Exhaust sampler and control means
First Claim
1. An apparatus for sampling the emission content of exhaust from an exhaust source comprising an exhaust inlet adapted for connection with the exhaust source, a dilution air inlet adapted for connection with said exhaust inlet to provide a mixture of exhaust and dilution air, means for defining a flow confining path for said mixture, means coupled with said flow confining path for establishing a flow of said mixture in said flow confining path, means for measuring the flow rate of said mixture comprising a subsonic venturi restriction, means for measuring the pressure and temperature of said mixture upstream of said subsonic venturi, means for measuring the pressure of said mixture in said subsonic venturi and a control unit for computing the flow rate of said mixture based on signals received from said upstream measuring means and said subsonic venturi measuring means, said sampling apparatus further comprising means for controlling the flow rate of said mixture in response to the computed flow rate of said mixture, means for extracting a sample of said mixture and means for controlling the flow rate of the extracted sample so as to maintain a preselected constant mass flow rate of said extracted sample.
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Abstract
An exhaust sampler for use in evaluating exhaust emissions of an exhaust source such as an internal combustion engine which utilizes a calibrated subsonic venturi for measuring the exhaust or exhaust/dilution air flow rate. Controls are provided for selecting and controlling a variety of flow rates between or during test periods. The system also provides a variety of control methods for extracting a sample from the bulkstream flow of exhaust and dilution air or from raw exhaust flow.
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Citations
32 Claims
- 1. An apparatus for sampling the emission content of exhaust from an exhaust source comprising an exhaust inlet adapted for connection with the exhaust source, a dilution air inlet adapted for connection with said exhaust inlet to provide a mixture of exhaust and dilution air, means for defining a flow confining path for said mixture, means coupled with said flow confining path for establishing a flow of said mixture in said flow confining path, means for measuring the flow rate of said mixture comprising a subsonic venturi restriction, means for measuring the pressure and temperature of said mixture upstream of said subsonic venturi, means for measuring the pressure of said mixture in said subsonic venturi and a control unit for computing the flow rate of said mixture based on signals received from said upstream measuring means and said subsonic venturi measuring means, said sampling apparatus further comprising means for controlling the flow rate of said mixture in response to the computed flow rate of said mixture, means for extracting a sample of said mixture and means for controlling the flow rate of the extracted sample so as to maintain a preselected constant mass flow rate of said extracted sample.
- 15. An apparatus for sampling the emission content of exhaust from an exhaust source comprising an exhaust inlet adapted for connection with the exhaust source, means for defining a flow confining path for said exhaust, means coupled with said exhaust flow confining path for establishing a flow in said exhaust flow confining path, means for measuring the flow rate of said exhaust comprising a subsonic venturi restriction, means for measuring the pressure and temperature of said exhaust upstream of said subsonic venturi, means for measuring the pressure of said exhaust in said subsonic venturi and a control unit for computing the flow rate of said exhaust based on signals received from said upstream measuring means and said subsonic venturi measuring means, and means for controlling the flow rate of said exhaust in response to the computed flow rate of said exhaust, said sampling apparatus further comprising means for extracting a sample of said exhaust comprising a sample flow confining path, means coupled to said sample flow confining path for supplying dilution gas to said sample to provide a mixture of exhaust sample and dilution gas, means for controlling the flow rate of the dilution gas in response to signals received from said control unit and means for controlling the flow rate of said mixture in response to signals received from said control unit so as to maintain a preselected constant mass flow rate of said mixture of exhaust sample and dilution gas.
- 20. An apparatus for sampling the emission content of exhaust from an exhaust source comprising an exhaust inlet adapted for connection with the exhaust source, means for defining a flow confining path for said exhaust, means coupled with said exhaust flow confining path for establishing a flow in said exhaust flow confining path, means for measuring the flow rate of said exhaust comprising a subsonic venturi restriction, means for measuring the pressure and temperature of said exhaust upstream of said subsonic venturi, means for measuring the pressure of said exhaust in said subsonic venturi and a control unit for computing the flow rate of said exhaust based on signal received from said upstream measuring means and said subsonic venturi measuring means and means for controlling the flow rate of said exhaust in response to the computed flow rate of said exhaust, said sampling apparatus further comprising means for extracting a sample of said exhaust comprising a sample flow confining path, means for controlling the flow rate of said sample in response to signals received from said control unit so as to maintain a preselected constant mass flow rate of said sample, means coupled to said sample flow confining path downstream of said sample controlling means for supplying dilution gas to said sample to provide a mixture of exhaust sample and dilution gas, and means for controlling the flow rate of the dilution gas in response to signals received from said control unit.
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25. An apparatus for sampling the emission content of exhaust from an exhaust source comprising:
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an exhaust inlet adapted for connection with the exhaust source; a dilution air inlet adapted for connection with said exhaust inlet to provide a mixture of exhaust and dilution air; means for defining flow confining path for said mixture; flow control means coupled with said flow confining path for establishing a flow of said mixture in said flow confining path; means for measuring the flow rate of said mixture including a subsonic venturi restriction; sampling zone located in said flow confining path upstream of said subsonic venturi restriction; means for extracting a sample of the mixture flowing through said sampling zone including means defining a sample flow path and for maintaining a preselected constant mass flow rate through said sample flow path; and controller means responsive to said measuring means for controlling said flow control means so as to create a predetermined mass flow rate of said mixture through said sampling zone related to said preselected constant mass flow rate of said extracted sample. - View Dependent Claims (26, 27, 28, 29, 30, 31)
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32. An apparatus for sampling the emission content of exhaust from an exhaust source comprising:
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an exhaust inlet adapted for connection with the exhaust source; a dilution air inlet adapted for connection with said exhaust inlet to provide a mixture of exhaust and dilution air; means for defining a flow confining path for said mixture; flow control means coupled with said flow confining path for establishing a flow of said mixture in said flow confining path; means fur measuring the flow rate of said mixture including a subsonic venturi restriction and transducer means for producing signals proportional to the temperature and pressure of said mixture upstream of said subsonic venturi restriction and the pressure of said mixture in said subsonic venturi restriction; a sampling zone located in said flow confining path upstream of said subsonic venturi restriction; means for extracting a sample of the mixture flowing through said flow confining path including a critical flow venturi connected to said sampling zone and means for maintaining a flow rate through said critical flow venturi at the critical flow condition of said critical flow venturi; and controller means responsive to said signals from said transducer means for controlling said flow control means so as to create predetermined pressure and temperature conditions in said sampling zone corresponding to said critical flow condition of said critical flow venturi.
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Specification