AU630300B2 - Throttle body - Google Patents

Description

P/00/01 1 Regutation 3.2

AUSTRALIA

PATENTS ACT 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT *0 ORIGINAL 4 0 0 0 Mim fApiat RB"0TBSH(USRLA T.LD 0 Acua Inetrs:PtrPn0n afe ik Adrs o evc: CLIA A RE 7 ig 3reKw 11 itra utat InvenTOonETCOMPLETEDRBYIAPPLICANT The folwn ttmn0safl ecito fti netoicuigtebs ehdo p~erfofApicanon t ROETBOCeASTAI)PT-LD -1- THROTFLE BODY The present invention relates to a throttle body for an internal combustion engine and relates particularly, though not exclusively, to a throttle body for fuel injection systems for internal combustion engines.

In the conventional fuel injection system of a modern automobile the throttle body controls the amount of air delivered to the combustion chambers.

The throttle body is a hollow body with one end opening into an air inlet for o t induction of air and the other end opening into an air manifold for distribution of air to the combustion chambers. Inside the throttle body is located a butterfly 0 0 4100 valve which is pivotally mounted across a diameter of the throat of the throttle body. The butterfly valve moves from a closed position, at which small amount of air for engine idle passes through the valve, to a fully opened position, where full engine speed is obtained. For engine idle speed control a bypass passage is provided which allows air to pass through the throttle body when the butterfly i '15. valve is closed. The argle of the butterfly valve is controlled by a cable from the accelerator pedal.

Throttle bodies have predominately been made from cast metal.

Accurate machining is necessary to ensure no uncontrolled leakage of air through the butterfly valve during its closure and for accurate mounting to the engine, Leakage of air can cause an increased idling speed which is undesirable from Ae drivers' view, and from the environmental aspect of pollution and use of nonrenewable resources. Accurate machining is time consuming and expensive for manufacturers. As the throttle body is cast there can be a porosity problem with the casting which again reduces the efficiency of operation. Metal castings are also -2heavy which increases the total weight of the engine.

To overcome the problems of metal cast throttle bodies it has been proposed to use throttle bodies formed from moulded plastics materials. The advantages of these proposals are obvious in relation to the reduction of weight.

These advantages are little, if any machining; cost savings; simplicity of manufacture; and elimination of the porosity problem.

Unfortunately, these proposals have up until the present time, proved ,o o impracticable. Plastics materials nave additional problems when used in the hostile S environment of an internal combustion engine. It is a lot harder to maintain 0 o 0 S accurate tolerances when compared with metal. Plastics materials have a larger coo efficient of expansion than metals. This shrinking can cause sticking of the butterfly valve. On the other hand, the expanding of plastics materials can result in leakage of air through the closed butterfly valve. Plastics materials have a much greater tendency to crack which can result in disastrous consequences. Such cracking can occur if the engine "back fires" or from other causes. A crack can cause bypass of air which results in an uncontrollable vehide speed. Most engine management systems will eventually correct for such an anomaly but will not react faster enough. Most systems must take several measurements to ensure that this type of problem is not a mere transient. Accordingly, such delays can result in accidents. Distortion of the plastics material will also occur when the throttle body is bolted to the engine. Most throttle bodies are mounted by four bolts which can introduce tensions into the throttle body. Such tensions, in the worst case, cause the shape of the throat to alter and affect the idle air calibration.

From the above it can be seen that the use of plastics material is I I I-r 7 -3desirable for throttle bodies but the safety problems associated therewith have so far precluded their use.

It is an object of the present invention to provide a throttle body which uses plastics materials but does not have the problems normally associated with their use.

A further object of the invention is to provides a throttle body which is cheap to manufacture.

c With these objects in view the present invention provide a throttle body for an internal combustion engine, said throttle body including a hollow body with 00 o o0 inlet and outlet ends, said hollow body being formed of a plastics material and 4 0 0 0 00 0° including an inner sleeve of dimensionally stable material; and a pivotal flap or butterfly valve located within said inner sleeve for controlling flow of air through said throttle body.

o0 0Preferably said inner sleeve is formed of metal and extends for a 015 substantial portion of the length of said throttle body.

0 'o04 In a preferred embodiment said pivotal flap or butterfly valve includes o a disk-shaped flap having an integral sleeve running diametrically therethrough 0 0 0 and an axle received in said sleeve which is fastened to said sleeve.

In yet a further preferred embodiment said inner sleeve includes at least one stop member projecting outwardly therefrom. Such a stop member will not creep or crack and allow maintenance of a precise idling speed compared with use of a plastics stop. The stop can be covered in a plastics material if required.

The invention will now be described with reference to preferred nonlimitative embodiments, with the aid of the accompanying drawing, in which; I r c- II-~ -4- Fig. 1 shows a cross-sectional view through a throttle body made in accordance with the invention; Fig. 2 is a side view of the throttle body of Fig. 1 with the throttle lever and linkage attached thereto; Fig. 3 is a perspective view of a manufactured inner sleeve for use with the throttle body; and Fig. 4 is a perspective view of an inner extruded sleeve for use with the a throttle body.

In Fig. 1 there is shown a throttle body 10 having a hollow casing 12 o O10- with an air inlet end 14 and an air outlet end 16. Casing 12 is formed of a plastics 0 0 material and includes a flange 18 allowing it to be attached to an internal combustion engine (not shown). Mounted within casing 12 is an inner metal sleeve 20 which extends for a substantial portion of the length of casing 12. Sleeve is preferably formed of extruded aluminium which is cheap to fabricate and will be porosity free. Although sleeve 12 is shown extending to air outlet end 16 this need not be so. Sleeve 20 can vary in length and position but must contain butterfly valve 22. Sleeve 20 may be pushed into casing 12 or may have casing 12 moulded therearound.

