US3898967A - Automatic choke assembly - Google Patents

Abstract

There is disclosed an automatic choke assembly for use with an internal combustion engine having an intake manifold, an exhaust manifold, an alternator for supplying electrical energy to the engine, at least one carburetor having a conduit therein for supplying air and fuel to the engine, and a valving means for controlling the ratio of the air and fuel. The choke assembly comprises a housing member with a pair of chambers therein, means for supplying heat to a first of said two chambers, a bimetal spring positioned within the first chamber, a heating means thermally connected to the bimetal spring, a terminal contact electrically connected to the engine''s alternator, and a thermally responsive and electrically conductive member within the second of said two chambers. This assembly provides an interconnection between the heating means and the terminal contact when the temperature about the member exceeds a predetermined level. In doing so, the heating means is energized during engine operation by electrical current supplied from the alternator.

Description

United States Patent [191 Bennett et al.

[451 Aug. 12, 1975 AUTOMATIC CHOKE ASSEMBLY [73] Assignee: GTE Sylvania Incorporated,

Stamford, Conn.

[22] Filed: June 4, 1973 [21] App]. No.: 366,347

[52] US. Cl 123/119 F; 261/39 R; 261/39 B;

261/39 E [51] Int. Cl. F02d 11/08; F02m l/lO; F02m 23/04 [58] Field of Search 123/119 F; 261/39 E, 39 B,

OTHER PUBLICATIONS Ford 1973 Preliminary Car Shop Manual Index Page, pages 24-11-01, 24-11-02, 24-11-03. Printed July, 1972. Ford Marketing Corporation, Dearbom, Mich.

Primary Examiner-Wendell E. Burns Attorney, Agent, or FirmNorman .I. OMalley; Donald R. Castle; Lawrence R. Fraley [5 7 ABSTRACT There is disclosed an automatic choke assembly for use with an internal combustion engine having an intake manifold, an exhaust manifold, an alternator for supplying electrical energy to the engine, at least one carburetor having a conduit therein for supplying air and fuel to the engine, and a valving means for controlling the ratio of the air and fuel. The choke assembly comprises a housing member with a pair of chambers therein, means for supplying heat to a first of said two chambers, a bimetal spring positioned within the first chamber, a heating means thermally connected to the bimetal spring, a terminal contact electrically connected to the engines alternator, and a thermally responsive and electrically conductive member within the second of said two chambers. This assembly provides an inter-connection between the heating means and the terminal contact when the temperature about the member exceeds a predetermined level. In doing so, the heating means is energized during engine operation by electrical current supplied from the alterna- 7 Claims, 4 Drawing Figures AUTOMATIC CHOKE ASSEMBLY BACKGROUND OF THE INVENTION The present invention relates to internal combustion engines and more particularly to automatic choke assemblies for use with such engines. Automatic choke assemblies as utilized in todays internal combustion engines most usually comprise a housing member having a bimetallic coil spring therein. This bimetallic coil spring is heat responsive with the heat being supplied via a duct or similar type heat exchange which derives heat from the exhaust manifold of the engine. In most prior art automatic choke assemblies of the nature described, an inherent problem exists concerning the emission of waste by-products of the internal combustion engine. This occurs primarily during warm engine operating temperatures when the engine is shut off for a relatively short period of time after which the operator may soon start the engine again. Upon doing so the above described bimetallic coil, which has returned substantially to its original unset condition, must again be activated. Therefore, when the operator starts the engine, the choke valving assembly which is directly or indirectly linked to this coiled spring is usually at the closed position causing a relatively rich mixture of fuel and air to be supplied to the engine. A quantity of this mixture is thereafter unburned, resulting in the spewing of many undesirable waste by-products from the engine for a period of time. This spewing occurs until the previously described bimetallic spring member again deflects to its fully open position thereby opening said valving means to provide the proper air to fuel ratio for the desired operating conditions of the engine. As can be appreciated, this problem of spewing of excessive hydrocarbons, sulfur dioxide, and other undesirable by-products results in a relatively high rate of pollution of the atmosphere surrounding the operating engine.

