US3859974A

US3859974A - Cold starting devices for internal combustion engines

Info

Publication number: US3859974A
Application number: US340469A
Authority: US
Inventors: Gray Ernest Donald Ross
Original assignee: Zenith Carburetter Co Ltd
Current assignee: Zenith Carburetter Co Ltd
Priority date: 1972-03-16
Filing date: 1973-03-12
Publication date: 1975-01-14
Anticipated expiration: 1992-01-14
Also published as: FR2176146B1; AU5336273A; GB1422633A; FR2176146A1; JPS4919226A; SE387157B; DE2312693A1; CA992821A; JPS5732215B2; AU468817B2; IT980610B; DE2312693C2

Abstract

A cold starting device for an i.c. engine has two throttles in an auxiliary air passage. The upstream throttle is closed and the downstream throttle is open for cranking. The upstream throttle opens progressively and the downstream throttle begins to close progressively when the engine begins to run under its own power. The downstream throttle is closed and the upstream throttle is open when the engine is running normally. One lever is fixed to the spindle of the downstream throttle and is connected via a lost motion connection to another lever journaled on that spindle. A temperature sensitive capsule controls rotary movement of the other lever. The two levers and the capsule are arranged so that closure movement of the downstream throttle is limited to that allowed by the lost motion connection and so that the downstream throttle is prevented from closing when the engine is cold, the other lever being moved by the capsule to permit further closure of the downstream throttle as the engine warms up. Means are provided to ensure that movement of the downstream throttle is accompanied by movement of the upstream throttle in the opposite sense. The lost motion connection between the two levers may comprise a post on the fixed lever which projects into an arcuate notch in the rotary lever. The arcuate length of the notch may be decreased as the engine temperature increases and vice versa.

Description

United States Patent [191 Ross [ Jan. 14,1975

[ COLD STARTING DEVICES FOR INTERNAL COMBUSTION ENGINES [75] Inventor: Gray Ernest Donald Ross, Tring,

England [73] Assignee: The Zenith Carburetter Company Limited, Stanmore, Middlesex, England 22 Filed: Mar. 12,1973

21 Appl. No.: 340,469

[30] Foreign Application Priority Data Mar. 16, 1972 Great Britain 12457/72 [52] US. Cl 123/179 G, 123/180 R, 261/23 A, 261/39 B, 261/52, 261/121 A [51] Int. Cl F02m 1/04 [58] Field of Search 123/180 R, 179 G, 180 T, 123/119 D, 119 F; 261/52, 39 A, 39 B, 23 A [56] References Cited UNITED STATES PATENTS 1,696,929 1/1929 Stokes 123/180 R 2,123,522 7/1938 Bryan 123/180 R X 2,323,222 6/1943 Holley et a1 123/180 R X 3,706,444 12/1972 Masaki et a1. 123/119 F Primary Examiner-Charles J. Myhre Assistant Examiner-W. Rutledge, Jr. Attorney, Agent, or FirmClelle W. Upchurch [57] ABSTRACT A cold starting device for an i.c. engine has two throttles in an auxiliary air passage. The upstream throttle is closed and the downstream throttle is open for cranking. The upstream throttle opens progressively and the downstream throttle begins to close progressively when the engine begins to run under its own power. The downstream throttle is closed and the upstream throttle is open when the engine is running normally. One lever is fixed to the spindle of the downstream throttle and is connected via a lost motion connection to another lever journaled on that spindle. A temperature sensitive capsule controls rotary movement of the other lever. The two levers and the capsule are arranged so that closure movement of the downstream throttle is limited to that allowed by the lost motion connection and so that the downstream throttle is prevented from closing when the engine is cold, the other lever being moved by the capsule to permit further closure of the downstream throttle as the engine warms up. Means are provided to ensure that movement of the downstream throttle is accompanied by movement of the upstream throttle in the opposite sense. The lost motion connection between the two levers may comprise a post'on the fixed lever which projects into an arcuate notch in the rotary lever. The arcuate length of the notch may be decreased 'as the engine temperature increases and vice versa.

15 Claims, 7 Drawing Figures PATENTEI] JAN 1 4I975

sum

1 or 6 PATENTEB JAN 1 4|975 SHEET 3 UF 6 PATENTEU JAN 1 4 I975 SMEHMIFG COLD STARTING DEVICES FOR INTERNAL COMBUSTION ENGINES This invention relates to cold starting devices for internal combustion engines, the cold starting devices being arranged so that the constitution of a fuel/air mixture supplied to the engine during starting from cold and warming up of the engine is changed firstly at the termination of the cranking period when the engine commences to run under its own power and is further changed progressively until the engine is running normally.

