US3779222A

US3779222A - Malfunction indicator for exhaust gas recirculation valve

Info

Publication number: US3779222A
Application number: US00291984A
Authority: US
Inventors: J Lorenz
Original assignee: Ranco Inc
Current assignee: Ranco Inc of Delaware; Robertshaw US Holding Corp
Priority date: 1972-09-25
Filing date: 1972-09-25
Publication date: 1973-12-18
Anticipated expiration: 1990-12-18

Abstract

A malfunction indicator for a vacuum operated exhaust recirculation valve in an internal combustion engine comprises an indicator means actuated in response to attainment of a gradually drawn vacuum in a chamber communicating with the valve operating vacuum source, the chamber adapted to be cut off from the vacuum source prior to attainment of the actuating vacuum by a valve operated in response to a given increase in resistance to flow of air through a capillary tube comprising a section of conduit connected to the vacuum source and subjected to the high temperatures of exhaust passing through the valve.

Description

United States Patent 1 1 1111 3,779,222

Lorenz 1 1 Dec. 18, 1973 1 MALFUNCTION INDICATOR FOR 3,202,161 8/1965 Richards 123/198 D x EXHAUST GAS RECIRCULATION VALVE 3,291,461 12/1966 Pope 123/119 F X Inventor: Jerome L. Lorenz, Columbus, Ohio Ranco Incorporated, Columbus, Ohio Sept. 25, 1972 Assignee:

Filed:

Appl. No.:

References Cited UNITED STATES PATENTS 4/1947 Wassman 1 1 A 123/119 A 6/1961 Smith 123/198 D X 12/1962 Stein 123/198 D Primary Examiner-Wendell E. Burns Attorney-Roy E. Raney [57] ABSTRACT A malfunction indicator for a vacuum operated exhaust recirculation valve in an internal combustion engine comprises an indicator means actuated in response to attainment of a gradually drawn vacuum in a chamber communicating with the valve operating vacuum source, the chamber adapted to be cut off from the vacuum source prior to attainment of the actuating vacuum by a valve operated in response to a given increase in resistance to flow of air through a capillary tube comprising a section of conduit connected to the vacuum source and subjected to the high temperatures of exhaust passing through the valve.

4 Claims, 1 Drawing Figure 64 56 F 1 so BACKGROUND OF THE INVENTION DESCRIPTION OF THE PREFERRED FORM OF THE INVENTION In the drawing, a conventional internal combustion It has been found desirable to reduce or eliminate ox- 5 a t m ti engine, not fully shown, includes an intake ides of nitrogen in the exhaust of internal combustion engine driven automobiles by directing a portion of the exhaust into the fuel intake of the engines during normal, relatively unloaded driving conditions of the automobiles. This practice is referred to as a recirculation of exhaust. Under certain other operating conditions of the automobiles, such as at idle, heavy loading of the engine and wide open throttle, recirculation of exhaust is unnecessary because little if any nitric oxides are produced under such conditions and, furthermore, recirculation of exhaust under these conditions results in rough and otherwise unsatisfactory operation of the engines. Valves have been provided to control the recirculation of exhaust so that the valves are closed when recirculation is unnecessary. Thus, the valves will at times be open and at other times closed during normal operation thereof. The failure of a valve of the type mentioned to open due to sticking or other malfunction cannot be readily detected by the operator of the automobile and consequently in the event the valve did not open the engine'would emit nitric oxides without the knowledge of the operator. Therefore, it is desirable that means be provided for indicating to the operator of the automobile that the exhaust recirculation valve is not opening during the conditions requiring opening thereof so that the malfunctioning valve may be corrected or replaced.

THE PRESENT INVENTION The present invention provides a valve for effecting the recirculation of exhaust in an internal combustion engine during operating conditions requiring such recirculation and shutting off recirculation of exhaust during other operating conditions, and means for indicating a failure of the valve to effect recirculation when such recirculation is desired.

In carrying out the invention, a valve is provided between the exhaust manifold and the intake manifold and is operated by a fluid pressure responsive motor, the fluid for operating the motor being regulated by suitable control means for causing proper opening and closing of the valve by the motor, and indicating means responding to the regulated fluid pressure to initiate a delayed signal producing operation when the fluid pressure is normally effective to cause opening of the valve, the delayed signal operation being deactivated by means responsive to exhaust passing through the valve.

Another object of the invention is the provision of an exhaust recirculation control valve and indicator means of the type mentioned in which one of the conduit means comprises a capillary tube subjected to the temperature of gases passing through the valve.

