocity becomes farther away as it approaches the rotor 1. Therefore, the static pressure is low on the inlet IA side of the rotor 1, and the static pressure is high on the outer peripheral side.

Therefore, it can be seen that in the communication portion 15 provided concentrically at a position equidistant from the axis 0, the static pressure in this portion 15 is kept constant over the entire circumference. That is, by this, a good flow condition can be maintained without causing the fluid to be diverted from the main exhaust passage 13A side to the auxiliary exhaust passage 13B side due to the pressure difference caused by the difference in radial position. . Next, the effect of the overlap formed in the communication portion 15 will be explained with reference to FIG. In this example, the edge portion 15A on the side of the main exhaust passage 13A is formed to protrude from the line of the main wall surface 5D on this side of the partition wall 5B, and the reason and effect thereof will be described later.

Now, as an example where no overlap is formed in the communication section 15, assume that the outer communication section wall 30A is located at the position indicated by the broken line. In this case, the edge part on the auxiliary exhaust passage 13B side is 1
5B', the radial position corresponding to this edge 15B' on the main exhaust passage 13A side is At, and the radial position corresponding to the edge 15A is A2. Furthermore, the radial position 81 is the intermediate position between the position ^l and A2 on the side of the auxiliary exhaust passage 13B.

However, in this case, the position ^1. The static pressures at A2 and B1 are PAl and PA!, respectively. Assuming that L and pei, the relationship PAi>pei>Pa holds true between these static pressures.

Therefore, if we do not form an overlap like this, from A1 to 81 as shown by the dashed line, and then to B1.
A secondary flow 40 is generated from A2 toward A2. That is, from the main exhaust passage 13A side, the auxiliary exhaust passage 13
The swirling flow jumps out to the B side, and the low energy fluid in the dead water region is instead returned to the main exhaust passage 13^ side from the auxiliary exhaust passage 13B side, and their mixing causes a loss of fluid energy.

On the other hand, the outer communication wall 30B is positioned as shown by the solid line in FIG. (overlap amount is Z), even if the tendency of the secondary flow as described above is suppressed, even if a part of the swirling flow flows from the main exhaust passage 13A side to the auxiliary exhaust passage 13B side. , from the auxiliary exhaust passage 13B side to the main exhaust passage 1 by the wall surface 5E of the partition fi5B.
Fluid flow to the 3A side is blocked, and energy loss can be suppressed to a minimum.

The present inventor conducted an experiment to confirm the effect of the above-mentioned overlap formation, and found a tendency for the efficiency to decrease as shown in FIG. 9. Here, the horizontal axis shows the ratio between the overlap measurement and the communication portion slit width B, and the vertical axis shows the turbine efficiency in a low speed region with respect to L/B. As is clear from this figure, the overlap L is zero, that is, the designated area on the left side of L/B=O (when the width B and the thickness of the partition wall 5B are constant, the slit of the communication part 15 (the slope becomes smaller as it goes to the left on the horizontal axis), the efficiency η7 decreases rapidly.

As is clear from the results of this experiment, it is preferable to set the overlap amount to at least zero, but even if such a setting is difficult due to design reasons, it is possible to set the negative overlap amount to a wide range. About 25% of B, that is, L/B =
It is desirable to keep it within about -0.25.

Next, the control and fluid operation in the engine medium speed rotation region will be explained. In this state, the on-off valve 25 is controlled to be approximately half open. Therefore, the exhaust gas flows outside the main exhaust passage 13A through the auxiliary exhaust passage 13B which is in a half-open state, but the gas flowing through the passage 13B is directed to the most downstream position of the communication portion 15, that is, depending on the degree of opening of the on-off valve 25. The gas starts to flow from the communication part 15 at the minimum passage position, and then the inflow range is gradually expanded upstream to guide the gas to the main exhaust passage 13A side.

