EP0304316A2 - A speed governed carburettor - Google Patents
A speed governed carburettor Download PDFInfo
- Publication number
- EP0304316A2 EP0304316A2 EP88307699A EP88307699A EP0304316A2 EP 0304316 A2 EP0304316 A2 EP 0304316A2 EP 88307699 A EP88307699 A EP 88307699A EP 88307699 A EP88307699 A EP 88307699A EP 0304316 A2 EP0304316 A2 EP 0304316A2
- Authority
- EP
- European Patent Office
- Prior art keywords
- engine
- governed
- carburettor
- speed
- pneumatic
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
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Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D9/00—Controlling engines by throttling air or fuel-and-air induction conduits or exhaust conduits
- F02D9/02—Controlling engines by throttling air or fuel-and-air induction conduits or exhaust conduits concerning induction conduits
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D11/00—Arrangements for, or adaptations to, non-automatic engine control initiation means, e.g. operator initiated
- F02D11/06—Arrangements for, or adaptations to, non-automatic engine control initiation means, e.g. operator initiated characterised by non-mechanical control linkages, e.g. fluid control linkages or by control linkages with power drive or assistance
- F02D11/08—Arrangements for, or adaptations to, non-automatic engine control initiation means, e.g. operator initiated characterised by non-mechanical control linkages, e.g. fluid control linkages or by control linkages with power drive or assistance of the pneumatic type
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D9/00—Controlling engines by throttling air or fuel-and-air induction conduits or exhaust conduits
- F02D9/02—Controlling engines by throttling air or fuel-and-air induction conduits or exhaust conduits concerning induction conduits
- F02D2009/0201—Arrangements; Control features; Details thereof
- F02D2009/0215—Pneumatic governor
Definitions
- a check valve (not shown) may be incorporated within the supply line 25 to eliminate at least some of the cyclic fluctuations in pressure derived from the intake manifold 15.
- the carburettor of this invention will be found to have most merit when applied to small I.C. engines such as used with lawn mowers, marine craft, portable power tools, and the like. Adjustment to the governed speed is preferably effected through effecting a change in tension of the upper spring 24 within the carburettor 10. It is now common practice on engines for the above purposes to provide only two speed conditions i.e. slow speed (or idling) and operating speed. Any one of the many presently available controls for effecting the change in tension may be incorporated.
- Figs 3 and 4 show other conditions of the governed carburettor 10 firstly where the engine has reached its governed speed and is unloaded and secondly where the engine speed is falling from its governed speed and is unloaded. From the latter condition any further decrease in speed resulting from closing movement of the valve 16 will cause the diaphragm 28 of the device 26 to move downwardly and open the valve 31 thereby effecting consequential opening of the poppet valve 16 in the carburettor 10.
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Supplying Secondary Fuel Or The Like To Fuel, Air Or Fuel-Air Mixtures (AREA)
- Lubrication Details And Ventilation Of Internal Combustion Engines (AREA)
Abstract
A carburettor (10) with inbuilt governor for speed control of an engine which comprises a throttle valve (16) actuated by a diaphragm (20) responding via a fluid line (25) to air pressure varying with engine speed, and also comprising a device (26) responding to air pressure varying with engine speed and connected in a duct (27) serving to vent said fluid line, said device including valving means (31) to control the degree of venting of said fluid line depending upon the response of said device to air pressure changes.
Description
- This invention relates to engine-speed governed carburettors, and especially those for incorporation upon engines required to maintain speed under changing load.
- Various forms of governors have been proposed for this purpose, such as centrifugal systems and flag or diaphragm pneumatic systems. These systems sometimes utilise exposed linkages, and invariably rely upon an initial drop in engine speed with increased load and, therefore, have a less than instantaneous response. Furthermore, the known governors do not allow for varying fuel mixture, altitude, barometric pressure, temperature of the engine, carbon build-up, or eventual engine wear.
- It is the object of the invention to provide a carburettor with an engine-speed governor which is of improved form.