Butterfly valve 22 is shown in the dosed position and includes a disk shaped flap 24 with an integral diametral sleeve 26 foimed therein. Flap 24 can be formed as a metal casting or be fabricated or be a plastics moulding. An axle 28 passes through sleeve 26 and is secured thereto by at least one fastener Axle 28 is adapted to be coupled to an accelerator pedal (not shown) to vary the angle of flap 24.

I i Butterfly valve 22 is stronger than the prior art valves as axle 28 is not weakened. The prior art valves comprise a disk flap which is inserted in a slot cut through or cut along the axle. The formation of the slot is time consuming and substantially weakens the axle. Axle 28 of the preferred embodiment avoids these problems by not requiring the formation of a slot.

From the above it is clear that the advantages of using plastics material are realised without the previously described disadvantages. As sleeve 20 is metal it will not distort and accordingly, the sticking and jamming of the butterfly valve 9 22 is avoided. Cracking of the sleeve cannot occur. Any shrinkage or expansion 00 0 of casing 12 will not cause any distortion to be transferred to sleeve 20. The cost o 0 and weight savings are obvious as are the substantial reductions in manufacturing and machining times. Tolerances are maintained because the inner sleeve is metal and the sleeve is strong enough to counter any compression or tensile forces generated by casing 12.

Fig. 2 shows the throttle body 10 assembled with a throttle lever 32 and throttle linIage 34. A cam 36 is secured to axle 28 to rotate butterfly valve 22.

Linkage 34 is pivotally coupled at either end to throttle lever 32 and cam 36.

Extending from sleeve 20 is a stop member 38 which acts as a primary stop to control the idle speed of the engine. The idle speed can be adjusted by turning threaded bolt 40 which is secured to stop member 38. To prevent movement of bolt 40, when the desired idle speed is set, bolt 40 includes a co-axial spring 42 located between stop member 38 and the head of bolt 40. The free end 44 of cam 36 will contact bolt 40 in the idling position.

If required a secondary stop member 46 on inner sleeve 20 can be -6provided. Stop member 46 has an adjustment member 48 associated therewith which may contact the free end 50 of throttle lever 32. In use, there is a small gap between member 48 and free end 50. Contact with member 48 will only occur if contact of bolt 40 with free end 44 is lost and is a backup idling speed safety feature. In this embodiment secondary stop member 46 is formed on inner sleeve but this is not necessary. As there is normally no contact with free end secondary stop member 46 is under no stress. Accordingly, it may be formed on casing 12 as a projection therefrom.

As an additional strengthening feature a boss 52 (see Fig. 3) is formed o on inner sleeve 20 and acts as a bearing support for axle 28.

S Fig. 3 shows inner sleeve 20 as a manufactured item i.e. stop member 38 and boss 50 have been welded to sleeve 20. Fig. 4 shows a variation in that sleeve 20 is extruded. In this embodiment stop member 38A can be machined to remove a portion thereof to allow access for cam 36.

It is clear that the invention is also applicable to throttle bodies for carburetted engines as well.

o It is believed that the invention and many of its attendant advantages will be understood from the foregoing description and it will be apparent that various changes may be made in the form, construction and arrangement of the parts and that changes may be made in the form, construction and arrangement of the throttle body described without departing from the spirit and scope of the invention or sacrificing all of its material advantages, the form hereinbefore described being merely a preferred embodiment thereof.

Claims (6)

1. A throttle body for an internal combustion engine, said throttle body including a hollow body with inlet and outlet ends, said hollow body being formed of a plastics material and including an inner sleeve of dimensionally stable material; and a pivotal flap or butterfly valve located within said inner sleeve for controlling flow of air through said throttle body.

2. The throttle body as claimed in claim 1, wherein said inner sleeve is formed of metal and extends for a substantial portion of the length of said throttle body.

3. The throttle body as claimed in claim 1 or 2, wherein said pivotal flap or butterfly valve includes a disk-shaped flap having an integral sleeve running diametrically therethrough and an axle received in said sleeve which is fastened to said sleeve.

4. The throttle body as claimed in any one of the preceding claims, wherein said inner sleeve includes at least one stop member projecting outwardly therefrom.

The throttle body as claimed in any one of the preceding claims, wherein said inner sleeve is formed from aluminium.

6. A throttle body for an internal combustion engine substantially as hereinbefore described with reference to the accompanying drawing. D A T E D this 23rd day of July, 1991. ROBERT BOSCH (AUSTRALIA) PTY. LTD. By its Patent Attorneys: CALLINAN LARIE I- Ad r_ I4 I 04 fee 0 0f 0 0 0 0 0 00 0 00 S0 00e 0 0 0. 0 0 t -1 -8- ABSTRACT The invention relates to a throttle body (10) for an internal combustion engine. Throttle body (10) includes a hollow casing (12) formed of a plastics material with an inner sleeve (20) of dimensionally stable material, preferably metal, mounted within casing A pivotal flap or butterfly valve (22) is located for movement within sleeve (20) for controlling flow of air through throttle bocy 0 0 000 4w 0) Y 00 0 i d o 0 4 I <r L.