It is an object of this invention to provide an improved cold starting device of the kind referred to which can supply an air/fuel mixture to the engine that will permit the engine to run normally at a lower speed than has generally been thought to be necessary heretofore and which is a leaner mixture than has hitherto been thought necessary to enable the engine to run normally.

According to one aspect of this invention there is provided a cold starting device for an internal combustion engine, the cold starting device comprising an auxiliary air supply passage, two throttle valve members in the auxiliary air supply passage, one of the throttle valve members being arranged so as to tend to be moved, by air flowing passed it to the engine, into a position in which it restricts or prevents the flow of air passed it to the engine and the other throttle valve member, which is upstream of said one throttle valve member, being arranged so as to tend to be moved to the open position by air flowing passed it to the engine,

and at least one fuel supply orifice which opens into the portion of the auxiliary air supply passage which extends between the closed portions of said two throttle valve members so that fuel can be drawn therethrough into said portion of the air supply passage by engine suction when said one throttle valve member is in the open position, the arrangement being such that said one throttle valve member is in the open position and said other throttle valve member is in the closed position during the cranking period, and said one throttle valve member begins to close progressively and said other throttle valve member begins to open progressively when the engine commences to run under its own power, the progressive closing of said one throttle valve member and the progressive opening of said other throttle valve member continuing until the engine is running normally whereupon the supply of fuel from the or each said fuel supply orifice into said portion of the auxiliary air supply passage ceases.

Because the portion of the auxiliary air supply passage between the closed positions of the two throttle valve members is subjected to full engine manifold depression during the cranking period and, once the engine commences to run under its own power, to a proportion of the full engine manifold depression which reduces from full engine manifold depression progressively until the engine is running normally, fuel drawn from said fuel supply orifice or orifices is atomised more effectively, and the atomised fuel is distributed and emulsified with air within the auxiliry air supply passage more effectively than if the supply of fuel/air mixture to the engine was controlled solely by said one throttle valve member or by a driver controlled throttle valve member of a conventional carburetter. Thus the engine can run normally at a lower speed than has generally been thought to be a minimum, and can run normally when supplied with a fuel/air mixture which is leaner than has generally been thought to be necessary. Furthermore the change of the fuel/ air mixture supplied to the engine by the cold starting device after the cranking period has terminated and before the engine is running normally is totally progressive and independent of any action by the driver.

Preferably said one throttle valve member engages an adjustable stop when in its closed position, the setting of the adjustable stop determining whether the auxiliary air supply passage is shut when said one throttle valve member is in its closed position so that airflow passed said one throttle valve member is prevented, or whether a restricted flow of air passed said one throttle valve member is permitted when it is in its closed position. Such a restricted flow of air may be varied by adjustment of the adjustable stop in order to meet the idling air requirements of the engine.

The two throttle valve members may be coupled together mechanically so as to ensure that said one throttle valve member is in the closed position when said other throttle valve member is in the open position and vice versa.

The throttle valve members may be set either by manually operable means, or by automatically operable means so that said one throttle valve member is in the open position and said other throttle valve member is in the closed position at the commencement of engine starting. The automatically operable means may be controlled thermostatically. Conveniently a lever is mounted pivotally on the spindle of said one throttle valve member and is coupled to the manually operable means or to the automatically operable means, there being a lost motion connection between the lever and said one throttle valve member which allows limited movement of said one throttle valve member relative to the lever in the closing direction caused by air flow in the auxiliary air supply passage due to engine suction.

The cold starting device may include two said fuel supply orifices through which a fuel/air mixture is arranged to be fed into the portion of the auxiliary air supply passage between the closed positions of said two throttle valve members. Conveniently said two fuel supply orifices are located adjacent to said one throttle valve member. Preferably a said fuel supply orifice is positioned adjacent to said other throttle valve and arranged so that fuel can be drawn therethrough into the auxiliary air supply passage only when said other throttle valve member is in the closed position. This ensures that a rich air/fuel mixture is supplied to the engine during the cranking period and thus minimises the risk that the engine will fail to start.

The cold starting device may include a further fuel supply orifice which opens into said auxiliary air supply passage downstream of the closed position of said one throttle valve member and through which an air/fuel mixture can be supplied to meet at least part of the engine idling fuel requirements. Adjustment means may be provided to vary the cross-sectional area of said further fuel supply orifice.

