JPS6019920A - Turbine scroll for turbo-supercharger - Google Patents

Abstract

PURPOSE:To obtain a satisfactory turbine efficiency, by making the exhaust gas volume fed to an exhaust gas turbine, variable at the inlet port section of a scrol in accordance with the operating condition of an engine. CONSTITUTION:When a rotary valve is in its closed condition in the low rotational speed range of an engine, although a dead water region is brought about on an auxiliary exhaust passage 13B side, no swirl flow is generated since the passge 13B have no opening for a rotor inlet port 1A. In the condition of the middle speed range, the rotary valve disposed in the auxiliary passage 13B is opened to an intermediate degree so that the main stream flows from the auxiliary exhaust passage 13B side through the rotary valve, in addition to from a main exhaust passage 13A side. When the rotary valve is fully opened, gas is led from the entire periphery of a communication passage 15 to the main exhaust passage 13A side so that all volume of gas is led to the rotary valve.

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, reference numeral 1 denotes a turbine rotor that is directly connected to a compressor shaft (not shown) by a rotor shaft 2, and a spiral passage turbine scroll 3 is provided on the outer periphery of the turbine rotor 1. Exhaust gas from four engine exhaust passages is guided to the engine exhaust passage.

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. These passage portions 3A and 3B are opened toward the inlet portion IA of the turbine rotor 1.

Reference numeral 8 designates an on-off valve 6 provided on the large exhaust passage 3A side of the exhaust passage 4 connected to the inlet portion 3c of the scroll, and 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, 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 B can be operated by a control mechanism (not shown) using boost pressure or the like, for example, 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 1 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 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 IA, 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 cut off by the on-off valve 6 in the low speed rotation region of the engine, this large exhaust A dead water area occurs in the passage 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 at this time, a swirling flow 10 as shown in FIG. The fluid will have centrifugal force. Therefore, a part of the gas fluid is 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. 2 CB) is generated there. This circulating flow 11 flows along the wall surface of the large exhaust passage 3A, loses energy due to friction loss, and joins the swirling flow 10 again.
Energy loss within the turbine scroll 3 is large, resulting in a decrease in turbine efficiency.

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 worse.

The purpose of the present invention is to focus on the above-mentioned problems, and to make it possible to effectively utilize exhaust energy, reduce losses, and maintain good turbine efficiency from low speed to high speed engine speeds. An object of the present invention is to provide a turbine scroll for a turbocharger that can contribute to maintaining sufficient high-speed output by reducing the back pressure of the engine.

In order to achieve such an objective, the present invention includes a spiral main exhaust passage that opens toward the turbine rotor inlet;
An auxiliary exhaust passage is installed in parallel with this and isolated from the turbine rotor inlet, and the partition wall that separates both exhaust passages has two concentric circles centered on the axis of the turbine rotor. A communication section limited to 100% is provided over almost the entire circumference of the rotor, and from the position where the communication section is provided, a second-class Jd
A valve whose passage area is variable is arranged in the auxiliary exhaust passage, and this valve is operated according to the operating state of the engine.

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 IA of the rotor l, and an auxiliary exhaust passage 13.8 provided in parallel with the main exhaust passage 13A.
A communication portion 15 is formed in the partition wall 5B between the main exhaust passage 13A and the main exhaust passage 13A.

As shown in FIG. 5, this communication part 15 has a shape that is bounded by two concentric circles centered on the axis 0 of the rotor shaft 2 from the downstream side near the tongue part 16, and has a shape that is limited by two concentric circles that are centered around the axis 0 of the rotor shaft 2, and as much as possible, However, in this example, the downstream end portion of the communication portion 15 is kept at the narrowest portion of the exhaust passage formed by the tongue portion 16. Note that R is the radius of the inner circumferential circle formed by the communicating portion 15, and B is the width of the communicating portion 15 in the radial direction.

