US3303003A - Apparatus for purifying exhaust gases of internal combustion engines - Google Patents

Description

Feb. 7, 1967 A. A. ZIMMER 3,303,003 APPARATUS FOR PURIFYING EXHAUST GASES OF INTERNAL COMBUSTION ENGINES Filed March 11, 1963 \AuTo EXAUST INTAKE MANIFOLD VACUUM INVENTOR AUSTIN A. ZIMMER AGENT United States Patent 3,303 003 APPARATUS FOR PURIF YING EXHAUST GASES OF INTERNAL COMBUSTION ENGINES Austin A. Zimmer, Elkridge, Md., assignor to W. R.

Grace & o., New York, N.Y., a corporation of Connecticut Filed Mar. 11, 1963, Ser. No. 264,133 4 Claims. (Cl. 23-288) This application is a continuation-in-part of my earlier filed copendin g application Ser. No. 204,399, filed June 22, 1962, and now abandoned.

This invention relates to an auto exhaust system. In particular this invention is directed to a novel process and combination of apparatus for automatically controlling the temperature of a catalytic exhaust purifier.

According to this invention, the automatic temperature control of the catalytic exhaust purifier is obtained by utilization of an air pump pivotally mounted on an automotive engine and connected to a pump actuating means and a temperature sensing and valve means associated with the exhaust purifier. In response to a signal from the temperature sensing means, a valve means associated therewith will open and permit air from the manifold section of the engine to flow through a conduit to the pump actuating means. The pump actuating means will then cause the air pump to pivot about a hinged connection, which varies the pitch diameter of the pump pulley and causes the pump to operate at an increased speed and to force additional air through the catalytic purifier. In this way, the temperature of the catalytic exhaust system can be automatically adjusted to compensate for deviation from a desired temperature.

The problem of air pollution is not a new one. However, the problem has been aggrevated in many cities in recent years. The air in most cities contains substantial quantities of both oxides of nitrogen and the products of incomplete combustion of organic fuels.

In the presence of sunlight, photolysis of the oxides of nitrogen leads to the formation of measurable quantitics of ozone. The ozone, in turn, reacts with various organic pollutants to form compounds which can cause the many undesirable manifestations of smog, such as eye irritations, visibility reduction and plant damage.

When meteorological conditions prevent the rapid dispersion of pollutants, a smog condition results. Furthermore, it is now known that in many cities a major portion of organic pollutants is derived from unburned or partially burned gasoline in auto exhausts.

Another pollutant of much concern is carbon monoxide which is undesirable because of its toxic nature. This too is derived mainly from auto exhaust emissions.

Almost since the advent of the automobile, attempts have been made to solve the problem by rending harmless and unobjectionable the noxious fumes which are the by-products of internal combustion engines. Various devices and filters using elementary catalytic materials, and from the 1920s on various modifications of filters and mufflers, have been designed in an attempt to solve this problem. To date, none of them have met with success complete enough for practical application. One of the most difiicult problems to overcome is the fact that although a given purification system Works well after the motor is warmed, the initial activity of the catalyst is too low.

Closely related to this problem is the problem that the process of my invention is designed to solve. That is, the problem that once the catalyst is warmed up to operating temperatures and the motor is idling, at idle speeds the motor is producing large quantities of hydrocarbons and carbon monoxide. Under idle conditions of automobile operation the catalyst temperature rises rapidly because of the exothermic'heat of the catalytic reaction. Severe damage to the catalyst and its container can result under these circumstances.

Several investigators have realized that the only practical way to treat fumes to reduce hydrocarbon and and carbon monoxide pollution is to oxidize the hydrocarbons to carbon dioxide and water and oxidize the carbon monoxide to carbon dioxide.