It is believed therefore that an automatic choke assembly which would provide a means for heating the bimetallic coiled spring member to a fully open position in a relatively short period of time thereby providing the desired air-fuel ratio in a substantially shorter period of time than heretofore known would constitute an advancement in the art.

OBJECTS AND SUMMARY OF THE INVENTION It is therefore a primary objective of the present invention to provide a new automatic choke assembly for an internal combustion engine.

It is a further object of the present invention to provide an automatic choke assembly which in turn provides for a more rapid opening of the choke valve controlling the ratio of air and fuel supplied said engine during warm engine operating temperatures.

The foregoing objects are achieved in one aspect of the invention by an automatic choke assembly for an engine having at least one intake and one exhaust manifold, at least one carburetor having a conduit therein for supplying air and fuel to the engine, a valving means for controlling the ratio of the air and fuel within said conduit, and an alternator for supplying electrical energy to the engine. This choke assembly comprises a housing member having first and second chambers therein, means for supplying heat to said first chamber, said heat indicative of the temperature of said engine, a bimetallic spring member positioned substantially within the first chamber and operatively connected to the valving means, a heating means thermally connected to the bimetallic spring member, a terminal contact member electrically connected to said alternator, and a thermally responsive and electrically conductive member positioned substantially within the second chamber. This thermally responsive and electrically conductive member has at least one arm portion which is thermally and electrically connected to the heating means. It also has at least one tongue portion adapted for electrically engaging the terminal contact member when the temperature surrounding said thermally responsive and electrically conductive member exceeds a predetermined level. In doing so, the heating means is energized.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevational view in section of the choke assembly of the present invention.

FIG. 2 is an isometric view showing the operation of the bimetallic coiled spring member of the present invention.

FIG. 3 is an isometric view illustrating the thermally responsive conductive member of the invention.

FIG. 4 is a partial isometric view showing the relative movement of the member of FIG. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENTS For a better understanding of the present invention, together with other and further objects, advantages and capabilities thereof, reference is made to the following disclosure and appended claims in connection with the above described drawings.

With reference to the drawings, in FIG. 1 there is shown a side elevational view of one embodiment of the present invention, automatic choke assembly 10. Assembly 10 is shown to comprise a housing member 11 defining a first chamber 13 and a second chamber 15. Positioned within first chamber 13 is the bimetallic spring member 17 which is illustrated as being operatively connected to the choke valving means 19 positioned within the conduit 21 of the carburetor assembly 23 which in turn is connected to an internal combustion engine (not shown), such as is used in todays automobiles. As is well known in the art, these and similar types of internal combustion engines comprise at least one intake and at least one exhaust manifold. Positioned in relationship to the intake manifold of the engine is at least one carburetor assembly. The function of this carburetor assembly is to provide the engine with a'mixture of air and fuel, said air and fuel supplied at a predetermined ratio in order for the engine to operate'in an efficient manner. An example of the previously. described engine arrangement is illustrated in US. Pat. Nos. 3,180,576 and 2,962,014. With particular reference to 3,180,576, the engine is shown to comprise an intake manifold 13, an exhaust manifold 36, and a carburetor 10 positioned on the intake manifold. Engines of this variety are well known in the art and further description is not felt necessary.

With particular reference to FIG. 1 which illustrates the present invention, the bimetallic spring 17 receives heat from an external source. This source, as described in the abovementioned patents, can be the exhaust manifold of the engine with heat being supplied first chamber 13 via a means for supplying heat, illustrated as pipe 25. When the engine isinitially started, the bimetallic spring member is in its unwound position and the valving means 19 is therefore in its normally almost closed position as illustrated. In other words, a full choke is now applied. When the engine is started, air is drawn down through conduit 21 of carburetor 23 in the direction indicated. This air is mixed with a supplied fuel source (not shown) to provide the desired air to fuel ratio. As can be appreciated, when the valving means is closed, a rich mixture or better defined as a mixture having an excessive amount of fuel therein is derived from the carburetor. Bimetallic coiled spring member 17 is typical of most similar type spring members of choke assemblies of the prior art and does not provide a means for fully opening valving means 19 thereby providing the desired air to fuel ratio mixture until the temperature of the engine reaches approximately 120 F. This incurs a time period of approximately 2 minutes in most internal combustion engines of the automotive and similar fields.