By forming the communication part 15 around the rotor inlet part IA at an equal distance, when the exhaust gas is led to the auxiliary exhaust passage 13B, the communication part 15 is formed from the passage 13B through the communication part 15. This is to maintain uniformity in the flow of fluid flowing into the inlet portion IA, thereby preventing loss due to non-uniform flow.

Furthermore, when setting the width B of the communicating portion 15, the following formula is used as a condition for obtaining the best supercharging characteristics as confirmed by the present inventor.

However, (1) AAT: AB at the throttle part 17A of the main exhaust passage 13A
T: Cross-sectional area of the auxiliary exhaust passage 13.8 at the constricted portion 17B RA: Distance from the rotor center to the constricted portion +7A center of gravity RB: Distance from the rotor center to the constricted portion 17B4<center H: At the inlet portion IA of the turbine rotor 1 Blade Width (See Figures 4 and 5 above) If it is necessary to narrow the width B of the communication part 15 due to design reasons, etc., keep in mind the conditions mentioned in 17 above. , care must be taken to minimize losses.

Next, 25 is the auxiliary exhaust passage 1.3B as shown in FIG.
An on-off valve disposed on the upstream side of the tongue portion 1B, for example, a rotary valve in this example, is operated via a control mechanism (not shown) to control the flow rate according to the operating state of the engine. can be adjusted.

FIG. 6 shows an example of the rotary valve 25. Here, the valve body 25 has a U-shaped notched circulation groove 26 and a rotation shaft 27 . 28 is a bolt 28 attached to the scroll inlet part of the auxiliary exhaust passage 13B.
30 is a cover that is attached through the cover 2.
This is a bushing fitted to the 8. With the valve rotating shaft 27 fitted to the bush 30, the valve body 25 is inserted into the valve mounting section, and the cover 28 is fixed to the scroll inlet section with bolts 29.

31 is a lever that rotates the rotation shaft 27. Note that such an on-off valve 25 is connected to the inlet 1 of the scroll bouncing 5.
Even if it is provided in an auxiliary exhaust passage (not shown) further upstream than 3G, the performance remains the same.

Next, the operation of the turbine scroll of the turbocharger configured as described above will be explained. In the turbine scroll of this example, when the rotary valve 25 is in an open state in the low speed rotation region of the engine, a dead water region occurs on the side of the auxiliary exhaust passage 13B. It does not have an opening toward the inlet IA, and therefore the swirling flow 10 as shown in FIG.
) does not generate the circulating flow 11 shown in FIG.

Furthermore, the flow velocity distribution on the side of the main exhaust passage 13A is based on the fluid dynamics law of VXRQ = constant (where Rc is the radius at any position on the scroll, and ■ is the flow velocity at the position of the radius RC). Since it is a free portex flow in which the flow velocity V increases in inverse proportion to ¥11, the static pressure of the fluid is low on the rotor inlet IA side and high on the outer peripheral side.

That is, in this example, since the communication part 15 is provided at a constant position relative to the radius R, no pressure difference occurs in this part due to a difference in the radial position, so that the fluid flows from the main exhaust passage 13A side to the auxiliary exhaust passage 13B side. The fluid flowing into the rotor 1 can be maintained in a good flow state without the fluid flowing into the rotor 1.

Then, when the engine is at medium speed, the auxiliary exhaust passage 13B
The rotary valve 25 provided at is guided to the communication portion 25, and in this case, the rotary valve 25 is rotated counterclockwise in FIG. 5 and opened, so that in the auxiliary exhaust passage 13B, An opening will be formed on the side, and therefore, in such a state, gas will flow along the inside of the outer wall 5C,
It flows from the winding end portion 15A of the communication portion 15 into the main exhaust passage 13A side according to the valve opening degree.

Furthermore, when the rotary valve 25 is fully open, the entire gas amount can be efficiently guided to the rotor 1 by guiding the gas from the entire circumference of the communication portion 15 to the main exhaust passage 13A side.
With this, it is possible to reduce the back pressure of the engine and improve its output direction.