A wide selection of oxidation catalysts have been produced in the past varying in both chemical composition and physical structure. With respect to chemical composition, the ability of a wide variety of metals and metal oxides, either alone or in combinations, to catalyze the complete oxidation of hydrocarbons has been noted. To be sufficiently eflicient for the removal of hydrocarbons and carbon monoxide from auto exhaust gases and to meet the standards of maximum emission currently under consideration in legislatures of various states, a catalyst for treating exhaust gases must become efiicient within a few minutes after engine startup and must maintain its activity throughout the various modes of engine operation. A catalytic converter must maintain its catalytic activity for a period of not less than one year and preferably two years or approximately 20,000 miles of engine operation.

A particularly difiicult problem is the problem occasioned by the operation of the automobile for short runs and operation of the engine at idling speeds. It has been found that after the catalyst has been warmed up and the engine speed is then reduced to idle, that excessive heat is generated in the catalytic converter. The reason for this condition is obvious. The catalyst has been warmed up to the temperature at which it is most efiicient and at idling speeds the amount of carbon monoxide and hydrocarbons is increased. Thus, the catalyst is converting a larger quantity of both hydrocarbons and carbon monoxide at a time when it is at its peak efiiciency. The conversion takes place very rapidly and the exothermic heat from the reaction causes the temperature of the catalyst bed to increase.

It is well known that catalytic reactions in automobile exhaust systems are generally exothermic and temperature control of the catalyst is required in order that the temperatures do not reach the point where the catalyst or the container or both would be damaged in any way. The usual method of operation is to use various control mechanisms to either divert the exhaust :gases away from the catalyst or to cool the gases by surface heat transfer methods.

It is known that the problem of excessive heating of .a catalytic mufiler while the engine is operating at idling speeds can be controlled by passing additional quantities of excess air through the mufller during such periods of operation. (See Patent Number 3,045,422.) According to such process the catalyst temperature is controlled by varying the amount of air passing over the catalyst bed from the amount theoretically necessary to eflect conversion of the carbon monoxide and hydrocarbons to an amount in excess of this theoretical quantity. This excess air will remove heat from the chemical reaction and thereby control the temperature Within the rnufiler. This principle is well known and does not form a specific part of this invention.

The devices which are known for implementing the above prior art process attempt to control the catalyst temperature by providing for a predetermined amount of air to be admitted to the rnuflier from a constant speed air blower through a valve opening in response to certain accelerator positions or muffler back pressures or pressure drops. The disadvantage with these devices is that, although all of these devices relate to the catalyst tem perature, they are not directly affected by the catalyst 3 temperature, nor consequently reactive to sudden or unscheduled different catalyst temperatures than those theoretically contemplated.

It is an object of this invention, therefore, to provide a process and a combination of apparatus whereby the above mentioned problems of the prior art are overcome. It is an additional object of this invention to provide a novel process and a combination of apparatus for automatically controlling the temperature of a catalytic exhaust system. Other objects, advantages, and features of this invention will be apparent to those skilled in the art in view of the following more detailed description of the invention.

These and other objects are achieved by means of this invention in which an air pump pivotally mounted on an internal combustion engine is used in combination with a pump actuating means and a temperature sensing and valve means associated with a catalytic exhaust purifier. According to this invention, the temperature within the exhaust purifier is measured, a valve means associated with the temperature sensing element is opened in response to a temperature reading which exceeds a predetermined value, and the speed of the air pump is then simultaneously adjusted by pivoting the air pump about a hinged connection, thereby varying the pitch diameter of the pump pulley and adjusting the speed of the pump. This increase in the speed of the air pump causes the pump to force additional amounts of air through the muffler. As a result, the temperature within the muffler will be decreased back to that desired.

The invention will be further understood by referring to the accompanying drawing. It should be understood that this drawing is intended to be only a means of illustrating the inventive concept and is not to be considered a limitation of same.