Once the engine has been operated for a period of time and thereafter turned off, bimetallic spring member 17 returns to its normally closed position. This bimetallic coiled spring will retain the position of the choke valving means in at least a partially closed position until the engine once again attains the desired operating temperature. Consequently,'upon restarting the engine after a relatively short period of time, an excessive amount of waste by-products from the engine are spewed into the engines exhaust and thereafter out into the atmosphere surrounding the automobile. To prevent this from occuring, a new and unique assembly is shown in which the bimetallic coiled spring is returned to a normally open operating position in a relatively shorter time period than previously known automatic choke assemblies. This is accomplished by providing a thermally responsive and electrically conductive member 27 within second chamber of housing member 11. As illustrated in both FIGS. 1 and 3, responsive member 27 comprises at least one shoulder portion 29 and at least one tongue portion 31. Tongue portion 31 is adapted for engaging a terminal contact member 33 which in turn is electrically connected to I the engines alternator (not shown). When the temper ature about responsive member 27 is at a predetermined level, tongue portion 31 remains engaged with contact 33 thereby providing an electrical connection between the alternator of the engine and a heating means 35 also positioned'within the second chamber of housing 11. Heating means 35 comprises a heater disc member of thermal generative material such as barium titanate. Once electrical current is supplied heater member 35, it thereby heats at a relatively high rate and in turn supplies heat to an interconnecting thermal conductive member 37. As shown in the drawings, the coiled spring member 17 is thermally joined to interconnecting thermal member 37 and is adapted for receiving heat therefrom. Thus, it can be seen that when responsive member 27 is in the fully engaged position as indicated in phantom, heating means 35 is actuated thereby providing heat in an indirect manner to coiled spring 17 during the operation of the internal combustion engine. This in turn keeps valving means 19 in the fully opened position. Thus, the desired air to fuel ratio to the internal combustion engine is'providedina relatively short period of time compared to the time involved when coiled spring 17 expands solely as a result of heat from pipe 25. v

With reference to FIGS. 1 and 2, a partial isometric view of coiled bimetallic spring 17 is shown. Coiled spring 17 is positioned within interconnecting thermal member 37 in the manner indicated. There is also illustrated the means by which coiled spring 17 serves to actuate valving means 19, this achieved by utilizing arm 39 joined to valving means 19 via a rotating shaft 41. As coil spring 17 unwindsin the direction indicated in FIG. 2 during increases in engine temperature, arm 39 swings choke valving means 19 in the open direction.

Referring particularly to FIG. 1, terminal contact 33 is electrically connected to the engines alternator via a connecting plug 43 which is readily adaptable for engaging a protruding portion of the contact 33. Plug 43 is only representative of several different varieties of electrical connection members which are suitable for the present invention. A source preferred for supplying heat indicative of the operating temperature of the engine to first chamber 13 is the engines exhaust manifold. However, this is not meant to be-restrictive in that any other type of heating mechanism could successfully be utilized provided this mechanism'could directly provide a means for indicating the engines operating temperature. As shown in the drawings, heat supplied from the exhaust manifold to the first chamber 13 is permitted to escape this chamber via a heat removal conduit 45 whichis connected at its other end to either a lower portion of the carburetor 23 or to the engines intake manifold. Also shown in FIG. 1 is an optional adjustment means, illustrated as a screw 46, which can be provided as a method for adjusting the spacing for the electrical connection between Contact 33 and responsive member 27. Screw 46 is threaded through contact 33 and consequently is electrically connected thereto. Thus, a means is provided for readily calibrating the engagement cycle between these members according to desired specifications.

