JP7168427B2 - exhaust turbocharger - Google Patents

Description

The present invention relates to an exhaust turbosupercharger in which at least the turbine housing is made of aluminum.

An exhaust turbocharger includes a turbine housing having a turbine scroll chamber in which turbine blades are arranged, and an exhaust gas inflow passage connected to a cylinder head or an exhaust manifold communicates with the turbine scroll chamber. A waste gate passage branches off from the exhaust gas inflow passage, and the output of supercharging is controlled by opening and closing the outlet of the waste gate passage with a waste gate valve.

A valve seat (valve seat) made of a hard metal is arranged on the end surface of the exit portion of the wastegate passage, as disclosed in Patent Document 1, because the wastegate valve repeatedly hits the end face. Although not disclosed in U.S. Pat. No. 6,200,000, valve seats are typically press-fit into the turbine housing.

JP 2016-98953 A

By the way, if the housing of the exhaust turbocharger is made of aluminum, it will be lighter and contribute to the improvement of fuel efficiency. However, since aluminum is vulnerable to heat, in an aluminum-made exhaust turbocharger, it is necessary to provide a water jacket at least in the turbine housing and cool it with cooling water. In particular, since the wastegate passage is in a severe thermal environment, there is a high need for cooling with cooling water.

However, with a structure in which the wastegate passage is simply cooled with cooling water, a large amount of heat is transferred from the exhaust gas to the cooling water, resulting in an increase in heat loss. may occur.

Further, in general, a catalyst is often placed downstream of the exhaust turbocharger. If the heat is actively radiated from the engine to the cooling water, the temperature of the exhaust gas reaching the catalyst is excessively lowered, and it takes a long time to activate the catalyst after the engine is started.

Furthermore, considering cooling by cooling water, it is necessary to set the wall thickness of the turbine housing so that the temperature rise is as uniform as possible in each part, and to minimize the thermal strain as much as possible. If the shape is too complicated, problems such as poor flow of the molten metal and poor machining accuracy are likely to occur.

The invention of the present application was made in view of the current situation, and aims to solve the problems caused by using aluminum and water-cooled turbine housings with a simple structure.

The exhaust turbocharger of the present invention is
A turbine housing made of aluminum in which a wastegate passage branches off from an exhaust gas inflow passage, a wastegate valve that opens and closes the exit of the wastegate passage, and an exit of the wastegate passage that contacts the wastegate valve. It is equipped with a valve seat placed in the
A water jacket is formed in the turbine housing so as to surround the wastegate passage."
It has a basic configuration.

And in the above basic configuration,
"The valve seat is provided with a cylindrical portion that enters the inside of the wastegate passage, and heat transfer from the cylindrical portion to the turbine housing is conducted between the cylindrical portion and the inner peripheral surface of the wastegate passage. A suppressing heat insulating space is formed so as to open toward the exhaust gas inflow passage ."
configuration is added.

In the present invention, "enclosing the wastegate passage" in relation to the water jacket does not necessarily enclose the entire circumference of the wastegate passage, and the water jacket is partially formed around the wastegate passage. It also includes cases. The same applies to the axial extent of the wastegate passage, and the water jacket need not be formed over the entire length of the wastegate passage.

In the invention of the present application, since the heat-insulating space is formed between the cylindrical portion of the valve seat and the inner peripheral surface of the wastegate passage, the exhaust gas does not flow in contact with the inner peripheral surface of the wastegate passage. Therefore, it is possible to suppress the temperature rise of the turbine housing while suppressing the heat transfer amount (heat release amount) from the exhaust gas passing through the waste gate passage to the cooling water.

Therefore, it is possible to suppress the flow rate of the cooling water flowing through the exhaust turbosupercharger, thereby contributing to the improvement of fuel efficiency through downsizing of the radiator and suppression of the output of the water pump. In addition, since the temperature drop of the exhaust gas can be suppressed, early activation of the catalyst arranged on the downstream side can be promoted, which contributes to improvement of purification performance of the exhaust gas. Furthermore, since the temperature rise of the turbine housing can be suppressed, the portion of the turbine housing where the wastegate passage is formed can suppress thermal strain without having a complicated shape. Therefore, it is possible to contribute to the improvement of casting accuracy and yield by smoothing the flow of molten metal during casting.

Further, since the cylindrical portion is provided on the valve seat, the structure and assembly are simple, and cost increases can be suppressed. In particular, since the heat insulation space is used as the heat shield, the structure is extremely simple, which is particularly advantageous in terms of cost.