Conveniently a lever is fixed to the spindle of said one throttle valve member and has a radially extending finger which is adapted to strike an element fixed to the spindle of the other throttle valve member during opening movement of said one throttle valve member so as to close said other throttle valve member with opening of said one throttle valve member. Also the lever may carry a resilient finger which is arranged to engage said element during closing movement of said one throttle member so as to ensure that said other throttle valve member is-opened with closure of said one throttle valve member. A lever fixed to the spindle of said one throttle valve may be arranged to engage an adjustable stop when in the closed position, the setting of the adjustable stop determining whether the auxiliary air supply passage is shut when said one throttle valve member is in its closed position so that air flow passed said one throttle valve member is prevented, or whether a re stricted flow of air passed said one throttle ,valve memher is permitted when it is in its closed position.

Conveniently the lost motion connection between said lever and said one throttle valve member com- I prises the engagement of a post carried by one of said lever and another lever, which is fixed to the spindle of said one throttle valve member within an arcuate notch defined by the other of the two levers. The arcuate length of the notch may be decreased as engine temperature is increased and vice versa. The arcuate notch may be defined between the lever which is mounted pivotally on the spindle of said one throttle valve memher, and a third lever. The third lever may have a slot at one end which is engaged with a post fixed to the lever which is mounted pivotally on the spindle of said one throttle valve member, the other end being pinned to the body of the device.

The cold starting device may form part of a carburetter which is arranged to control a supply of fuel/air mixture to the engine when the engine isrunnin'g normally, in which case the downstream end of the auxiliary air supply passage may be arranged to open into the induction passage through which fuel/air mixture is supplied to the engine normally, the auxiliary air supply passage opening into the induction passage at a point downstream of the main throttle valve controlling normal operation of the engine. Alternatively the cold starting device may have its own float chamber from which fuel is drawn through a metering orifice and fed to the auxiliary air supply passage through said one or more fuel supply orifices.

According to another aspect of this invention there is provided a lost motion connection between a first member fixed to a spindle and a second member journaled on the spindle, including a post carried by one of the members and engaged within an arcuate notch defined by the other of the members, the arcuate notch being defined between said other member and a lever, which is pinned at one end to said other member and has its other'end engaged with a post which is fixed relative to the spindle, the arrangement being such that the arcuate length of the notch is decreased with rotary movement of the spindle in one sense and is increased with rotary movement of the spindle in the opposite sense.

Two embodiments of this invention will be described now by way of example only with reference to the accompanying drawings, of which:

FIG. is a schematic illustration of one form of cold starting device according to this invention;

FIG. 2 is a side elevation of another form of cold starting device according to this invention;

FIG. 3 is a section on the line III-III of FIG. 2;

FIG. 4 is a section on the line IV-IV of FIG. 2;

FIG. 5 is a section on the line V-V of FIG. 2;

FIG. 6 is a fragmentary elevation of the cold starting device shown in FIGS. 2 5 as seen along arrow A of FIG. 3; and

FIG. 7 is an exploded perspective view ofa modification of the cold starting device as shown in FIGS. 2 6.

The automatic cold starting device illustrated in FIG. 1 comprises a body 10 which defines a vertical through bore 11 and a float chamber 12. The body 10 has an annular flange 13 which surrounds the lower. end of the through bore 11, and which is arranged to be bolted onto the induction manifold of an internal combustion engine, the arrangement being such that the through bore 11 is in communication through its lower end with the induction manifold. The arrangement of the float chamber 12 is conventional, the level of fuel within the float chamber 12 being maintained substantially constant by the action of the float 14 which floats on the fuel in thefloat chamber and which acts through a pivotally mounted arm 15 to control the location of an inlet valve member 16 relative to the inlet valve seat 17 of a fuel inlet valve 18 mounted within a fuel supply pipe 19 which is in communication with the vehicle fuel tank. The space above the level of fuel in the float chamber -is in communication with atmosphere via a passage 20 which opens into the through bore 11 near the upper end thereof.

A vertical bore 21 formed in the body 10 between the through bore 11 and the float chamber 12 has a restriction 22 at'its upper end which is open to atmosphere. The bore 21 communicates with the through bore 11 through three vertically spaced orifices 23, 24 and 250. A screw 251 has a pointedend remote from its head and is screwed into a tapped hole 252 which extends from the bore 21 to the outer surface of the body 10 so that the pointed end projects into the lowest orifice 250. The screw 251 is held in position by a compression spring 253 which acts between the head of the screw 251 and the outer surface portion of the body 10 which surrounds the tapped hole 252. A passage 25 in the body 10 opens at one end into the bore 21 at a level above the normal level of fuel maintained within the float chamber 12 and communicates via a metering orifice 26 at its other end with the interior of the float chamber 12 below the normal level of fuel maintained within the float chamber 12. A fourth orifice 27 in the wall of the through bore 11 above the normal level of fuel in the float chamber 12 is in communicationwith the float chamber 12 via a passage 28 which has a second metering orifice 29 at its other end below the level of fuel in the float chamber 12.

