JPS6143943Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an intake system for a turbocharged engine.

In general, the intake system of a turbocharged engine is
A turbo supercharger is provided in the intake passage on the upstream side of the throttle valve, and intake air is pressurized by the supercharger and supplied to the engine.The turbo supercharger includes a turpin provided in the exhaust passage, It consists of a blower installed in the intake passage and rotated integrally with the turbine.

By the way, conventionally, a bypass passage having a waste gate valve is provided in the exhaust gas passage in which the turbine of the turbocharger is installed, in order to prevent the supercharging pressure from the turbocharger from exceeding a set value. It is designed to be opened and closed by an actuator operated by boost pressure. However, if this wastegate valve becomes stuck due to high-temperature exhaust gas, or if the actuator breaks down and the boost pressure becomes abnormally high, the engine may be damaged or the engine may be dangerously overpowered. It was hot.

Therefore, in order to solve such problems, conventionally,
As shown in Japanese Utility Model Application Publication No. 52-47612,
An air chamber for accumulating supply air is provided with a cylinder and a piston, and a relief hole is provided in the side wall of the cylinder, the opening area of which changes as the piston slides.When the boost pressure becomes abnormally high, the relief hole closes. There was one that opened to allow air to escape outside. However, in such conventional devices, the throttle valve closes during sudden deceleration, while the turbine continues to rotate due to its inertia, resulting in an abnormal rise in boost pressure.In this case, too, the relief hole suddenly closes. There was a problem in that the air was opened and the supply air was relieved to the outside, and at this time, relief air noise was generated, causing noise. Additionally, as the air calculated by the airflow meter is discharged outward, the amount of air supplied to the engine decreases compared to the amount of fuel, causing the problem that the air-fuel ratio during deceleration becomes rich. Ta.

The present invention was made in view of the problems of the conventional ones, and in a turbocharged engine, a supercharging air relief port is provided in the intake passage between the throttle valve and the supercharger. A valve device having a pressure chamber that receives the boost pressure of the intake passage and opens and closes the relief port using the boost pressure, and a communication passage that communicates the intake passage and the pressure chamber; An object of the present invention is to provide an intake system for a turbocharged engine that can reduce relief air noise during deceleration and prevent the air-fuel ratio from becoming rich during deceleration.

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

1 and 2 show an embodiment of the present invention,
In the figure, 1 is an intake passage;
is provided with a throttle valve 2 that controls the amount of air sucked into the engine. Further, a turbo supercharger 3 is provided upstream of the throttle valve 2 in the intake passage 1, and the turbo supercharger 3 has a turbine installed in the exhaust gas passage and rotated by the exhaust gas, and a turbine installed in the intake passage. The turbine is provided with a blower that is rotatably driven integrally with the turbine.

A relief valve 4 consisting of a valve mounting portion 5 and a diaphragm device 6 serving as a valve device is screwed and fixed between the throttle valve 2 of the intake passage 1 and the turbo supercharger 3. The valve mounting part 5 is approximately cylindrical, and has a spanner hook part 5a formed at its rear (left side in FIG. 1) and a threaded part 5b at its front part. A relief port 5d is formed in the bottom of the recess 5c formed in the front end, and a holding port 5e having a larger diameter is formed at the rear end of the valve mounting portion 5 following the relief port 5d. has been done.

Further, a front case 7 of the diaphragm device 6 is fitted and fixed in the holding port 5e. The front case 7 has a generally cylindrical shape, and a held portion 7e that is fitted into and secured to the holding port 5e is formed in the front portion of the front case 7. A circular portion is formed on the front end surface of the held portion 7e further forward. An annular guide portion 7a is integrally formed. Further, three approximately elliptical relief air introduction holes 7b are bored outside the guide portion 7a on the front end surface, and a plurality of relief air discharge holes 7c are bored in the rear side of the front case 7. Furthermore, a mounting flange portion 7d is provided at the rear end of the front case 7.
is integrally formed facing outward. Further, a relief air guide tube 8 having a slightly larger diameter and having a mounting flange portion 8a at its rear end is fitted to the outer side of the front case 7.

A rear case 9 is disposed behind the front case 7, and the rear case 9 has a bottom surface 9.
The mounting flange part 9b integrally formed on the front end of the cylindrical part having a diameter of
The relief air guide cylinder 8 is fitted and fixed to the mounting flange portion 7d of the air guide cylinder 8 and the mounting flange portion 8a of the relief air guide cylinder 8.

In the guide portion 7a of the front case 7,
A valve stem 10 is inserted so as to be slidable in the front and back direction (left and right in FIG. 1), and a disc-shaped valve plate 1 is attached to the front end of the valve stem 10.
1 is fitted and fixed, and an annular seal member 11a is fixed to the rear surface of the valve plate 11, so that it can come into contact with the peripheral edge of the front end surface of the relief port 5d.

Further, a washer 1 is attached to the rear end of the valve stem 10.
2, spring locking member 13, diaphragm 1
4. Diaphragm pressing member 15 and washer 16
are sequentially fitted and fixed with a fixing nut 17. The spring locking member 13 and the diaphragm holding member 15 are both dish-shaped with a fitting hole in the center, and the diaphragm 14 is made of a flexible member such as rubber and has a roughly disc-like shape. The diaphragm has a fitting hole in its center, and its outer peripheral edge is fitted and fixed between the mounting flanges 7d and 9b of the front and rear cases 7 and 9. A space surrounded by the rear case 14 and the rear case 9 serves as a pressure chamber 19. Further, a coil spring 18 is provided between the spring locking member 13 and the front end surface of the front case 7.
is interposed, and the valve stem 10 is urged rearward by the coil spring 18, so that the sealing member 11a of the valve plate 11 presses into contact with the peripheral edge of the front end surface of the relief port 5d. There is.

