JPH0415369B2 - - Google Patents

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.

Figure 1 shows an example of a conventional turbine scroll with variable capacity of this type.
This is disclosed in No. 11233. here,
A turbine rotor 1 is directly connected to a compressor impeller (not shown) by a rotor shaft 2. A turbine scroll 3 with a spiral passage is provided on the outer periphery of the turbine rotor 1. Exhaust gas from passage 4 is guided.

Further, in the turbine scroll 3 of this example, the housing 5 has a wall 5 projecting from an oblique direction with respect to the shaft 2.
The large exhaust passage section 3A and the small exhaust passage section 3B form a spiral chamber, and these passage sections 3A and 3B are opened toward the inlet section 1A of the rotor 1. I'm letting you do it.

Reference numeral 6 denotes an on-off valve provided on the large exhaust passage 3A side of the exhaust passage 4 connected to the inlet portion 3C of the scroll 3. This on-off valve 6 changes the volume of exhaust gas flowing into the large exhaust passage 3A. can be done. 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,
In order to maintain compatibility between the turbocharger and the engine and obtain good supercharging characteristics at low speeds, it is necessary to reduce the gas passage area. (1) allows the on-off valve 6 to be operated to adjust the volume of gas passing through the large exhaust passage 3A. Furthermore, when the engine is in a high speed rotation region, the large exhaust passage 3
Gas is supplied to the rotor 1 from both A 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 in this way, both the large exhaust passage 3A and the small exhaust passage 3B have a shape that opens toward the rotor inlet portion 1A, and furthermore, Since the gas flow rate of the large exhaust passage 3A is configured to be throttled by the valve 6, when the gas supply to the large exhaust passage 3A is suddenly cut off by the on-off valve 6 in the low speed rotation region of the engine, this A dead water area occurs in the large exhaust passage 3A.

In such a state, gas flows from the rotor inlet 1A to the rotor 1 via the small exhaust passage 3B.
At this time, a swirling flow 10 as shown in FIG. 2A is generated near the inlet portion 1A, so that the gas fluid forming the swirling flow 10 has a centrifugal force. A part of the gas fluid is then dissipated 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. 2B is generated there. Since this circulating flow 11 flows along the wall surface of the large exhaust passage 3A, it loses energy due to friction loss and joins the swirling flow 10 again, so the energy loss within the turbine scroll 3 is large and the turbine efficiency is reduced. resulting in a decrease in

Furthermore, FIG. 3 shows a commonly used double entry housing type scroll 3, in which the housing 5 is divided in the axial direction by a wall 5A projecting from the outer periphery. 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 that of a single-entry turbine scroll, and the rise of turbocharging pressure at low speeds becomes difficult.

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 such an object, the present invention has a main exhaust passage that is open toward almost the entire circumference of the turbine rotor inlet, and a main exhaust passage that is arranged in parallel with the main exhaust passage via a partition wall and is isolated from the turbine rotor inlet. A partition wall is provided between the main exhaust passage and the auxiliary exhaust passage along the outer periphery of the exhaust passage of the spiral housing, which also has an auxiliary exhaust passage whose introduction of exhaust gas is controlled according to the operating condition of the engine. The present invention is characterized in that a communicating portion is provided, and the range of the communicating portion is from a passage constriction portion corresponding to the beginning of winding of the spiral to a minimum passage portion corresponding to the end of winding.

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

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

As shown in FIG. 5A, this communication portion 15 is continuously provided at a position along the inner circumferential surface of the scroll housing 5, and the width B of the groove-shaped communication portion 15 is kept constant. The range in which the communication portion 15 is provided is from the smallest passage portion of the tongue portion 16 of the scroll 13 on the rotor 1 side to the throttle portion, that is, the throat portion 17 formed by the tongue portion 16 and the housing 5. However, if it is not possible to provide the communication part 15 continuously in this range as shown in FIG. 5 due to design or structural reasons, the area where the communication part 15 is not provided is made as short as possible and The increase in loss due to non-uniformity of the channel structure in the portion 1A is suppressed.

Reference numeral 18 denotes an on-off valve provided on the auxiliary passage 13B side of the exhaust passage 4 that connects to the inlet portion 13C of the scroll 13, and is opened and closed via a control mechanism and a drive mechanism (not shown) in the low speed rotation region of the engine. This on-off valve 18 is closed.

The following formula has been confirmed by the inventor as a condition for obtaining the best supercharging characteristics when setting the width B of the communication portion 15.

B≧A _BT /R _B /A _AT /R _A +A _BT /R _B ×H …(1) However, in equation (1), A _AT : Area of the main exhaust passage 13A at the constricted part 17A A _BT : Auxiliary exhaust Area of the passage 13B at the throttle section 17B R _A : Distance from the rotor center O to the center of gravity of the throttle section 17A R _B : Distance from the rotor center O to the center of gravity of the throttle section 17B H: Blade width at the inlet section 1A of the turbine rotor 1 , When it is necessary to make the width B of the communication portion 15 taper toward the downstream due to design reasons, etc.,
Keeping the above conditions in mind, care must be taken to minimize losses.

