JPS6229626Y2 - - Google Patents

Description

[Detailed description of the invention] This invention uses the action of a compressor driven by the turbine rotated by the exhaust gas of the internal combustion engine to compress the air supplied to the internal combustion engine. The present invention relates to a wastegate valve actuator that controls the rotation of a turbine by opening a wastegate valve and releasing a portion of gas.

As shown in FIG. 1, this type of turbocharger equipped with a wastegate valve has an engine exhaust passage 1 in the turbocharger body 10.
A turbine 12 is disposed in the engine and rotated by exhaust gas from the exhaust manifold, and a compressor 14 is disposed in the intake passage 13 of the engine and pressurizes intake air and supplies it to the intake manifold. . The compressor 14
is integrally connected to the turbine 12 via the shaft 15 and is driven by the rotation of the turbine 12.
A wastegate valve 17 is provided for discharging a portion of exhaust gas flowing into the turbine 12 into a bypass passage 16 without passing through the turbine 12, and the valve 17 is connected to a wastegate actuator via a swing shaft 18. 19 drive rods 20. The drive rod 20 is secured to a diaphragm 22 which forms a pressure chamber 21 within the actuator, and the pressure chamber 21 is further communicated with the downstream side (discharge side) of the compressor 14 via a passage 23. The diaphragm 22 is normally biased by a spring 24 in the direction of closing the wastegate valve 17, that is, in the right direction in the drawing, and when the compressor boost pressure introduced into the pressure chamber 21 of the actuator 19 exceeds a set value, the diaphragm 22 is biased by the spring 24 The diaphragm 22 is displaced to the left in the figure against the biasing force of the diaphragm 24, and the displacement of the diaphragm 22 causes the drive rod 20
is transmitted to the swing shaft 18 via the exhaust gas, which opens the wastegate valve 17 and allows a portion of the exhaust gas to bypass the turbine 12 and thereby maintain the supercharging pressure of the compressor 14 below a set value. It's getting old.

In this way, the conventional wastegate valve actuator controls the amount of exhaust gas flowing into the turbine in response to the compressor boost pressure.
It is generally known that it is desirable not to operate the turbocharger when starting the engine.
However, in the turbocharger disclosed in Japanese Utility Model Application Publication No. 57-53033, which has been proposed as a prior art, no consideration is given to bypass flow rate control when the engine is low temperature. As a result, the turbocharger operates when the engine is cold, and at this time, the lubricating oil is not sufficiently circulated, causing a problem in which the bearing of the turbocharger body becomes stuck, making it more likely to burn out. .

SUMMARY OF THE INVENTION In view of the problems of the prior art described above, an object of the present invention is to bypass the exhaust gas flowing into the turbine by opening the waste gate valve when the engine temperature is low.

In order to achieve this purpose, the wastegate valve actuator according to the present invention uses a shape memory alloy as the material of the spring that biases the diaphragm, and the temperature characteristics of the shape memory alloy spring are below the set temperature. In this case, the mounting load is small, and the mounting load becomes large when the temperature exceeds the set temperature. By adopting this configuration, the biasing force of the spring becomes weak when the engine is cold, so the wastegate valve is opened at low boost pressure, and the biasing force of the spring becomes strong during normal driving.
The wastegate valve can be opened at a predetermined boost pressure, achieving the intended purpose.

Furthermore, in the present invention, by attaching the above-mentioned waste gate valve actuator to the turbo charger, there is an advantage that the warm-up operation of a turbocharged automobile engine, which is generally performed, can be abolished, and the engine At low temperatures, the circulation of lubricating oil is insufficient and conventional devices tend to damage the bearings of the turbocharger, but the present invention has the effect of protecting the turbocharger at low temperatures.

An example embodying the present invention will be described below.
The explanation will be based on the attached drawings.

A wastegate valve actuator 30 according to the present invention shown in FIG. 2 has a body 32 with a pressure signal port 31 and a cover 33 integrally coupled to the body 32. The outer periphery of the diaphragm 34 is clamped between the body 32 and the cover 33, and the drive rod 3 is attached to the inner periphery of the diaphragm 34.
5 is fixed at one end. The diaphragm 34 forms a pressure chamber 36 in the body 32 and an atmospheric chamber 37 in the cover 33, which are airtightly separated from each other. The pressure chamber 36 communicates with the downstream side of the compressor 13 via the passage 23 shown in FIG. 1, and the supercharging pressure of the compressor 14 is always introduced therein. On the other hand, a spring 40 whose one end abuts against the cover 33 via a retainer 39 is disposed in the atmospheric chamber 37 which is constantly in communication with the atmosphere through the atmospheric hole 38 . The diaphragm 34 is urged rightward in the drawing. The other end of the drive rod 35 is connected to the wastegate valve 17 via a swing shaft 18 shown in FIG.

Now, a shape memory alloy is used as the material of the spring 40 described above, and the load-temperature characteristics of the spring 40 are such that the mounting load is small below the set temperature and becomes large above the set temperature. The figure shows a temperature characteristic graph when the set temperature is 80°C.

The boost pressure of the compressor 14 is introduced into the pressure chamber 36, and when the boost pressure exceeds a set value, the diaphragm 34 moves in the direction shown in the figure against the biasing force of the spring 40. At this time, as the diaphragm 34 moves, the drive rod 35 also moves to the left in the figure, so the waste gate valve 17 opens and a portion of the exhaust gas flows into the bypass passage 16. by the way,
Since the present invention uses a shape memory alloy spring 40 having the temperature characteristics shown in FIG. During driving, the valve can be opened at a predetermined boost pressure. FIG. 4 shows the stroke characteristics of the drive rod 35 with respect to the compressor boost pressure, and shows that the boost pressure at which the waste gate valve 17 opens differs when the engine is at a low temperature and when the engine is at a high temperature.

In addition, by using two shape memory alloys with different specifications as the spring means for biasing the diaphragm 34, as shown in FIG. The opening pressure of the wastegate valve 17 can also be changed in stages in response to engine temperature in order to open the wastegate valve 17 and improve engine drivability.

[Brief explanation of drawings]

Fig. 1 is a system diagram showing the operation of the turbocharger, Fig. 2 is a sectional view showing an embodiment of the wastegate valve actuator according to the present invention, and Fig. 3 is a system diagram showing the operation of the turbocharger. The load temperature characteristic diagram of the spring, Figure 4 is the stroke characteristic diagram for the boost pressure of the drive rod shown in Figure 2, and Figure 5 is the stroke characteristic diagram similar to Figure 4, but with two different specifications. FIG. 2 is a characteristic diagram showing a case where a shape memory alloy of 1 is used. 17... Waste gate valve, 30... Waste gate valve actuator, 34... Diaphragm, 35... Drive rod, 36... Pressure chamber, 40... Spring.

Claims (1)

[Scope of utility model registration request] Drive rod that connects to the wastegate valve,
A diaphragm fixed to the drive rod, a housing having a pressure chamber formed by the diaphragm therein, and a spring disposed within the housing to bias the diaphragm,
When the supercharging pressure supplied to the pressure chamber exceeds a set value, the diaphragm is displaced against the biasing force of the spring, causing the wastegate valve actuator to hold the wastegate valve in the open position. A shape memory alloy is used as the material of the spring, and the temperature characteristic of the spring made of the shape memory alloy is such that the mounting load is small below a set temperature and becomes large above the set temperature. wastegate valve actuator.