JPS6134321A - Engine with turbo-charger - Google Patents

Abstract

PURPOSE:To improve the accelerating performance of an engine which is provided with a turbo-charger and has a turbine disposed at the lower side of the catalyst in an exhaust passage by feeding air into the upstream exhaust passage of the catalyst. CONSTITUTION:When a car which is running at a low speed is acceleratted, an air pump 9 is driven by an engine. A discharge pressure PA from an air pump 9 is low and another discharge pressure PB therefrom becomes the atmosphere pressure, since a throttle valve 8 is kept open, so that a regulation valve 23 is opened. Compressed air is then sent into an exhaust passage 2 and CO which is a chief composition of exhaust gas reacts to a catalyst 3 and oxidized, whereby increasing temperature at the inlet 7 of a turbine 4. Revolution of the turbine 4 will then be boosted so that the problem of turbo lag may be dissolved. This operation is completed within a short period (a few minutes) before completion of acceleration. Revolution of the air pump 9 is increased in accordance with increase in engine speed. The resultant increase in discharged pressure PA will act on pressure in a pressure chamber 17. A regulation valve 14 is then closed to interrupt supply of air, whereby restraining increase in pressure at the inlet of the turbine.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) This invention relates to a turbocharged engine, and more particularly to a device for improving turbo lag in the engine.

Turbocharged engines have the advantage of being able to increase engine torque by using the engine's exhaust energy to pressurize the intake air, but on the other hand, when accelerating from low speeds at full speed, the engine speed rises slowly, which is called turbo lag.・There is a problem.

By the way, another problem with turbocharged engines is that the exhaust temperature is lowered by the turbine, which worsens exhaust emissions. Proposition 1.1 has been proposed.

This system is equipped with a catalyst and a turbine in that order in the exhaust passage of the engine, and a compressor driven by the turbine compresses air, which is then supplied to the engine as supercharging air.

In this conventional type, there is a turbine after the catalyst, so the exhaust gas does not drop. Therefore, an oxygen sensor in the exhaust gas detects the oxygen concentration and the air-fuel ratio is feedback-controlled.
'It can clean the exhaust air.

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However, although such a conventional turbocharged engine solves the latter problem of worsening exhaust emissions, it cannot solve the former problem of turbo lag during acceleration.

In other words, the conventional structure was such that the engine exhaust gas passed through the catalyst as it was, so the temperature at the turbine inlet rose due to the catalytic reaction by an amount corresponding to the amount of oxygen (02) contained in the engine exhaust gas. When the engine is accelerating, the exhaust gas does not contain the 02 component, and the temperature rise is small, and when accelerating at full throttle, the gradient of temperature rise with respect to time becomes gentle. However, the engine could not respond to acceleration in a very short period of time, and there was no hope for improvement in turbo lag.

This invention was made in view of these conventional problems. Air is supplied to the exhaust passage further upstream of the catalyst upstream of the turbine, and the temperature increase due to combustion of CO and HC in the exhaust gas is utilized. The purpose is to solve the above problems by doing so.

[Solution]

To achieve the above object, the present invention provides a turbocharged engine in which a compressor installed in an intake passage is driven by a turbine installed downstream of a catalyst in the exhaust passage, in which air is supplied to the exhaust passage upstream of the catalyst. It is equipped with an air supply device.

[Effect]

During acceleration, more fuel is supplied to the engine, and therefore more unburned substances CO and HC are present in the exhaust.

At this time, air is supplied upstream of the catalyst, so that unburned substances are oxidized by the reaction in the catalyst, raising the exhaust temperature and the turbine inlet temperature.

Therefore, the turbine rotates at high speed due to the increase in exhaust energy, and the coaxial compressor is also rotated at high speed, so that the supercharging pressure of the intake air increases quickly, and acceleration is performed quickly. That is, turbo lag is eliminated. Of course, as before,
Exhaust emissions are also good 1″″iit, a・
, :.

Examples of the present invention will be described below.

〔Example〕

FIG. 1 shows an embodiment of the invention.

