US3835831A

US3835831A - Automatic cold starting devices for internal combustion engines

Info

Publication number: US3835831A
Application number: US00243312A
Authority: US
Inventors: G Ross
Original assignee: Zenith Carburetter Co Ltd
Current assignee: Zenith Carburetter Co Ltd
Priority date: 1971-04-15
Filing date: 1972-04-12
Publication date: 1974-09-17
Anticipated expiration: 1991-09-17
Also published as: IT958743B; DE2218048A1; GB1364052A; JPS5442046B1; DE2218048C2; CA960533A; FR2136465A5; NL7205100A; SE373186B

Abstract

An automatic cold starting device for an internal combustion engine comprises, in an auxiliary passage leading into the main induction passage through which fuel/air mixture is normally supplied to the engine downstream of the main throttle valve, a second throttle valve and a fuel supply source controlled by a fuel valve, the second throttle valve and fuel valve being fully open when the engine is cold, being initially partly closed by suction in the auxiliary passage when the engine starts, and being then controlled for progressive further closing by a temperature sensitive device responsive to engine temperature.

Description

United States Patent [191 Ross [ AUTOMATIC COLD STARTING DEVICES FOR INTERNAL COMBUSTION ENGINES [75] Inventor: Gray Ernest Donald Ross,

Wiggington, England [73] Assignee: The Zenith Carburetter Company Limited, Middlesex, England [22] Filed: Apr. 12, 1972 [21] Appl. No.: 243,312

[30] Foreign Application Priority Data Apr. 15, 1971 Great Britain 9459/71 [52] US. Cl. 123/179 G, 123/180 R, 123/180 T [51] Int. Cl. F02m 1/04, F02m 1/10 [58] Field of Search 123/179 G, 180 R, 180 T;

[ Sept. 17, 1974 Primary Examiner-Charles J. Myhre Assistant ExaminerW. Rutledge, Jr. Attorney, Agent, or Firm-Clelle W. Upchurch [5 7 ABSTRACT An automatic cold starting device for an internal combustion engine comprises, in an auxiliary passage leading into the main induction passage through which fuel/air mixture is normally supplied to the engine downstream of the main throttle valve, a second throttle valve and a fuel supply source controlled by a fuel valve, the second throttle valve and fuel valve being fully open when the engine is cold, being initially partly closed by suction in the auxiliary passage when the engine starts, and being then controlled for progressive further closing by a temperature sensitive device responsive to engine temperature.

AUTOMATIC COLD STARTING DEVICES FOR INTERNAL COMBUSTION ENGINES This invention relates to automatic cold starting devices for internal combustion engines in which 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 with increase of engine temperature until normal running temperature is reached.

It is the object of the invention to provide an improved automatic cold starting device.

According to one aspect of this invention there is provided an automatic cold starting device for an internal combustion engine having an induction passage through which fuel/air mixture is normally supplied to the engine and a main throttle valve in the said induction passage to control the flow of fuel/air mixture therein during normal operation of the engine, said automatic cold starting device comprising, in an auxiliary passage opening at its outlet end into said induction passage downstream of the main throttle valve and being connected to a source of air at its inlet end, a second throttle valve, said second throttle valve being so arranged that engine suction acting in said auxiliary passage tends to urge it in the closing direction, a fuel supply source arranged to supply a metered quantity of fuel to said auxiliary passage, and a thermostatically controlled mechanism operative to limit the closing of said second throttle valve so that, once the engine has started to run, both the air flow in said auxiliary passage, and the supply of fuel thereto, are progressively decreased with increase of temperature.

Preferably the automatic cold starting device includes a fuel flow control valve to control the supply of fuel from said source to said auxiliary passage. The thermostatically controlled mechanism may be operative to operate the fuel flow control valve.

According to another aspect of this invention there is provided an automatic cold starting device for an internal combustion engine having an induction passage through which fuel/air mixture is normally supplied to the engine and a main throttle valve in the said induction passage to control the flow of fuel/air mixture therein during normal operation of the engine, said automatic cold starting device comprising, in an auxiliary passage opening at its outlet end into said induction passage downstream of the main throttle valve and being connected to a source of air at its inlet end, a second throttle valve, said second throttle valve being so arranged that engine suction acting in said auxiliary passage tends to urge it in the closing direction, a fuel supply source connected to said auxiliary passage, a fuel flow control valve to control the supply of fuel from said source, and a thermostatically controlled mechanism operative to limit the closing of said second throttle valve and to operate the fuel flow control valve so that once the engine has started to run, both the air flow in said auxiliary passage, and the supply of fuel thereto, are progressively decreased with increase of temperature.

