JPH0524334B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a water-cooled exhaust turbo supercharger having a water jacket formed in a housing, and more specifically to a method for controlling the amount of cooling water in such a supercharger. It is about the mechanism.

(Prior Art) A known example of a water-cooled exhaust turbo supercharger is disclosed in Japanese Patent Application Laid-open No. 178828/1983, for example.

By the way, in such a water-cooled exhaust turbo supercharger (hereinafter simply referred to as a supercharger), the turbine that comes into contact with the exhaust gas is cooled by cooling water, so the temperature of the exhaust gas is lower than that of the supercharger. Although the temperature of the exhaust gas is lowered by passing through the engine, such a decrease in exhaust gas temperature is unfavorable in view of the exhaust characteristics of the engine. That is, in the case of an engine in which exhaust gas purification is performed using a catalytic converter installed in the exhaust passage, the exhaust gas is reduced in a light load operating region (so-called emission region) such as during idling operation where exhaust gas purification is required. When the temperature of the catalytic converter decreases, the activity of the catalytic converter decreases, and when the engine is cold, the exhaust temperature is low, causing the problem that it takes time to raise the catalytic converter to the desired activation temperature. .

Incidentally, the present applicant has already filed a patent application regarding the cooling structure of a water-cooled exhaust turbo supercharger (Japanese Patent Application No. 85951/1982).

(Object of the Invention) The present invention is an attempt to solve the problems pointed out in the above-mentioned section of the prior art. By suppressing the temperature drop of the exhaust gas flowing into the catalytic converter, the reduction in the activity of the catalytic converter is suppressed, and at the same time, secondary air is supplied to the catalytic converter to actively increase its activity. The purpose is to improve the exhaust characteristics of the engine.

(Means for Achieving the Object) As a means for achieving the above object, the present invention provides a blower provided in an intake passage of an engine equipped with a catalytic converter for purifying exhaust gas on the downstream side of the exhaust passage; In an exhaust turbo supercharger in which a turbine provided in a passage is housed in a casing and engine cooling water can be introduced into a water jacket formed in the casing, the engine is in a cold state or is operated under light load. an operating state detecting means for detecting the operating state, and an amount of cooling water introduced into the water jacket when the engine is in a cold state or a light load operating state in response to a signal from the operating state detecting means; a secondary air supply means for supplying secondary air to the upstream side of the catalytic converter; and a signal from the operating state detection means to cause the engine to be in a cold state or a light load operating state. The apparatus is characterized in that it includes a secondary air control means for causing the secondary air supply means to supply secondary air in some cases.

(Function) The present invention employs the above means, i.e., flow rate control that reduces the amount of cooling water supplied to the supercharger when the engine is in a light load operating region or in a cold state than in other cases. By providing this means, the amount of cooling water supplied to the turbocharger is reduced (the total amount is also cut) during light load operation where exhaust emissions may deteriorate or when the catalytic converter is in a cold state where it is necessary to quickly raise the catalytic converter to its activation temperature. ), thereby suppressing the temperature drop in the exhaust gas. At the same time, secondary air is supplied to the catalytic converter in the above operating state, and the catalytic converter is actively activated. As a synergistic effect of the two, exhaust gas purification is realized under good activity.

(Embodiments) Hereinafter, preferred embodiments of the present invention will be described based on the drawings.

The drawing shows a system for an automobile engine 1 equipped with an exhaust turbocharger 4 according to an embodiment of the present invention.

This supercharger 4 has its blower side interposed in the intake passage 2 of the engine 1 and its turbine side interposed in the exhaust passage 3 of the engine 1. The rotational force of the rotated turbine is transmitted to the blower, and the blower supercharges the intake air. Moreover, this supercharger 4 is a water-cooled supercharger that cools the support part of the shaft that connects the turbine and the blower with water (engine cooling water is used in this embodiment). A water jacket 28 is formed within the housing.

An air cleaner 5 and an air flow meter 6 are installed in the intake passage 2 on the intake upstream side from the supercharger 4 mounting position.
However, there is also a throttle valve 7 and a fuel injector 8 on the intake downstream side from the supercharger 4 mounting position.
are installed sequentially from the intake upstream side to the intake downstream side.