Other objects and advantages of the invention will be apparent from the following description of a preferred form of the invention, reference being made to the accompanying drawing which is a schematic showing of a valve for controlling the flow of exhaust of an internal combustion automotive engine with the intake manifold and an indicator for sensing a malfunction of the valve.

manifold 10, a carburetor feeding air and fuel into the manifold and comprising a venturi throat I l, and an exhaust manifold 12. Recirculationof exhaust gases into the intake manifold to reduce nitric oxide emissions is controlled by a valve 13. The valve 13 comprises a body 14, having an inlet port 15 connected with the exhaust manifold, and an outlet 16 connected with the intake manifold. The opening of the port 15 is controlled by a valve plate 17 which is moved to and from the inlet opening by a stem 20 attached thereto.

The stem 20 is reciprocated to open and close the port 15 by a vacuum motor 21 which comprises a casing 22 having a flexible diaphragm 23 dividing the casing into

separate chambers

24,25. The chamber 24 is open to atmosphere and the chamber 25 is connected by a conduit 26 with the intake manifold 10 through a vacuum control means 27. A compression spring 30 in the chamber 25 urges the diaphragm 23 in a direction to cause the stem 20 to move the valve member 17 to close the port 15. A vacuum drawn in the chamber 25 will cause atmospheric pressure to shift the diaphragm 23 against the spring 30 and remove the valve member 17 from the inlet opening. The degree of vacuum drawn in chamber 25 will depend upon the vacuum in the intake manifold 10 and the regulation thereof by the control means 27. Typically, the vacuum fed to the motor 21 through the control means will be insufiicient to open the valve 13 until the vacuum in the intake manifold rises to 4 inches Hg.

The control means 27 is shown schematically and it may take any suitable form. For example, it may be like the control means disclosed in copending US. Pat. applications Ser. Nos. 168,595 and 202,783 assigned to the assignee'of the present application. Suffice to say, the control means 27 is connected with the intake manifold 10 by a conduit 32 so that the vacuum for operating the motor 21 is derived from the intake manifold. The control means 27 increases the vacuum in the conduit 26 when conditions prevail which indicate that the valve 13 should open. Conversely, where conditions are such that no exhaust recirculation is desired, the degree of vacuum in the conduit 26 is reduced so that the valve 13 closes.

According to the invention, means is provided for indicating the failure of the valve 13 to open in spite of the fact that vacuum source in conduit 26 exceeds 4 inches Hg. The indicating means comprises a signal lamp 35 which is connected in a circuit including a battery 36, and a normally open switch 37. The lamp may be located in any convenient position so as to be readily seen by the operator of the automobile. It is to be understood that the indicator could take any form desired. The switch 37 comprises contacts 40 which may be bridged by a contact bar 41 carried by a switch arm 42. The arm 42 is pivoted at 43 and is inherently biased from the contacts 40. The switch 37 is closed when the arm 42 is momentarily drawn to the right, as viewed in the drawing, and is retained in the switch closing position by an electromagnet 44. The circuit for the magnet 44 includes the switch 37 so that once the magnet is energized, the switch arm 42 is retained in its switch closed position until the circuit for the magnet is broken. For example, the magnet circuit could also include the ignition switch which opens the circuit when the ignition is turned off. 7

The switch arm 42 is adapted to be moved to close the switch 37 and into the field of the magnet 44 by a fluid operated motor 45. The motor 45 comprises acylindrical shell or casing 46 having a transversely extending diaphragm 47. The diaphragm 47 has a connecting rod 50 attached thereto which extends through a bushing 51 in the end wall of the casing 46. The rod 50 is attached to a lever 52 pivoted at 53, which lever guides the rod in reciprocating movements. A stop 54 on the rod engages the switch arm 42 during movement of the rod to the right and causes the switch arm to close the switch 37. The rod 50 may move to the left independently of the switch arm so that while the magnet 44 is energized the switch 37 is closed irrespective of the movement of the rod 50. The inner end of the bushing 51 limits movement of the diaphragm 47 and rod 50 to the left.

A relatively rigid wall 55 extends transversely of the casing 46 and is spaced from the diaphragm 47. A compression spring 56 between the diaphragm 44 and the wall 55 urges the diaphragm and the rod 50 to the left. The area in the casing between the diaphragm 47 and the wall 55 comprises a chamber 57 and an opening 60 in the casing wall connects the chamber 57 with atmosphere.

A second diaphragm 61 extends transversely of the casing 46 and cooperates with the walls of the side and end of the casing and the wall 55 to form

chambers

62,63. The

chambers

62,63 are sealed from one another except by way of a valve port 64 formed in the wall 55. The port 64 is adapted to be closed by the diaphragm 61 moving thereover in response to a fluid pressure differential established between the

chambers

62,63.

