JPS6021462Y2 - Internal combustion engine with supercharger - Google Patents

Description

[Detailed description of the invention] This invention is an internal combustion engine equipped with an exhaust turbine type supercharger,
In particular, the present invention relates to a supercharged internal combustion engine in which a catalyst device is interposed in an exhaust passage downstream of a turbine of a supercharger.

. BACKGROUND ART Conventionally, it is well known to provide an internal combustion engine with a supercharger that supplies pressurized air or air-fuel mixture to improve charging efficiency and improve the output of the internal combustion engine.

The above-mentioned supercharger may also be an exhaust turbine type supercharger that uses a turbine driven by exhaust gas and a compressor connected to the turbine to pressurize the air or air-fuel mixture supplied to the internal combustion engine. well known.

However, in an internal combustion engine equipped with this type of exhaust turbine type supercharger, since the heat capacity of the turbine is large, when the exhaust gas passes through the turbine, heat is taken away from the exhaust gas, and the temperature of the exhaust gas after passing through the turbine increases. decreases.

However, this decrease in exhaust gas temperature reduces the exhaust gas purification performance of the catalyst device installed in the exhaust passage downstream of the turbine to purify the exhaust gas. Since the temperature of the catalytic device itself is low during cold periods when the engine temperature is low, especially immediately after the engine is started, the catalytic device does not sufficiently purify the exhaust gas, causing the problem of emitting harmful components into the atmosphere.

The present invention has been made in view of these points, and while it is equipped with an exhaust turbine type supercharger to improve output, a catalyst device is interposed in the exhaust passage downstream of the turbine of the supercharger to exhaust air. In a supercharged internal combustion engine designed to purify gas, a bypass passage is formed in the exhaust passage upstream of the catalyst device to bypass the turbine, and this bypass passage is provided with an on-off valve that opens the bypass passage when the engine is cold. Furthermore, by opening a secondary air passage in the exhaust passage upstream of the turbine and downstream of the branching part of the bypass passage, which supplies secondary air at least when the on-off valve opens, the exhaust gas is removed when the engine is cold. By opening the on-off valve and supplying secondary air, which cuts off the flow to the turbine, the air flows down into the bypass passage along with a portion of the secondary air without passing through the turbine, which has a large heat capacity, and the temperature of the exhaust gas is lowered. The exhaust gas temperature is maintained as high as possible, and the exhaust gas temperature is increased by an oxidation reaction with the secondary air so that it flows into the catalytic device installed downstream of the exhaust passage, thereby increasing the temperature in the catalytic device. Therefore, sufficient exhaust gas purification performance can be maintained even when the engine is cold.

Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings.

In FIG. 1, 1 is an internal combustion engine main body, 2 is an exhaust turbine type supercharger consisting of a compressor 2a installed in an intake passage 3 and a turbine 2b installed in an exhaust passage 4. 2b is connected by a shaft 2C and rotates as a unit.

Reference numeral 5 denotes a catalyst device installed in the exhaust passage 4 downstream of the turbine 2b of the supercharger 2, and the downstream side of the catalyst device 5 is open to the atmosphere.

6 is an intake passage 3 downstream of the compressor 2a of the supercharger 2
The intake manifold 7 forms the intake manifold 6.
It is a throttle valve located inside.

8 is a supercharger 2 in the exhaust passage 4 upstream of the catalyst device 5.
The bypass passage 8 is provided with an on-off valve 11 that opens and closes the bypass passage 8 in conjunction with the waste gate 10 near a branching part 9 where the bypass passage 8 branches from the exhaust passage 4. Intervention is provided.

The wastegate 10 is conventionally provided in the supercharger 2, and is used to prevent excessive supercharging and control the amount of supercharging.

That is, the pressure (supercharging pressure) in the intake manifold 6 upstream of the throttle valve 7 pressurized by the compressor 2a is applied to one chamber 10a of the wastegate 10 through the passage 12, while the other chamber 10b is provided so that atmospheric pressure is applied through the atmosphere opening port 13, and the supercharging pressure in the intake manifold 6 upstream of the throttle valve 7 pressurized by the compressor 2a of the supercharger 2 is set to a predetermined value. Higher, the wastegate 10 has rods 14 and links 15.
The on-off valve 11 connected to the turbine 2b is opened to allow a part of the exhaust gas to flow into the bypass passage 8 that bypasses the turbine 2b, thereby controlling the amount of exhaust gas entering the turbine 2b. The rotation of the compressor 2a driven by the turbine 2b is controlled, thereby controlling the amount of supercharging.

