JPH03111624A - Waste gate valve structure of internal combustion engine with tubocharger - Google Patents

Abstract

PURPOSE:To obtain a high supercharging pressure in an intermediate speed region while securing the strength of component parts in a high speed region by setting the valve opening pressure of a second waste gate valve higher than that of a first waste gate valve. CONSTITUTION:In a turbo charger 1, a waste gate port 11 is constituted of two openings 11a, 11b formed in an exhaust pipe wall, and waste gate valves 12, 13 for opening/closing the openings 11a, 11b are provided respectively. The valve opening pressure of the first waste gate valve 12 is set at a first predetermined value so as to obtain a desired high supercharging pressure in a vehicle operation region at an intermediate speed. The valve opening pressure of the second waste gate valve 13 is higher than the first predetermined value, namely, it is set at a second predetermined value so as to obtain a supercharging pressure enough to satisfy durability of the turbo charger 1 and component parts of a combustion chamber in the vehicle operation region at a high speed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a turbocharger, and more particularly to a wastegate valve structure for an internal combustion engine equipped with a turbocharger, which includes a wastegate valve for controlling boost pressure.

[Conventional technology]

Generally, in an internal combustion engine equipped with a turbocharger (for example, an automobile engine), the pressure of the intake air compressed by the turbocharger compressor, that is, the upper limit of the boost pressure is controlled, so when the boost pressure exceeds a predetermined value. A wastegate valve is provided that opens to open a bypass passage that bypasses the turbine and bypasses a portion of the exhaust gas introduced into the turbine.

[Problem to be solved by the invention]

By the way, in a turbocharged internal combustion engine equipped with a wastegate valve as described above, if a high supercharging pressure is to be obtained when the vehicle is at medium speed, the opening operation setting value of the wastegate valve is as follows. It is necessary to set the valve actuator so that it does not open at medium speeds. However, in such a case, as shown by the solid line in Figure 3, the boost pressure increase due to high-speed operation outweighs the boost pressure increase suppression effect by bypassing a portion of the exhaust gas at high speeds, and as a result, Even if the wastegate valve starts to open, the supercharging pressure will rise for a while, putting a strain on the components of the turbocharger and combustion chamber, and possibly impairing their durability. Conversely, if the wastegate valve opening operation setting value is set so that the strength of the turbocharger at high speeds is not a problem, the target supercharging will be achieved in the engine medium speed range, as shown by the dotted line in the figure. There is a problem that pressure cannot be obtained. The present invention has been made in view of the current situation, and has two contradictory objectives: ensuring the strength of the turbocharger and combustion chamber components in the high-speed range and obtaining high supercharging pressure in the medium-speed range. An object of the present invention is to provide a wastegate valve structure for a turbocharged internal combustion engine that can achieve the following.

[Means for Solving the Problems] For the above purpose, according to the present invention, in order to prevent the supercharging pressure of the turbocharger from rising excessively, a part of the exhaust gas introduced into the turbine is bypassed according to the supercharging pressure. , a wastegate valve structure for an internal combustion engine with a turbocharger, which is provided in a bypass passage that bypasses the turbine, and opens when the boost pressure reaches a first predetermined value in a vehicle high speed range to exhaust gas. a first wastegate valve that bypasses a portion of the bypass passage; and a first wastegate valve that is provided in the bypass passage and operates to open when the boost pressure reaches a second predetermined value higher than the first predetermined value. A wastegate valve structure for an internal combustion engine with a turbocharger is provided, which includes a second wastegate valve that increases the area of the exhaust bypass passage formed by opening the first wastegate valve.

[For production]

By opening the first waste gate valve when the vehicle is in a high speed range, it is possible to secure a high boost pressure suitable for a medium speed range. Further, the opening operation of the second wastegate valve is set to a valve opening operation setting value of the first wastegate valve, that is, a setting value (second setting value) higher than the first setting value. As a result, as the amount of exhaust bypass increases, the effect of suppressing the increase in supercharging pressure can be enhanced.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a cross-sectional view of a turbocharger (including intake and exhaust pipes) equipped with a wastegate valve structure according to the present invention, and shows an internal combustion engine (hereinafter referred to as engine) not shown.
Intake air flows in the direction of arrow A toward the combustion chamber, and exhaust air from the combustion chamber flows in the direction of arrow B.

The turbocharger 1 mainly includes a compressor 3 installed in an intake passage 2, a turbine 5 installed in an exhaust passage 4, and a turbine shaft 6 connecting the compressor 3 and the turbine 5. , these are compressor housing 7, center housing 8
and is housed within the turbine housing 9.

In the exhaust passage 4, portions of the exhaust passage 4 on the exhaust upstream side and the exhaust downstream side of the turbine 5 are connected by a bypass passage 10 that bypasses the turbine 5. This bypass passage 10 allows a part of the exhaust gas introduced from the engine body to the turbine 5 to bypass the turbine 5 according to the pressure of the intake air compressed by the compressor 3, that is, the boost pressure.
The bypass passage 10 is provided to control the rotation of the turbine 5 which is the drive source of the compressor 3.
A wastegate valve that controls the introduction of exhaust gas into the bypass passage 9 is provided in the wastegate boat 11 which is a connection part with the exhaust passage 4 on the upstream side of the exhaust gas from the turbine 5 .

