JPH0511308Y2 - - Google Patents

Description

[Detailed description of the invention] (Industrial application field) The invention is a boost pressure control system for a turbocharged engine that uses exhaust pressure energy to rotate an exhaust turbine and pressurizes air intake with an intake compressor. It is related to.

(Prior art) Conventionally, an exhaust turbine is provided in the exhaust passage and an intake compressor is provided in the intake passage, the exhaust turbine is rotated by exhaust pressure energy to drive the intake compressor, and the intake compressor is used to compress supply air. It is known to use a turbocharger to increase charging efficiency and improve output.

Such turbochargers are highly efficient in order to maintain high supercharging pressure in the low speed range, and to suppress exhaust pressure reduction and excessive rise in supercharging pressure in the high speed range. An exhaust bypass passage is provided that connects the upstream and downstream sides of the exhaust turbine of the turbo supercharger and bypasses the exhaust turbine, and a wastegate valve that opens and closes the exhaust bypass passage on the downstream side of the exhaust gas is provided, and the wastegate valve is operated by an actuator. Opening/closing control is performed to prevent the supercharging pressure from exceeding a certain pressure (see, for example, Japanese Utility Model Application No. 60-6834). Note that if the wastegate valve is opened toward the upstream side, there is a risk that the wastegate valve may become stuck closed when the exhaust pressure rises rapidly, so it is designed to be opened and closed on the downstream side of the exhaust gas.

(Problem to be solved by the invention) By the way, in the above-mentioned system, when trying to increase the output of the engine, the wastegate valve
Since the wastegate valve is designed to open and close on the downstream side of the exhaust gas, there is a tendency for the wastegate valve to open due to exhaust pressure. The larger the difference, the more noticeable it becomes, so it is desirable to have a large difference between the waste gate valve and the waste gate hole.However, if the difference in size between the waste gate valve and the waste gate hole is large, the waste gate valve opens at the same time. The pressure difference between upstream and downstream disappears, and the exhaust pressure difference that acts directly on the wastegate valve disappears, and the wastegate valve closes. Furthermore, at the same time as the valve is closed, the exhaust pressure difference increases, causing the valve to open again, resulting in increased surging.

Therefore, conventionally, in order to prevent surging, the difference in size between the wastegate valve and the wastegate hole is made small, which limits the supercharging pressure characteristics with respect to the engine speed.

The actuator of the wastegate valve is usually a diaphragm device, which is divided into a first chamber into which the internal pressure of the intake pipe is introduced by the diaphragm and a second chamber into which a spring is compressed. The waste gate valve is opened and closed in such a way that the boost pressure does not always exceed a certain pressure depending on the balance between the pressure and the spring force of the spring in the second chamber. It is desirable to be influenced only by the pressure inside the intake pipe without being affected by the pressure difference between upstream and downstream of the gate valve.

However, the force acting on the diaphragm changes depending on the pressure difference between the pressures P ₁ and P ₂ that act on each side of the upstream and downstream sides of the wastegate valve. difficult to control. In other words, for example, if the upstream pressure P ₁ is higher than the downstream pressure P ₂ , that is, P ₁ > P ₂ , the wastegate valve will open more easily and the upper limit of the supercharging pressure will decrease, and conversely, P ₂ > If P ₁ , the wastegate valve becomes difficult to open and the upper limit of supercharging pressure increases.

The present invention has been developed in view of these points, and is a turbo supercharger that can control the opening and closing of the wastegate valve without increasing the surging of the wastegate valve and without being affected by differential pressures upstream and downstream of the wastegate valve. The purpose of this invention is to provide a supercharging pressure control device for an equipped engine.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides an engine equipped with a turbocharger, in which the upstream and downstream sides of the exhaust turbine of the turbocharger are connected to bypass the exhaust turbine. an exhaust bypass passage that opens and closes the exhaust bypass passage on the downstream side of the exhaust gas, a main biasing means that biases the wastegate valve toward the downstream side of the exhaust gas in response to an increase in supercharging pressure; The waste gate valve includes biasing force correction means for biasing the waste gate valve in a direction to cancel the pressure difference in accordance with the magnitude of the pressure difference between upstream and downstream sides of the gate valve.

(Function) The biasing force correction means cancels the effect on the wastegate valve due to the differential pressure upstream and downstream of the wastegate valve, eliminates the influence of the differential pressure, and increases the supercharging pressure by the main biasing device. Accordingly, the wastegate valve is biased toward the exhaust downstream side.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

In FIG. 1 showing the overall configuration of a boost pressure control device for a turbocharged engine, 1 is a turbocharger, an exhaust turbine 3 disposed in an exhaust passage 2,
It has an exhaust turbine 3 disposed in an intake passage 4 and an intake compressor 5 connected to it.

The exhaust passage 2 upstream and downstream of the exhaust turbine 3 is
They are connected through an exhaust bypass passage 6, forming a bypass passage that bypasses the exhaust turbine 3.
The waste gate hole 6a at the upstream end of the exhaust bypass passage 6 is provided with a waste gate valve 7 that can be opened and closed to open and close the exhaust bypass passage 6 on the exhaust downstream side.

