Throttle device for an internal combustion engine

Details Throttle device for an internal combustion engine Throttle device for an internal combustion engine

1995-06-06

1997-04-01

Fox, John C.

Valves and valve actuation

Rotary valves

Butterfly

251358, 123403, F16K 122

Patent

active

056158610

DESCRIPTION:

BRIEF SUMMARY
STATE OF THE ART

The invention proceeds from a throttle device for an internal combustion engine. There is already a known throttle device (German Offenlegungsschrift 4,022,826), in which an actuating shaft is connected fixedly in terms of rotation to a throttle member, for example to a throttle flap which is rotated by means of an actuating drive. The actuating shaft is mounted on both sides in a throttle-flap connection piece of the throttle device, for which purpose receiving orifices, into which the bearing arrangements, for example in the form of needle bearings, are inserted, are worked out from the throttle-flap connection piece. When the throttle device is made from aluminum in the die-casting technique, a careful remachining of the receiving orifices extending into the vicinity of the throttle flap is necessary in order to fit the bearing arrangements exactly without any tilting. It has therefore already been proposed to produce the throttle-flap connection piece from plastic by the injection-molding process. The advantage of such throttle-flap connection pieces consisting of plastic is that they are lighter than aluminum housings, that the production material is cheaper and that inserts, for example inserts provided with threaded bores or inserts designed as rolling bearings for the mounting of the throttle member, can be pressed into orifices formed at the same time during the injection-molding operation, so that remachining can be reduced to a minimum. The disadvantage of such throttle-flap connection pieces consisting of plastic is that they shrink during and after the injection molding and warp after removal from the mold, and that, furthermore, they have poor dimensional stability under the effect of temperature and force. It must be remembered, here, that the engine compartment of a motor vehicle and therefore also the throttle device or the throttle-flap connection piece are subject to high temperature fluctuations, since, on the one hand, temperatures of well below zero can occur in the open in winter when the motor vehicle is parked and, on the other hand, temperatures of more than 120.degree. C. can occur when the motor vehicle is running, particularly on hot summer days, and after the internal-combustion engine has been switched off. For these reasons, there is no guarantee of dimensional stability of the suction wall of such throttle-flap connection pieces consisting of plastic. However, such dimensional stability is necessary, so that each position of the pivotable throttle member corresponds to an exactly defined throughflow cross section and, above all, so that a minimum exactly defined residual gap or a complete shut-off is possible in an end position of the throttle member. For reasons of environmental protection and to reduce the fuel consumption, very low idling speeds of the internal-combustion engine are demanded today, the throttle member assuming an idling position in which only a small air quantity may flow past the throttle member. It is therefore particularly important that the suction wall of the throttle-flap connection piece of the throttle device should maintain its dimensional stability even over many years of operation, particularly in the region of the so-called idling position of the throttle member, in order to guarantee a readjustment of the throttle member by means of a uniformly small gap width. A further disadvantage is that the position and axial alignment of the bearings for the throttle member also vary, for example as a result of the temperature fluctuations, and this can lead to a jamming of the throttle member. Where use in motor vehicles is concerned, a jamming would mean that the engine revolutions and the speed can no longer be influenced by the driver.


ADVANTAGES OF THE INVENTION

In contrast to this, the advantage of the throttle device according to the invention is that, even in a design of the throttle-flap connection piece made of plastic, a high dimensional stability of the suction wall of the throttle-flap connection piece is guaranteed in

REFERENCES:
patent: 3233861 (1966-02-01), Stillwagon
patent: 5131626 (1992-07-01), Kobayashi

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