A butterfly type throttle valve member 30 is fixed on a spindle 31 which extends across the vertical bore 11.

The spindle 31 if offset from the centre of the valve member 30 as that air flow in the vertical bore 11 tends to urge the valve member 30 into the closed position. An adjustable stop screw 350 is screwed into a tapped hole 351. The tapped hole 351 extends through the wall of the vertical bore 11. The adjustable stop screw 351 is held in position by a compression spring 352 which acts between the head of the screw 350 and the outer surface portion of the body 10 which surrounds the tapped hole 351, the head of the screw 350 being outside the body 10. A peripheral portion of the valve member 30 is arranged to abut the end of the screw 350 remote from its head when the valve member 30 is in its closed position, so that the closed position of the valve member 30 is determined by the setting of the adjustable stop screw 350. The spindle 31 is located within the vertical bore 11 so that, when the valve member 30 is in the closed position, the portion of the periphery thereof nearest to the orifice 24 is positioned just below th orifice 24, which is the lower of the middle pair of the four orifices and so that the said nearest peripheral portion of the valve member 30 passes near to the middle pair of orifices 23 and 24 during movement between the closed position and the open position.

A lever 32 is mounted pivotally on the spindle 31. One end 33 of the lever 32 is coupled by any convenient means to a temperature sensitive device which controls the position adopted by the lever 32 within the body 10. The other end 34 of the lever 32 defines a notch 35. Conveniently the end 33 of the lever 32 carries a cam follower which engages the profiled edge of a cam. The angular position of the cam is controlled by a temperature sensitive capsule which functions as the temperature sensitive device and which is filled with wax or other suitable substance having a high coefficient of thermal expansion. The arrangement is such that, with increase of temperature, the wax or other substance expands and acts through a rod to rotate the cam in a direction to turn the lever 32 in the same direction as that in which the spindle 31 rotates with closing movement of the throttle valve member 30. The temperature sensitive device conveniently is sensitive to the engine water temperature, an electric heater or any other suitable means by which the position of the lever can be related to the temperature of the engine.

A cranked lever 36 is fixed at its elbow to the spindle 31. The end of the lever 36 nearer tothe notch 35 carries a post 37 which extends into the notch 35. The diameter of the post 37 is less than the arcuate length of the notch 35 so that movement of the cranked lever 36, and thus the spindle 31, relative to the lever 32 is permitted by movement of the post 37 within the notch 35. The cranked lever 36 is spring urged in the valve opening direction relative to the lever 32 so that the post 37 is spring loaded towards the respective end of the notch 35. The other end 38 of the cranked lever 36 is pinned to a connecting rod (not shown) which is pinned at its other end to the free end 39 of a lever 40 which is fixed to and extends radially from a spindle 41 upon which is mounted another butterfly type throttle valve member 42. The spindle 41 extends across the vertical bore 11, is offset from the centre of the valve member 42 so that air flow in the vertical bore 11 tends to urge the valve member 42 into the open position, and is located within the vertical bore 11 so that, when the valve member 42 is in the closed position, the portion of the periphery thereof nearest to the fourth orifice 27 is positioned just above the fourth orifice 27.

When an engine to which the cold starting device is fitted is cold, the temperature sensitive device holds the lever 32 in a position so that the valve member 30 takes up its fully open position due to the action of the spring loading on the cranked lever 36. The connecting rod, the cranked lever 36 and the lever 40 on the spindle 41 carrying the other valve member 42 are arranged so that the other valve member is in the closed position.

When the engine is cranked for starting, the parts remain in these positions, and suction exerted by the engine causes petrol to be drawn into the vertical bore 11 through the fourth orifice 27 and a mixture of air from the orifice 22 with a metered quantity of fuel drawn from the float chamber 12 via the metering orifice 26, to be drawn into the vertical bore 11 through the orifices 23 and 24.

When the engine begins to run under its own power, increased suction exerted by the engine acts to open the other valve member 42 and to close the valve member 30 provided such movement is permitted by the notch 35 and the connecting rod. Thus the quantity of air admitted to the engine via the auxiliary air supply passage afforded by the vertical bore, and in consequence the speed of the engine, is controlled by the two valves in accordance with the temperature of the engine.