First, to explain the configuration, the engine 1 has an exhaust passage 2 on the right side.
A catalyst 3 is provided downstream of the catalyst 3, and a turbine 4 is further provided downstream of the catalyst 3.

The turbine 4 is equipped with a coaxial compressor 5 on the left side, thereby forming a turbocharger iν20. The compressor 5 is interposed in an intake passage 6, and the intake passage 6 has a
It is equipped with an accelerator, a second 10, and a first 0-meter 11, and a throttle valve 8 linked to an accelerator pedal for controlling the amount of intake air downstream.

The air pump 9 is driven by the engine 1 using a means such as a belt, and bleeds air from downstream of the air cleaner 10 through an intake pipe 21 , and injects air from an injection port 31 into the exhaust passage 2 upstream of the catalyst 3 through a control valve 13 through a discharge pipe 12 . Supply injection.

The control valve 13 includes a valve body 22 and a valve seat (air supply port) 23 in a valve chamber, and the valve body 22 is connected to a diaphragm 18 of an actuator 14 with a valve rod 24 to open and close the supply port 23.

The actuator 14 is configured to introduce the intake pressure PB downstream of the throttle valve 8 into the pressure type 16 on the right side, introduce the discharge pressure PA of the air pump 9 into the pressure chamber 17 on the left side, and connect the return spring 15 to the pressure horn chamber. Install it on the 16 side.

The catalyst 3 is an oxidation catalyst having a metal component such as PT or PD, and is also called a catalytic combustor because it performs a combustion reaction between oxygen in the injected air and unburned CO and HC.

An exhaust bypass valve 25 is provided at the lower inlet of the turbine 4, and the supercharging pressure of the compressor is guided to the actuator 26 of the valve 25 through a passage 30. When the supercharging pressure is equal to or higher than a specified value, the actuator 26 operates to open the bypass valve 25 and bypass the exhaust gas through the bypass passage 27. Exhaust is routed from the downstream side of the turbine 4 to an exhaust pipe 28 and an exhaust purifying contact 12.
9 and then released into the atmosphere.

Note that a temperature sensor 19 such as a thermocouple or a thermistor is inserted downstream of the catalyst 3 to monitor the temperature and warn the driver of overheating of the catalyst system with a lamp or buzzer. This warning reduces the burden on the driver and prevents melting of the catalyst or thermal damage to the turbine. Alternatively, the gate valve (
(Figure 1) may be automatically closed to stop air injection.

Next, we will explain the operation.When accelerating at full throttle from relatively low speed operation, the turbocharger's rotation speed rises slowly and does not rapidly follow the throttle valve opening, resulting in so-called turbo lag.In this example, the engine At low speed rotation, that is, at the intercept point (Fig. 5 IC
Detects full-open acceleration at low speed near ), opens the air supply port of the regulating valve and supplies pressurized air to the exhaust passage, converting CO and )-10 (actually mostly CO) in the exhaust gas to the catalyst. The reaction occurs in the combustor 3, increases the temperature of the turbine lower, and accelerates the rise in rotation of the turbine 4 during acceleration.

■When the engine is running at low speed and with low load: In this case, the intake pressure Pa is a large negative pressure due to the closing of the throttle valve 8, so the actuator 14 moves the diaphragm 18 to the right against the spring 15 due to negative pressure in the pressure chamber 16. The control valve 13 closes the air supply port 23 because the valve rod 24 and the valve body 22 are moved to the right. In other words, air is not supplied to the exhaust passage 2.

In this case, the discharge pressure of the air pump 9 is low due to low rotation, and this small pressure acts on the left side of the diaphragm 18, but this, together with the negative pressure value on the right side, closes the control valve 13. .

■ At low speed and high load: In this case, the throttle valve is fully open, which requires acceleration. That is, the discharge pressure PA of the air pump 9
is low due to low speed, and on the other hand, throttle valve 8 is fully open or almost fully open)
Therefore, the intake pressure Ps becomes near atmospheric pressure, so the diaphragm 18 is pushed to the left by the force of the spring 15, and the valve rod 24 and the valve body 22 are moved to the left.