In the turbine scroll 13 configured in this way, the on-off valve 18 is closed in the low speed rotation region of the engine.
When the auxiliary exhaust passage 13B is closed, a dead water area occurs in the auxiliary exhaust passage 13B, but the auxiliary exhaust passage 13B
Since it is separated from the main exhaust passage 13A by B, it is not opened toward the inlet 1A of the rotor 1, and therefore, there is a gap on the auxiliary exhaust passage 13B side as explained in FIGS. 2A and B. No flow occurs. Thus, although the communication section 15 exists, the main exhaust flow flows through the main exhaust passage 1 in almost the same manner as if the partition wall 5B were present in this section 15.
A limited amount of 3A flows into the rotor 1.

Therefore, the rise characteristics of the supercharging pressure in the low speed rotation region are similar to those of a single entry turbine scroll having a small throttle area, and good low speed supercharging characteristics can be maintained.

Furthermore, from such a rise in supercharging pressure,
After the predetermined pressure is reached, the on-off valve 18 begins to open via a control mechanism using boost pressure, etc., so that exhaust gas is guided to both the main exhaust passage 13A and the auxiliary exhaust passage 13B, where the auxiliary exhaust The exhaust gas guided to the passage 13B passes through the communication part 15 to the main exhaust passage 13.
It flows into the A side and is guided to the rotor 1 together with the exhaust gas from the main exhaust passage 13A side.

In particular, the communication portion 15 is provided at a position along the inner circumference of the scroll 13, and is the part of the scroll 13 where the flow velocity is the slowest. The loss when the exhaust gas is mixed in is also kept to a minimum, and even in the high-speed rotation region, that is, when the exhaust flow rate is large, there is no problem with the decrease in efficiency due to the exhaust gas passing through the communication hole 15, and good supercharging is achieved. Characteristics can be retained.

As described above, according to the present invention, there is a main exhaust passage that is open toward almost the entire circumference of the turbine rotor inlet, and a main exhaust passage that is arranged in parallel with the main exhaust passage via a partition wall, and which is connected to the turbine rotor inlet. A partition wall is provided between the main exhaust passage and the auxiliary exhaust passage along the outer periphery of the exhaust passage of the spiral housing, which has an auxiliary exhaust passage that is isolated from the main exhaust passage and whose introduction of exhaust gas is controlled according to the operating state of the engine. We have provided a communication part that communicates with the air, and the range of the communication part is from the passage constriction part corresponding to the beginning of the spiral winding to the minimum passage part corresponding to the end of the spiral winding. Even if the exhaust gas is controlled to be blocked, the dead water region generated in the auxiliary exhaust passage will not be carried into the rotor with energy loss, and an appropriate boost pressure can be supplied, resulting in good turbine efficiency. .

Furthermore, even at high speeds, the exhaust gas can be guided directly to the rotor for supercharging, so there is less loss of exhaust energy and the back pressure of the engine can be lowered, which of course contributes to high-speed output. Nor.

In the above explanation, the partition wall is configured to have a surface perpendicular to the rotation axis, but depending on the spiral shape of the scroll to be set, the partition wall does not necessarily have to be a surface perpendicular to the rotation axis. , the surface may be slightly inclined from this angle.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing an example of the configuration of a conventional variable displacement turbine scroll, and Figs. 2 A and B show the swirling flow generated around the turbine rotor and the large exhaust passage when the on-off valve is closed. FIG. 3 is a sectional view showing an example of a conventional turbine scroll of the double entry housing type, and FIG. 4 is a sectional view showing an example of the structure of the turbine scroll of the turbocharger of the present invention. 5A is a cross-sectional view taken along the line A--A, and FIG. 5B is a partial cross-sectional view of the constricted portion of FIG. 5A. 1... Turbine rotor, 1A... Inlet part, 2... Shaft,
3, 13...Turbine scroll, 3A, 3B, 4
...Exhaust passage, 3C, 13C...Inlet part, 5...Housing, 5A...Wall, 6, 18...Opening/closing valve, 7...Gas outlet, 10...Swirling flow, 11...Circulating flow, 13A, 13
B...Exhaust passage, 14...Opening part, 15...Communication part, 1
6... Tongue portion, 17, 17A, 17B... Squeezed portion.

Claims (1)

[Claims] 1. A main exhaust passage that is open toward almost the entire circumference of the turbine rotor inlet, and a main exhaust passage that is parallel to the main exhaust passage via a partition wall, is isolated from the turbine rotor inlet, and is arranged in accordance with the operating state of the engine. A communication portion is provided in the partition wall along the outer periphery of the exhaust passage of the spiral housing having an auxiliary exhaust passage in which the introduction of exhaust gas is controlled by the main exhaust passage. A turbine scroll for a turbocharger, characterized in that the communication portion is arranged in a range from a passage constriction portion corresponding to the start of winding of the spiral to a minimum passage portion corresponding to the end of winding.