Partial opening of the two valve members 30 and 42 results in an increase in the pressure in that portion of the vertical bore 11 between the two valve members 30 and 42 so that the supply of petrol via the fourth orifice 27 stops. It is important to ensure that the diameter of that part of the vertical bore 11 across which the spindle 41 extends is large enough to ensure that the supply of petrol via the fourth orifice 27 stops when the upper valve member 42 opens. As the engine temperature increases the lever 32 is moved until closure of the valve member 30 is possible. As the portion of the periphery of the valve member 30 which is nearest to the orifice 23 and 24 moves towards the closed position it cooperates with the wall of the vertical bore 11 to define a venturi nozzle which induces flow of the fuel/air mixture from the orifices 23 and 24 towards the engine. Finally the valve member 30 engages the adjustable stop 350 and, closes when the engine reaches normal working temperature. It will be appreciated that airflow passed the valve member 30 is prevented or restricted when the valve member is closed. However fuel/air mixture is supplied to the engine through the bore 11 after closure of the valve member 30, the volume of such a fuel/air mixture supplied being determined by the position of the pointed end of the screw 251 within the lowest orifice 250 through which the fuel/air mixture passes into the bore 11. Such a fuel/air mixture may be a proportion of engine fuel requirement under engine idling conditions.

If the cold starting deviceis used in combination with one or more main carburetters, the adjustable screws 251 and 350 may be set so that the idling air requirements of the engine are met by restricted air flow passed the valve member 30 in its closed position and so that the idling fuel requirements of the engine are met by fuel/air flow through the lowest orifice 250. Changes in the engine idling air and fuel requirements can be catered for by adjustment of the setting of the screws 251 and 350. Thus the idling air and fuel supply settings of the or each main carburetter may be fixed so that the need to provide adjustment means on such carburetters is avoided. Provision of the idling fuel supply orifice 250 minimises risk of the float chamber 12 overfilling. Provision of the adjustable stop screw 350 prevents fretting between the periphery of the valve member 30 and the co-operating wall portion of the through bore 11 and thus avoids jamming of the valve member 30.

The automatic cold starting device illustrated in FIGS. 2 6, comprises a body 50 which defines an angled through passage 51 (see FIG. 3) that serves as an auxiliary air supply passage, the axis of the inlet end 52 of the through passage 51 being normal to the axis of the outlet end 53. The body 50 is designed to be mounted in position in a vehicle with the longitudinal axes of the through passage 51 extending substantially horizontally and with the outlet end 53 connected to the induction manifold of an internal combustion engine of the vehicle. The inlet end 52 would be connected to an air cleaner. The body has two ports 54 and 55 (see FIGS. 3 and 6) which are for connection via separate pipes to the float chamber of a carburetter which controls the supply of fuel to the engine when the engine is running normally.

FIG. 3 shows that the port 54 communicates via a fuel metering orifice 56 with one end of a fuel supply passage 57 which extends within the body 50 parallel to the axis of the outlet end 53. Said one end of the fuel supply passage 57 also communicates with the angled through passage 51 in the region of the elbow of that angled through passage 51 via a metering orifice 58.

The other end of the passage 57 communicates with the angled through passage 51 through two

further orifices

59 and 60 between the elbow and the outlet end 53. A volume screw 61, similar to the screw 251, controls the supply of fuel/air mixture from the fuel supply passage 57 to a fourth orifice 62 which opens into the angled through passage 51 downstream of the

orifices

59 and 60.

The port 55 communicates with the through passage 51 via another metering orifice (not shown) which is adjacent to the metering orifice 58.

A butterfly type throttle valve member 70 is fixed on a spindle 7 which extends across the angled passage 51. The spindle 71 is offset from the centre of the valve member 70 so that air flow in the angled through bore 51 tends to urge the valve member 70 into the closed position. The spindle 71 is located within the angled through passage 51 so that, when the valve member 70 is in the closed position, the portion of the periphery thereof nearest to-the orifice 60, which is downstream of the orifice 59, is adjacent to the orifice 59 so that the said nearest peripheral portion of the valve member 70 passes near to the pair of

orifices

59 and 60 during 1 movement between the closed position and the open position.

Referring now to FIGS. 4 and 5, the body 50 defines a recess 72 which is abovethe through passage 51 when the body 50 is mounted in position in a vehicle. The spindle 71 projects through a bore 73 in that part of the body 50 which separates the recess 72 from the through passage 51. The bore 73 is counterbored at its end remote from the through passage 51. The spindle 71 is surrounded by a sleeve 74 which is spigotted into the counterbore 75. A lever 76 is mounted pivotally on the sleeve 74. Another lever 77 is fixed to the end of the spindle 71 remote from the through passage 51. The lever 76 has a post 78 which extends into an arcuate notch 79 in the outer periphery of the lever 77. The post 78 is urged towards one end of the notch 79 by a torsion spring 80 which surrounds the sleeve 74 and is anchored at its other end to a part 81 of the lever 77 which is integral with and projects from the main part of the lever 77 towards the through passage 51. Thus movement of the post 78 towards the other end of the notch 79 is opposed by the torsion spring 80. A second torsion spring 82, which is secured at one end to the lever 76, is anchored at its other end to the body 50. The lever 76 is urged in the valve closing direction by the spring 82. The spring 80 acts to urge the lever 77 in the valve opening direction relative to the lever 76. The lever 77 has a laterally extending finger 83.