In this embodiment, furthermore, the other room 10 of the waste gate 10
b, a negative pressure passage 16 that applies negative intake pressure of the intake manifold 6 downstream of the throttle valve 7 is connected to the atmosphere opening port 13 that introduces the atmospheric pressure, and this juxtaposed portion has a A three-way solenoid valve 17 is provided, and the three-way solenoid valve 17 is a water temperature switch that detects the temperature of the cooling water that cools the internal combustion engine body 1 and closes when the water temperature is below a predetermined temperature (that is, when the engine is cold). It is activated by opening and closing of water temperature switch 1.
8 is closed (when the engine is cold), the negative pressure passage 16 is opened and at the same time the atmosphere opening port 13 is closed, while the water temperature switch 1 is closed.
8, the atmosphere opening port 13 is opened and the negative pressure passage 16 is closed at the same time, that is, the atmosphere opening port 13 and the negative pressure passage 16 are selectively switched with respect to the other chamber 10b of the wastegate 10. It is composed of

In addition, 19 and 20 are one room lea of West Gate 10.
and a bellows and a spring housed in the other chamber 10b.

On the other hand, 21 is a secondary air passage that supplies secondary air from the internal combustion engine main body 1 by driving the air pump 22, and the supply port 21a at the other end of the secondary air passage 21 is connected to the turbine 2.
b, and opens into the exhaust passage 4 upstream from the branch part 9 of the bypass passage 8, and opens into the secondary air passage 21.
A control valve 23 for opening and closing the secondary air passage 21 is interposed in the middle of the secondary air passage 21, and the control valve 23 is operated at least when the on-off valve 11 is opened (that is, when the water temperature switch 18 is closed). When the bypass passage 8 is closed, it is opened to supply secondary air to the exhaust passage upstream from the turbine 2b and downstream from the branch part 9 of the bypass passage 8.

Note that the control valve 23 may be opened to supply secondary air to the exhaust passage 4 other than when the on-off valve 11 is opened;
8 is closed (when the engine is cold), it always opens.

Next, to explain the operation of the above embodiment, when the engine is cold, such as when starting operation, when the temperature of the cooling water is lower than a predetermined value, the water temperature switch 18 is closed, so a current flows through the three-way solenoid valve 17, and it is excited. However, since the atmosphere opening port 13 is closed and the negative pressure passage 16 is opened, the negative intake pressure of the intake manifold 6 downstream of the throttle valve 7 acts on the other chamber 10b of the wastegate 10.

On the other hand, atmospheric pressure upstream of the throttle valve 7 acts on the chamber 10a of the wastegate 10.

Thereby, the on-off valve 1 connected to the waste gate 10
Reference numeral 1 indicates a secondary air passage which opens into the exhaust passage 4 upstream from the turbine 2b and downstream from the branch portion 9 of the bypass passage 8, and the control valve 23 is opened by the opening operation of the on-off valve 11. By supplying the secondary air from the supply port 21a of 21, the flow of the exhaust gas to the turbine 2b is blocked, and most of the exhaust gas, together with a part of the secondary air, enters the bypass passage that bypasses the turbine 2b. 8 and flows into the catalyst device 5, the temperature of the exhaust gas is maintained high.Furthermore, during this time, the exhaust gas and secondary air undergo an oxidation reaction, causing the temperature of the exhaust gas to rise. 5
Exhaust gas purification can be effectively carried out within the vehicle.

After that, when the engine warms up and the temperature of the cooling water reaches a predetermined value or higher, the water temperature switch 18 opens, and no current flows through the three-way solenoid valve 17. Negative pressure passage 1 is pushed back by the force of
6 is closed and the atmosphere opening port 13 is opened at the same time, and when atmospheric pressure acts on the other chamber 10b of the wastegate 10 through the atmosphere opening port 13, the original function of the wastegate is thereafter disabled.

That is, the supercharging pressure increased by the compressor 2a acts on one chamber 10a of the waste gate 10, and the waste gate 10 reaches a position where this supercharging pressure and the spring force of the spring 20 compressed in the other chamber 10b are balanced. The operation of the gate 10 is controlled, and accordingly, the on-off valve 11 connected to the waste gate 10 opens and closes. When supercharging pressure is high and excessive supercharging is performed, the on-off valve 11 opens and closes the turbine 2b. Since the amount of exhaust gas passing through decreases, the rotation speed of the turbine 2b decreases, and the supercharging capacity of the compressor 2a decreases.

On the other hand, when the boost pressure is low and there is a shortage in supercharging, the on-off valve 11 closes and a large amount of exhaust gas passes through the turbine 2b, increasing the supercharging capacity and therefore always providing effective Supercharging can be performed.

