| 摘要 |
A vehicle emissions control system includes an air pump (12), a catalytic converter (22) communicated to the air pump, and a bleed control valve (28) which controls the quantity of air communicated from the air pump to the catalytic converter. The bleed valve includes a support arm (50) which suspends a valve element (40) adjacent a tapered valve surface (36). The support arm relaxes in response to repeated flexing due to the pulsating output of the air pump. Accordingly, when the vehicle is new, the valve element is held away from the valve seat to permit substantially uninhibited communication through the bleed valve so that almost all of the air which would otherwise be communicated to the catalytic converter is bled off. As the vehicle is used, the support arm relaxes, which permits the valve element to move progressively closer to the valve surface, thereby decreasing the quantity of air bled off through the bleed valve to thereby progressively increase the quantity of air communicated to the catalytic converter.
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