A catalytic converter 9 for purifying exhaust gas is installed in the exhaust passage 3 at a position downstream of the position where the supercharger 4 is installed. Further, this exhaust passage 3 connects an intermediate position between the supercharger 4 and the engine 1 to the throttle valve 7 of the intake passage 2 via an exhaust recirculation pipe 25 having an exhaust recirculation valve 14 in the middle thereof. It communicates with the downstream position. This exhaust recirculation valve 14
The valve is configured to open only when an exhaust gas recirculation signal S7 is output from the computer 16, which will be described later, to recirculate a part of the exhaust gas G to the intake passage 2 side, and to close otherwise. There is.

A water jacket (not shown) provided in the cylinder head and cylinder block of the engine 1 is in contact with the radiator 10 via a cooling water return pipe 22 and a cooling water supply pipe 21. It is cooled by cooling water W that is forcibly circulated within the cooling system by a water pump 11 attached to the 21 side.

Further, the inlet 28a of the water jacket 28 of the supercharger 4 is connected to the water jacket (not shown) in the engine 1 via the supercharger inlet pipe 23.
The outflow ports 28b are connected to the cooling water supply pipe 21 and the suction side of the water pump 11 via the supercharger outflow pipe 24, respectively.
Further, this supercharger outflow pipe 24 is provided with a cooling water control valve 15 that receives a cooling water signal S8 from a computer 16 to be described later and adjusts the passage area of the supercharger outflow pipe 24 in two stages, large and small. There is. Therefore, the supercharger 4 is cooled by a portion of the engine cooling water W, and its flow rate (in other words, cooling performance) is controlled by the valve position of the cooling water control valve 15. . In this embodiment, the cooling water control valve 15 corresponds to flow rate control means in the claims. In addition, this cooling water control valve 15
When the cooling water signal S8 is input from the computer 16, the valve is positioned at the closed valve position (in this embodiment, it is not fully closed but refers to a state in which the flow rate of cooling water is reduced by a predetermined amount compared to when it is fully open). However, in other cases (that is, when the cooling water signal S8 is not output), the fully open state is maintained.

On the other hand, an air pump 12 driven by the engine 1 is attached to the side of the engine 1. This air pump 12 supplies secondary air to the catalytic converter 9 side provided in the exhaust passage 3, and its intake port is located between the air flow meter 6 and the air cleaner 5 in the intake passage 2 via an air intake pipe 26. The discharge port is connected to the exhaust passage 3 at a position immediately upstream of the catalytic converter 9 via an air discharge pipe 27 having an air control valve 13 attached therebetween. This air control valve 13 is operated in response to an air signal S5 from a computer 16, which will be described later, and controls the amount of air supplied to the exhaust passage 3 (ON-OFF control in this embodiment). Note that this air control valve 13 receives an air signal S5.
It is configured to open the valve to enable air supply when the air pressure is applied, and otherwise keep the valve closed and cut off the air supply.

In this embodiment, the air pump 1
2 corresponds to the secondary air supply means in the claims, and the air control valve 13 corresponds to the secondary air control means in the claims.

The computer 16 performs fuel control, exhaust gas recirculation amount control, secondary air control, and supercharger cooling water control in accordance with the operating state of the engine 1, and controls the load output from the air flow meter 6. A signal S1, a throttle opening signal S2 output from a throttle opening sensor 17 attached to the electric throttle valve 7, and a rotation speed signal S3 output from a rotation speed sensor 18 attached to the engine 1.
and an oxygen signal S4 output from an oxygen sensor 19 provided upstream of the catalytic converter 9, and outputs a fuel injection signal to the fuel injector 8 according to the operating state of the engine 1. In addition to performing fuel control, engine 1
In a specific operating region, that is, in a light load operating region including an idling operating region, the so-called emission region, the air signal S5 is sent to the air control valve 13.
, an exhaust recirculation signal S7 is sent to the exhaust recirculation valve 14, and a cooling water signal S8 is sent to the cooling water control valve 15.
It is designed to output each.

Next, the operation of this engine 1 and supercharger 4 will be explained.

When the engine 1 is operated, the exhaust energy of the exhaust gas G drives the supercharger 4 to perform intake supercharging, and the water pump 11 is driven to circulate the cooling water W between the radiator 10 and the supercharger 4. As a result, the engine 1 is efficiently cooled. Furthermore, a portion of the cooling water W that is forcibly circulated by the water pump 11 is introduced into the water jacket 28 of the supercharger 4, and the bearing portion of the supercharger 44 is cooled.

Here, if the operating state of the engine 1 is in the non-emission region, that is, in the medium or high load operating region,
Both the secondary air supply to the catalytic converter 9 side and the exhaust gas recirculation to the intake passage 2 are stopped. Furthermore, the cooling water control valve 15 is kept fully open because the cooling water signal S8 is not output. Therefore, the flow rate of the cooling water introduced into the water jacket 28 of the supercharger 4 is maintained at a maximum, and the supercharger 4 is efficiently cooled.