A preferred method for providing an electrical ground to the previously described circuit is to ground thermal conductive member 37; This can be'achieved by simply affixing an external lead to member 37 which exits first chamber 15 through insulative housing 11. Another relatively simple grounding means could be achievedrby providing member 37 with a protruding portion which is adapted for exiting first chamber 13 through housing 11. As the above described electrical grounding procedures are easily understood by those in the art, it is not felt necessary to illustrate them here or to provide further description at this time. It can also be readily understood that the described circuit can be grounded at several other locations, for example, members 27 or 35 respectively. As stated, however, it is preferred to do so at thermal member 37.

In FIG. 3 there is shown a more detailed view of thermally' responsive and electrically conductive member 27. Member 27 is shown to compriseat least oneshoulder portion 29 and at least one tongue portion 31. In

the preferred embodiment, member 27 comprises a bimetallic member having a low expansion surface 47 and a high expansion surface 49. This bimetallic member is formed preferably from a single or unitary standard sheet of bimetallic material and is available from the w. M. Chace Company, Detroit, Mich., sold under thetradename Chace 2400". Chace 2400" bimetal has a low expanding side of Invar of 36% nickel with side of said bimetal is about 10 X 10 per F over a temperature range of from about F to about 150 F. Chace 2400 is especially preferred in the present invention because bimetallic spring 17 can also be pro.- duced from this material. Terminal member 33 may be of any sound electrical conductive material while it is preferred that the material for interconnecting thermal conductive member 37 be of a good thermal conductive material such as brass. Housing 11 is preferably of an electrically insulative material such as the higher heat withstanding plastics, i.e., phenolic.

The preferred embodiment for thermal responsive and electrical conductive member 27 as shown in FIG. 3 comprises two shoulder portions 29 and only one tongue portion 31. Shoulder portions 29 are separated from tongue portion 31 by a pair of openings 51. Looking closer at tongue portion 31, it can be seen that this portion has the pair of substantially parallel aligned slots 53 formed therein. Slots 53 are located longitudinally within tongue portion 31 and define a central strip 55 and two exterior lateral strips 57. It is to be understood, however, that slots 53 may be formed in the bimetallic member in any desired shape and that if desired, may be otherwise fabricated from a plurality of elements. Located on each of exterior lateral strips 57 is an upstanding knee portion 59. As illustrated, central strip 55 is bowed upwardly in comparison to exterior lateral strips 57. Thus, as can be seen in FIG. 4, when the temperature surrounding member 27 attains a predetermined level, central strip 55 will deflect in a downward direction in comparison to its previous position. This in turn insures a snap-acting motion by tongue portion 31 to the terminal engaging position. A preferred temperature range at which the above described action takes place is substantially between 80 F and 1 F.

It can therefore be seen that when the engine temperature is within the above described range of between 80 F and 1 10 F, thermally responsive and electrically conductive member 27 remains in the engaged position interconnecting terminal contact 33 with heating means 35. Thus, if the engine is turned off after operating for a period of time and once again turned on, heating means 35 will be supplied with a flow of electrical current provided the temperature about member 27 is within the preferred range of from about 80 F to 1 10 F. This supply of current causes heating means 35 to become rapidly heated, thereafter heating bimetallic coil spring 17 to open choke valving means 19 in a shorter time period than herebefore known in the art. When valving means 19 is at an open position and the engine is at the warmer operating temperature, the proper ratio of air to fuel is attained and fewer waste byproducts are emitted from the exhaust of the engine.

To assure a sound electrical connection between thermally responsive and electrically conductive member 27 and terminal contact 33, tongue portion 31 has a portion 61 of noble metal affixed thereto. Portion 61,

shownin FlG. 1 as directly engaging a screw 46 and consequently terminal contact 33 once the described temperatures are attained, is preferably in the form of a relatively thin sheet of either gold or silver alloy and is'affixed to tongue 31 by any of the several known conventional methods of bonding, such as welding.

Thus, there has been described an automatic choke assembly which provides for rapid heating of the bimetallic coil element of the assembly to in turn open the choke valving means in the carburetor conduit to thereby assure a more rapid attainment of a proper air to fuel ratio during warmer operating conditions of the internal combustion engine.