The inlet end of the auxiliary passage may be connected to the main induction passage upstream of the main throttle valve.

Preferably, the second throttle valve is mounted on a spindle, and the thermostatically controlled mechanism comprises an arm fixed on said spindle, one lever mounted pivotally on said spindle, and a biassing spring acting between the fixed arm and said one lever, relative angular movement between the fixed arm and said one lever being limited, and the position of said one lever being governed by a thermo-sensitive member which is responsive to the temperature of an engine on which the starting device is mounted, the thermosensitive device acting, with increase of temperature, to rotate said one lever in a direction which allows movement of the second throttle valve in the closing direction, the arrangement being such that, once the engine starts to run, the second throttle valve is moved relative to said one lever in the closing direction by the action of engine suction, the amount of such closing movement of the second throttle valve being limited to the permitted angular movement of said fixed arm relative to said one lever, progressive movement of the second throttle valve in the closing direction being governed thereafter by the action of said thermo-sensitive member on said one lever. Said one lever may carry a cam follower, and a cam, which is engaged by the cam follower may be connected operatively to the thermosensitive member which acts, with increase of temperature, to rotate the cam in a direction such that the resulting movement of the follower rotates said one lever in the direction to close said second throttle member. Said one lever may be held in contact with the cam by a tension spring acting to urge said one lever in a direction to open the second throttle valve. The second throttle valve spindle may be coupled to the fuel flow control valve so that movement of the second throttle valve in the closing direction is accompanied by a corresponding decrease in the supply of fuel to the auxiliary passage. Said second throttle valve spindle may be coupled to the fuel flow control valve by another lever which is mounted pivotally on said spindle, relative angular movement between the other lever and the fixed arm being limited and another biassing spring acting between said other lever and the fixed arm and causing said other lever to follow movement of the second throttle valve spindle until the fuel flow control valve is closed.

The fuel flow control valve may comprise a profiled needle movable axially in an orifice to vary the effective area thereof, the said needle carrying a sealing member operative to close the said orifice at the end of the movement of said needle in the direction to reduce the effective area of the orifice.

One embodiment of the invention will now be described by way of example with reference to the accompanying drawing, the single FIGURE of which shows, in diagrammatic form, a carburetor having an auxiliary passage around the main throttle valve and a second throttle valve in the said auxiliary passage, together with a mechanism for controlling said second throttle valve and for controlling a fuel valve for admitting fuel to the said auxiliary passage. In the drawing, the fuel valve is shown disconnected from the mecha nism but the connection is indicated by a dotted line, the fuel supply connection between the fuel valve and the auxiliary throttle valve is shown by a chain dotted line, and the second throttle valve is shown twice for convenience, once to indicate its position in the auxiliary passage, and a second time to show its connection to the mechanism. The mechanism would, of course, be contained in a suitable housing, but it is not deemed necessary to illustrate this, since the design of the housing would be a simple matter for any competent engineer.

Referring to the drawing, the body of a carburetor of the fixed choke type is shown at 10, the main induction passage 11 therein being adapted for connection to the atmosphere through a conventional air cleaner (not shown) at its end 12, and for connection to the inlet manifold of an internal combustion engine (not shown) at its end 13. A venturi throat is formed at 14 in the induction passage 11, and a main fuel supply passage 15 is provided to supply fuel from a suitable source, such as a float chamber, to the supply passage 15.

A main throttle valve 16 of the butterfly type is mounted in the induction passage 11 down-stream of the throat 14, the throttle valve being provided with a conventional driver operated control mechanism (not shown) and having its closing limited by an adjustable stop 17.

An auxiliary passage 18 in the carburetor body opens at one end, at 19, into the main induction passage 11 upstream of the venturi throat l4 and at the other end, 21, into the said main induction passage downstream of the main throttle valve 16. A venturi throat 22 in the passage 18 has opening thereinto a fuel supply passage 23, and a second throttle valve 24 is mounted in the said auxiliary passage 18 downstream of the throat 22, the throttle valve 24 being fixed on a spindle 25 which is offset from the center of the said throttle valve 24 so as to have its axis along a chord thereof, the arrangement being such that air flow towards the engine cylinders in the passage 18 tends to urge the said throttle valve 24 towards a closed position. The spindle 25 is mounted in suitable bearings (not shown) and has fixed to a portion of it which projects through the wall of the passage 18, an arm 26 which carries two posts 27 and 28 projecting on opposite sides thereof, parallel to the spindle 25 and extending respectively into notches 29, 31 one in each of two levers 32, 33 mounted to turn on the spindle 25, the notches 29 and 31 both being wider than the posts 27 and 28, to allow relative angular movement of both levers 32 and 33 with respect to the fixed arm 26. Torsion springs 34 and 35 acting respectively between the lever 32 and the fixed arm and between the lever 33 and the fixed arm urge both levers in the same rotational direction relative to the auxiliary throttle valve 24.