On the other hand, when the operating state of the engine 1 is in the emission region, the air signal S5 is sent from the computer 16.
Since both the exhaust recirculation signal S7 and the cooling water signal S8 are output, secondary air A is sent to the catalytic converter 9.
However, part of the exhaust gas G is supplied to the intake passage 2, and the cooling water control valve 1
5 is closed, and the amount of cooling water W that cools the supercharger 4 is reduced compared to the case of non-emission region operation. Therefore, since the combustion temperature of the air-fuel mixture is suppressed by the exhaust gas G recirculated to the intake passage 2, the NOx component in the exhaust gas G is reduced, and at the same time, the NOx component in the exhaust gas G is reduced. Next, the activation of the catalyst itself is promoted by the air, and unforeseen gas components (HC) in the exhaust gas are
is removed by oxidation.

Furthermore, since the amount of cooling water flowing through the water jacket 28 of the supercharger 4 is reduced compared to the case of non-emission region operation, the temperature of the exhaust gas G decreases accordingly, and the temperature of the exhaust gas G increases to a high temperature. maintained. Therefore, the catalytic converter 9
By flowing the high-temperature exhaust gas G through the side, the oxidation removal action of unresolved gas components in the exhaust gas G and the activation of the catalyst are further promoted, resulting in a higher level of exhaust purification performance. In addition, during operation in this emission region, the amount of exhaust gas G itself is originally small and the degree of cooling requirement of the supercharger 4 is accordingly low, so even if the flow rate of cooling water is lower than in the emission region, this cooling requirement will not be met. It is possible to sufficiently cope with the temperature and provide good cooling performance.

In the above embodiment, the amount of cooling water W introduced into the water jacket 28 of the supercharger 4 is reduced when the operating state of the engine 1 is in the emission region, but the present invention is not limited to this, for example, engine 1
The flow rate of the cooling water W may be reduced even when the machine is cold. If you do this,
There is an advantage that the catalyst can be quickly raised to a predetermined activation temperature by the high-temperature exhaust gas G, and the exhaust purification action can be started at an earlier stage.

(Effects of the Invention) As is clear from the above description, the present invention improves the idling operation in which the cooling requirement of the supercharger is low and the exhaust emissions deteriorate due to the engine operating condition where the amount of exhaust gas emissions is low. The water-cooled Although it is an exhaust turbo supercharger, the temperature drop of exhaust gas is small.
Furthermore, in such an operating state, the activation of the catalytic converter itself is promoted by controlling the amount of cooling water and supplying secondary air to the catalytic converter, and as a synergistic effect, the activation of the catalytic converter itself is promoted.
The exhaust purification performance of the engine is maintained well.

[Brief explanation of the drawing]

The drawing is a system diagram of an engine equipped with an exhaust turbo supercharger according to an embodiment of the invention. 1...Engine, 2...Intake passage, 3...Exhaust passage, 4...Exhaust turbo supercharger, 5...Air cleaner, 6...Air flow meter, 7...Throttle valve, 8...Fuel indicator Ector, 9
...Catalytic converter, 10...Radiator, 11
...Water pump, 12 ...Air pump, 13
...Air control valve, 14...Exhaust recirculation valve, 15...Cooling water control valve, 16...
...Computer, 17...Throttle opening sensor, 18...Rotational speed sensor, 19...Oxygen sensor, 21...Cooling water supply pipe, 22...Cooling water return pipe, 23...Supercharger inflow pipe, 24 ...Supercharger outflow pipe, 25...Exhaust recirculation pipe, 26...Air suction pipe,
27...Air discharge pipe, 28...Water jacket.

Claims (1)

[Scope of Claims] 1. A blower provided in the intake passage of an engine including a catalytic converter for exhaust purification on the downstream side of the exhaust passage and a turbine provided in the exhaust passage are housed in a casing, and An exhaust turbo supercharger capable of introducing engine cooling water into a water jacket formed in a casing, comprising: an operating state detection means for detecting a cold state or a light load operating state of the engine; a flow control means for reducing the amount of cooling water introduced into the water jacket when the engine is in a cold state or a light load operating state in response to a signal from the means; a secondary air supply means for supplying secondary air to the side; An exhaust turbo supercharger for an engine, comprising: secondary air control means for supplying air;