FIG. 3 is a perspective view of the turbine housing according to the embodiment as seen from the exhaust outlet. (A) is a plan view of the turbine housing, and (B) is a front view of the turbine housing. It is a partial longitudinal front view. ( A) is a cross-sectional view showing a main part , and (B) is a cross-sectional view of a reference example . FIG. 11 is a cross-sectional view of another reference example ;

(1). Basic Structure of Exhaust Turbocharger Next, an embodiment in which the present invention is applied to an exhaust turbocharger for an internal combustion engine for an automobile will be described with reference to the drawings. First, an overview will be given with reference to FIGS.

In this embodiment, the terms front-rear, left-right, and up-down are used to clarify the directions. The direction perpendicular to the exhaust side surface is defined as the front-rear direction. Regarding the front and rear, the direction facing from the cylinder head H is defined as front. The vertical direction is the vertical direction. Just to make sure, the directions are clearly shown in FIGS. 1 and 2(A).

As shown in FIG. 3, the exhaust turbosupercharger includes turbine blades 1 and compressor blades (not shown). Fixed. Further, as shown in FIG. 2B, the exhaust turbocharger has a turbine housing 3, a compressor housing 4, and a bearing housing (center housing) 5 positioned between them. 3 and bearing housing 5 are integrally manufactured as an aluminum casting. The compressor housing 4 is an aluminum die-cast or casting.

A turbine scroll chamber 6 is formed in the turbine housing 3 so as to surround the turbine blades 1 , and an exhaust outlet hole 7 opening in the rotation axis direction of the turbine blades 1 is formed. The turbine scroll chamber 6 has a spiral shape in which the distance from the rotation axis of the turbine blade 1 gradually decreases from the starting end to the terminal end. A gas inflow passage 8 (see FIG. 3) is in communication.

Therefore, the turbine housing 3 has a circular portion 3a in which the turbine scroll chamber 6 is formed, and an inlet cylindrical portion 3b in which the exhaust gas inflow passage 8 is formed. A protruding side projecting portion 3c is formed in a state of being integrally connected with the circular portion 3a and the inlet cylinder portion 3b. An inlet-side flange 9 is formed at the rear end of the inlet cylindrical portion 3b and fixed to the cylinder head H (or the collective portion of the exhaust manifold) with bolts.

Further, as shown in FIGS. 1 and 3, a waste gate passage 10 branched from the exhaust gas inflow passage 8 opens toward the side opposite to the bearing housing 5, and the waste gate passage 10 and the exhaust outlet hole 7 are connected. communicate with each other inside the side projecting portion 3c. For this reason, the side projecting portion 3c is elongated in the vertical direction.

The wastegate passage 10 is opened and closed by a wastegate valve 11 shown in simplified form in FIG. A valve shaft hole 12 into which a valve shaft for driving the waste gate valve 11 is fitted is formed in the upper end portion of the side protruding portion 3c so as to penetrate therethrough substantially in the vertical direction. Therefore, the upper portion of the inside of the side projecting portion 3c forms a wastegate space 13 that allows the wastegate valve 11 to rotate.

The wastegate valve 11 is driven by a diaphragm type actuator provided in the compressor housing 4, an electric negative pressure type actuator provided in the compressor housing 4 or the turbine housing 3, or the like.

An outlet-side flange 14 is formed on the side projecting portion 3c of the turbine housing 3, and although not shown, a catalyst case containing a catalyst is fixed to the outlet-side flange 14. As shown in FIG.

As shown in FIG. 3, the bearing housing 5 is formed with a bearing portion 16 that rotatably holds the rotating shaft 2 via a floating metal 15 . The bearing housing 5 is also formed with an oil supply hole 17 that opens upward and an oil discharge hole 18 that opens downward. As shown in FIG. 3 , a shroud piece 19 forming an inner peripheral portion of the turbine scroll chamber 6 is attached to the exhaust outlet hole 7 .

A water jacket through which cooling water flows is formed in the turbine housing 3 . The water jacket is composed of an inside jacket 20 located on the bearing housing 5 side and an outside jacket 21 located on the exhaust outlet hole 7 side. are separated into left and right by a center partition wall 22 extending so as to bisect each of them into left and right. The left and right jackets 20 and 21 may be integrally communicated with each other without being separated by the center partition wall 22 (they may be separated by intermittently arranged bridge portions).

The outside jacket 21 surrounds the wastegate passage 10 and also surrounds the exhaust outlet hole 7 . The inside jacket 20 and the outside jacket 21 communicate with each other at their lower ends, and a cooling water inlet for sending cooling water toward the inside jacket 20 and the outside jacket 21 is provided at the lower end of the circular portion 3 a of the turbine housing 3 . A port 23 is formed to open downward.