The fluid pressure in chamber 62 is affected by con necting the chamber with the regulated valve operating vacuum conduit 26 by way of a conduit 65. The conduit 6S communicates with the chamber 62 through a restrictor orifice 66. The fluid pressure in the chamber 63 is affected by connection of the chamber with the vacuum conduit 26 through a conduit 67 which includes a section of a capillary tube 70.'The chamber 63 is vented to atmosphere through a restrictor orifice 71. The length and internal diameter of the capillary tube 70 is such that when the temperature of the tube is increased from about 250F. to the neighborhood of 350F.-The viscosity of the air in the tube correspondingly increases so that an appreciable resistance to the flow of air through the conduit 67 is established. When the capillary 70 is at temperatures of 250F. and below the resistance to the flow of air therethrough is substantially reduced from that effected by a temperature of 350F. as just mentioned. U.S. Pat. No. 2,589,251 discloses the effect on the viscosity of air passing through a capillary tube.

When the engine is inopertive, the diaphragm 47 is moved to the open position for the switch 37 by the spring 56. Upon starting of the engine and the creation of a vacuum in conduit 26 for opening the valve 13, initially substantially equal vacuums will be drawn in the

chambers

62,63 through the

conduits

65 and 67 connected with the vacuum conduit 26. With the opening of the valve 13 hot exhaust gases flow through the valve body 14 and heat the capillary tube 70 to about 350F.

This increases the resistance to the flow of air therethrough and as a result a higher vacuum is drawn in chamber 62 than in chamber 63. The ensuing pressure differential of the chambers causes the diaphragm 61 to close on the port 64, shutting off the chamber 57 from the vacuum induced in the chamber 62. Thus, the action of the spring 56 maintains the switch 37 in its open position.

Should the valve 13 fail to open in response to the usual valve opening control vacuums established in the conduit 26 by the control means 27, the capillary tube will not become heated above about 250F. and the flow of air passing from chamber 63 to the conduit 26 is relatively unimpeded. This results in a relatively low pressure in the chamber 63 substantially equal to the low pressure in the chamber 62 and the diaphragm 61 cannot be closed on the port 64 or maintained on the port. Consequently, the chamber 57 will be subjected to the vacuum signal of the conduit 26, less the slight influx of atmosphere through the restricted orifice 60. This reduction in pressure in the chamber 57 results in movement of the diaphragm 47 to the right which closes the switch 37.

To. avoid false malfunction signals due to the relatively short period required for the capillary tube 70 to become heated by the exhaust flowing through the valve body, the opening 60 is of such diameter that several seconds are required to evacuate the chamber 57 to the degree necessary to cause the diaphragm 47 to shift to the switch closing position. If during this period of delay in closing the switch 37 the tube 70 becomes heated by the passage of exhaust through the valve, the vacuum drawn in chamber 63 through the capillary tube is rapidly reduced and the diaphragm 61 will be shifted to close the port 64 and seal the chamber 57 from the vacuum conduit 26. Thus, the means to effect the delayed operation of the signal switch 37 is deactivated in response to the passage of exhaust through the valve, as desired. I

I claim:

1. A valve for controlling the flow of exhaust into the intake manifold of the internal combustion enging comprising, motor means for opening and closing said valve, control means regulating said motor means in response to operating conditions of said engine, indicator means for indicating a malfunction of said valve, delayed action means responsive to said control means to activate said indicator means a period after control of said motor is established, and means responsive to the flow of exhaust gas through said valve for interrupting operation of said delayed action means whereby activation of said indicator means is prevented.

2. A valve for controlling the flow of exhaust into the intake manifold of the internal combustion engine comprising, fluid motor means for opening and closing said valve, means providing fluid flow, control means regulating the flow of fluid for operating said motor means, indicator means for indicating a malfunction of said valve, means responsive to said controlled fluid flow and operative to activate said indicator means a period after a given fluid flow condition is established, and means responsive to the flow of exhaust gas through said valve for interrupting operation of said means whereby activation of said indicator means is prevented.

3. A valve as defined in claim 2 further characterized by said means providing a fluid flow comprising a conduit connected with said intake manifold.

4. A valve as defined in claim 2 further characterized apply said controlled fluid to opposite sides of said wall, and means responsive to the presence of exhaust gas passing through said valve to change the fluid pressure by said means to activate said signal comprising a 5 applied to one side of Said chamber having a movable wall, means to gradually

Claims

4. A valve as defined in claim 2 further characterized by said means to activate said signal comprising a chamber having a movable wall, means to gradually apply said controlled fluid to opposite sides of said wall, and means responsive to the presence of exhaust gas passing through said valve to change the fluid pressure applied to one side of said wall.