Thus, in the high-speed rotation region of the engine, the on-off valve 25 is fully opened, and gas efficiently flows from the auxiliary exhaust passage 13B side through the entire circumference of the communication portion 15 to the main exhaust passage layer 13A side, and the turbine Since it is guided to the rotor 1, it is possible to reduce the turbine inlet pressure, that is, the back pressure of the engine, compared to the conventional case, and contribute to the output direction of the engine.

In addition, in FIG. 8, the wall surface 5C on the rotor 1 side, which is limited by the communication portion 15 of the partition wall 5B, is made to protrude from the main wall surface 5D by a dimension C, and there is an edge portion on the partition wall 5B at this portion! 5A was formed, and its effects will be supplementarily explained. As mentioned above, when gas is also supplied to the auxiliary exhaust passage 13B side, the fluid that has lost energy due to friction with the wall surface of the auxiliary exhaust passage 13B gathers on the inner peripheral surface side of the passage +313, and this secondary The flow will be directed directly to the rotor inlet l^. Partition wall 5 on the rotor 1 side forming edge portion 15A
B not only acts as an obstacle (boundary rare fence) to prevent such secondary flow from being guided to the rotor inlet IA, but also acts as a barrier between the communication portion 15 and the main exhaust passage +3.
It serves to help the gas flow guided to the A side and the main flow flowing through the main exhaust passage 13A, and improves the flow around the turbine inlet IA to improve turbine efficiency and maintain good turbine performance over the entire operating range. Performance can be maintained.

Furthermore, the fact that the partition wall 5B on the rotor l side protrudes by the dimension C reverses the boundary layer generated on the partition wall surface 5D on the main exhaust passage 13A side,
By guiding it to the 3B side, the effect of further preventing the above-mentioned secondary flow from being directly guided to the rotor inlet IA can be obtained.

Note that it is preferable to set the radial position of the communicating portion 15 at a radius as large as possible based on the design, in order to improve efficiency in the medium and high speed range where exhaust gas is guided to the auxiliary exhaust passage 13B side.

FIG. 1θ shows another embodiment of the present invention. In this example, the valve is a flap valve 35, and 38 is its opening/closing shaft. In this case, the housing 5 forming the auxiliary exhaust passage 13B
A valve seat portion 37 is provided on the wall surface of the valve a5, and when the valve a5 is closed, the main body of the valve 35 comes into contact with the stepped valve seat portion 37 to prevent leakage and improve performance at low speeds.

FIG. 11 shows still another embodiment of the present invention, in which auxiliary exhaust passages are provided in multiple stages. Here, 13B and 130 are auxiliary exhaust passages, and 5G is a partition wall between auxiliary exhaust passages 13B and 130.

Therefore, a communication portion 15 as shown in FIG. 4 or FIG. 8 is provided at a substantially relative position between the partitions Jg15B and 5G,
Furthermore, although not shown in the figure, auxiliary exhaust passages 13B and 130
An on-off valve shall be provided for each.

The other configurations are the same as those shown in FIG. 4, and their explanation will be omitted. In the turbine scroll 13 configured in this manner, the flow rate range can be greatly changed by appropriately controlling the on-off valves provided in each of the auxiliary passages 13B and 130, and the control is easy.

Furthermore, in this example, although not shown, the auxiliary exhaust passage 13
It goes without saying that a generally known exhaust bypass valve can be provided at B or 130, and the supercharging pressure of the engine can be controlled by this exhaust bypass valve.

As explained above, according to the present invention, there is a spiral main exhaust passage that opens directly toward the inlet of the terpino rotor, and a spiral main exhaust passage that is arranged in parallel with the main exhaust passage and that does not directly open to the rotor inlet. An auxiliary exhaust passage is provided, and a communication part of a constant width defined by two concentric circles centered on the axis of the rotor is provided on the partition wall between both exhaust passages, and this communication part is provided over almost the entire circumference of the rotor. The slit shape of the section is inclined in a direction approaching the axis from the main exhaust passage side to the auxiliary exhaust passage side, and this inclination allows the wall surfaces to overlap between both passages. Since the engine is equipped with a valve that adjusts the amount of exhaust gas supplied to the rotor, it is possible to prevent the exhaust gas from the dead water region generated in the auxiliary exhaust passage from being carried into the rotor with energy loss even when the engine is at low speed. , suitable boost pressure can be supplied and good turbine efficiency can be obtained.

