JPS63186915A - Exhaust turbine type supercharger in variable capacity type - Google Patents

Abstract

PURPOSE:To obtain the superior supercharge faculty over the all revolution speed range of an engine by specifying the ratio of the representative values which represent the capacity of the turbine cases of the scroll chamber parts, in the constitution in which the scroll chamber in the turbine casing is divided into two chambers. CONSTITUTION:The scroll chamber of the turbine case 4 of an exhaust turbine type supercharger is divided into the first and second scroll chambers 7 and 8 by a partitioning wall 9, and nozzle parts 7a and 8a are formed on the inner peripheral side of the scroll chambers 7 and 8. A turbine inlet 4a is constituted of the first and second exhaust gas introducing passages 9 and 10 communicating to the scroll chambers 7 and 8, and a flow passage control valve 13 which cooperates with a valve seat body 14 is arranged inside the second exhaust gas introducing passage 10. In this case, if the flow passage area of the winding start part of the scroll of the turbine case 4 is represented by A, and the distance from the turbine axis center to the center of gravity of the area A is represented by R, the reatio S between the A/R values of the scroll chambers 7 and 8, namely the ratio S =Ar2/Ar1 is set to 2 or less.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a variable displacement exhaust turbine supercharger.

[Conventional technology]

Conventionally, as disclosed in, for example, Japanese Unexamined Patent Application Publication No. 60-19918, a first.
A second scroll chamber is provided, and in the low speed range of the internal combustion engine, the exhaust gas flows toward the first scroll chamber, and in the high speed range, the exhaust gas flows into the first scroll chamber. A variable displacement exhaust turbine supercharger that rotates a turbine by flowing exhaust gas into both second scroll chambers has been put into practical use.

This type of supercharger allows the exhaust gas to flow only to the first scroll chamber side of the supercharger when the exhaust gas is in a small flow rate, such as in the low-speed range of an internal combustion engine. In other words, in order to increase the output of the internal combustion engine at low speeds, we aim to increase the output of the internal combustion engine at low speeds by reducing the flow rate of the ratio (flow rate characteristic), that is, by accelerating the rise of the turbocharging pressure of the turbine in the small flow rate range.In addition, in the high speed range, in response to the increase in exhaust gas, First, exhaust gas. It flows into both second scroll chambers to increase output during high-speed operation.

By the way, in this type of supercharger, generally the A/R on the first scroll chamber side (A/R is a representative value representing the capacity of the turbine case, A is the flow path area at the beginning of scroll winding of the turbine case, R is is the distance from the turbine axis to the center of gravity of area A (expressed in inches), which is reduced to a certain extent (usually A/
On the other hand, the A/R on the second scroll chamber side tends to be larger than the first scroll chamber in order to accommodate a large amount of exhaust gas flow rate. When the A/R size of the second scroll is varied as described above, there are the following points to be improved.

[Problem that the invention seeks to solve]

That is, in the above prior art, A of the first scroll chamber
/ RT A of the second scroll chamber compared to A r t
/ When RHA r 2 is increased.

(1) When the exhaust gas inlet of the second scroll chamber is closed and the exhaust gas flows to the first scroll chamber side when the internal combustion engine is running at low speed, the larger the A/R on the second scroll chamber side, the more Since the exhaust gas flowing through the first scroll chamber leaks into the second scroll chamber through the nozzle portion, there has been a problem in that it is difficult to reduce the turbine flow rate characteristics by the amount of leakage. It is also possible to anticipate such a leakage amount in advance and further reduce A/R, Art of the first scroll chamber, but in this case, the flow path resistance of the first scroll chamber will increase and the turbine insulation will be reduced. The efficiency (work rate) decreased, and it was not sufficient as a measure to improve the low-speed performance of internal combustion engines.

(2) When the internal combustion engine is running at high speed, the first. The second scroll chamber is opened to introduce exhaust gas into both scroll chambers, but in this case, there is a dimensional restriction on the nozzle width of the nozzle section that guides the exhaust gas in the scroll chamber toward the turbine impeller. As the A/R on the scroll chamber side increases, that is, as the exhaust gas flow rate in the second scroll chamber increases, the ventilation resistance of the nozzle increases, and the turbine insulation efficiency decreases due to resistance loss. increases, the exhaust efficiency of the internal combustion engine decreases, and the output of the engine tends to decrease.

