Air dispensing apparatus

A tire inflation apparatus comprising:

• an entry facility operable manually for recording in the apparatus a desired tire pressure to which in use of the apparatus a tire is to be inflated, said facility being arranged to provide output signals representative of a desired pressure entry;
• an air pressure transducer arranged so as to be capable of being exposed to the air pressure of a tire when the apparatus is being used for inflating the said tire, the transducer providing an output signal proportional to the incident air pressure;
• converter means coupled to the output of the transducer for generating a periodic output signal at a frequency which is a function of the transducer output;
• a counter coupled to the output of the converter means and arranged for counting excursions of said periodic signal;
• comparator means arranged so as to be responsive to the count held in the counter and to the output signals from the desired pressure entry facility for providing an indication as to the relationship between the tire pressure, as sensed by the transducer and translated by means of the converter means into a corresponding count held in the counter, and the desired tire pressure;
• valve means arranged to be responsive to the indication provided by the comparator means for determining the inflation of the tire from a compressed air supply;
• indicator means for providing an indication to a user when the comparator means senses that the pressure within the tire is the desired tire pressure;
• and
• timing control means controlling the operations of the counter means and the comparator means such that, in operation of the apparatus, a cyclic timing sequence is established during each cycle whereof the output of the converter means is gated into the counter for a first predetermined time period and during a second predetermined time period said valve means is controlled in dependence upon the count accumulated in the counter during said first time period.