Therefore, the control valve 13 opens the air supply port 23, supplies pressurized air to the exhaust passage 2, reacts and oxidizes mainly CO in the exhaust gas with the catalyst 3, and raises the temperature of the turbine lower.

During acceleration, extra fuel is normally supplied, and unburned CO in the exhaust gas increases by several percent, so the temperature rise due to oxidation is several hundred percent.
degree Celsius, the increase in enthalpy at the turbine inlet increases the rotational speed of the turbine and therefore the compressor, quickly increasing the supercharging pressure and completing an increase in engine torque and rapid acceleration.

Incidentally, it has been confirmed that if 1% of CO is present, the exhaust temperature will rise by approximately 100°C due to its combustion.

This eliminates turbo lag. This acceleration state takes a short time (several seconds) until the acceleration is completed, and as the rotation of the engine and therefore the air pump 9 increases, the increased discharge pressure PA acts on the pressure chamber 17, causing the diaphragm 18 to move to the right. The control valve 14 is closed, the supply of air is stopped, and the temperature rise at the turbine inlet is suppressed.

That is, since the turbine inlet temperature affects the temperature rise of the entire turbo charger and the heat resistance strength of the turbine rotor, the maximum temperature is suppressed to about 95C). However, as mentioned above, the temperature rise time is short, only a few seconds, so if we take into account the heat capacity of the exhaust pipe and oxidation catalyst, the temperature is 95'.
The humidity may be higher than 0°C.

■ At high speed and high load': In this case, the acceleration in ■ is completed. That is, when the engine rotates at a high speed due to acceleration, the air pump 190 rotations also increase, and the diaphragm 18 moves to the right due to the increase in the discharge pressure pA, compressing the spring 15 and closing the control valve 13.

■ At high speed and low load: In this case, the comparison valve is closed after the engine accelerates, and the intake pressure Pa becomes a large negative pressure, so the control valve 13 is closed by moving the diaphragm 18 of the actuator 14 to the right. In addition, since the valve body 22 which is closed in the state (3) receives the discharge pressure PA of the air pump 9 on its surface, the closed state of the valve continues.

In addition, in order to increase the temperature at the turbine inlet more effectively, it is recommended to use heat insulation inside the exhaust passage and heat insulation of the external pipe system, and to improve the mixing of the exhaust gas and air, 31 is preferably provided on the upstream side, that is, near the exhaust valve.

FIG. 2 shows another embodiment. In this embodiment, as an air supply device, pressure is accumulated in a tank using an air pump in advance.
It is designed to instantly supply air when needed.

Hereinafter, the same parts as in the embodiment shown in FIG. 1 will be given the same reference numerals to avoid redundant explanation.

That is, the air pump 9 is an electric pump that bleeds air from the suction pipe 21, stores the pressure in the factory tank 40, and pumps the control valve 42 through the discharge pipe 41.
The fuel is injected and supplied from an injection port to the exhaust passage 2 upstream of the catalyst 3 via.

The electric air pump 9 is turned on and off by a pressure switch 43 provided in the air tank 40, and is always maintained at a predetermined pressure (for example, 5k).
a/am2). Note that the discharge pipe 41 is provided with a throttle 44, and the flow rate is set so as not to supply more air than necessary to the exhaust passage 2 at the maximum air pressure.

The control valve 42 is connected to a controller 45 , and signals from the temperature sensor 19 and the accelerator switch 46 are input to the controller 45 .

When the accelerator pedal is depressed to accelerate, the accelerator switch 46 is turned on and activated by a predetermined depression amount.
The signal is input to the controller 45, and the temperature sensor 19
The signal from the exhaust air is low (for example, below 600℃)
When this happens, it is determined that air supply is necessary, and the control valve 42 is opened. As a result, the air stored in the air tank 40 is quickly injected and supplied, causing an oxidation reaction with CO and HC in the exhaust gas, thereby rapidly raising the exhaust temperature.

When the temperature sensor 19 detects that the catalyst outlet temperature has risen too much (for example, 950° C. or higher) due to air supply, the control valve 42 is closed and the supply of air is stopped.