Further, a communicating passage 10a is bored through the valve stem 10 along its central axis.
a communicates the intake passage 1 and the pressure chamber 19. A throttle member 20 is screwed and fixed to the rear end of the communication path 10a, and the throttle member 20 has a cylindrical shape with a bottom surface, and an orifice, that is, a throttle 20a is bored in the bottom surface. This throttle 20a is for slowly guiding the supercharging air on the intake passage 1 side to the pressure chamber 19.

Next, the operation will be explained using FIGS. 1 to 3.

Here, FIG. 3 is a diagram showing temporal changes in supercharging pressure in the vicinity of the attachment portion of the relief valve 4 in the intake passage 1.

First, during sudden deceleration, the accelerator pedal suddenly returns from its depressed position to its original position, and the throttle valve 2 suddenly closes the intake passage 1, resulting in a sudden decrease in exhaust gas. However, due to its inertia, the turbocharger 3 rotates for a while at a speed close to the rotational speed immediately before deceleration, and then is gradually decelerated. Therefore, the boost pressure is the third
As shown in the figure, from the first boost pressure P ₀ when the accelerator pedal is pressed just before deceleration, to when the deceleration starts.
At t ₀ , the relief supercharging pressure P ₁ which opens the relief port 5 d is rapidly increased to far exceed it. After that, the boost pressure gradually decreases, and at time _t1 , the first
The supercharging pressure becomes equal to the supercharging pressure P ₀ , and the supercharging pressure continues to decrease. Here, t in FIG. 3 is the delay time between time t ₀ and t ₁ . After time _t0 , the supercharged air in the intake passage 1 is guided to the pressure chamber 19 through the communication passage 10a and the throttle 20a, as shown by the dashed line arrow in FIG. Pressure increases gradually. However, since the flow rate of the supercharging air introduced into the pressure chamber 19 is restricted by the throttle 20a, the pressure within the pressure chamber 19 does not reach the relief supercharging pressure _P1 within time t, and the Therefore, the pressure of the supercharging air in the intake passage 1 becomes lower than the relief supercharging pressure P ₁ before the pressure in the pressure chamber 19 reaches the relief supercharging pressure P ₁ .
is not slid forward, so the relief port 5d remains closed.

Next, a case will be described in which the supercharging pressure of the turbocharger 3 is abnormally increased due to a failure of a waste gate valve (not shown) that adjusts the supercharging pressure of the turbo supercharger 3. In this case as well, the supercharging air in the intake passage 1 is controlled by the throttle 20.
At step a, the flow rate is restricted and guided to the pressure chamber 19, but if the waste gate valve fails, the high supercharging pressure will continue for a while, so
The pressure in the pressure chamber 19 exceeds the relief supercharging pressure _P1 , and the diaphragm 14 of the valve rod 10 is pushed by the pressure in the pressure chamber 19 and slides forward, thereby opening the relief port 5d. As shown by the solid line arrow in FIG.
Relief air introduction hole 7b, relief air discharge hole 7
c. Further, the air is discharged to the outside through the space between the front case 7 and the relief air guide cylinder 8, and as a result, the supercharging pressure is maintained below a predetermined pressure.

In this way, in the intake system of the turbocharged engine of this embodiment, the throttle 20a is provided in the communication passage 10a to restrict the sudden introduction of supercharging air into the pressure chamber 19, The pressure in the intake passage 1 is made to rise slowly even if the pressure rises suddenly, so the relief port 5d does not open even during sudden deceleration, reducing the relief air noise and reducing the waste air pressure. If boost pressure rises abnormally due to gate valve failure, etc., as before,
The pressure causes the relief port 5d to open, allowing the supercharging pressure to be maintained normally. Furthermore, during the deceleration operation described above, the supercharging air is not discharged to the outside, so the air-fuel ratio does not become rich.

In the above embodiment, the communication path 10a is connected to the valve stem 1.
Although this communication passage is provided by penetrating through the pressure chamber 19, it is sufficient that the communication passage communicates the intake passage 1 and the pressure chamber 19. For example, a pipe that communicates the two may be provided outside the relief valve 4. In this case, the throttle 20a may be provided in the middle of this piping.

As described above, according to the intake system for a turbocharged engine according to the present invention, a supercharging air relief port is provided in the intake passage between the throttle valve and the turbocharger, and the air intake system in the intake passage is A valve device that has a pressure chamber that receives supply pressure and opens and closes the relief port using the boost pressure, and a communication passage that communicates the intake passage and the pressure chamber are provided, and a restriction is provided in the communication passage. , the supercharging air relief port does not open during deceleration, reducing relief air noise, and supercharging air is not discharged outward during deceleration, which has the effect of preventing the air-fuel ratio from becoming rich. be.

[Brief explanation of the drawing]

Fig. 1 is a schematic configuration diagram of an intake system for a turbocharged engine according to an embodiment of the present invention, Fig. 2 is a sectional view taken along the line - - of Fig. 1, and Fig. 3 explains the operation of the device of the above embodiment. This is a diagram for 1...Intake passage, 2...Throttle valve, 3...
Turbo supercharger, 5d...Supercharging air relief port, 6
... Valve device (diaphragm device), 10a... Communication path, 19... Pressure chamber, 20a... Throttle.

Claims (1)

[Scope of utility model registration request] In an engine in which a turbocharger is provided in the intake passage upstream of the throttle valve, a supercharging air relief port provided in the intake passage between the throttle valve and the turbocharger, and a supercharging pressure in the intake passage. a valve device that opens and closes the supercharging air relief port according to the supercharging pressure; a communication passage that communicates the intake passage with the pressure chamber; and a throttle provided in the communication passage. An intake system for an engine equipped with a turbocharger.