JPH0310347Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to an intake system for an engine equipped with a turbocharger, and in particular, to an intake system for an engine equipped with a turbocharger, and in particular to an intake system that maintains the intake air in the intake passage between the turbocharger and the throttle valve in an operating state. This is related to an improvement to provide relief depending on the situation.

(Prior Art) Conventionally, in an engine equipped with a turbocharger, as disclosed in Japanese Patent Laid-Open No. 53-146025, the supercharging pressure in the intake passage downstream of the turbocharger exceeds a set value. By installing a blow-off valve that opens to relieve intake air when Engines designed to prevent engine damage in such cases are known.

(Problem to be solved by the invention) By the way, in such a turbocharged engine, during light load operation, the pressure of the exhaust gas introduced into the turbine is low, so the rotational driving force of the turbocharger is weak and , since the throttle valve opening is small and the intake pressure upstream of the throttle valve is higher than atmospheric pressure, this pressure acts as back pressure on the compressor and becomes rotational resistance of the supercharger, so the rotational speed of the supercharger increases. is kept low. For this reason, when opening the throttle valve and starting acceleration operation from such a light load operating state, the problem arises that the turbocharger rotation speed does not rise well and there is a time lag for the boost pressure to rise, resulting in poor acceleration response. .

Therefore, a relief valve is installed in the intake passage between the supercharger and the throttle valve in a turbocharged engine that opens to relieve intake air when the intake negative pressure downstream of the throttle valve exceeds a set value, such as during light load. By reducing the back pressure of the compressor to around atmospheric pressure during light loads and reducing the rotational resistance of the supercharger, the supercharger rotational speed during light loads can be maintained as high as possible, improving acceleration response. It is conceivable to try to improve this.

However, if this relief valve is used in addition to the conventional blow-off valve described above, two valves will be provided in the intake device, resulting in a large and heavy intake device.

The present invention has been developed in view of these points, and its purpose is to provide a blow-off valve function that suppresses the increase in supercharging pressure in a turbocharged engine as described above, and to suppress the increase in back pressure on the compressor side. The purpose of the present invention is to reduce the size and weight of an intake device for a turbocharged engine that can protect the engine and improve acceleration by performing the suppression relief valve function with a single valve.

(Means for Solving the Problems) In order to achieve the above object, the solution of the present invention is based on an intake system of a turbocharged engine that is equipped with a turbocharger upstream of a throttle valve in the intake passage. In contrast, the following control valve is provided. That is, the control valve includes a valve chamber having a relief hole and a connection port communicating with the intake passage between the turbocharger and the throttle valve, and a valve chamber that is connected to the connection port from the valve chamber side. A valve body that opens and closes the connection port by separating the valve body, a diaphragm that slidably supports the valve stem of the valve body, and a diaphragm that forms a section at the back of the valve chamber to prevent intake negative pressure downstream of the throttle valve in the intake passage. a negative pressure chamber to be introduced; a stopper provided on the valve stem of the valve element and engaged with the diaphragm so as to open the valve element when the diaphragm is biased toward the negative pressure chamber; A blow-off spring biases the diaphragm in the valve-closing direction with a spring force that opposes the valve-opening force that acts on the valve body at the supply pressure value, and a blow-off spring that biases the diaphragm from the suction force that acts on the diaphragm at the set intake negative pressure value. and a relief spring that biases the valve body in the direction of closing the valve with a spring force equal to the spring force of the valve body.

(Function) With the above configuration, in the present invention, during light load operation when the intake negative pressure introduced into the negative pressure chamber exceeds the set value, the diaphragm is activated to combine the blow-off spring and the relief spring by the suction force caused by this negative pressure. By being biased toward the negative pressure chamber while engaged with the stopper against the spring force, the valve element separates from the connection port and opens the connection port, thereby causing the intake air in the intake passage upstream of the throttle valve to Pressure is relieved from the valve chamber to the relief hole. On the other hand, when the boost pressure downstream of the turbocharger in the intake passage exceeds the set value, the valve opening force due to this boost pressure causes only the valve body to resist the spring force of the blow-off spring without engaging the diaphragm. The connecting port is opened by moving away from the connecting port, whereby the supercharging pressure in the intake passage is relieved from the valve chamber to the relief hole. In this way, the control valve has both the functions of a relief valve and a blow-off valve.