The present invention has been made in view of the above points, and its purpose is to solve the problems (1) and (2) above and improve supercharging performance even in the low speed range and high speed range of the internal combustion engine. An object of the present invention is to provide a variable displacement exhaust turbine supercharger that can effectively improve the performance of an internal combustion engine.

[Means for solving problems]

The above purpose is to reduce the A/R value Arz of the first scroll chamber and the A/R value of the second scroll chamber in this type of supercharger.
This is achieved by not increasing the ratio 5=Arz/A r 1 to the value Arz so much and by making S≦2.

[Effect]

In order to improve the supercharging performance of an exhaust turbine supercharger, it is first necessary to accelerate the rise of the boost pressure characteristics in the low speed range of the internal combustion engine as much as possible. It is necessary to reduce the flow rate characteristics (expansion ratio - flow rate characteristics).

Secondly, it is necessary to improve the adiabatic efficiency of the turbine. In the present invention, first. As a result of various studies on the relationship between the second scroll chamber, it was possible to improve the turbine performance by devising the A/R ratio S of the first and second scroll chambers as follows. That is, 1st. A/R of the second scroll chamber
When the ratio S''A r 2/A r 1 is set within a predetermined range (S≦2), the space ratio of the second scroll chamber to the space of the first scroll chamber is not very large, so
The leakage space on the second scroll chamber side becomes smaller, and as a result, the amount of exhaust gas leaking into the second scroll chamber is reduced when exhaust gas flows only to the first scroll chamber side in the low speed range of the internal combustion engine. Therefore, it is possible to effectively reduce the turbine flow rate characteristics.

In addition, in the high-speed range of an internal combustion engine, as the amount of exhaust gas to flow into the turbine increases, the exhaust gas is introduced into the first scroll chamber and the second scroll chamber. Since the size is not increased, the flow rate of the exhaust gas flowing through the second scroll chamber does not become excessive, and therefore, the flow path resistance of the exhaust gas passing through the nozzle portion in the turbine case is reduced, and the turbine adiabatic efficiency can be improved. In addition, 1. The reason why the A/R ratio S of the second scroll is set to S≦2 is because of the first scroll. As a result of varying the A/H ratio of the second scroll, the adiabatic efficiency of the turbine required to obtain satisfactory internal combustion engine performance is determined to be R≦ ηt = 60%.
This is because it was obtained within the range of 2.

〔Example〕

An embodiment of the present invention will be explained based on FIGS. 1 to 10.

FIG. 1 is a partial sectional view of a variable displacement exhaust turbine type supercharger to which this embodiment is applied, and FIG. 2 is a perspective view of a flow path control valve used in the supercharger.

In FIG. 1, numeral 1 indicates an internal combustion engine to be supercharged.

2 is an exhaust gas flow path that guides exhaust gas from the internal combustion engine to the supercharger 3 side. The supercharger 3 is a turbine in which a turbine wheel 5 is housed within a turbine case 4 .

A compressor 6 fixedly arranged on the same axis as this turbine
It becomes more. 4a is a turbine inlet, 4b is a turbine outlet, and the scroll chamber of the turbine case 4 is divided by a partition 9 into a first scroll chamber 7 and a second scroll chamber 8. Nozzle portions 7a and 8a communicating with the housing portion of the turbine impeller 5 are formed on the inner peripheral side of the second scroll chambers 7 and 8.

The partition wall 9 extends halfway into the turbine inlet 4a.

The turbine population 4a has a first turbine connected to the first scroll chamber 7.
Exhaust gas introduction passage 9 and a second passage leading to second scroll chamber 8
It is connected to the exhaust gas introduction path 10.

The flange 11 of the turbine inlet 4a and the exhaust gas flow path 2
The flange 12 of is bolted.

A flow path control valve 13 is arranged inside the second exhaust gas introduction path 10 so as to open in the flow direction of the exhaust gas. The flow path control valve 13 is controlled to open and close by a negative pressure actuator, an electric actuator, or the like.