Furthermore, even at medium-high speeds, the exhaust gas can be guided directly to the rotor for supercharging, so there is little loss of exhaust energy and the back pressure of the engine can be lowered, contributing to medium-high speed output. It goes without saying that it can be done.

In addition, in the above explanation, the partition wall is configured to be a surface perpendicular to the rotation axis, but depending on the spiral form of the scroll to be set, it may not necessarily be a surface perpendicular to the rotation axis. The surface may be tilted more than this.

[Brief explanation of drawings]

Figure 1 is a sectional view showing an example of the configuration of a conventional variable capacity turbine Sugeroll; Figures 2 (A) and (B) are swirling flows generated around the turbine rotor when the on-off valve is open and closed. and,
Explanatory diagrams showing the tendency of circulation flow generated in the large exhaust passage, FIG. 3 is a sectional view showing an example of a conventional turbine scroll of double entry housing type, and FIG. 4 is a configuration of the turbine scroll of the turbocharger of the present invention. FIG. 5 is a cross-sectional view showing details of the communication portion thereof; FIG. 6 is a cross-sectional view showing a state in which a rotary valve is provided in the auxiliary exhaust passage of the turbine scroll according to the present invention; FIG. 7 is a sectional view taken along Y-Y line of the rotary valve shown in FIG. 6; FIG. 8 is a sectional view for explaining the state in which harmful secondary drift is prevented by the communication portion of the turbine scroll according to the present invention; The figure is a characteristic curve diagram showing how the turbine efficiency decreases when the ratio between the width of the slit and the amount of overlap in the communication section is changed, and Figures 10 (A) and (B) are other embodiments of the present invention. As an example, a cross-sectional view showing a state in which a flap valve is provided in an auxiliary exhaust passage and a cross-sectional view taken along the line X-X, and FIG. 11 is a cross-sectional view of a turbine scroll according to still another embodiment of the present invention. l...Turbine rotor, IA...Inlet section, 2...Shaft, 3.13...Turbine scroll, 3^, 3B, 4...Exhaust road, 30.13G...Inlet Part, 5... Housing, 5A... Wall, 5B; 5G... Partition wall, 5G, 5D, 5E... Wall surface, [1, 25, 35... Valve, 7... Gas outlet , IO...Swirling flow, 11...Circulating flow, 13A, 13B, 13D...Exhaust passage, 14...Opening part, 15...Communication part, 15A, 15B, 15B'...Edge Department. ]6... Tongue, 17... Throat, 28... Cover, 27... Bush, 28... Shaft, 28... Lever, 30A, 30B... Wall, Al, A2 ．． Bl...position, 36...opening/closing axis, 37...valve seat, 40...flow. Patent applicant Nissan Motor Co., Ltd. Figure 1 Figure 2 (B) Figure 3

Claims (1)

[Scope of Claims] A spiral main exhaust passage having an opening facing the turbine rotor inlet, an auxiliary exhaust passage provided alongside the main exhaust passage and separated from the turbine rotor inlet by a partition wall; a valve that makes the amount of exhaust gas supplied to the auxiliary passage variable depending on the operating state of the engine; A communication portion having a width extending substantially over the entire circumference of the turbine rotor is provided, and a cross-sectional shape including the axis of the communication portion is arranged in a direction from the main exhaust passage side to the auxiliary exhaust passage side toward the axis of the turbine rotor. the main exhaust passageway and the auxiliary exhaust passageway to prevent the exhaust gas from directly moving in the direction of the axis via the communication part, and to direct the exhaust gas to the communication part. so that communication is possible only along the slope of the engine, and in a low speed rotation region of the engine, the auxiliary exhaust passage is closed by the valve and the exhaust gas is supplied to the turbine rotor only through the main exhaust passage. A turbine scroll for a turbocharger, which is characterized by being made to do so. (Hereafter, margin)