In this embodiment, since the tank pressure accumulation type is used, the supply air flow rate rises quickly, and the exhaust moisture can be rapidly increased at the beginning of acceleration, and the air pump 9 does not need to be constantly driven, so driving loss is reduced. It is possible to do so.

Furthermore, although this embodiment shows an example in which the air pump is used to accumulate pressure, the air pump may also be used in place of the air pump by directing the supercharging pressure of the compressor 5 to the air tank 40 via a branch passage, although not shown. . In this case, a check valve is inserted in the branch passage.

FIG. 3 shows another embodiment. This embodiment is useful for reducing the size of the catalytic combustor and reducing exhaust pressure loss when the exhaust passage is divided into two groups, such as in a 6-cylinder engine, or in the case of a large-capacity engine or an engine with many CO2 emissions. This is what we aim to achieve.

That is, two groups of exhaust passages 2 of a V-type six-cylinder engine 1
and 2-, a catalyst is provided only downstream of the exhaust passage 2 for three cylinders, an air discharge pipe 12 connected to the air pump 9 and a control valve 13 is provided upstream of the catalyst, and the exhaust passage 2 for the other three cylinders is provided downstream. Since the catalyst 3 is connected to the turbine 4 through the catalyst 1, a small catalyst 3 is sufficient.

Note that in this case, another catalyst is provided downstream of the turbine 4,
In particular, unburned substances in the exhaust passage 2' may be treated.

FIG. 4 shows another embodiment. In this embodiment, in order to further improve turbo lag, a catalyst 3 is provided for each cylinder.
An air injection port 31 is also opened in each upstream exhaust passage. This is particularly suitable for small engines.

Figure 5 is a torque performance diagram with the throttle valve fully open, with engine speed on the horizontal axis and engine torque on the vertical axis. In this case, the range A is the range to which air is to be supplied, and the other ranges are (1) low speed reference load, (2) high speed high load, and (2) high speed low load, in which air is not supplied.

In the figure, I indicates the idle rotation speed, lc indicates the intercept rotation speed, the state above the X-ray indicates the supercharging pressure (positive pressure), and the state below the X-ray indicates the negative pressure.

〔Effect of the invention〕

As explained above, according to the present invention, the configuration is such that an air supply device that supplies air is provided upstream of a catalyst provided upstream of a turbine for driving a compressor. During acceleration to almost full throttle, it is possible to measure the rise in turbine inlet temperature due to the combustion of unburned substances in the exhaust gas, and this allows the turbocharger rotation speed, engine intake air volume, cylinder filling efficiency, and boost pressure to be adjusted. This results in the effect that engine acceleration performance can be improved.

Further, unburned substances in the exhaust gas, such as CO, which were conventionally treated downstream of the turbine, can be converted into heat upstream of the turbine and can be effectively utilized as supercharging work for the turbocharger, resulting in the effect of improving fuel efficiency.

[Brief explanation of drawings]

FIG. 1 is an overall view of one embodiment of the present invention, and FIGS.
The figure is a plan view of the main part of another embodiment, and FIG. 5 is a performance curve diagram. Explanation of the symbols shown in the drawings 1: Engine, 2: Exhaust passage, 3: Catalyst (combustor), 4
: Turbine, 5: Compressor, 8: Throttle valve, 9: Air pump, 12: Discharge pipe, 13: Control valve, 14: Actuator, 20: Turbocharger, 23: Air supply port, 3
1: Air injection port, PB nibost pressure (intake pressure), PA:
Air pump discharge pressure

Claims (2)

[Claims] (1) In a turbocharged engine in which a compressor installed in the intake passage is driven by a turbine installed downstream of the catalyst in the exhaust passage, an air supply device is provided to supply air to the exhaust passage upstream of the catalyst. A turbocharged engine characterized by: (2) The turbocharged engine according to claim 1, wherein the air supply device includes a control valve that opens the air supply port when the engine accelerates from a low load to when the throttle valve is almost fully opened.