In this example, the end edge 5D of the partition wall 5B on the rotor 1 side where the communication portion 15 is provided is left in a state of protruding in the radial direction of the rotor 1. This end edge 5D is the auxiliary exhaust passage 1
Among the exhaust gas flowing on the 3B side, it stagnates on the friction loss side and functions as a barrier (boundary rare fence) to prevent it from flowing into the main exhaust passage 13A side via the communication part 15, thereby reducing turbine efficiency. In addition to suppressing the flow of gas flowing in through the communication section 5, it contributes to smooth contact with the main flow of gas flowing in through the communication section 5, and makes it possible to always supply a flow in good condition to the rotor 1 from the rotor inlet IA. can.

As described above, according to the present invention, a spiral main exhaust passage that opens toward the turbine rotor inlet, and an auxiliary exhaust passage that is arranged parallel to the spiral main exhaust passage and isolated from the turbine rotor inlet are provided. The partition wall that separates the dual exhaust passages is provided with a communication part that is limited in width to a certain width by two concentric circles centered on the axis of the turbine rotor, extending almost all the way around the rotor, to ensure communication between the auxiliary exhaust passages. An on-off valve is placed on the upstream side of the section, and the on-off valve is controlled according to the engine operating status, so fluid loss due to dead water area caused by closing the on-off valve in the low-speed engine operating range is reduced. Not only can this prevent the exhaust energy from being carried into the turbine rotor, but it can also effectively utilize exhaust energy from the engine's low-speed rotation range to the high-speed rotation range, supplying an appropriate boost pressure, and maintaining a good turbine. Gain 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 it goes without saying that the back pressure of the engine can be lowered, contributing to high-pressure output. Nor.

In addition, in the above explanation, the partition wall was configured to be a surface perpendicular to the rotation axis, but depending on the spiral shape of the scroll to be set, the surface does not necessarily have to be perpendicular to the rotation axis, and it may be configured to have a surface slightly inclined from this. It can also be used as a mask.

[Brief explanation of drawings]

Figure 1 is a sectional view showing an example of the configuration of a conventional variable capacity turbine scroll, Figure 2 (A) and Figure 2 (B).
) is an explanatory diagram showing the tendency of the swirling flow generated around the turbine rotor and the circulating flow generated in the large exhaust passage when the valve is closed. 4 is a sectional view showing an example of the configuration of the turbine scroll of the turbocharger of the present invention, FIG. 5 is a sectional view taken along line A-A, and FIG. 6 is an open/close view of FIG. 5. The valve installation is a sectional view of the parts. 1... Turbine rotor, IA... Inlet part, 2... Shaft, 3.13... Turbine scroll, 3A, 3B, 4... Exhaust passage. 5...Housing, 5A, 5B, 5G...Wall, 5D...Edge, 6.25...Opening/closing valve, ?...Gas outlet, 10...Swirling flow, 11... - Circulation flow. 13A, 13B...Exhaust passage, l5...Communication portion, 16...Tongue, 25-9-rotary valve (on/off valve), 26...Flow groove, 27...times Dynamic shaft, 28...Cover, 29...Bolt, 30...Button, 31...Lever. Patent applicant Nissan Motor Co., Ltd.

Claims (1)

[Claims] A vortex-type main exhaust passage having an opening facing the Kubin rotor inlet, and an auxiliary exhaust passage arranged in parallel with the main exhaust passage and isolated from the turbine rotor inlet, the auxiliary exhaust passage and the main A communication portion with a constant width defined by two concentric circles centered on the axis of the turbine rotor is provided between the exhaust passage and the exhaust passage, and a communication portion is provided around the turbine rotor to allow the exhaust gas to freely flow therethrough. A valve is provided upstream of the communication portion of the auxiliary exhaust passage to adjust the amount of exhaust gas supplied to the turbine rotor, and in the low speed rotation region of the engine, the auxiliary passage is closed by the valve and only the main exhaust passage is closed. A turbine scroll for a turbocharger, wherein the exhaust gas is supplied to the turbine rotor.