JPH0128207B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a secondary air control device for an engine.

(Prior art) Generally, in automobile engines, a catalytic converter is installed in the middle of the exhaust passage to reduce the
It purifies harmful components such as NOx, HC, and CO. In such engines, in order to make effective use of the catalytic converter, an exhaust sensor is installed in the exhaust passage upstream of the catalytic converter.
The air-fuel ratio of the air-fuel mixture supplied to the engine is feedback-controlled to the target value according to the output from the exhaust sensor, that is, the properties of the exhaust gas, while the air-fuel ratio upstream of the exhaust sensor is For example, in the side exhaust passage,
As shown in the figure, secondary air is supplied.

By the way, generally when idling,
In order to keep the idle speed constant, when the engine load increases due to the operation of the cooler or power steering, auxiliary air is supplied into the intake passage downstream of the throttle valve, or the throttle valve is The tutle valve is slightly opened to increase engine filling efficiency.

However, if the charging efficiency of the engine is increased during idling in this way, the catalytic converter will become overactivated due to the fact that during idling, cooling due to the running wind is not normally obtained, and the above-mentioned supply of secondary air is combined. A problem arises in that the temperature becomes extremely high and thermal deterioration is likely to occur.

(Object of the Invention) The present invention solves the above-mentioned problems, and aims to improve the secondary catalytic converter of the engine so that thermal deterioration of the catalytic converter does not occur even when the charging efficiency of the engine is increased during idling. The purpose is to provide an air control device.

(Structure of the Invention) In order to achieve the above-mentioned object, in the present invention, during idling, when the wheels are generally in a stopped state and the catalyst cooling effect by the running wind cannot be obtained,
When a cooler or the like operates and the engine load increases, the secondary supply is cut off.

Specifically, there is a load detector that detects the operation of coolers, power steering, etc. that cause an increase in engine load and issues a detection signal, and a secondary A control means is provided for closing an air control valve provided in the air supply passage to cut off secondary air supply into the exhaust passage.

(Example) In FIG. 1, 1 is an air control valve, and an inlet 1b, an outlet 1c, and a relief port 1d are opened to a valve chamber 1a. This inlet 1b is connected to an air pump (not shown), and the outlet 1c is connected to an air pump (not shown).
is connected to an exhaust passage (not shown), and the relief port 1d is connected to an air cleaner (not shown), respectively.
From this inlet 1b through the valve chamber 1a, the outlet 1c
The path leading to this constitutes a part of the secondary air supply passage.

The air control valve 1 is of a negative pressure operating type, and has a negative pressure chamber 1f defined by a diaphragm 1e and an atmospheric chamber 1g, which are connected to each other according to the displacement of the diaphragm 1f. Valve stem 1h
The valve body 1i is displaced via the inlet 1b to open and close the communication between the inlet 1b and the outlet 1c, that is, to open and close the secondary air supply passage. That is, in the air control valve 1, when the diaphragm 1e is displaced downward in the figure, the valve body 1i seats on the valve seat 1j and blocks the inlet 1b and the outlet 1c, while blocking the inlet 1b. It communicates with the relief port 1d to release pressurized secondary air from the air pump to the air cleaner side. On the contrary, diaphragm 1e
When is displaced upward in the figure and the valve body 1i is seated on the valve seat 1k, the inflow port 1b and the relief port 1d are cut off, while the inflow port 1b is communicated with the outflow port 1c, so that the air is removed from the air pump. The pressurized secondary air is supplied to the exhaust passage. and,
The diaphragm 1e is normally urged downward in the figure, that is, in the valve closing direction, by a return spring 1l.

Negative pressure chamber 1f of the air control valve 1
is the first of the three-way electromagnetic switching valve 3 via the signal pipe 2.
The switching valve 3 is connected to the connection port 3a, and the second connection port 3b of the switching valve 3 is connected to an intake manifold (both not shown) via a signal pipe. When this switching valve 3 is energized, its valve body 3c is displaced to the left in the figure to communicate the first connection port 3a with the second connection port 3b, and when demagnetized, the valve body 3c is displaced to the right in the figure. The first connection port 3a is displaced to communicate with the atmosphere release port 3d.

Reference numeral 4 in FIG. 1 denotes a control circuit that controls the operation of the air control valve 1 by energizing or demagnetizing the coil 3e of the switching valve 3. This control circuit 4 receives an output from an idle switch 5 for detecting whether the engine is idling or not, as well as a cooler switch 6 and a power switch for detecting whether the engine load has increased. The output from the steering switch 7 is input, and the control circuit 4 outputs the coil 3e of the switching valve 3.
It is now output to .

In the above configuration, when idling and the cooler and power steering are not operating, the control circuit 4 controls the switching valve 3.
The coil 3e is excited, and the first connection port 3a is
is communicated with the second connection port 3b, and intake negative pressure is transmitted to the negative pressure chamber 1f of the air control valve 1.
As a result, the diaphragm 1e, that is, the valve body 1i
is displaced upward in the figure, its inlet 1b and outlet 1c are communicated with each other, and secondary air is supplied to the exhaust passage.

When at least one of the cooler or power steering is operated during this idling, the control circuit 4 demagnetizes the coil 3e of the switching valve 3, and the first connection port 3a thereof is communicated with the atmosphere release port 3d. Therefore, in this case, atmospheric pressure is transmitted to the negative pressure chamber 1f of the air control valve 1, and the diaphragm 1e, that is, the valve body 1i, is displaced downward in the figure by the return spring 1l, and the inlet port 1b and the outlet port 1c are and the supply of secondary air to the exhaust passage is stopped. Then, even if the engine filling efficiency is increased due to the operation of the cooler etc. due to the stoppage of the supply of secondary air,
The catalytic converter will not be activated abnormally,
Its thermal deterioration is prevented.

FIG. 2 shows another embodiment of the present invention, in which the operation of a cooler or the like is indirectly detected and the supply of secondary air is stopped. Specifically, when a cooler or the like operates, auxiliary air is supplied to the intake passage to increase filling efficiency, and the operating state of the flow rate control valve that controls this auxiliary air supply is indirectly It is designed to be used for load detection.

Referring to FIG. 2 in detail below, 8 is an intake passage, and the intake passage 8 is divided into a primary side intake passage 8a and a secondary side intake passage 8b by a partition wall 9, and the primary side intake passage A primary throttle valve 10a is disposed in the secondary intake passage 8a, and a secondary throttle valve 10b is disposed in the secondary intake passage 8b.

Both throttle valves 10 are provided in the intake passage 8.
On the upstream side of a and 10b, the auxiliary intake passage 11
The upstream end 11a of the auxiliary intake passage 11 is opened.
The downstream end 11b of the primary throttle valve 10
It opens to the primary side intake passage 8a on the downstream side of a.

A flow control valve 12 is connected to the auxiliary intake passage 11 . The flow rate control valve 12 is of a negative pressure operating type, and has a negative pressure chamber 12b defined by a diaphragm 12a and an atmospheric chamber 12c, and a valve connected thereto changes according to the displacement of the diaphragm 12a. The valve body 12e is displaced via the rod 12d to open and close the auxiliary intake passage 11. The flow rate control valve 12 has an opening degree that increases as the diaphragm 12a, that is, the valve body 12e, moves upward in the figure, and is normally attached downward in the figure, that is, in the valve closing direction, by the return spring 12f. Forced.

The negative pressure chamber 12b of the flow control valve 12 is communicated with the intake passage 8 on the upstream side of both throttle valves 10a, 10b via the signal pipe 13 and its first branch pipe 13a. It communicates with the primary intake passage 8a on the downstream side of the primary throttle valve 10a via the second branch pipe 13b.

A first electromagnetic on-off valve 14 is provided in the first branch pipe 13a.
is connected to the second branch pipe 13b, and a second electromagnetic on-off valve 15 is connected to the second branch pipe 13b. When the two electromagnetic on-off valves 14 and 15 are energized, the first electromagnetic on-off valve 14 is closed, while the second electromagnetic on-off valve 1 is closed.
5 is open, and during demagnetization, the first electromagnetic on-off valve 14 is open, while the second electromagnetic on-off valve 15 is closed.

In FIG. 2, 16 is a control unit consisting of a microcomputer, which controls the first and second electromagnetic on-off valves 14, 1.
5 and the three-way electromagnetic switching valve 3 in the above embodiment. For this reason, the control unit 16
In addition to inputting the outputs from the cooler switch 6 and the power steering switch 7 in the above embodiment, the outputs from the throttle valve opening sensor 17 and engine speed sensor 18, and the opening of the flow rate control valve 12, i.e. An output from a position meter 19 that detects the displacement position of the valve body 12e is input. Further, from the control unit 16, each coil 14a, 15 of the first and second electromagnetic on-off valves 14, 15 is connected.
a and the coil 3e of the three-way electromagnetic switching valve 3.

In the above configuration, when at least one of the cooler and power steering is operated, the output of at least one of the switches 6 and 7 is input to the control circuit 20, and the output of at least one of the switches 6 and 7 is input to the control circuit 20. However, the first electromagnetic on-off valve 14 is energized to close it, and the second electromagnetic on-off valve 15 is also energized and opened. As a result, the flow control valve 12
Intake negative pressure acts on the negative pressure chamber 12b, and the diaphragm 12a, that is, the valve body 12e, is displaced upward in FIG. 2, and the flow rate control valve 12 is opened. By opening this flow rate control valve 12, the primary throttle valve 10 is inserted into the primary intake passage 8a.
Auxiliary air is supplied from the auxiliary intake passage 11 that bypasses the auxiliary intake passage 11, thereby increasing the filling efficiency of the engine.

The displacement of the valve body 12e in the opening direction is input from the position meter 19 to the circuit 21 as a detected potential corresponding to this displacement position. In this circuit 21, the detected potential is compared with a reference voltage at a predetermined opening position of the valve body 12e, and when it is determined that the valve body 12e is in the open position as described above. , from the circuit 21 to the AND circuit 2
Output to 2. In such a state, if the throttle valves 10a and 10b are fully closed and the engine speed is a predetermined idle speed, the circuit 23 that receives the outputs from both sensors 17 and 18 performs a zone judgment (driving mode). The result of the determination (determination) is determined to be idling, and is output from the circuit 23 to the AND circuit 22. The AND circuit 22 receiving both outputs from the circuits 21 and 23 demagnetizes the three-way electromagnetic switching valve 3 shown in FIG. 1 and closes the air control valve 1, that is, stops the supply of secondary air.

In this way, an increase in engine load is indirectly detected as the displacement position of the valve body 12e of the flow control valve 12, and during idling when auxiliary air is supplied and charging efficiency is increased, the supply of secondary air is It will be blocked.

Of course, even when idling (circuit 23
(in a state where the air is being output from the air to the AND circuit 22), if the engine load is not increasing because the cooler etc. are not operating, the supply of auxiliary air is stopped, while the secondary air is supplied. That is, in this case, both the electromagnetic on-off valves 14 and 15 are demagnetized, the electromagnetic on-off valve 14 is opened, the electromagnetic on-off valve 15 is closed, and the negative pressure chamber 12b of the flow control valve 12 is filled with atmospheric pressure ( The pressure inside the intake passage upstream of both throttle valves 10a and 10b acts, and the flow rate control valve 12 is closed. When the valve body 12e of the flow rate control valve 12 is in the closed position, no output is made from the circuit 21 to the AND circuit 22, so that the three-way electromagnetic switching valve 3 shown in FIG. 1 is in an excited state, that is, the air control valve 1 is in an open state and secondary air is supplied.

Although the embodiments have been described above, the present invention is not limited thereto, and includes, for example, the following cases.

The engine load can include any appropriate cases, such as when an electric fan is activated, or when the gear shift position of an automobile equipped with an automatic transmission is in a driving range such as a drive range.

A check valve may be provided instead of the air pump so that secondary air is supplied to the exhaust passage by exhaust pulsation.

The air control valve 1 and the flow rate control valve 12 may be electrically operated using a solenoid instead of a negative pressure operated type.

The control unit 16 can be composed of not only an analog type computer but also a digital type computer.

(Effects of the Invention) As is clear from the above, the present invention prevents thermal deterioration of the catalytic converter when a load such as a cooler is activated during idling.
Its durability can be improved.

[Brief explanation of drawings]

FIG. 1 is a sectional view of essential parts showing an embodiment of the present invention.
FIG. 2 is a sectional system diagram of main parts showing another embodiment of the present invention. 1... Air control valve, 1a... Valve chamber (secondary air supply passage), 1b... Inlet (secondary air supply passage), 1c... Outlet (secondary air supply passage), 6... Cooler Switch (load detector), 7...
…power steering switch (load detector),
14...control circuit, 16...control unit.

Claims (1)

[Claims] 1. An air control valve that provides a secondary air supply passage that supplies secondary air to the exhaust passage in which the catalyst device is disposed, and controls the supply of secondary air to the secondary air supply passage. In an engine that is equipped with a load detector that detects the operation of the cooler, power steering, etc. and issues a detection signal in an engine that increases intake air when a load such as a cooler or power steering operates while the engine is idling, and control means for operating the air control valve to cut off the supply of secondary air when a cooler, power steering, etc. is activated in response to a signal from the load detector. secondary air control device for engines with