- In accordance with the invention there is provided an engine-speed governed carburettor for an engine comprising a housing defining a through passage for the supply of a working fluid to an engine, a movable throttle valve within said passage, a first pneumatic-responsive device connected to said throttle valve, a supply line connecting said device to a pneumatic source, means for venting to atmosphere said supply line, and a second pneumatic-responsive device operating in response to the speed of said engine to determine the degree of venting by said venting means so as to effect closing movement of said throttle valve with increasing speed of said engine.
- The invention will be described more precisely with reference to the accompanying drawings in which:
- Fig. 1 diagrammatically depicts a carburettor incorporating an engine-speed governor according to this invention;
- Figs 2(A) and (B) depict a dynamic condition of the carburettor in a condition where the associated engine is fully loaded and rotating at its governed speed;
- Figs 3(A) and (B) are similar views with the engine at its governed speed and in an unloaded condition; and
- Figs 4(A) and (B) relate to a dynamic condition where the engine is unloaded and decelerating from its governed speed.
- The
carburettor 10 shown in Fig. 1, consists of anair intake chamber 11 having aventuri 12 where fuel is induced or injected via apassage 13 which being mixed with the air flow through theventuri 12 produces an induced working fluid in thethroat 14 for delivery to theintake manifold 15 of an I.C. engine (not shown). Athrottle valve 16 is axially movable along thethroat 14 to control the flow of working fluid to themanifold 15. Thethrottle valve 16 may be of any kind, such as a poppet valve as shown, or a butterfly valve. Thestem 17 of thepoppet valve 16 is supported in abearing 18 and is connected at itsdistal end 19 to aflexible diaphragm 20 which with an enclosingcasing 21 defines anair chamber 22. Bias springs 23 and 24 of predetermined rate act upon thediaphragm 20 to maintain it in equilibrium. Avacuum line 25 connects thechamber 22 with theintake manifold 15 to create sub-atmospheric pressure within thechamber 22 during running of the engine serviced by thecarburettor 10. Alternatively, the inlet 25A to theline 25 may be connected to any source of pneumatic pressure available on the engine, or accessory thereto. When connected as shown to the intake manifold 15 the air pressure at themanifold 15 fluctuates cyclically with engine operation, but within reasonable tolerances for adequate functioning of the governor. One source of relatively non-cyclically fluctuating pneumatic pressure is the crankcase of a 2-stroke engine. - As shown in Fig. 1, it will be noted that the
chamber 22 is sealed and reduced pressure therein permits thediaphragm 20 to move upwardly to close the poppet valve upon theventuri 12. As is conventional, idling passages may be provided around thevalve 16 for sufficient fuel intake to maintain the engine at idling speed. For simplicity of explanation thecarburettor 10 is depicted purely diagrammatically in Fig. 1. The carburettor housing may be of a variety of forms without departing from the spirit of the invention, and may or may not enclose thecasing 21. If necessary a check valve (not shown) may be incorporated within thesupply line 25 to eliminate at least some of the cyclic fluctuations in pressure derived from theintake manifold 15. - In the form of governor so far described increasing engine speed will create reduced pressure within the
supply line 25 which will result in a closing movement of thevalve 16. However, the response is quite slow and excessive swings in engine speed occur about the desired preset governed speed. It has been found that this slow response can be avoided by the use of a supplementarypneumatic device 26 connected byfluid line 27 to thesupply line 25. Thedevice 26 includes adiaphragm 28 supported betweenhelical springs poppet valve 31 co-operating with avalve seat 32. Thedevice 26 has aninternal chamber 33 connected byorifice 34 to atmosphere. Thus, it will be seen that depending upon the degree to which thevalve 31 is removed from itsseat 32 thefluid line 27, and therefore thesupply line 25, will be more or less vented to atmosphere through theorifice 34. Anupper chamber 35 above thediaphragm 28 is connected byairline 36 to a position of sub-atmospheric pressure in the cowling 37 housing theengine cooling fan 38 in say a small air-cooled engine (not shown). Therefore, the faster the rotation of thefan 38, the lower will be the air pressure in theline 36 to effect greater closing of thevalve 31 upon itsseat 32. In such a condition less venting of thesupply line 25 occurs so that thediaphragm 20 in thecarburettor 10 will be caused to rise and close its associatedvalve 16. With rising air pressure in theline 36, resulting from slowing of the engine, thepoppet valve 16 in thecarburettor 10 will move in an opening direction. - The carburettor of this invention will be found to have most merit when applied to small I.C. engines such as used with lawn mowers, marine craft, portable power tools, and the like. Adjustment to the governed speed is preferably effected through effecting a change in tension of the