Further, a second exhaust gas introduction path 1 is provided between the flanges 11 and 12 at the turbine inlet 4a in cooperation with the flow path control valve 13.
A valve seat body 14 that adjusts the flow rate of exhaust gas flowing into the valve body 14 is sandwiched therein. As shown in FIG. 2, the valve seat body 14 includes a held portion 15 held between flanges 11 and 12, and a first
It is made up of a first opening 16 communicating with the exhaust gas introduction path 9, a second opening 17 communicating with the second exhaust gas introduction path 10, and a cylindrical portion 18 separating the second opening 17 from the first exhaust gas introduction path 9.
It is molded from a heat-resistant material such as stainless steel. 19
20 is a bypass hole that connects the first exhaust gas introduction path 9 and the turbine outlet 4b; 20 is a bypass valve;
The amount of exhaust gas flowing into the first scroll chamber 7 can be adjusted by opening and closing.

Therefore, in the low speed range of the internal combustion engine, the supercharger in this embodiment closes the second exhaust gas introduction path 1o on the second scroll chamber 8 side with the valve 13, and closes only the first exhaust gas introduction path 9 side. It is opened to allow exhaust gas to flow toward the first scroll chamber 7 to cope with a smaller flow rate of exhaust gas, and on the other hand, in the high speed range of the internal combustion engine.

Open the valve 13 and turn on the first valve. Exhaust gas is allowed to flow into both of the second scroll chambers 7.8. In this embodiment, in particular, the A/R value of the first scroll chamber 7, Arl, and the second
A/R value of scroll chamber 8, ratio with Arz S=Ar2/
Ar1 is set so that S≦2.

Below, Part 1. The influence of A/R of the second scroll chambers 7 and 8 on turbine performance will be explained based on experimental data shown in FIGS. 3 to 10.

First, as an example, a turbine A is constructed in which the A/R value (unit: 1 inch) of the first scroll chamber 7 is set as Ar1 = 0.25, and the A/R value of the second scroll chamber 8 is set as Arz = 0.37.
S=A rx/A rx= 1.48).

Similarly, Arx=0.25 and Arz=
Turbine B (S=Arz/Ar1=
The turbine performance with 2.56) will be explained with reference to FIGS. 3 and 4. Here, the only difference between the turbines A and B is regarding the A/R of the scroll, and the other conditions are the same.

FIG. 3 shows the corrected flow rate bin flow rate of turbine A and turbine B, Ptz: turbine inlet pressure, Po: condition pressure in standard state, To: 1? Condition temperature of I quasi-state.

T, 1: Changes in the expansion ratio (pressure ratio between the turbine head and the outlet) with respect to the turbine inlet temperature) are compared. According to this, when the flow path control valve 13 is fully open.

In other words, when introducing exhaust gas only into the first scroll chamber 7 side, the flow rate characteristic 60a of turbine A causes the expansion ratio to rise earlier in the small flow rate region than the flow rate characteristic 61a of turbine B, and the flow rate characteristic A result was obtained in which the flow rate-expansion ratio characteristic was reduced to a small flow rate. As described above, the reason why the flow rate characteristic of turbine A is smaller than that of turbine B is because the smaller the ratio of the space size of second scroll chamber 8 to first scroll chamber 7, the smaller the ratio of the space size of second scroll chamber 8 to first scroll chamber 7, This is because the leakage space for exhaust gas leaking from the scroll chamber 7 to the second scroll chamber 8 side becomes smaller, and the flow rate characteristics in the small flow rate region can be improved by that much. On the other hand, as the space to the second scroll chamber 8 becomes larger, the amount of exhaust gas leaking from the first scroll chamber 7 to the second scroll chamber 8 via the nozzles 7a and 8a increases, and the amount of exhaust gas leaking into the second scroll chamber 8 increases accordingly. The amount of gas required to obtain the expansion ratio increases, making it difficult to reduce the flow rate characteristics. Note that when the flow path control valve 13 is fully open, the first and second
Although exhaust gas flows into the scroll chambers 7 and 8, in this case as well, the flow rate characteristic 60b of turbine A is smaller than the flow rate characteristic 61b of turbine B, as shown in FIG.

This is the first. This is because the sum of A/H of the second scroll chamber 7.8 is smaller in turbine A than in turbine B.