(Example) Hereinafter, an example of the present invention will be described based on the drawings.

1 and 2 show an embodiment of the invention.
In Figure 1, 1 is the engine, 2 is the engine 1
3 is an exhaust passage for discharging exhaust gas from the engine 1, and 4 is a throttle valve disposed in the intake passage 2 to control the amount of intake air. Reference numeral 5 denotes a turbo supercharger, which includes a turbine 6 disposed in the exhaust passage 3 and rotationally driven by the exhaust gas flow, and an intake passage 2.
a compressor 8 disposed upstream of the throttle valve 4 and drivingly connected to the turbine 6 via a connecting shaft 7;
The compressor 8 is rotationally driven by the rotation of the turbine 6 caused by the exhaust gas, and the intake air is supercharged to the engine 1 by the rotation of the compressor 8.

An induction chamber 9 is provided in the intake passage 5 between the turbocharger 5 (compressor 8) and the throttle valve 4, and the induction chamber 9 is provided with a control valve 10 for relieving intake air. ing.

The control valve 10, as shown in detail in FIG.
It is provided in the upper half of the casing 11 and has relief holes 12, 12 opened in the side wall, and communicates with the induction chamber 9 (intake passage 2 between the turbocharger 5 and the throttle valve 4) at the center of the upper part. A valve chamber 14 in which the connection port 13 is opened, and the valve chamber 14
a valve body 15 disposed within the valve chamber 14 to open and close the connection port 14 by moving toward and away from the connection port 13 from the valve chamber 14 side; and a valve rod 16 provided below the valve chamber 14 and extending downward from the valve body 15. A diaphragm 17 that slidably and airtightly supports the valve chamber 14 is defined in the casing 11 at the back of the valve chamber 14 (lower part in FIG. 2), and is connected to the throttle valve via a negative pressure passage 18. 4 a negative pressure chamber 19 into which intake negative pressure of the downstream intake passage 2 is introduced; and a valve stem 1 of the valve body 15;
a ring-shaped stopper 20 provided at the lower end of the diaphragm 17 and engaged with the diaphragm 17 to pull the valve body 15 downward and open the valve when the diaphragm 17 is biased toward the negative pressure chamber 19 side (lower side); A valve opening force is compressed between a spring receiver 21 fixed to the casing 11 above the diaphragm 17 and the valve body 15, and acts on the valve body 15 at a set supercharging pressure value.
A blow-off spring 22 that urges _{the valve in the valve closing direction with a spring force P 1 (} =P ₀ ) opposed to P 0 , and the negative pressure chamber 1
9, _the diaphragm 17 is set to a spring force P ₂ (= _{P 3 -} P ₁ ) and a relief spring 23 that biases the valve body 15 in the direction of closing the valve. The valve opening pressure of the blow-off spring 22 that resists the spring force _P1 is set to a value greater than the valve opening pressure of the waste gate valve 27, which will be described later.

Note that 24 is an intercooler provided in the intake passage 2 downstream of the compressor 8 and upstream of the induction chamber 9. 26 is a bypass passage that bypasses the turbine 6 of the exhaust passage 3; 27 is a waste gate valve that opens and closes the bypass passage 26;
When this supercharging pressure is equal to or higher than a predetermined value (maximum supercharging pressure), it opens and allows a part of the exhaust gas flow to flow down through the bypass passage 26, bypassing the turbine 6. This is to maintain the boost pressure at a predetermined value (maximum boost pressure). 28 is a fuel injection valve provided in the intake passage 2 upstream of the throttle valve 4.