The fuel supply passage 23 opening into the auxiliary passage is controlled by a fuel flow control valve 36 comprising a tubular body 37 in which is slidable a plunger 38 carrying a profiled needle 39 movable axially in an orifice 41 defined by a restriction of the bore of the tubular body 37, the plunger 38 also carrying, at the larger-diameter end of the profiled needle 39, a sealing ring 42 adapted to close the orifice 41.

A projection 43 on the lever 32 engages a lateral notch 44 in the valve plunger 38 so that angular movement of the lever 32 moves the plunger 38 axially in the bore, movement of the lever in an angular direction corresponding to closing movement of the second throttle valve 24, which direction is indicated by the arrow A in the drawing, moving the plunger in a direction to progressively increase the restriction of the orifice 41 and ultimately to close that orifice. The lower end of the bore of the valve body 37 is open to a fuel supply reservoir indicated diagrammatically at 45, and a lateral port 46 in the said bore, above the orifice 41, is connected, as indicated by the chain-dotted line 47, to the fuel supply passage 23.

The torsion spring 34 acts in a direction such that the clearance provided by the difference in width between the post 27 and the notch 29 is on the side of the post which is ahead of the said post in the direction of closing of the second throttle valve and, after the fuel supply control valve is fully closed, the spindle 25 can continue to rotate in the closing direction of the second throttle valve, further loading the spring 34.

The other lever 33 carries a cam follower pin 48 engaging the profiled edge of a cam 49 the angular position of which is controlled by a bi-metallic coil 51 which is sensitive to change of temperature of the engine and with increase of temperature, rotates the cam 49 in a direction to turn the said lever 33 in the same direction as that, indicated by the arrow A, in which the spindle 25 rotates with closing movement of the second throttle valve 24. The cam 49 is, of course, rotatably mounted on a spindle, (not shown) the bi-metallic coil 51 being anchored at its inner end and engaging a post 52 on the cam 49 at its outer end.

The torsion spring 34 acting between the first lever 32 and the arm 26 urges that lever in such a direction that it tends to follow the closing movement of the second throttle valve 24 and cause simultaneous closing movement of the fuel supply orifice, and the torsion spring 35 acting between the other lever 33 and the said arm tends to urge the second throttle valve 24 towards its open position to the maximum degree of opening permitted by the cam.

The lever 33 is acted on by a tension spring 53 provided with a fixed anchorage at 54 and tending to urge the follower 48 aginst the profile of the cam 49. Thus the position of the lever 33 is at all times determined by the position of the cam 49. The torsion spring 35 urges the arm 26 and spindle 25 in the opposite angular direction to the arrow A, so that the said arm and spindle tend to move as far in that direction as is allowed by the clearance of the post 28 in the notch 31, thus positioning the second throttle valve 24 in the most widely open position allowed by the cam 49. This is assuming that there is no air flow in the auxiliary passage 18.

When an engine to which the cold starting device is fitted is cold, the bi-metallic coil holds the cam 49 in a position such that the second throttle valve 24 takes up its fully open position. The lever 32 being held by the associated post 27 on the arm 26, locates the plunger 38 in its corresponding position.

When the engine is cranked for starting the parts remain in these positions until the engine commences to run under its own power, when the air flow velocity increase in the auxiliary passage 18 acts to urge the second throttle valve 24 towards its closed position, the closing movement being limited by the angular extent of the notch 31 in the lever 33. The lever 32 follows the movement of the second throttle valve 24 and reduces the effective area of the fuel orifice 41. As the engine warms up, the cam 49 is rotated by the bi-metallic coil 51 to allow progressive further closing of the second throttle valve 24 and of the fuel orifice 41, until the sealing ring 42 on the profiled needle 39 closes the said fuel orifice and shuts off the auxiliary fuel supply. The second throttle valve 24, at this stage, is not fully closed, so that a greater flow of air is available than can take place through the main throttle valve 16, providing a fast idle condition. The cam 49 continues to be moved until a predetermined temperature is reached, the post 27 on the arm 26 which co-operates with the first lever 32 moving away from the side of the notch 29 in that lever with which it has been in engagement, until the throttle valve 24 is closed or brought to a position of minimum opening at which it remains for normal running.