In the drawing, the numeral 1 designates a standard type of automotive muffler with an exhaust inlet 9 and outlet 10. The muffler contained a conventional, commercially available exhaust oxidation catalyst. A temperature sensing element 12 is positioned within the muffler. A three-way valve 13 is associated with the temperature sensing element and is positioned within a conduit '6 which connects the manifold section of an internal combustion engine with a pump actuating means 4. In this embodiment, the pump actuating means is comprised of a pair of vacuum diaphragms and is connected to the base of the air pump 2. The air pump 2 is also one of standard construction and is capable of being driven at varying speeds of operation. The air pump is pivotally connected at 3 to the automotive engine. The pump is driven by means of a belt and pulley arrangement comprised of a variable pitch, spring loaded sheave pulley 5 which is attached directly to the air pump and a second pulley 7 mounted on the automobile fan. A flexible =hose connection 8 carries the air from the pump 2 back to the inlet to the catalytic muffler 9.

The process of this invention operates as follows. The air pump 2 provides the air necessary for the normal operation of the catalytic converter. The air is mixed with the exhaust gases from the engine manifold which move through the pipe to the catalytic mufller. As the gases are converted they pass out through the exit of the mufller 10. As the temperature within the muffler exceeds the pre-determined desired temperature (generally, approximately 1200 F.), the temperature sensing element 12 will open the three-way valve 13 thereby'connecting the pump actuating means 4 with the manifold of the internal combustion engine. The actuating means will actuate the air pump 2 by pivoting the pump about the hinged connection 3. This will cause the pump to move to the alternate position shown in the broken line on the drawing, thereby varying the pitch diameter of the pump pulley and increasing the speed of the pump. The increased speed of the pump increased the air output of the pump and concomitantly the amount of air which is passing through the catalytic mufiler 1. This increase in the amount of air, i.e., the excess in the amount of air theoretically required for conversion of carbon monoxide and hydrocarbons, will return the temperature within the mother to the desired temperature within a relatively short period of time. When the temperature within the mufller has returned to the desired temperature, the sensing element 12 will close the valve 13, thereby actuating the pump actuating means 4 to return the air pump 2 to its normal position. When the pump 2 has returned to its usual position the air output is decreased and the volume of air passing to the mufller through flexible connection 8 and the inlet 9 will also be decreased.

The above described operation of this invention will occur automatically when the automobile engine is operating at idle speeds, for it is at these speeds that the temperature within the muffler will increase. In general,

it is desired to maintain the temperature within the muf- Example I The magnitude of the problem was illustrated in a series of runs in which an automobile was operated at a speed of 3050 miles per hour over the highway and the temperature in the catalyst bed measured. After several minutes of operation the automobile was stopped. The engine was slowed down to idle. The data collected in one of these runs is shown in Table I:

TABLE I Time in Speed Temperature Minutes in m.p.l1. of Exhaust Gases in F.

0 50 960 3 50 860 6 50 910 9 30 850 12 Idle 950 15 Idle 1, 010 18 Idle 1, 21 Idle 1, 310 24 Idle 1, 400

It is apparent from an examination of these data that a temperature increase of about 500 F. takes place when the automobile is operated at idle after being operated at a speed of about 50 miles an hour. The temperature rise took place in this particular instance over a period of 12 minutes.

The air was being fed to the catalyst bed at the rate of 3.5 cubic feet per minute during this run.

Example I II The combination of apparatus described in this invention was installed on a standard eight cylinder automobile. The automobile was driven at a speed of approximately 50 miles per hour for several miles. The automobile was then brought to a stop and the engine permitted to idle (an air pump speed of approximately 600 r.p.m.). At the beginning of the idle cycle, the air pump output was approximately 4 cubic feet per minute. After 1 /2 minutes the catalyst temperature had risen from 1010 F. to over 1200 F. The temperature sensing element opened the three way valve thereby establishing communication between the manifold of the engine and the pump actuating means. The pump actuating means then activated the air pump, causing the pump to pivot about its hinged connection to the engine and operate at an increased speed (1500 r.p.m.). The output of the air pump when oper ating at this speed was between and 11 cubic feed per minute. of approximately 1540 F. had been reached. This temperature was then reduced to 1400 F. in 1 /2 minutes and further lowered to 1200 F. during an additional 4 /2 minutes of operation. After this time, the temperature was held substantially constant at approximately 1200" F. by the automatic control action.