In the wastegate valve structure of a turbocharger constructed as described above, according to this embodiment, the wastegate port 11 is composed of two openings 11a and 11b formed in the exhaust pipe wall, and A first wastegate valve 12 and a second wastegate valve 13 that open and close the openings 11a and 11b, respectively.
will be provided. The first and second wastegate valves 12.13 have valve bodies 14 and 15 that sit in and close the openings 1a and 1b, respectively, when inactive, and valve bodies 14.15. Pressure operated actuators 16 and 17 to be driven and links 18 and 19 connecting valve body 14.15 and pressure operated actuators 16 and 17.
and each actuator 1.
Inside the frame 6.1 are diaphragms 20 and 21 which are secured to one end of each link 18, 19, and diaphragms 20.
Compression springs 22 and 23 are provided to urge actuator 21 to the left in the figure, and pressure chambers 24 and 25 defined within actuator 16 and 17 are connected to the compressor via pipes 26 and 27, respectively. The intake passage 2 is connected to the intake passage 2 on the downstream side of the intake passage 3, and the exhaust passage 4 is connected to the exhaust passage 4 on the exhaust upstream side of the turbine 5.

Next, the general operation of a wastegate valve for a turbocharged engine will be explained using the first wastegate valve 12 in FIG. 1 as an example. The thermodynamic energy of the exhaust gas becomes kinetic energy of the turbine 5, which drives the compressor 3. As a result, intake air taken in from the outside is compressed and supercharged to the engine body. When this supercharging pressure exceeds a certain value, the pressure in the pressure chamber 24 increased through the vibrator 26 overcomes the biasing force of the compression spring 22, and the valve body 14 is moved through the link 18 to the opening 1.
1a, the bypass passage 10 and the exhaust passage 4 are communicated with each other, so that a part of the exhaust gas bypasses the turbine 5, and an excessive rise in supercharging pressure is suppressed.

FIG. 2 shows the opening operation pressure values of the first and second wastegate valves 12 and 13, which are the characteristics of the present invention, regarding the operation of the wastegate valve described above. As is clear from the figure, according to this embodiment, the opening operating pressures of the two wastegate valves 12 and 13 are not the same, that is, the first wastegate valve 12
The valve-opening pressure of the 1st valve is set to the same value as the conventional 1st valve opening pressure, which has the same purpose, so that the target high boost pressure can be obtained in the medium-speed driving range of the vehicle.
The pressure value is set approximately equal to a pressure value that ignores high-speed durability of the turbocharger with a wastegate valve and the components of the combustion chamber (this value is hereinafter referred to as a first predetermined value). The opening operating pressure of the second wastegate valve 13 is higher than the first predetermined value, so that even if the vehicle reaches a high speed range, the exhaust bypass is performed by opening the second wastegate valve 13. The boost pressure is set to a value (hereinafter referred to as a second predetermined value) such that the boost pressure does not increase as much as indicated by the dotted line in FIG. 2 due to an increase in the cross-sectional area of the flow path. Note that this different set value is, for example, for each waste gate valve 12°1.
This can be achieved by changing the initial set load of the compression springs 21, 22 inside the actuator 16.1 corresponding to the second wastegate valve 1.
3 Regarding the supercharging pressure curve after the start of valve opening, the diameter of the valve body 14.15 of the waste gate valve 12.13 and the link 1
Arm ratio of 8.19, shape of diaphragm 20.21.
An ideal curve may be obtained by changing the material or the shape of the openings 11a, 11b.

According to this embodiment, as explained above, by opening the first wastegate valve 11 with the first set value, the supercharging is high in the medium speed range as shown by the solid line in FIG. pressure is obtained, and then the second wastegate valve 12 opens with the second set value, increasing the cross-sectional area of the exhaust bypass flow path, which causes the supercharging pressure to drop rapidly. The durability of the turbocharger and combustion chamber components at high speeds can be satisfied. Furthermore, when exhaust pressure is used as an input to the actuator 16 of the second wastegate valve 12 as in the illustrated embodiment, exhaust pressure fluctuations associated with fluctuations in engine speed within a high-speed range are generally more rapid than fluctuations in boost pressure. Therefore, the boost pressure control response in the high speed range can be improved.

〔effect〕

As explained above, according to the present invention, by providing two wastegate valves with different valve opening operation setting values, it is possible to rapidly reduce the supercharging pressure when both valves are open. , the durability of the turbocharger and combustion chamber components can be ensured. Also,
Since the valve opening setting value of the first wastegate valve is set to the first predetermined value in the high speed range, high supercharging pressure can be ensured at medium speeds.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing a waste gate valve structure of a turbocharger according to the present invention; FIG. 2 is a diagram showing a supercharging pressure curve according to the present invention structure; FIG. 3 is a diagram showing a supercharging pressure curve in a conventional structure. 1...turbocharger, 5...turbine, 10...
...Bypass passage, 12...First waste gate valve, 13...
Second wastegate valve. Diagram

Claims (1)

[Claims] 1. A wastegate valve structure for an internal combustion engine with a turbocharger that bypasses a part of exhaust gas introduced into the turbine according to the boost pressure in order to prevent an excessive increase in the boost pressure of the turbocharger, a first wastegate valve that is provided in a bypass passage that bypasses the bypass passage, and that opens and bypasses a portion of the exhaust gas when the boost pressure reaches a first predetermined value in a vehicle high speed range; A valve is provided in the passage when the boost pressure reaches a second predetermined value higher than the first predetermined value.
A wastegate valve structure for an internal combustion engine with a turbocharger, comprising a second wastegate valve that increases an area of an exhaust bypass passage formed by opening the wastegate valve.