The inside jacket 20 and the outside jacket 21 are also communicated at their upper ends. Therefore, a cooling water outlet port 24 communicating with the inside jacket 20 and the outside jacket 21 is formed upward at the upper end portion of the inlet tubular portion 3 b of the turbine housing 3 .

(2) Thermal insulation structure of the wastegate passage As shown in FIG. The seat 25 is integrally formed with a tubular portion 26 that enters the inside of the waste gate passage 10 . The tubular portion 26 extends over substantially the entire length of the wastegate passage 10 .

In the example shown in FIG. 4A, the cylindrical portion 26 has a straight structure as a whole, and the outer diameter of the cylindrical portion 26 is set smaller than the inner diameter of the wastegate passage 10 by a certain dimension. As a result, between the cylindrical portion 26 and the inner peripheral surface of the wastegate passage 10, a certain amount of heat insulating space 27 is formed as a heat insulating portion. Therefore, in the example shown in (A), the heat insulation space 27 opens toward the exhaust gas inflow passage 8 .

On the other hand, in the reference example shown in FIG. 4B, a flange portion (diameter enlarged portion) 28 is formed at the tip of the cylindrical portion 26 to abut against the inner peripheral surface of the waste gate passage 10 . Therefore, in the reference example shown in (B), the heat insulating space 27 is a closed space. In either case, the valve seat 25 is non-detachably fitted into a counterbore groove 29 formed in the end face of the outlet of the wastegate passage 10 .

When the heat insulation space 27 is formed in the inner circumference of the wastegate passage 10 in this way, the exhaust gas does not flow in the heat insulation space 27 and remains accumulated there, so that the exhaust gas is not transmitted to the inner circumference of the wastegate passage 10 . The amount of heat is significantly reduced compared to the case where the exhaust gas hits the inner peripheral surface of the wastegate passage 10 and flows. Therefore, the temperature rise of the inner peripheral portion of the wastegate passage 10 is suppressed, and the amount of heat transferred to the cooling water of the outside jacket 21 is also reduced.

Therefore, heat loss from the cooling water via the radiator can be suppressed. As a result, it is possible to contribute to the improvement of fuel efficiency through the miniaturization of the radiator and the suppression of the discharge amount of the water pump. In addition, since the temperature drop of the exhaust gas can be suppressed, the catalyst can be activated early after the internal combustion engine is started, which contributes to the enhancement of the purification performance of the exhaust gas. Furthermore, since thermal strain around the wastegate passage 10 can be suppressed, when designing the turbine housing 3, complicated tuning can be eliminated and a simple shape can be adopted, resulting in improved casting accuracy. can.

In another reference example shown in FIG. 5, an inorganic heat insulating material 30 is sandwiched between the cylindrical portion 26 of the valve seat 25 and the inner peripheral surface of the waste gate passage 10 as a heat shield. The heat insulating material 30 has a flange 30a that overlaps the valve seat 25. As shown in FIG. Therefore, the heat shielding property can be further improved.

In the example of FIG. 5, the cylindrical portion 26 is straight over the entire length, but the type of FIG. 4B and the heat insulating material 30 may be combined. Alternatively, the heat insulating material 30 may be formed in a simple tubular shape and arranged only at the tubular portion 26 .

Although the embodiments of the present invention have been described above, the present invention can be embodied in various other ways.

The present invention can be embodied in an exhaust turbocharger. Therefore, it can be used industrially.

Reference Signs List 1 turbine blade 2 rotating shaft 3 turbine housing 4 compressor housing 5 bearing housing 6 turbine scroll chamber 7 exhaust outlet hole 8 exhaust gas inflow passage 10 waste gate passage 11 waste gate valve 20, 21 water jacket 25 valve seat 26 cylindrical portion 27 heat shield Insulated space as an example of part 28 Flange part

Claims (1)

An aluminum turbine housing in which a wastegate passage branches from an exhaust gas inflow passage, a wastegate valve that opens and closes an outlet of the wastegate passage, and an outlet portion of the wastegate passage so that the wastegate valve abuts. It is equipped with a valve seat and a
A water jacket is formed in the turbine housing so as to surround the wastegate passage,
The valve seat is provided with a cylindrical portion that enters the interior of the wastegate passage, and between the cylindrical portion and the inner peripheral surface of the wastegate passage, heat transfer from the cylindrical portion to the turbine housing is suppressed. A heat insulating space is formed to open toward the exhaust gas inflow passage ,
Exhaust turbocharger.

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