GB2106987A - Engine speed control of variable venturi carburettors - Google Patents
Engine speed control of variable venturi carburettors Download PDFInfo
- Publication number
- GB2106987A GB2106987A GB08129065A GB8129065A GB2106987A GB 2106987 A GB2106987 A GB 2106987A GB 08129065 A GB08129065 A GB 08129065A GB 8129065 A GB8129065 A GB 8129065A GB 2106987 A GB2106987 A GB 2106987A
- Authority
- GB
- United Kingdom
- Prior art keywords
- engine
- engine speed
- diaphragm
- venturi
- passage
- 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- Withdrawn
Links
Classifications
-
- 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
- F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
- F02M9/00—Carburettors having air or fuel-air mixture passage throttling valves other than of butterfly type; Carburettors having fuel-air mixing chambers of variable shape or position
- F02M9/10—Carburettors having air or fuel-air mixture passage throttling valves other than of butterfly type; Carburettors having fuel-air mixing chambers of variable shape or position having valves, or like controls, of elastic-wall type for controlling the passage, or for varying cross-sectional area, of fuel-air mixing chambers or of the entry passage
- F02M9/106—Pneumatic or hydraulic control
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Control Of The Air-Fuel Ratio Of Carburetors (AREA)
Abstract
An air bleed 17 which reduces the depression in a vacuum motor 10 positioning the venturi member 3 is operated by a stepping motor 20 controlled by a microprocessor 21 in response to an engine speed sensor 22. The microprocessor may be programmed to limit maximum engine speed and optimise acceleration. <IMAGE>
Description
SPECIFICATION
Engine speed control system
The present invention relates to engine speed control systems.
Our European Patent Specification No. 8499 discloses a carburettor of the variable venturi type in which a venturi member positioned in a passage for conducting air into an engine is movable across the passage to define a venturi therein. A metering needle movable with the venturi member co-operates with a fuel jet to control the flow of fuel into the passage. A control mechanism, in the form of a vacuum motor operable in response to variations in the engine intake pressure, is provided for varying the position of the venturi member in accordance with the load on the engine.
According to the present invention, there is provided an engine speed control system comprising a carburettor, having a passage for conducting air into the engine, a venturi member movable across the passage to define a venturi therein, a metering needle movable with the venturi member and cooperating with a fuel jet to control the flow of fuel into the passage, and a control mechanism for varying the position of the venturi member in the passage, in response to variations in engine load characterised in that the control mechanism also varies the position of the venturi member in response to engine speed.
By providing a control mechanism which positions the venturi member in accordance with the speed of the engine as well as with the load on the engine, it is possible to control the maximum speed and/or the rate of acceleration of the engine, thereby improving the fuel economy of the engine. The invention may also be used for otherwise controlling the performance of the engine, for example to reduce noise emissions.
Any suitable control mechanism may be used.
It is however convenient to utilise a vacuum motor having a movable diaphragm drivingly connected to the venturi member, means for transmitting to one side of the diaphragm variations in depression in the engine intake, and means for varying the pressure differential across the diaphragm in accordance with engine speed.
It is envisaged that the means for varying the pressure difference across the diaphragm may comprise an air bleed valve for reducing the depression applied to the one side of the diaphragm, and means for controlling the setting of the air bleed valve in accordance with engine speed. For example, the air bleed valve may comprise a needle valve operably by an electrical motor, and a microprocessor for controlling the electric motor in response to electrical control signals representative of engine speed.
A preferred embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawing which is a sketch of a control system in accordance with the invention.
Referring to the drawing, a carburettor 1 comprises a passage 2 for conducting air into an engine (not shown). A venturi member 3 mounted on a pivot shaft 4 is movable across the passage 2 to define a venturi 5 therein. A metering needle 6 is mounted on the venturi member 3 for movement therewith into and out of a fuel jet 7 so as to control the flow of fuel into the passage 2 induced by the pressure drop across the fuel jet 7 at the venturi 5. A throttle 8 is positioned in the passage 2 downstream from the venturi member 3.
A control mechanism for controlling the position of the venturi member 3 comprises a vacuum motor 10 of conventional construction having a housing across which a diaphragm 11 is secured. The diaphragm 11 is connected by a link 12 to a lever 1 3 which is in turn fixed to the pivot shaft 4 to which the venturi member 3 is fixed. A spring 14 acts on one side of the diaphragm 11 to bias the diaphragm 11 to the left as seen in the drawing, thereby moving the venturi member 3 across the passage 2 and closing the fuel jet 6.
A conduit 1 6 places the one side of the diaphragm in fluid communication with the inlet passage 2 downstream of the venturi and upstream from the throttle 8. An air bleed valve 17 places the conduit 1 6 in fluid communication with air at atmospheric pressure.
The bleed valve 1 7 comprises a needle 1 8 which may be moved into and out of a metering orifice 19 by means of an electrical stepping motor 20 which is itself controlled by a microprocessor 21. The microprocessor 21 receives signals representative of the engine speed from a speed sensor 22 mounted, for example, on the distributor or the crankshaft of the engine, and positions the bleed valve in accordance with a predetermined programme sorted therein. A lost motion linkage may be provided between the throttle plate 8 and the venturi member 5 which limits the maximum extent to which the venturi member 5 can be moved as the throttle plate approaches its wideopen position, thereby further limiting the maximum speed of the engine.
When the engine is running, opening the throttle plate 8 communicates the passage 2 between the venturi 5 and the throttle plate 8 with the depression in the engine intake. This depression is communicated to the vacuum motor 10 and generates a pressure differential across the diaphragm 11 which moves the diaphragm 11, and hence the venturi member 3, to the right as seen in the drawings, thereby opening the fuel jet 7. Increases in engine load reduce the depression in the engine intake, thereby allowing the venturi member to move to the left under the influence of the spring 14. Since the venturi 5 decreases in size, the pressure at the jet 7 remains constant.
