Member For Controlling Exhaust Gas Purifying Device

Abstract

To regulate the supply of secondary air to the exhaust system of an internal combustion engine, a valve is positioned in the line supplying the secondary air so that the air can be selectively directed to the exhaust system or into the atmosphere. Detector members are arranged to monitor various operating characteristics of the internal combustion engine and to signal a control member which, in turn, regulates a control valve which controls, in part, the passage of engine manifold negative pressure to the valve. The valve contains a number of compartments and the pressure relationship between the compartments, certain of which are selectively exposed to the manifold negative pressure, determines the operation of the valve in selectively directing the flow of the secondary air.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a member for controlling an exhaust gas purifying device for use in gasoline engines for automobiles of the type in which secondary air is supplied into the exhaust system.

2. Description of the Prior Art

Recently, due to the increasingly stricter regulations imposed on automobile exhaust gases throughout the world, considerable efforts have been expended by a number of automobile manufacturers to develop effective devices for purifying or cleaning the exhaust gases before they are discharged into the atmosphere. To purify imperfectly burned or unburned gas components in exhaust gas, such as carbon monoxide, hydrocarbons and the like, generally a device is used which supplies secondary air into the exhaust gases discharged from the combustion chamber so that the air reacts with the gases. Although such a device is quite effective where the air-fuel ratio is lower than the theoretical air ratio or theoretical fuel ratio because, under such situations, the reaction temperature is not raised to excess, a problem arises when the air-fuel mixture becomes rich due to the choke operation at cold start-up or when percolation takes place in a hot or overheated engine and produces an enriched mixture. In such situations, the reaction in the exhaust system causes an excessive rise in the exhaust temperature and such temperture rise poses a problem for the durability of the purifying device itself and for the heat resistability of the parts located around or adjacent to the exhaust pipe.

SUMMARY OF THE INVENTION

Therefore, the object of the present invention is to provide a means for controlling an exhaust gas purifying device which solves the problems mentioned above.

In accordance with the present invention, a member is provided for controlling the exhaust gas purifying device so that any tendency for incrased afterburning temperatures is avoided. The member involves a valve through which secondary air is directed into the exhaust system and the valve is arranged to release the secondary air directly into the atmosphere when certain operating conditions of the engine fall outside certain predetermined operating ranges. Further, the invention includes an improved arrangement in the valve for bypassing the secondary air to the atmosphere so that the heat resistability of the parts disposed around or adjacent the exhaust pipe is not adversely affected.

The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its use, reference should be had to the accompanying drawings and descriptive matter in which there is illustrated and described a preferred embodiment of the invention .

BRIEF DESCRIPTION OF THE DRAWING

In the drawing:

FIG. 1 is a longitudinal sectional view of an air by-pass valve embodying the present invention;

FIG. 2 is a view similar to FIG. 1, however, showing the valve is a different operating condition;

FIG. 3 is a schematic illustration of an exhaust gas purifying device embodying the present invention; and

FIGS. 4 and 5 are similar views of a choke performance detector member and each figure shows a different operating position of the parts making up the member.

DETAILED DESCRIPTION OF THE INVENTION

In FIGS. 1 and 2, an air by-pass assembly 1 is illustrated and includes an on-off valve 1'. The interior of the valve 1' is divided into an upper chamber A, an intermediate chamber B and a lower or secondary air chamber C. The secondary air chamber C has a secondary air inlet port 3 and its interior with which the port 3 communicates is divided by a pair of valves 6 and 7 into a pair of outlet compartments C.sub.1 and C.sub.2. A secondary air outlet port 4 communicates with the outlet compartment C.sub.1 and a vent 5 connects the outlet compartment C.sub.2 with the atmosphere.

The interior of the intermediate chamber B is divided by a diaphragm 9 into a negative pressure chamber 8, located below the diaphragm, and an upper compartment or air chamber 12, located above the diaphragm. A negative pressure detection port 2 opens into the negative pressure chamber 8. Extending through the diaphragm 9 is a metering orifice 10 which provides communication between the negative pressure chamber 8 and the air chamber 12. A check valve 11 is mounted on the diaphragm 9. Disposed within the negative pressure chamber 8 and contacting the lower surface of the diaphragm 9 is a spring 13 which normally biases the diaphragm in the upward direction. In the upper chamber a diaphragm 16 divides it into an upper compartment or negative pressure chamber 15 and a lower compartment A.sub.1. An inlet connection 14 in the upper portion of the valve 1' admits manifold negative pressure into the chamber 15. The body of the valve provides an opening 17a between the lower compartment A.sub.1 of the upper chamber A and the air chamber 12 of the intermediate chamber B. A valve 17, connected to the diaphragm 16, forms a closure for the opening 17a. Within the negative pressure chamber 15, a spring 18 biases the diaphragm 16 in the downward direction, while in the lower compartment A.sub.1 another spring 19 biases the valve 17 into position for closing the opening 17a. An air inlet port 20 including a filter element is arranged to provide atmospheric air into the lower compartment A.sub.1.

The valves 6 and 7 are connected to the diaphragm 9. Both the diaphragm 9 in the intermediate chamber B and the diaphragm 16 in the upper chamber A are movably displaceable in response to the pressure conditions on the opposite sides of the diaphragms for positioning the valves 6 and 7 and the valve 17, respectively.

In FIG. 3 the mechanical arrangement of the purifying device, embodying the present invention, is shown schematically. A secondary air supply pump 22 is connected to the air by-pass valve assembly 1 and the assembly, in turn, is connected to an internal combustion engine 21 with a check valve 23 and a secondary air manifold pipe 24 positioned in the line between the valve assembly and the engine. When the valve 6 is in the position indicated in FIG. 1 the secondary air passes through the on-off valve 1' to the outlet port 4 and then into the exhaust ports of the cylinders in the engine 21. Engine cooling water 25 is used for heating the riser of the intake pipe and a water temperature detector 26 is arranged to sense the warmedup condition of the engine as represented by the engine cooling water. Mounted on the engine is a carburetor 27 to which a fast idle cam behavior detector 28 is attached for monitoring the action of the fast idle cam. The details of the detector 28 are shown in FIGS. 4 and 5. Further, a vehicle (engine) speed indicator 29 is shown connected to an electronic control member 30 which controls a magnetic valve 31 for regulating the flow of manifold negative pressure to the valve assembly 1. An outlet 32 for the negative pressure is connected to the engine intake manifold pipe. In addition to the vehicle speed indicator 29, the cam behavior detector 28 and the water temperature detector 26 are connected to the electronic control member 30 for relaying signals which indicate certain operating characteristics of the engine.

In FIGS. 4 and 5 the modes of operation of the switch for detecting the fast idle cam behavior in the carburetor 27 is shown. A choke valve 33 is located within the carburetor. Connected to the choke valve 33 is a choke bimetal member 34 which is connected to a link 35' and moves the link in response to the movement of the choke valve. Further, a lever 35 is interlocked with the choke valve 33 and is coupled to a link 36. At the opposite end of the link 36 from the lever 35 an insulator 37 is positioned for connecting the link to the fast idle cam 38. A lead wire 39 is connected to and extends from the cam. The cam 38 is pivotally mounted on the carburetor 27 by means of an insulating bearing 40 which insulates the cam from the carburetor. Positioned within the carburetor and spaced from the choke valve 33 is a throttle valve 41 to which a lever 42 is connected. In the pivoted position of the cam, shown in FIG. 4, the cam is in engagement with the lever 42.

The air by-pass valve assembly 1 operates in the following manner:

Signals are transmitted from the cooling water temperature detector 26, the fast idle cam behavior detector 28 and the vehicle speed detector 29 to the electronic control member 30 and if the signal indicates that certain predetermined operating conditions of the engine are not met, the line connecting the manifold negative pressure outlet 32 to the inlet connection 14 is closed and, as a result, the negative pressure chamber 15 is in communication with the atmosphere. With atmospheric pressure acting on both sides of the diaphragm 16, that is in the negative pressure chamber 15 and in the lower compartment A.sub.1 the spring 18 biases the diaphragm downwardly causing the valve to open so that atmospheric pressure within the lower compartment A.sub.1 is admitted to the air chamber 12 through the opening 17a. At the same time, the manifold negative pressure from the manifold pipe 32 is introduced into the negative pressure chamber 8 through the port 2 and, since the metering orifice 10 is small in size, a difference in pressure exists between the air chamber 12 and the negative pressure chamber 8 so that the diaphragm 9 separating the two depresses the spring 13 whereby the valve 6 closes and the valve 7 opens. With valve 6 closed the flow of secondary air to the port 4 is blocked and it flows instead through the open valve 7 and vent 5 for release into the atmosphere.

If the cooling water detector 26, the fast idle cam behavior detector 28 and the vehicle speed detector 29 all signal that the characteristics being monitored fall within certain preset conditions, the negative pressure circuit through the valve 31 is opened and manifold negative pressure is directed through the inlet connection 14 into the negative pressure chamber 15. As an example of the engine operating conditions checked, a signal is transmitted from the member 30 to the valve 31 for maintaining the valve open if the vehicle speed is less than a predetermined speed, the cooling water temperature is within the predetermined temperature range (no secondary air is supplied when the water temperature is lower than the lower limit of the temperature range or higher than the upper limit) and also if the fast idle cam 38 is not in contact with the lever 42 which is interlocked with the throttle valve 41, not the arrangement in FIG. 5. With the manifold negative pressure acting within the chamber 15, the atmospheric pressure within the lower compartment A.sub.1 overcomes the biasing action of the spring 18 and moves the diaphragm 16 upwardly so that the valve 17 closes the opening 17a. Consequently, the manifold negative pressure introduced into the negative pressure chamber 8 through the port 2 gradually enters into the chamber 12 until the pressure on both sides of the diaphragm 9 is equalized at which point the force of the spring 13 moves the diaphragm upwardly and the valves 6 and 7 connected to it move in the upward direction into the position indicated in FIG. 1. With the valve 7 in its closed position and the valve 6 in the open position the secondary air flowing through the inlet port 3 is guided to the outlet port 4 and then through the check valve 23 and the air manifold pipe 24 into the exhaust ports of the cylinders in the internal combustion engine.

Conventionally, in automobile exhaust gas purifying devices in which secondary air is fed into the exhaust system to effect an oxidation reaction, when the air-fuel mixture becomes too rich due to the choke operation at cold start-up or when percolation occurs in a hot or overheated engine, an enriched mixture is produced. With the enriched mixture the reaction taking place within the exhaust system would cause an abnormal rise in the exhaust temperature and could well cause the floor mat to catch fire or the parts adjacent the exhaust system to be disadvantageously affected due to the overheating. In the present invention, however, by means of the by-pass valve assembly it is possible to avoid any abnormal rise in the exhaust temperature during deceleration and thereby eliminating the danger that the floor mat might burn or that the parts adjacent the exhaust system might be damaged. Further, even during high speed operation of the engine, any sharp increase in the temperature in the exhaust system can be prevented by timely releasing the secondary air into the atmosphere.

While a specific embodiment of the invention has been shown and described in detail to illustrate the application of the inventive principles, it will be understood that the invention may be embodied otherwise without departing from such principles.

Claims

What is claimed is:

1. An exhaust gas purifying device for use in supplying secondary air into the exhaust system of an internal combustion engine, comprising a first valve located in the path of the secondary air into the exhaust system and displaceable between a first position for supplying secondary air into the exhaust system and a second position for discharging the secondary air into the atmosphere, a second valve for regulating the supply of manifold negative pressure from the internal combustion engine into said first valve, first means for operating said second valve, second means for detecting various operating conditions of the internal combustion engine, said second means connected to said first means for operating said second valve for transmitting an input signal to said first means so that said second valve regulates the supply of manifold negative pressure to said first valve whereby said first valve is disposed in the first or second position based on the operating conditions of the engine checked by said second means, and said second means comprise an engine cooling water temperature detector, a fast idle cam position detector and a vehicle speed detector each connected to said first means and each of said engine cooling water temperature detector, fast idle cam position detector and vehicle speed detector being arranged so that predetermined conditions for each of said detectors must be detected before said first means operates said second valve.