At this time, when the exhaust gas passes through the turbine 2b, the exhaust gas temperature at the outlet of the turbine 2b will be lower than that of the turbine 2b due to the absorption of heat by the turbine 2b, which has a large heat capacity.
However, since the exhaust gas temperature is sufficiently high and the temperature of the main body of the catalyst device 5 is also high, sufficient purification of the exhaust gas in the catalyst device 5 is achieved.

Further, FIG. 2 shows another embodiment of the present invention, in which a turbine 2
supply port 21 of the secondary air passage 21' that opens into the exhaust passage 4 upstream from b and downstream from the branch part 9 of the bypass passage 8;
'a is opened to face the flow of the exhaust passage 4, thereby further blocking the flow of exhaust gas to the turbine 2b by the secondary air supplied simultaneously with the opening of the on-off valve 11 when the engine is cold. It is designed to be carried out effectively and reliably.

The rest of the structure is the same as that of the above embodiment, and the same parts as in FIG. 1 are given the same reference numerals, and the explanation thereof will be omitted.

In the case of this embodiment, when the engine is cold, the exhaust gas is
b, and the temperature of the exhaust gas flowing into the catalyst device 5 can be maintained high as in the above embodiment.

In the above embodiment, the case was described in which a conventionally known waste gate for controlling the amount of supercharging was used. It goes without saying that a bypass passage that detours around the turbine 2b may be provided separately, and an on-off valve that opens this bypass passage when the engine is cold may be provided in the bypass passage, but as in the above embodiment, It is better to use a wastegate because it is possible to improve the exhaust gas purification performance of the catalyst device during cold conditions, which is the gist of the present invention, by applying simple means to the wastegate device, so it has been provided in the past. This has an extremely large advantage in that the device can be used.

In the above embodiment, the water temperature switch 18 is used to operate the three-way solenoid valve 17, but the water temperature switch 18 is not limited to detecting the water temperature, and the three-way solenoid valve can also be used to detect the engine choke signal, catalyst temperature, exhaust temperature, etc. It may also be for controlling the valve 17.

As described above, according to the present invention, in an exhaust turbine supercharged internal combustion engine equipped with a catalyst device, a bypass passage that bypasses the turbine is formed in the exhaust passage upstream of the catalyst device, and a bypass passage that bypasses the turbine is formed in the exhaust passage upstream of the catalyst device. A secondary air passage is provided with an on-off valve that opens the bypass passage when the engine is cold, and supplies secondary air to the exhaust passage upstream of the turbine and downstream of the branch of the bypass passage at least when the on-off valve opens. By opening the exhaust gas, when the engine is cold, the exhaust gas does not flow through the turbocharger turbine, preventing the exhaust gas temperature from decreasing due to the heat of the exhaust gas being taken away by the turbine. At the same time, the temperature of the exhaust gas can be raised by the oxidation reaction between the bypassing exhaust gas and the secondary air, so the temperature of the exhaust gas flowing into the catalyst device can be maintained high, thereby reducing the cold temperature of the engine. It is possible to maintain good exhaust gas purification performance even at times.

[Brief explanation of the drawing]

The drawings illustrate embodiments of the present invention, and FIG. 1 is a general schematic diagram showing one embodiment, and FIG. 2 is a cross-sectional side view of main parts showing another embodiment. 1... Internal combustion engine main body, 2... Exhaust turbine supercharger, 2a... Compressor, 2b.
...Turbine, 3...Intake passage, 4...
...Exhaust passage, 5...Catalyst device, Death...
...Bypass passage, 9... Branch, 10...
...Wastegate, 11...Opening/closing valve, 13
...Atmospheric release port, 16...Negative pressure passage,
17...Three-way solenoid valve, 18...Water temperature switch, 21, 21'...Secondary air passage, 21
a, 21'a... Supply port, 23... Control valve.

Claims (1)

[Scope of utility model registration request] In a supercharged internal combustion engine equipped with an exhaust turbine type supercharger and a catalyst device interposed in an exhaust passage downstream of the turbine of the supercharger, a bypass that bypasses the turbine in the exhaust passage upstream of the catalyst device. Along with forming a passage,
The bypass passage is provided with an on-off valve that opens the bypass passage when the engine is cold, and at least secondary air is supplied to the exhaust passage upstream of the turbine and downstream of the branch of the bypass passage when the on-off valve opens. An internal combustion engine with a supercharger, characterized in that a secondary air passage for supplying air is opened.