Next, to explain the operation of the above embodiment,
During light load operation, when the opening degree of the throttle valve 4 is small and the intake negative pressure downstream of the throttle valve 4 in the intake passage 2 exceeds the set value, the suction force due to this negative pressure introduced into the negative pressure chamber 19 of the control valve 10 increases. Due to P ₃ , the diaphragm 17 receives the combined spring force (P ₁ + P ₂ ) of the blow-off spring 22 and the relief spring 23.
The valve body 15 is biased towards the negative pressure chamber 19 side while being engaged with the stopper 20 against the
The connection port 13 is opened away from the connection port 13 as shown by the imaginary line in the figure, and the intake pressure in the induction chamber 9 of the intake passage 2 is transferred from the valve chamber 14 to the relief holes 12 and 1.
Relief to 2. By operating the control valve 10 as a relief valve in this way, the intake pressure upstream of the throttle valve 4, that is, the back pressure of the compressor 8, decreases to approximately atmospheric pressure, reducing the rotational resistance of the supercharger 5, and reducing the The rotational speed can be maintained as high as possible and acceleration response can be improved.

On the other hand, if the wastegate valve 27 becomes stuck in a closed state due to high-temperature exhaust gas, and the intake pressure (supercharging pressure) downstream of the turbocharger 5 (compressor 8) in the intake passage 2 exceeds the set value, This supercharging pressure acts on the valve body 15 from the induction chamber 9 through the connection port 13, and this valve opening force (>
P ₀ ), the valve body 15 resists the spring force P ₁ of the blow-off spring 22 and moves away from the connection port 13 to open the connection port 13, as shown by the imaginary line in FIG. It is relieved from the relief holes 12, 12. At this time, since no negative pressure is acting on the negative pressure chamber 19, the diaphragm 17 is not operated and is in the state shown in FIG. 2. In this way, the control valve 10
By operating as a blow-off valve, the supercharging pressure can be maintained below the set supercharging pressure value to reduce the load on the engine and the intake/exhaust system, and damage to the engine can be prevented.

Therefore, in the above embodiment, the relief valve and the blow-off valve are integrally and compactly configured by one control valve 10, so that the intake device can be made smaller and lighter. This also facilitates the layout of auxiliary equipment around the engine, increasing the degree of freedom.

(Effects of the invention) As explained above, according to the intake system for a turbocharged engine of the invention, a single control valve has a relief valve function that suppresses an increase in compressor back pressure, and a boost pressure The blow-off valve function suppresses an abnormal rise in air pressure, thereby creating a small and lightweight intake system that protects the engine by suppressing increases in boost pressure and improves acceleration by suppressing increases in compressor back pressure. In addition, the degree of freedom in the layout of auxiliary equipment around the engine can be increased accordingly.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, with FIG. 1 being an overall schematic diagram and FIG. 2 being an enlarged sectional view of a control valve. DESCRIPTION OF SYMBOLS 1...Engine, 2...Intake passage, 4...Throttle valve, 5...Turbocharger, 6...Turbine, 8...Compressor, 10...Control valve, 12
... Relief hole, 13 ... Connection port, 14 ... Valve chamber, 15 ... Valve body, 16 ... Valve stem, 17 ... Diaphragm, 19 ... Negative pressure chamber, 20 ... Stopper,
22...Blow-off spring, 23...Relief spring.

Claims (1)

[Scope of utility model registration request] In an intake system for a turbocharged engine that is equipped with a turbocharger upstream of a throttle valve in the intake passage, a relief hole is opened and the connection between the turbocharger and the throttle valve communicates with the intake passage. a valve chamber with an opening; a valve body that approaches and separates from the connection port from the valve chamber side to open and close the connection port; and a diaphragm that slidably supports a valve stem of the valve body;
A negative pressure chamber is defined at the back of the valve chamber by the diaphragm and into which the intake negative pressure downstream of the throttle valve of the intake passage is introduced; a stopper that engages with the diaphragm to open the valve body;
A blow-off spring biases the valve body in the valve closing direction with a spring force that opposes the valve opening force acting on the valve body at a set supercharging pressure value, and a blow-off spring that biases the diaphragm in the valve closing direction at a set intake negative pressure value. A turbo supercharger characterized in that a control valve is provided with a relief spring that biases the valve body in the direction of closing with a spring force equal to the suction force minus the spring force of the blow-off spring. Air intake system for the engine.