2. An exhaust gas purifying device, as set forth in claim 1, wherein said first valve comprises a housing having at least one chamber therein, said chamber having an inlet for supplying secondary air to said chamber, a first outlet for directing the secondary air from said chamber to the exhaust system and a second outlet for discharging the secondary air from said chamber into the atmosphere, a valve member positioned within said chamber for directing flow from said inlet to one of said first and second outlets, and third means positioned within said housing for displacing said valve member for selectively directing the flow of secondary air from said inlet to one of said first and second outlets.

3. An exhaust gas purifying device, as set forth in claim 1, wherein said first valve comprises a housing with said housing arranged for dividing the interior of said first valve into a first chamber, a second chamber and a third chamber, a first displaceably mounted wall member located within said first chamber and dividing it into a first compartment and a second compartment, a second displaceably mounted wall member located within said second chamber and dividing it into a third compartment and a fourth compartment, said housing forming an opening between said second compartment and said third compartment, a first valve member located in the opening between said second compartment and third compartment and displaceable between a first position for closing the opening and a second position for admitting flow from said second compartment into said third compartment, said housing forming an inlet for admitting secondary air into said third chamber and a first outlet and a second outlet for discharging the secondary air from said third chamber, and a second valve member located within said third chamber and displaceable therein between a first position for directing the flow from said inlet to said first outlet and blocking off flow to said second outlet and a second position for directing flow from said inlet to said second outlet and blocking off flow to said first outlet.

4. An exhaust gas purifying device, as set forth in claim 3, wherein said housing forms an inlet for admitting manifold negative pressure from the internal combustion engine into said first compartment and an inlet for admitting atmospheric air into said second compartment, a spring member positioned within said first compartment and in contact with said first wall means for biasing said first wall member toward said second compartment, and said first valve member is connected to said first wall member for positioning said first valve member in accordance with the pressure relationship between said first and second compartments which pressure relationship movably displaces said displaceably mounted wall member.

5. An exhaust gas purifying device, as set forth in claim 4, wherein a second spring member is disposed in contact with said first valve member for biasing it into position for closing the opening formed between said second and third compartments.

6. An exhaust gas purifying device, as set forth in claim 3, wherein said second valve member is connected to said second wall, said housing forms an inlet communicating with said fourth compartment for admitting manifold negative pressure from the internal combustion engine, the flow of manifold negative pressure into said inlet to said fourth compartment is regulated by said second valve, said second wall has a metering orifice therethrough between said third and fourth compartments, and a spring biasing said second wall in the direction of said third compartment.

7. An exhaust gas purifying device, as set forth in claim 4, including a conduit arranged to transmit negative pressure from the internal combustion engine to said inlet to said fourth compartment, a branch conduit communicating between said conduit and said second valve, another conduit connecting said second valve and said inlet to said first compartment for admitting manifold negative pressure to said inlet when said second valve is opened by said means for operating said second valve.

8. An exhaust gas purifying device, as set forth in claim 1, including a carburetor arranged to be mounted on the engine, a throttle valve and a choke valve positioned within said carburetor, said fast idle cam position detector comprising a fast idle cam, means for pivotally mounting said cam on said carburetor and for insulating said cam from said carburetor, a lever connected to said throttle valve and displaceable therewith, said lever is engageable with said cam under certain operating conditions of said internal combustion engine, a link, a bimetal member connecting said choke valve to said link, a second lever connected to said choke valve, a link connected at one end to said second lever and an insulating member positioned on the other end of said link for attaching it to said cam, and a lead wire connected to said cam and extending outwardly therefrom.