A cam 84 is journaled on a hollow shaft 85 which is fixed in the body 50. The lever 76 is associated with the cam 84 in the manner of a cam follower. The cam 84 has a post 86 which projects away from the through passage 51. The post 86 is engaged by an anular flange 87 which is carried by a rod 88. The rod 88 extends across the lever 77 and on the side thereof remote from the passage 51 to a temperature sensitive capsule 89 which is similar to that referred to in the foregoing description with reference to FIG. I and to which it is connected. The temperature sensitive capsule 89, which functions as a device sensitive to engine temperature, is arranged so that, with an increase in engine temperature, it urges the rod 88 away from itself and against the action of a coil spring 90 which acts upon the annular flange 87. The torsion spring 82 acts upon the cam 84 through the lever 76 and ensures that the cam 84 follows such movement of the annular flange 87 with increase in engine temperature, such move- 'ment of. the cam 84 being accompanied by following movement of the lever 76 which is in the same direction as that in whichthe spindle 71 rotates with closing movement of the throttle valve member 70. The coil spring 90 takes its reaction from the body 50.

Referring again to FIG. 3, there is a secondary throttle valve member, within the through passage 51 and upstream of the throttle valve member which is the primary throttle valve member. The secondary throttle valve member 91 is mounted upon a spindle 92. The spindle 92 extends across the through passage 51, and is offset from the centre of the valve member 91 so that airflow in the through passage 51 tends to urge the valve member 91 into the open position.

Referring to FIG. 4, the spindle 92 carries a lever 93 within the recess 72. The lever 93 has a post 94 which projects away from the through passage 51 and which is spaced from the spindle 92. When the primary throttle valve 70 is in the open position, the secondary throttle valve member 91 is held closed by engagement of the finger 83 with the nearer side of thepost 94. The primary lever 77 carries a resilient finger 95, such as a length of wire, which extends on the side of the post 94 opposite the finger 83 and engages the post 94 during closing movement of the primary throttle valve member 70 in order to ensure that such movement of the primary throttle valve member 70 is accompanied by opening movement of the secondary throttle valve member 91.

Operation of the cold starting device described above with reference to FIGS. 2 6 is generally similar to that of the cold starting device described above with reference to FIG. 1. Thus much of the detailed operation of the cold starting device described above with reference to FIGS. 2 6 will not be described herein. The parts of the cold starting device described above with reference to FIGS. 2 6 which correspond to the parts of the cold starting device described above with reference to FIG. 1 will be apparent to the reader from the foregoing description.

When the engine is crankedfor starting suction exerted by the engine causes petrol to be drawn into the through passage 51 through the

orifices

55 and 58.

When the engine begins to run under its own power and the

valve members

70 and 91 begin to close or open respectively, the supply of petrol via the

orifices

55 and 58 stops, and a mixture of air, which is drawn from the through passage 51 into the passage 57 via the orifice 58, with a metered quantity of fuel drawn through the fuel metering orifice 56 is drawn into the through passage 51 via the two

orifices

59 and 60.

It is desirable for the arcuate length of the

notch

35 or 79 to be decreased as engine temperature increases and vice versa. A modified form of primary and floating levers for mounting on the primary spindle 71, which in combination with a third lever results in such a variation in the arcuate length of the notch being achieved will be described now by way of example with reference to FIG. 7.

The modified primary lever 96 is fixed to the end of the spindle 71 remote from the through passage 51 and has a laterally extending finger 97. Two angularly spaced

tabs

98 and 99 project from the periphery of the lever 96 towards the respective throttle valve member 70 and are normal to the plane of the lever 96. The primary lever 96 also carries a resilient finger 100. The

fingers

97 and 100 extend on opposite sides of the post 94 carried by the secondary throttle lever 93 and cooperate therewith in a manner similar to the

fingers

83 and 95 in the embodiment described above with reference to FIGS. 2 6. The screw 101 serving as an adjustable throttle stop for the primary throttle.

The tab 98 depends into the notch 102 which is defined between the floating lever 103 and a third lever 104. The third lever 104 has a slot 105 at one end and is pinned at its other end 106 to the body. The floating lever 103 has one upstanding post 107 which is engaged within the slot 105, as well as another post 108 which follows the profile of the cam 84. It will be apparent that relative movement between the floating lever 103 and the third lever 104 occurs, with rotary movement of the spindle 71. The arcuate length of the notch 102 defined between the two

levers

103 and 104 varies with such relative movement between the levers 103' and 104, and the arrangement is such that the arcuate length of the notch 102 defined is reduced with closing movement of the primary throttle valve member 70.