The data from this example is shown in Table H.

TABLE II Time in Speed in Air Flow Temperature Minutes m.p.h. in c.1'.m. of Catalyst Bed in F.

0 Idle 4 1, 010 1% Idle 4 1, 280 3 Idle 4 1, 540 4% Idle 10 1, 400 6 Idle 10 1, 360 7% Idle 10 1, 300 9 Idle 10 1, 220 10% Idle 10 1, 210 12 Idle 10 1,190 13% Idle 4 1, 200 15 Idle 10 1, 210

An analysis of the exhaust gases was made at both the high and low air flows (4 cubic feet per minute and 10 cubic feet per minute). The conversion was found to be approximately 91% for the carbon monoxide and 86% for the hydrocarbons. The efiect of the conversion when changing the air flow from 4 to 10 cubic feet per minute was found to be negligible. Thus, it is apparent that decreasing the temperature of the catalyst by the use of excess air has no deleterious effect on the function of the catalyst.

Many modifications and variations of the invention herein set forth may be made without a departure from the essence and scope of the invention. This invention is intended to cover all methods and combinations of apparatus in which a sensing device placed in the catalyst mufiler directly controls the admission of air to the muf- At the end of three minutes, a peak temperaturev fler through a direct connection means, such as pressure, vacuum, or electricity, between the sensing device and the means for controlling the air delivery to the muffier. Only such limitations as indicated in the appendant claims should be applied to this invention.

I claim:

1. A combination of apparatus for automatically controlling the temperature of a catalytic exhaust purifier comprising,

(a) means for purifying exhaust gases including a housing containing an oxidation catalyst,

(b) inlet and outlet openings within said purifying means for the exhaust gases to enter and exit therefrom,

(c) a temperature sensing means positioned Within said purifying means,

(d) valve means associated with said sensing means and positioned within a conduit connecting a manifold section of an internal combustion engine with a pump actuating means connected to a variable speed belt driven spring loaded air pump pivotally attached to said engine,

(e) and a second conduit connecting said pump means with said exhaust inlet opening.

2. The combination of claim 1 in which the pump actuating means comprises a pair of vacuum diaphragms.

3. The combination of claim 2 wherein the air pump is belt-driven through a spring loaded, variable pitch sheave pulley.

4. The combination of claim 3 wherein the valve means is a three-way valve and is regulated so as to open when the temperature within the purifier exceeds 1200 F.

References Cited by the Examiner UNITED STATES PATENTS 2,743,529 5/1956 Hayes 23288 X 3,065,595 11/1962 Gary 232 X 3,172,738 3/.19-65 Houdry 23288 X OSCAR R. VERTIZ, Primary Examiner.

EARL C. THOMAS, Examiner.

Claims (1)

1. A COMBINATION OF APPARATUS FOR AUTOMATICALLY CONTROLLING THE TEMPERATURE OF A CATALYTIC EXHAUST PURIFIER COMPRISING, (A) MEANS FOR PURIFYING EXHAUST GASES INCLUDING A HOUSING CONTAINING AN OXIDATION CATALYST, (B) INLET AND OUTLET OPENINGS WITHIN SAID PURIFYING MEANS FOR THE EXHAUST GASES TO ENTER AND EXIT THEREFROM, (C) A TEMPERATURE SENSING MEANS POSITIONED WITHIN SAID PURIFYING MEANS, (D) VALVE MEANS ASSOCIATED WITH SAID SENSING MEANS AND POSITIONED WITHIN A CONDUIT CONNECTING A MANIFOLD SECTION OF AN INTERNAL COMBUSTION ENGINE WITH A PUMP ACTUATING MEANS CONNECTED TO A VARIABLE SPEED BELT DRIVEN SPRING LOADED AIR PUMP PIVOTALLY ATTACHED TO SAID ENGINE, (E) AND A SECOND CONDUIT CONNECTING SAID PUMP MEANS WITH SAID EXHAUST INLET OPENING.

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