While there have been shown and described what are at present considered to be the preferred embodiments of the invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the scope of the invention as defined by the appended claims.

What is claimed is:

1. In an automatic choke assembly for an internal combustion engine having intake and exhaust manifolds, at least one carburetor having a conduit therein adapted for supplying air and fuel to said engine, a valving means for controlling the ratio of said air and fuel within said conduit, and an alternator for supplying electrical energy to said engine, wherein said choke assembly comprises a housing member defining first and second chambers, means for supplying heat indicative of the temperature of said engine to said first chamber, a bimetallic spring member positioned within said first chamber and operatively connected to said valving means, a heating means thermally connected to said bimetallic spring member, and a terminal contact member electrically connected to said alternator, the improvement comprising:

a thermally responsive and electrically conductive member positioned within said second chamber, said thermally responsive and electrically conductive member having at least one arm portion thermally and electrically connected to said heating means and at least one tongue portion adapted for moving in a snap-action manner to engage said terminal contact member when the temperature surrounding said thermally responsive and electrically conductive member exceeds a predetermined level whereby said heating means is energized during operation of said engine, said tongue portion comprising a pair of spacedly positioned lateral strip members and a contact strip member positioned substantially therebetween, said central strip member separated from each of said lateral strip members by a longitudinal slot.

2. The improvement according to claim 1 wherein said thermally responsive and electrically conductive member is a bimetal.

3. The improvement according to claim 2 wherein the difference in average coefficients of expansion between the high expanding side and the low expanding side of said bimetal is about 10 X 10 per F over a temperature range of from OF to about 150F.

4. The improvement according to claim 1 wherein said predetermined temperature level at which said tongue portion is adapted for engaging said terminal contact member is substantially between F and 1 10F.

5. The improvement according to claim 1 wherein each of said lateral strip members includes at least one upstanding knee portion thereon.

6. The improvement according to claim 1 wherein 7; The improvement according to claim 1 wherein said thermally responsive and electrically conductive member comprises two arm portions thermally and said tongue portion includes a contacting portion of a electrically connected to said heating means noble metallic material.

Claims (7)

1. In an automatic choke assembly for an internal combustion engine having intake and exhaust manifolds, at least one carburetor having a conduit therein adapted for supplying air and fuel to said engine, a valving means for controlling the ratio of said air and fuel within said conduit, and an alternator for supplying electrical energy to said engine, wherein said choke assembly comprises a housing member defining first and second chambers, means for supplying heat indicative of the temperature of said engine to said first chamber, a bimetallic spring member positioned within said first chamber and operatively connected to said valving means, a heating means thermally connected to said bimetallic spring member, and a terminal contact member electrically connected to said alternator, the improvement comprising: a thermally responsive and electrically conductive member positioned within said second chamber, said thermally responsive and electrically conductive member having at least one arm portion thermally and electrically connected to said heating means and at least one tongue portion adapted for moving in a snap-action manner to engage said terminal contact member when the temperature surrounding said thermally responsive and electrically conductive member exceeds a predetermined level whereby said heating means is energized during operation of said engine, said tongue portion comprising a pair of spacedly positioned lateral strip members and a contact strip member positioned substantially therebetween, said central strip member separated from each of said lateral strip members by a longitudinal slot.

2. The improvement according to claim 1 wherein said thermally responsive and electrically conductive member is a bimetal.

3. The improvement according to claim 2 wherein the difference in average coefficients of expansion between the high expanding side and the low expanding side of said bimetal is about 10 X 10 6 per *F over a temperature range of from 0*F to about 150*F.

4. The improvement according to claim 1 wherein said predetermined temperature level at which said tongue portion is adapted for engaging said terminal contact member is substantially between 80*F and 110*F.

5. The improvement according to claim 1 wherein each of said lateral strip members includes at least one upstanding knee portion thereon.

6. The improvement according to claim 1 wherein said tongue portion includes a contacting portion of a noble metallic material.

7. The improvement according to claim 1 wherein said thermally responsive and electrically conductive member comprises two arm portions thermally and electrically connected to said heating means.

Images