Various other modifications of the embodiments described above may be incorporated without departing from the scope of this invention. For example, the

lever

32 or 76 may be operated manually instead of automatically by the temperature sensitive device. There need be no more than one fuel supply orifice for delivery of fuel into the auxiliary air supply passage, which would be one of the pair of

orifices

23 and 24, or 59 and 60. If the

orifice

250 or 62 is omitted, the

bore

21 or 57 would be closed at its lower end and the

screw

251 or 61 would be omitted. As an alternative to the adjustable stop for the primary throttle afforded by the screw 350, a screw in the body 50 may be arranged to cooperate with the primary lever 77 to serve the same purpose.

I claim:

1. A cold starting device for an internal combustion engine, the cold starting device comprising a housing enclosing an auxiliary air supply passage, first and second throttle valve members disposed in the auxiliary air supply passage with the said second throttle valve upstream of the first throttle valve, resilient means for biasing said first throttle valve member towards the open position and the second throttle valve member towards the closed position, said first throttle valve member being arranged to be moved against the action of said resilient biasing means by air flowing past it to the engine into a position in which it restricts or prevents the flow of air past it to the engine and the second throttle valve member being arranged so as to tend to be moved against the action of said resilient biasing means to the open position by air flowing past it to the engine, at least one fuel supply orifice which opens into the portion of the auxiliary air supply passage which extends between the closed positions of said two throttle valve members whereby fuel can be drawn therethrough into said portion of the air supply passage by engine suction when said first throttle valve member is in the open position, and thermostatically operable control means for limiting movement of the two throttle valve members in the direction opposite to that in which they are biased by the resilient biasing means in accordance with engine temperature, the degree of movement of the two throttle valve members permitted by the thermostatically operable control means being increased as the engine temperature increases, said first throttle valve member being in the open position and said second throttle valve member being in the closed position at the commencement of engine starting and during the cranking period, and said first throttle valve member begins to close progressively and said other throttle valve member begins to open progressively when the engine commences to rununder its own power, the progressive closing of said first throttle valve member and the progressive opening of said second throttle valve member continuing until the engine is running normally whereupon the supply of fuel into said portion of the auxiliary air supply passage ceases.

2. The cold starting device of claim 1 wherein said first throttle valve member is mounted on a spindle and a lever is mounted pivotally on that spindle, the said lever being coupled to the thermostatically operable control means so that there is a lost motion connection between the lever and said one throttle valve member which allows limited movement of said first throttle valve member relative to the lever in the closing direction caused by air flow in the auxiliary air supply passage due to engine suction.

3. The cold starting device of claim 1 wherein said first throttle valve member is mounted on one spindle, said second throttle valve member is mounted on another spindle and a lever fixed to said first spindle has a radially extending finger which is adapted to strike an element fixed to the other spindle during opening movement of said first throttle valve member so as to close said second throttle valve member with opening of said first throttle valve member.

4. A cold starting device as claimed in claim 1, wherein the throttle valves have spindles and a lever is mounted pivotally on the spindle of said first throttle valve member and is coupled to a setting means, said first throttle member being connected to the lever by means of a lost motion connection which allows limited movement of said first throttle valve member relative to the lever in the closing direction caused by air flow in the auxiliary air supply passage due to engine suction.

5. A cold starting device as claimed in claim 1, including two said fuel supply orifices through which a fuel/air mixture is arranged to be fed into the portion of the auxiliary air supply passage between the closed positions of said two throttle valve members said two fuel supply orifices being located adjacent to said first throttle valve member.

6. A cold starting device as claimed in claim 5, wherein there is a said fuel supply orifice positioned adjacent to said second throttle valve member and arranged so that fuel can be drawn therethrough into the auxiliary air supply passage only when said second throttle valve member is in the closed position.

7. A cold starting device as claimed in claim 1, including a further fuel supply orifice which opens into said auxiliary air supply passage downstream of the closed position of said first throttle valve member and adjustment means are provided to vary the crosssectional area of said further fuel supply orifice through which an air/fuel mixture can be supplied to meet at least part of the engine idling requirements.

8. A cold starting device as claimed in claim 1, wherein the two throttle valve members are coupled together mechanically so as to ensure that said first throttle valve member is in the closed position when said second throttle valve member is in the open position and vice versa.

9. A cold starting device as claimed in claim 3, wherein the lever also carries a resilient finger which is arranged to engage said element during closing movement of said first throttle valve member so as to ensure that said second throttle valve member is opened with closure of said first throttle valve member.

10. A cold starting device as claimed in claim 4, wherein the lost motion connection between said lever and said first throttle valve member comprises the engagement of a post carried by one of said lever and another lever, which is fixed to the spindle of said first throttle valve member, within an arcuate notch defined by the other of the two levers.

11. A cold starting device as claimed in claim 10, wherein the arcuate length of the arcuate notch is decreased as engine temperature increases and vice versa.

12. A cold starting device as claimed in claim 11, wherein the arcuate notch is defined between the lever which is mounted pivotally on the spindle of said first throttle valve member and a third lever.

13. A cold starting device as claimed in claim 12, wherein the third lever has a slot at one end which is mounted pivotally on the spindle of said first throttle valve member, the other being pinned to the body of the device.

14. An apparatus responsive to engine temperature for feeding a fuel-air mixture to an intake manifold of an internal combustion engine comprising a housing adapted to be fastened to the said manifold and having a bore therethrough which is in fluid flow connection with the manifold, first and second throttle valves pivotally disposed in spaced relationship in the bore with the first valve nearest the said manifold, means for biasing said first throttle valve towards an open position, means responsive to movement of the first throttle valve for moving the second throttle valve towards an open position as the first throttle valve moves towards its closed position, said first throttle valve being disposed to be moved towards its closed position by air flow through the bore and said second throttle valve being disposed to be moved towards its open position by air flow through the bore, means responsive to the temperature of the engine for opposing movement of the first throttle valve away from its open position, said temperature reponsive means being adapted to require decreasingly less force for movement of the first throttle valve as the temperature of the engine increases,

and means for introducing fuel into the bore between the two throttle valves.

15. The apparatus of claim 14 wherein the two throttle valves have spindles pivotally secured to the housing and a lever couples the two spindles together for simultaneous pivoting thereof.

Claims

1. A cold starting device for an internal combustion engine, the cold starting device comprising a housing enclosing an auxiliary air supply passage, first and second throttle valve members disposed in the auxiliary air supply passage with the said second throttle valve upstream of the first throttle valve, resilient means for biasing said first throttle valve member towards the open position and the second throttle valve member towards the closed position, said first throttle valve member being arranged to be moved against the action of said resilient biasing means by air flowing past it to the engine into a position in which it restricts or prevents the flow of air past it to the engine and the second throttle valve member being arranged so as to tend to be moved against the action of said resilient biasing means to the open position by air flowing past it to the engine, at least one fuel supply orifice which opens into the portion of the auxiliary air supply passage which extends between the closed positions of said two throttle valve members whereby fuel can be drawn therethrough into said portion of the air supply passage by engine suction when said first throttle valve member is in the open position, and thermostatically operable control means for limiting movement of the two throttle valve members in the direction opposite to that in which they are biased by the resilient biasing means in accordance with engine temperature, the degree of movement of the two throttle valve members permitted by the thermostatically operable control means being increased as the engine temperature increases, said first throttle valve member being in the open position and said second throttle valve member being in the closed position at the commencement of engine starting and during the cranking period, and said first throttle valve member begins to close progressively and said other throttle valve member begins to open progressively when the engine commences to run under its own power, the progressive closing of said first throttle valve member and the progressive opening of said second throttle valve member continuing until the engine is running normally whereupon the supply of fuel into said portion of the auxiliary air supply passage ceases.

7. A cold starting device as claimed in claim 1, including a further fuel supply orifice which opens into said auxiliary air supply passage downstream of the closed position of said first throttle valve member and adjustment means are provided to vary the cross-sectional area of said further fuel supply orifice through which an air/fuel mixture can be supplied to meet at least part of the engine idling requirements.

14. An apparatus responsive to engine temperature for feeding a fuel-air mixture to an intake manifold of an internal combustion engine comprising a housing adapted to be fastened to the said manifold and having a bore therethrough which is in fluid flow connection with the manifold, first and second throttle valves pivotally disposed in spaced relationship in the bore with the first valve nearest the said manifold, means for biasing said first throttle valve towards an open position, means responsive to movement of the first throttle valve for moving the second throttle valve towards an open position as the first thrOttle valve moves towards its closed position, said first throttle valve being disposed to be moved towards its closed position by air flow through the bore and said second throttle valve being disposed to be moved towards its open position by air flow through the bore, means responsive to the temperature of the engine for opposing movement of the first throttle valve away from its open position, said temperature reponsive means being adapted to require decreasingly less force for movement of the first throttle valve as the temperature of the engine increases, and means for introducing fuel into the bore between the two throttle valves.