It will be apparent that the rate of closing of the second throttle valve 24 in relation to temperature rise can be determined by the profile of the cam 49, and the rate of change of fuel supply can be determined by selection of the profile of the needle 39, so that the air and fuel supply can be independently determined. The initial reduction in auxiliary mixture supply due to air flow in the passage 18 when the engine commences to run can be determined by selecting the length of the notch 31 in the lever 33.

While the automatic cold starting device according to the invention has been shown and described as applied to a carburetor of the fixed choke type, it may also be used with carburetors of the constant depression type, a passage corresponding to the passage 18 shown in the drawing being provided, which passage leads from a position at which it receives air at substantially atmospheric pressure into the induction passage downstream of the main throttle valve. Alternatively the automatic cold starting device according to the invention may be used with carburetors of either the constant depression type or the fixed choke type, a passage corresponding to the passage 18 shown in the drawing being provided which leads from the induction passage between the throat and the main throttle valve into the induction passage downstream of the main throttle valve.

As an alternative to the bi-metallic coil 51 described above, other forms of thermo-sensitive member, such as a thermo-sensitive capsule, may be employed.

I claim:

1. In an internal combustion engine having an induction passage through which fuel/air mixture is normally supplied to the engine and a main throttle valve in the said induction passage to control the flow of fuel/air mixture therein during normal operation of the engine, an automatic cold starting device comprising, means defining an auxiliary passage opening at its outlet end into said induction passage downstream of the main throttle valve and being connected to a source of air at its inlet end, a second throttle valve, in said auxiliary passage, said second throttle valve being so arranged that engine suction acting in said auxiliary passage tends to urge it in the closing direction, a fuel supply source, a fuel flow control valve to control the supply of fuel from said source to said auxiliary passage, and a thermostatically controlled mechanism operative to operate the fuel flow control valve and to limit the closing of said second throttle valve so that, once the engine has started to run, both the air flow in said auxiliary passage, and the supply of fuel thereto, are progressively decreased with increase of temperature.

2. In an internal combustion engine having an induction passage through which fuel/air mixture is normally supplied to the engine and a main throttle valve in the said induction passage to control the flow of fuel/air mixture therein during normal operation of the engine, an automatic cold starting device comprising, means defining an auxiliary passage opening at its outlet end into said induction passage downstream of the main throttle valve and being connected to a source of air at its inlet end, a second throttle valve in said auxiliary passage, said second throttle valve being so arranged that engine suction acting in said auxiliary passage tends to urge it in the closing direction, a fuel supply source connected to said auxiliary passage, a fuel flow control valve to control the supply of fuel from said source, and a thermostatically controlled mechanism operative to limit the closing of said second throttle valve and to operate the fuel flow control valve, so that, once the engine has started to run, both the air flow in said auxiliary passage, and the supply of fuel thereto, are progressively decreased with increase of temperature.

3. An automatic cold starting device according to claim 2, wherein the inlet end of the auxiliary passage is connected to the main induction passage upstream of the main throttle valve.

4. In an internal combustion engine having an induction passage through which fuel/air mixture is normally supplied to the engine and a main throttle valve in the said induction passage to control the flow of fuel/air mixture therein during normal operation of the engine, an automatic cold starting device comprising, means defining an auxiliary passage opening at its outlet end into said induction passage downstream of the main throttle valve and being connected to a source of air at its inlet end, a second throttle valve in said auxiliary passage, said second throttle valve being mounted on a spindle, said second throttle valve being so arranged that engine suction acting in said auxiliary passage tends to urge it in the closing direction, a fuel supply source connected to said auxiliary passage, a fuel flow control valve to control the supply of fuel from said source, and a thermostatically controlled mechanism operative to limit the closing of said second throttle valve and to operate the fuel flow control valve, said thermostatically controlled mechanism comprises an arm fixed on said spindle, one lever mounted pivotally on said spindle, and a biassing spring acting between the fixed arm and said one lever, relative angular movement between the fixed arm and said one lever being limited, and the position of said one lever being governed by a thermo-sensitive member which is responsive to the temperature of an engine on which the starting device is mounted, the thermo-sensitive device acting with increase of temperature, to rotate said one lever in a direction which allows movement of the second throttle valve in the closing direction, the arrangement being such that, once the engine starts to run, the second throttle valve is moved relative to said one lever in the closing direction by the action of engine suction, the amount of such closing movement of the second throttle valve being limited to the permitted angular movement of said fixed arm relative to said one lever, progressive movement of the second throttle valve in the closing direction being governed thereafter by the action of said thermo-sensitive member on said one lever, said one lever carrying a cam follower, and a cam, which is engaged by the cam follower, being connected operatively to the thermo-sensitive member which acts, with increase of temperature to rotate the cam in a direction such that the resulting movement of the follower rotates said one lever in the direction to close said second throttle member.