upper spring 24 within thecarburettor 10. It is now common practice on engines for the above purposes to provide only two speed conditions i.e. slow speed (or idling) and operating speed. Any one of the many presently available controls for effecting the change in tension may be incorporated. - The condition of the
carburettor 10 as depicted in Fig. 1 is consistent with the engine rotating at the governed speed without load. This condition corresponds to low speed for the engine. In operation thepoppet valve 16 is continuously fluctuating about a position consistent with the governed speed, so that fractional changes to the throttle position occur in order to maintain essentially constant speed of the engine. As load on the engine increases, the engine speed will tend to slow which will effect opening of thevalve 31 in thedevice 26 having the effect of greater venting of thesupply line 25 whereby thediaphragm 20 moves towards equilibrium and opens thepoppet valve 16 of thecarburettor 10 to increase engine speed. Thevalve 16 will finally stabilise at an increased open condition capable of restoring engine speed at the selected level with the increased load. The supplementarypneumatic device 26 may, or may not, be integrally formed with the housing of thecarburettor 10. - The condition shown by Fig. 2 relates to a fully loaded state of the engine which is travelling at its governed speed. The
valve 31 of thedevice 26 is fully open so that thediaphragm 20 of thecarburettor 10 is allowed to move under the tension ofspring 24 to fully open thepoppet valve 16. Should additional load be imposed upon the engine no response will occur in thediaphragm 20 nor thevalve 16. Each of the graphs of Fig. 2(B), 3(B) and 4(B) plot resulting torque against engine revolutions with rising and falling of torque, as indicated by the arrows X, to meet changing loads. - Figs 3 and 4 show other conditions of the governed
carburettor 10 firstly where the engine has reached its governed speed and is unloaded and secondly where the engine speed is falling from its governed speed and is unloaded. From the latter condition any further decrease in speed resulting from closing movement of thevalve 16 will cause thediaphragm 28 of thedevice 26 to move downwardly and open thevalve 31 thereby effecting consequential opening of thepoppet valve 16 in thecarburettor 10. - Whereas the
supply line 25 has been described as being connected to a source of sub-atmospheric pressure, the invention is not limited thereto. The use of super-atmospheric pressure in theline 25, as well as in thesupply line 36 to thedevice 26, will achieve similar operation of thecarburettor 10 as described above, providing that a modified connection between thediaphragms valve - The modification to the valves need only be confined to the linkage connection thereto from their associated
diaphragms poppet valves venturi 12 and theseat 32. - Whereas a preferred embodiment has been described in the foregoing passages it should be understood that other forms, modifications and refinements are feasible within the scope of this invention.
Claims (10)
1. An engine-speed governed carburettor for an engine comprising a housing (12) defining a through passage (14) for the supply of a working fluid to an engine, a movable throttle valve (16) within said passage, a first pneumatic-responsive device (20) connected to said throttle valve, a supply line (25) connecting said device to a pneumatic source (25A), means (27) for venting to atmosphere said supply line, and a second pneumatic-responsive device (26) operating in response to the speed of said engine to determine the degree of venting by said venting means so as to effect closing movement of said throttle valve with increasing speed of said engine.
2. A governed carburettor according to claim 1, wherein said pneumatic source is a source of sub-atmospheric pressure.
3. A governed carburettor according to claim 1 or 2, wherein said pneumatic source is the interior of the intake manifold (15) of said engine.
4. A governed carburettor according to any one of the preceding claims, wherein said engine is a 2-stroke engine and said pneumatic source is the interior of the crankcase of said engine.