In addition, in the case of turbine A, the sum of A/R, that is, the first
．． It is possible that the total capacity of the second scroll chamber becomes relatively small, and as a result, the capacity for receiving exhaust gas sent from the engine exceeds the capacity limit. By opening the bypass valve 20 provided at the exhaust gas inlet 9 and allowing the exhaust gas to flow from the bypass hole 19 to the turbine outlet 4b side, the problem of insufficient capacity for receiving exhaust gas in the dub can be solved.

Figure 4 shows the speed ratio U/C between turbine A and turbine B.
(Here, U: Turbine circumferential speed, C: Theoretical flow velocity of exhaust gas)
This is a comparison of changes in turbine adiabatic efficiency. When the flow path control valve 13 is closed and the exhaust gas flows only to the first scroll chamber 7 side, the adiabatic efficiency 62a of the turbine A is
and the adiabatic efficiency 63a of turbine B are almost equal. this is,
This is because the A/R of both first scrolls have the same setting conditions. Also, the flow path control valve 13 is opened and the first. When exhaust gas flows into the second scroll chambers 7 and 8, the adiabatic efficiency 62b of turbine A is higher than the adiabatic efficiency 62b of turbine B.
Experimental results showed that the insulation efficiency was about 10% better than that of 3b. This is because although the width of the nozzle 8a of the second scroll chamber 8 of turbine A and i-bin B is the same, the width of the nozzle 8a of the second scroll chamber 8 of turbine A is larger than that of turbine B.
This is because /R is small, so the amount of exhaust gas flowing into the second scroll chamber 8 is reduced, and the ventilation resistance of the nozzle portion 8 is reduced by that much, making it possible to improve the heat insulation efficiency. If you turn it over, it will be on the turbine B side.

Since the A/R of the second scroll chamber is large, flow path resistance at the nozzle portion increases, which causes a decrease in turbine adiabatic efficiency.

FIG. 5 shows the A/R-insulation efficiency characteristic of the second scroll chamber when the flow path control valve 13 is fully closed when the A/R of the first scroll chamber is 0.25. As is clear from the experimental data shown in the figure, if only the A/R of the second scroll chamber is increased, the insulation efficiency decreases for the above-mentioned reason.

In addition, as mentioned above, A/ in turbine A and turbine B is
R is the same on the first scroll chamber 7 side (Apl=0.25
), and when the second scroll chamber 8 side is different (Ar
z=0.37,0.64).

When exhaust gas is introduced only to the first scroll chamber side.

The flow characteristics in turbine B are reduced, but in this case,
The A/R of the second scroll chamber is kept as Arz=0.64, and the A/R1Arx of the first scroll chamber is set to 0625.
If it is made smaller to some extent (in the experimental results, Art=0
．． 22) The same small flow characteristics as turbine A can be obtained. Figure 6 shows a turbine C (S=Arz/Art: 2 .91) and the modified flow rate-expansion ratio characteristics of the turbine A described above.

As shown in the figure, when the flow path control valve 13 is fully closed (flow only to the first scroll chamber side), the A
By making /R smaller than that of turbine A, the flow rate characteristic 64a of turbine C can be made almost the same as the flow rate characteristic of turbine A. However, the turbine adiabatic efficiency of turbine C is lower than that of turbine A, as shown in FIG. FIG. 7 shows a comparison of the speed ratio-turbine adiabatic efficiency characteristics of turbines A and C. As is clear from the experimental data in the same figure, when only the first scroll chamber side flows, The result was that the adiabatic efficiency 65a of the turbine C was lower than the adiabatic efficiency 62a of the turbine A by about 8%. The reason for this is that in order to reduce the flow rate characteristics, the A/R of the first scroll was made smaller in turbine C than in turbine A, resulting in an increase in flow path resistance and a reduction in adiabatic efficiency by the amount of resistance loss. It is. Note that when the flow path control valve is fully open, the adiabatic efficiency 65b of turbine C is equal to that of turbine A.
The reason why the adiabatic efficiency 63b of the turbine B is lower than that of the adiabatic efficiency 62b shown in FIG.

As mentioned in the ``effect'' section of the invention, in order to improve the performance of this type of supercharger, it is necessary to reduce the turbine flow rate characteristics in the low speed range of the internal combustion engine and to insulate the turbine. However, improvements in efficiency are required.