The waste gate valve 7 has an intermediate link mechanism 8
It is connected to a connecting rod 10 of an actuator 9 via the actuator 9, and is controlled to open and close by the actuator 9.

As shown in FIG. 2, the actuator 9 has a casing 11 divided into two by a partition wall 12,
The first diaphragm device 13 serves as a main biasing means that biases the wastegate valve 7 in the valve opening direction as the supercharging pressure increases, and the A second biasing force correcting means that biases the waste gate valve 7 in the valve closing direction.
diaphragm device 14.

The first diaphragm device 13 is formed on one side of the partition wall 12 of the casing 11, and is divided by the diaphragm 15 into a first chamber 16 (the partition wall 12
side) and a second chamber 17, and the intake pipe pressure downstream of the intake compressor 5 is introduced into the first chamber 16 through a pressure passage 18, while a spring 19 is compressed in the second chamber 17 to reduce the intake pipe pressure. By the balance between the spring force of the spring 19 and the spring force of the spring 19, the connecting rod 10 connected and fixed to the diaphragm 15 is displaced.

Further, the second diaphragm device 14 includes the partition wall 12
It has a first chamber 21 and a second chamber 22 (on the partition wall 12 side) formed on the other side and divided by a diaphragm 20. The downstream exhaust pipe pressure is
Exhaust pipe pressures upstream from the upstream end of the exhaust bypass passage 6 are respectively introduced into the second chamber 22 through another pressure passage 24, and the displacement amount of the connecting rod 10 connected to the diaphragm 20 is corrected by the differential pressure. I'm starting to do that. Note that the bearing portion of the connecting rod 10 in the partition wall 12 is completely sealed, and the first chamber 1 of the first diaphragm device 13 is completely sealed.
6 and the second chamber 22 of the second diaphragm device 14, and the internal pressure of the actuator 9 is also prevented from leaking to the outside air.

By the way, as shown in FIG. 2, in order to offset the differential pressure P ₂ - _{P 1} acting on the waste gate valve 7,
The area of waste gate valve 7 is A ₁ , and the area of connecting rod 1 is
Let the length of the intermediate link 8a connected to the waste gate valve 7 be _l1 , the length of the other link 8b connected to the wastegate valve 7 be _l2 , and the area of the diaphragm 20 of the second diaphragm device 14 be _A2. For example, the following formula holds: (P ₂ - P ₁ ) A ₂ l ₁ = (P ₂ - P ₁ ) A ₁ l ₂ Therefore, the area A ₂ of the diaphragm 20 is A ₂ = l ₂ /l ₁ Determined by A ₁ .

If configured as above, waste gate valve 7
The moment due to the differential pressure acting on both sides of the second
Since the deflection of the diaphragm 20 due to the differential pressure acting on the diaphragm device 14 cancels it out, the wastegate valve 7 is operated by the intake pipe pressure acting on the first chamber 16 of the first diaphragm device 13 and the spring 19 of the second chamber 17. Opening/closing is controlled by balancing the spring force caused by the pressure difference, and surging based on the differential pressure described above will not occur.

In this way, since the influence of surging can be eliminated, sealing performance can be ensured by increasing the difference in size between the waste gate valve 7 and the waste gate hole 6a, and flexibility in setting boost pressure characteristics can be achieved. increases. For example, as shown in Figures 3 and 4,
Boost pressure characteristics can be set in the low to medium rotation range and the medium to high rotation range. The broken line is the example of the present invention, the solid line is the conventional example,
Output Ne, cylinder output Pe and waste gate valve 6a
The aperture ratio S is shown.

In the above embodiment, the first diaphragm device 13 is integrally provided on the side opposite to the waste gate valve 7 of the second diaphragm device 14, but it is of course possible to provide the first diaphragm device 13 separately. A first diaphragm device may be provided on the valve 7 side.

(Effects of the invention) As described above, the present invention can offset the influence of the pressure difference between the upstream and downstream sides of the wastegate valve using the biasing force correction means, so the opening and closing control of the wastegate valve can be controlled without causing surging. This increases the degree of freedom in setting boost pressure characteristics.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, and Fig. 1 shows the overall configuration of a boost pressure control device for a turbocharged engine, and Fig. 2 shows the relationship between the areas of the waste gate valve and the diaphragm of the second diaphragm device. The explanatory diagrams shown in FIGS. 3 and 4 are diagrams showing boost pressure characteristics in a low to medium rotation range and a medium to high rotation range. 1... Turbo supercharger, 2... Exhaust passage, 3...
Exhaust turbine, 6...Exhaust bypass passage, 6a...
...Wastegate hole, 7...Wastegate valve,
13...first diaphragm device, 14...second diaphragm device, 18, 23, 24...pressure passage.

Claims (1)

[Scope of utility model registration request] In an engine equipped with a turbo supercharger, an exhaust bypass passage connects upstream and downstream of an exhaust turbine of the turbo supercharger and bypasses the exhaust turbine, and a waste gate valve opens and closes the exhaust bypass passage on the exhaust downstream side. , a main biasing means for biasing the wastegate valve toward the exhaust downstream side in response to an increase in supercharging pressure; 1. A supercharging pressure control device for a turbocharged engine, comprising biasing force correction means for biasing in a direction to cancel pressure.