5. A governed carburettor according to claim 1, wherein said pneumatic source is a source of super-atmospheric pressure.
6. A governed carburettor according to any one of the preceding claims, comprising also a check valve positioned with said supply line to reduce cyclic fluctuations in the pressure derived from said pneumatic source.
7. A governed carburettor according to any one of the preceding claims, wherein said throttle valve is a poppet valve (16), and said first pneumatic-responsive device comprises a diaphragm (20) connected on one side with the poppet valve and exposed upon its opposite side to pressure from said pneumatic source.
8. A governed carburettor according to any one of the preceding claims, wherein said second pneumatic-responsive device comprises a diaphragm (28) connected on one side to valving means (31 and 32) and exposed on its opposite side to a source of air, the pressure of which varies with the speed of the engine, and said venting means is a fluid line (27) connecting said supply line to atmosphere via said valving means whereby venting of said supply line is reduced with increasing speed of said engine.
9. A governed carburettor according to claim 8, wherein said valving means is a poppet valve (31) and associated valve seat (32), and the pressure of said source of air is reduced with increasing speed of said engine.
10. An engine-speed governed carburettor substantially as hereinbefore described with reference to the accompanying drawings.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AU386687 | 1987-08-20 | ||
AU3866/87 | 1987-08-20 |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0304316A2 true EP0304316A2 (en) | 1989-02-22 |
EP0304316A3 EP0304316A3 (en) | 1989-12-20 |
Family
ID=3694338
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP88307699A Withdrawn EP0304316A3 (en) | 1987-08-20 | 1988-08-19 | A speed governed carburettor |
Country Status (1)
Country | Link |
---|---|
EP (1) | EP0304316A3 (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP1813141A3 (en) * | 2006-01-26 | 2009-07-29 | HONDA MOTOR CO., Ltd. | Engine-driven work machine |
Citations (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
NL270564A (en) * | ||||
US2424836A (en) * | 1942-06-08 | 1947-07-29 | Mallory Marion | Engine governor |
DE887129C (en) * | 1940-10-19 | 1953-08-20 | Daimler Benz Ag | Device for limiting the speed of motor vehicle engines |
US3068849A (en) * | 1959-05-22 | 1962-12-18 | Robert H Thorner | Speed regulating mechanism |
US3153325A (en) * | 1960-12-07 | 1964-10-20 | Robert H Thorner | Vehicle speed regulating device |
DE2346896A1 (en) * | 1972-09-20 | 1974-04-04 | Victa Ltd | CARBURETOR WITH ADJUSTABLE THROTTLE |
FR2561312A1 (en) * | 1984-02-21 | 1985-09-20 | Stihl Andreas | TWO-STROKE ENGINE |
-
1988
- 1988-08-19 EP EP88307699A patent/EP0304316A3/en not_active Withdrawn
Patent Citations (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
NL270564A (en) * | ||||
DE887129C (en) * | 1940-10-19 | 1953-08-20 | Daimler Benz Ag | Device for limiting the speed of motor vehicle engines |
US2424836A (en) * | 1942-06-08 | 1947-07-29 | Mallory Marion | Engine governor |
US3068849A (en) * | 1959-05-22 | 1962-12-18 | Robert H Thorner | Speed regulating mechanism |
US3153325A (en) * | 1960-12-07 | 1964-10-20 | Robert H Thorner | Vehicle speed regulating device |
DE2346896A1 (en) * | 1972-09-20 | 1974-04-04 | Victa Ltd | CARBURETOR WITH ADJUSTABLE THROTTLE |
FR2561312A1 (en) * | 1984-02-21 | 1985-09-20 | Stihl Andreas | TWO-STROKE ENGINE |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP1813141A3 (en) * | 2006-01-26 | 2009-07-29 | HONDA MOTOR CO., Ltd. | Engine-driven work machine |
US7744503B2 (en) | 2006-01-26 | 2010-06-29 | Honda Motor Co., Ltd. | Enigne-driven work machine |
Also Published As
Publication number | Publication date |
---|---|
EP0304316A3 (en) | 1989-12-20 |
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Effective date: 19900621 |