In order to improve the turbine flow rate characteristics and adiabatic efficiency, it is necessary to improve not only the A/R of the first scroll chamber but also the A/R of the second scroll chamber, as explained using the experimental data shown in Figures 3 to 7.
It is necessary to consider R6. Also, A / R of the first scroll chamber 7 ([A r t and A of the second scroll chamber 8
/ R (f! The limit value of the ratio S with A r z is S≦2
The reason for setting this numerical value will be explained here.

Prior to the explanation, in this example, A of the first scroll chamber.
The reason why /R was set to 0.25 will be explained first. To improve the low speed performance of internal combustion engines.

It is necessary to reduce the flow rate characteristics of the turbine, and the means to achieve this is to reduce the A/R of the turbine scroll, but if the A/R is reduced, the flow path resistance increases and the turbine adiabatic efficiency decreases. Therefore, it cannot be made infinitely small, and the A/R must be determined within a range that ensures the turbine adiabatic efficiency ηt=60% necessary to obtain satisfactory performance of the internal combustion engine. Figure 8 shows A of this first scroll chamber.
This figure shows the change in turbine adiabatic efficiency with respect to /H. As is clear from the experimental data in the same figure, the adiabatic efficiency 66 of the first scroll chamber decreases as A/R decreases, and is not satisfied. In order to obtain the turbine adiabatic efficiency ηt = 60% necessary to obtain the low speed performance of the engine, A/
R needs to be 0.25 or more, and based on the above results, the first
The A/R of the scroll chamber is set to 0.25.

Further, FIG. 9 shows the case where the A/R of the first scroll chamber is set to 0.25 and the A/R of the second scroll chamber is changed when the flow path control valve 13 is fully closed (only the first scroll chamber is in flow). Turbine adiabatic efficiency characteristics 67 and when the flow path control valve is fully open (1st.
The turbine adiabatic efficiency characteristic 68 of the second scroll chamber (flow through the second scroll chamber) is shown for the ratio 5=Arz/Arl of A/R, Ar1 of the first scroll chamber and A/R, Arz of the second scroll chamber. be. In FIG. 9, S=O is the case where the second scroll chamber does not exist, and as is clear from the experimental data in the same figure, the turbine adiabatic efficiency characteristic 67 when the flow path control valve 13 is fully closed is O<S In the range of ≦2, the flow rate remains at about 60%, but when S>2, the exhaust gas flow loss due to leakage from the first scroll chamber to the second scroll chamber begins to increase, and as S increases, the insulation decreases. The efficiency characteristic 67 is reduced. Further, the turbine adiabatic efficiency characteristic 68 when the flow path control valve is fully open decreases as S increases, and the ratio S of A/R decreases.
When =Ar2/Ar1 becomes S>3, the insulation efficiency becomes 60% or less. This is because even if S increases (even if A/R of the second scroll chamber increases), the nozzle width of the second scroll chamber remains constant.

As the amount of gas flowing through the second scroll chamber increases,
The flow path resistance at the nozzle portion increases, and the adiabatic efficiency 68 increases.
This is because S continues to decrease from an arbitrary value.

The above phenomenon is observed even when the A/R of the first scroll chamber is other than 0.25. According to the experimental data shown in Figures 8 and 9, in order to obtain the turbine adiabatic efficiency ηt = 60%, which is necessary for both low-speed performance and high-speed performance of the internal combustion engine, it is necessary to satisfy S≦2. be.

In addition, A/R between the first scroll chamber and the second scroll chamber
In order to further narrow down the ratio S from within the range of S≦2 and determine the optimum value, the turbine blades and turbine casing (other than A/R)
It is necessary to set the optimum value of the A/R ratio S that meets these conditions depending on the shape of the A/R ratio S. FIG. 10 shows the 1. Second
This shows experimental data for determining the optimal value of the A/R ratio S of the scroll chamber (note that the A/R of the first scroll chamber is 0).
．． It is set to 25. ), S=Ar2/Ar1 and turbine inlet maximum pressure Pt for turbine flow rate Gt
This represents the characteristics of the adiabatic efficiency ηt. Here, the maximum pressure at the turbine inlet is large (I see, from the perspective of the internal combustion engine, the exhaust efficiency decreases and the output decreases. Therefore, in order to prevent the output decrease.

It is necessary to reduce the maximum turbine inlet pressure as much as possible. Under the experimental conditions shown in FIG. 10, when the flow path control valve is fully open (when the first and second scroll chambers are flowing), the A/R of the second scroll chamber is set to A/R=0.37, that is. A result was obtained in which the maximum turbine inlet pressure was the lowest when S=1.48. Then, when S=1.48 or less, as S becomes smaller, A// of the second scroll chamber becomes smaller.
As R decreases, the maximum turbine inlet pressure P, increases, while for S=1.48 and above, as S increases.

When the flow path control valve is fully open, the ventilation resistance of the nozzle portion of the second scroll chamber increases, and as a result, the turbine adiabatic efficiency decreases, resulting in an increase in the maximum pressure at the turbine inlet.

Therefore, in this embodiment, the first. If you do the second scan,
The result was the optimum value.

To summarize the explanations from Fig. 3 to Fig. 10 above, when the flow path control valve is fully open (flow only to the first scroll chamber), the turbine performance decreases due to exhaust gas leaking into the second scroll chamber. Therefore, it is better for S to be small to a certain extent. On the other hand, the turbine performance when the flow path control valve is fully open (flow to the first and second scroll chambers) is also greatly influenced by S, and in this case, the turbine performance (turbine adiabatic efficiency ) is the best, and that optimal value is the first. The A/R ratio of the second scroll chamber is determined from within the range of 0 x S≦2.

According to this embodiment, the adiabatic efficiency of the turbine is not reduced when the flow path control valve is fully open.

Since the flow rate characteristics can be reduced to a small flow rate, the low speed performance of the internal combustion engine can be improved. Further, in the same way, the turbine adiabatic efficiency when the flow path control valve is open can be significantly improved, thereby reducing the turbine inlet pressure of the internal combustion engine and preventing a decrease in the output of the internal combustion engine.

Therefore, it is possible to improve the supercharging performance in the low speed range and high speed range of the internal combustion engine, and in turn, it is possible to effectively improve the performance of the internal combustion engine.

〔Effect of the invention〕

As described above, according to the present invention, the first. By devising the A/R ratio S of the second scroll chamber.

It is possible to improve the supercharging performance in the low speed range and high speed range of the internal combustion engine, and in turn, it is possible to effectively improve the performance of the internal combustion engine.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway sectional view showing an example of a supercharger to which the present invention is applied, FIG. 2 is a perspective view of a flow path control valve used in the above-mentioned supercharger, and FIGS. The figure shows the first part of the above supercharger. Diagrams showing the relationship between the corrected flow rate and the expansion ratio when the A/R ratio S of the second scroll chamber is changed, and Figures 4 and 7 show the speed ratio when the AZR ratio S is changed in the same manner as above. FIG. 5 is a diagram showing the relationship between A/R of the second scroll chamber, Arz and turbine adiabatic efficiency, and FIG. 8 is a diagram showing the A/R of the first scroll chamber. A diagram showing the relationship between Ar1 and turbine adiabatic efficiency. Figure 9 shows the above 1. A/R ratio of the second scroll chamber 5=
A diagram showing the relationship between Atz/Art and turbine adiabatic efficiency, FIG. 10, is based on the above-mentioned 1. FIG. 2 is a diagram showing the relationship between the A/R ratio A r x /A r 1 of the second scroll chamber, the turbine flow rate, the maximum pressure at the turbine inlet, and the turbine adiabatic efficiency. l... Internal combustion engine, 3... Supercharger, 4... Turbine case, 5... Turbine impeller, 6... Compressor, 7... First scroll chamber, 8... No. 2 scroll chamber, 13...flow path control valve.

Claims (1)

[Claims] 1. The exhaust type turbine and the compressor are fixedly arranged on the same axis, and the scroll chamber in the turbine case is divided into a first and second scroll chamber, and depending on the rotational speed of the engine, the scroll chamber is divided into the first scroll chamber or the first, second scroll chamber. In a variable capacity supercharger that drives a turbine by flowing exhaust gas into both second scroll chambers, A is the A/R value of the first scroll chamber.
r_1 and Ar, which is the A/R value of the second scroll chamber.
A variable displacement exhaust turbine supercharger, characterized in that the ratio S=Ar_2/Ar_1 to S=Ar_2/Ar_1 is set so that S≦2.