In order to limit the maximum speed of the engine, the microprocessor 21 may be programmed to withdraw the needle 1 8 from the orifice 1 9 in the bleed rate 17 when a predetermined engine speed is detected by the speed sensor 22 thereby allowing air at atmospheric pressure into the one side of the vacuum motor 10 and reducing the pressure differential thereacross, so that the diaphragm 11 moves to the left as seen in the drawings under the influence of the spring 14, thereby moving the venturi member 3 towards the fuel jet 7 and reducing the fuel supply.
Alternatively, by appropriate programming of the microprocessor 21 the depression applied to the one side of the vacuum motor 10 may be modulated by appropriate positioning of the air bleed valve throughout the whole speed range of the engine so that acceleration of the engine to its maximum speed always occurs under controlled conditions. In this way the acceleration of the engine can always be carried out under conditions which optimise fuel consumption. The precise conditions for optimum fuel consumption will vary with engine type, and would be determined experimentally.
As a further alternative, the microprocessor 21 may be programmed in such a way that the acceleration occurs under conditions in which the noise emitted from the engine is kept within desired limits. Thus, compliance with legal limits for vehicle engine noise emissions is usually determined by test driving the vehicle under controlled conditions past a noise detector. The maximum rate of acceleration of the engine which produces an acceptable noise level can therefore be determined experimentally. By using the resulting data to programme the microprocessor 21, the carburettor can be controlled so that the maximum rate of acceleration thus determined is never exceeded.
Claims (5)
1. An engine speed control system comprising a carburettor, having a passage for conducting air into the engine, a venturi member movable across the passage to define a venturi therein, a metering needle movable with the venturi member and cooperating with a fuel jet to control the flow of fuel into the passage, and a control mechanism for varying the position of the venturi member in the passage in response to variations in engine load, characterised in that the control mechanism also varies the position of the venturi member in response to engine speed.
2. A system according to claim 1 wherein the control mechanism comprises a vacuum motor having a movable diaphragm drivingly connected to the venturi member, one side of the diaphragm being in connection with the pressure in the engine intake, and means for varying the pressure differential across the diaphragm in accordance with engine speed.
3. A system according to claim 2 wherein the means for varying the pressure difference across the diaphragm comprises an air bleed valve for reducing the depression applied to the said one side of the diaphragm, and means for controlling the position of the air bleed valve in response to engine speed.
4. A system according to claim 2 wherein the air bleed valve is operable by an electric motor controlled by a microprocessor.
5. An engine speed control system substantially as hereinbefore described and as illustrated in the drawings.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB08129065A GB2106987A (en) | 1981-09-25 | 1981-09-25 | Engine speed control of variable venturi carburettors |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB08129065A GB2106987A (en) | 1981-09-25 | 1981-09-25 | Engine speed control of variable venturi carburettors |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| GB2106987A true GB2106987A (en) | 1983-04-20 |
Family
ID=10524747
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB08129065A Withdrawn GB2106987A (en) | 1981-09-25 | 1981-09-25 | Engine speed control of variable venturi carburettors |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2106987A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7278988B2 (en) | 2000-12-15 | 2007-10-09 | Kimberly-Clark Worldwide, Inc. | Dual-use pantiliner |
-
1981
- 1981-09-25 GB GB08129065A patent/GB2106987A/en not_active Withdrawn
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7278988B2 (en) | 2000-12-15 | 2007-10-09 | Kimberly-Clark Worldwide, Inc. | Dual-use pantiliner |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US4228773A (en) | Device to activate an adjusting member in dependence on load | |
| US5509395A (en) | Canister purge flow regulator | |
| GB2066930A (en) | Apparatus for controlling the idling speed of an internal combustion engine | |
| US3852391A (en) | Carburetor with deceleration circuit | |
| US3936516A (en) | Carburetor having an altitude-effects compensation mechanism and a method for the manufacture of same | |
| CA1046366A (en) | Control apparatus for diesel engine | |
| GB1587237A (en) | Arrangement for regulating the composition of the operating mixture of an internal combustion engine | |
| US5002705A (en) | Carburetor including an idling adjustment system | |
| US3628024A (en) | Photo-optic transducer using apertured shade and moveable shutter | |
| US4099505A (en) | Fuel injection system | |
| US4089308A (en) | Carburation devices | |
| US4387693A (en) | Exhaust gas recirculation control | |
| US3968189A (en) | Method and apparatus for varying fuel flow from a variable venturi carburetor to compensate for changes in barometric pressure and altitude | |
| GB1464591A (en) | Internal combustion engine with means for compensating for air density variation | |
| US3638627A (en) | Variable advance engine ignition timing control | |
| GB2106987A (en) | Engine speed control of variable venturi carburettors | |
| US4620520A (en) | Apparatus for controlling recirculated exhaust gas quantities in internal combustion engines | |
| CA1151033A (en) | Carburetor air bleed control system | |
| US4156415A (en) | Fuel-air mixture control apparatus | |
| US3930479A (en) | Fuel metering device for externally ignited internal combustion engines with compression of the air-fuel mixture | |
| US4462359A (en) | Pulsed bleed air throttle position controller | |
| US3768450A (en) | Automatic idle speed controller | |
| US4671246A (en) | Apparatus for controlling recirculated quantities of exhaust gas in internal combustion engines | |
| US4462365A (en) | Apparatus for supplying fuel to an internal combustion engine | |
| US4282840A (en) | Internal combustion engine with altitude compensation device |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |