Claims
- 1. A vapor recovery fuel dispenser comprising
- a liquid fuel line extending from a liquid fuel source to a liquid fuel outlet and including a meter that generates a pulse stream at a rate corresponding to a rate of flow of fuel through said line,
- a vapor recovery line extending from said liquid fuel outlet to a vapor reservoir,
- a vapor impeller in said vapor recovery line to impel vapor to move from said liquid fuel outlet to said vapor reservoir, and
- a control for said impeller connected to receive said pulse stream, said control including a pulse source that generates pulses at a rate faster than an expected pulse rate from said meter and a counter to count the number of pulses from said pulse source during an interval between pulses from said meter, said control deriving a control signal for said impeller from the counted number of pulses.
- 2. A vapor recovery fuel dispenser as claimed in claim 1 wherein said vapor impeller is a variable speed positive displacement pump driven by a motor.
- 3. A vapor recovery fuel dispenser as claimed in claim 1 wherein said vapor impeller is a constant speed pump and a variable position valve controlled by said control.
- 4. A method of recovering vapor in a fuel dispenser comprising
- pumping liquid fuel along a line extending from a liquid fuel source to a liquid fuel outlet and generating a first pulse stream at a rate corresponding to the rate of flow of fuel through the line,
- withdrawing vapor along a vapor recovery line extending from the liquid fuel outlet to a vapor reservoir,
- pumping vapor in the vapor recovery line from said liquid fuel outlet to said vapor reservoir at a volumetric rate determined by,
- generating second pulses at a rate faster than an expected pulse rate in the first pulse stream,
- counting the number of second pulses generated during an interval between pulses in the first pulse stream and
- deriving a control signal for said vapor pumping step from the counted number of second pulses.
- 5. A vapor recovery method as claimed in claim 4 wherein said withdrawing step includes driving a variable speed positive displacement pump by a motor.
- 6. A vapor recovery method as claimed in claim 4 wherein said withdrawing step includes driving a constant speed pump and varying a valve in accordance with the control signal.
Parent Case Info
This application is a division of application Ser. No. 08/294,108, filed Aug. 22, 1994, now U.S. Pat. No. 5,542,458.
US Referenced Citations (21)
Foreign Referenced Citations (2)
Number |
Date |
Country |
8717378 U |
Sep 1988 |
DEX |
1253283 |
Nov 1971 |
GBX |
Divisions (1)
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Number |
Date |
Country |
Parent |
294108 |
Aug 1994 |
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