5. An automatic cold starting device according to claim 4, wherein said one lever is held in contact with the cam by a tension spring acting to urge said one lever in a direction to open the second throttle valve.

6. An automatic cold starting device according to claim 4, wherein the spindle is coupled to the fuel flow control valve so that movement of the second throttle valve in the closing direction is accompanied by a cor responding decrease in the supply of fuel to the auxiliary passage.

7. An automatic cold starting device according to claim 6, wherein said spindle is coupled to the fuel flow control valve by another lever which is mounted pivotally on said spindle, relative angular movement between the other lever and the fixed arm being limited and another biassing spring acting between said other lever and the fixed arm and causing said other lever to follow movement of the spindle until the fuel flow control valve is closed.

8. An automatic cold starting device according to claim 2, wherein the fuel flow control valve comprises a profiled needle movable axially in an orifice to vary the effective area thereof, the said needle carrying a sealing member operative to close the said orifice at the end of the movement of said needle in the direction to reduce the effective area of the orifice.

9. In an internal combustion engine having an induction passage through which fuel/air mixture is normally supplied to the engine and a main throttle valve in the said induction passage to control the flow of fuel/air mixture therein during normal operation of the engine, an automatic cold starting device comprising, means defining an auxiliary passage opening at its outlet end into said induction passage downstream of the main throttle valve and being connected to a source of air at its inlet end, a second throttle valve, in said auxiliary passage said second throttle valve being so arranged that engine suction acting in said auxiliary passage tends to urge it in the closing direction, a fuel supply source arranged to supply metered quantities of fuel to said auxiliary passage, a thermostatically controlled mechanism operative to limit the closing of said second throttle valve, said thermostatically controlled mechanism comprises an arm fixed on a spindle, one lever mounted pivotally on said spindle, and a biassing spring acting between the fixed arm and said one lever, relative angular movement between the fixed arm and said one lever being limited, and the position of said one lever being governed by a thermo-sensitive member which is responsive to the temperature of an engine on which the starting device is mounted, the thermosensitive device acting with increase of temperature, to rotate said one lever in a direction which allows movement of the second throttle valve in the closing direction, the arrangement being such that, once the engine starts to run, the second throttle valve is moved relative to said one lever in the closing direction by the action of engine suction, the amount of such closing movement of the second throttle valve being limited to the permitted angular movement of said fixed arm relative to said one lever, progressive movement of the second throttle valve in the closing direction being governed thereafter by the action of said thermo-sensitive member on said one lever.

Claims

6. An automatic cold starting device according to claim 4, wherein the spindle is coupled to the fuel flow control valve so that movement of the second throttle valve in the closing direction is accompanied by a corresponding decrease in the supply of fuel to the auxiliary passage.

9. In an internal combustion engine having an induction passage through which fuel/air mixture is normally supplied to the engine and a main throttle valve in the said induction passage to control the flow of fuel/air mixture therein during normal operation of the engine, an automatic cold starting device comprising, means defining an auxiliary passage opening at its outlet end into said induction passage downstream of the main throttLe valve and being connected to a source of air at its inlet end, a second throttle valve, in said auxiliary passage said second throttle valve being so arranged that engine suction acting in said auxiliary passage tends to urge it in the closing direction, a fuel supply source arranged to supply metered quantities of fuel to said auxiliary passage, a thermostatically controlled mechanism operative to limit the closing of said second throttle valve, said thermostatically controlled mechanism comprises an arm fixed on a spindle, one lever mounted pivotally on said spindle, and a biassing spring acting between the fixed arm and said one lever, relative angular movement between the fixed arm and said one lever being limited, and the position of said one lever being governed by a thermo-sensitive member which is responsive to the temperature of an engine on which the starting device is mounted, the thermo-sensitive device acting with increase of temperature, to rotate said one lever in a direction which allows movement of the second throttle valve in the closing direction, the arrangement being such that, once the engine starts to run, the second throttle valve is moved relative to said one lever in the closing direction by the action of engine suction, the amount of such closing movement of the second throttle valve being limited to the permitted angular movement of said fixed arm relative to said one lever, progressive movement of the second throttle valve in the closing direction being governed thereafter by the action of said thermo-sensitive member on said one lever.