Self-testing combustion products detector

Claim 2

In a combustion products detector (10) having a sensor (12) for producing an output signal in response to the presence of an amount of combustion products in excess of a threshold amount, wherein the threshold amount varies inversely with the sensitivity of the sensor, and wherein the desired sensitivity is in a predetermined range between minimum and maximum sensitivities, the improvement comprising: test means (35-40) for simulating the presence of combustion products in an amount slightly less than the amount corresponding to the maximum sensitivity, control means (30) for actuating said test means, and alarm means (24) coupled to the sensor and responsive to an output signal therefrom for producing a fault indication, whereby a fault indication is produced in response to actuation of said test means when the sensitivity of the sensor exceeds the maximum sensitivity.

Claim 3

The combustion products detector of claim 1, wherein the sensor (12) is an ionization-type sensor.

Claim 4

The combustion products detector of claim 1, wherein said test means (35-40) includes electronic switch means (36,39).

Claim 5

The combustion products detector of claim 1, wherein said control means (30) includes means (32) for automatically periodically actuating said test means.

Claim 6

The combustion products detector of claim 4, and further including manually-operated means (20) for testing the sensitivity of the sensor.

Claim 7

The combustion products detector of claim 1, wherein said control means includes timing means (32) main­taining said test means actuated for a predetermined time interval, and means (33,34) for delaying the production of a fault indication by said alarm means in response to actuation of said test means until after the expiration of said predetermined time interval.

Claim 8

The combustion products detector of claim 6, wherein said delaying means (53,34) includes means (44) for inhibiting the operation of said alarm means during said predetermined time interval.

Claim 9

The combustion products detector of claim 1, wherein said test means (30) includes electronic switch means (36,39), said control means including timing means (32) for periodically closing said switch means for a predeter­mined time interval, means (33,34) for registering the presence of an output signal from the sensor during said predetermined time interval, means (44) for inhibiting the operation of said alarm means during said predetermined time interval, and means (45) coupled to said registering means and responsive to registration thereby of an output signal from the sensor for causing said alarm means to produce a fault indication after the expiration of said predetermined time period.

Claim 10

In a combustion products detector (10) including a sensor (12) for producing an output signal in response to the presence of combustion products and test means (35-40) for simulating the presence of combustion products, the im­provement comprising: drive means (32) for operating the test means, and timing means (32) for automatically period­cally actuating the drive means.

Claim 11

In a combustion products detector (10) including a sensor (12) for producing an output signal in response to the presence of combustion products and test means (35-40) for simulating the presence of combustion products, the im­provement comprising: drive means (32) for operating the test means, and timing means (32) for automatically period­cally actuating the drive means.

Claim 12

The combustion products detector of claim 9, wherein the sensor is an ionization-type sensor.

Claim 13

The combustion products detector of claim 9, wherein the test means is electronically operated.

Claim 14

The combustion products detector of claim 9, wherein said drive means (32) and said timing means (32) are part of an integrated circuit.

Claim 15

In a combustion products detector (10) having a sensor (12) for producing an output signal in response to the presence of an amount of combustion products in excess of a threshold amount, wherein the threshold amount varies inversely with the sensitivity of the sensor, and wherein the desired sensitivity is in a predetermined range between minimum and maximum sensitivities, the improvement comprising: test means (35-40) having first and second operating conditions, said test means in the first operating condition thereof simulating the presence of a first amount of combustion products slightly less than the amount corresponding to the maximum sensitivity, said test means in the second operating condition thereof simulating the presence of a second amount of combustion products slightly greater than the amount corresponding to the minimum sensitivity, control means (32) for operating said test means in the first and second operating conditions thereof, and alarm means (24) coupled to the sensor and to said control means and operative for producing a fault indication, said control means including means (33) responsive to an output signal from the sensor when said test means is in its first operating condition for causing said alarm means to produce a fault indication, said control means including means (34) responsive to the absence of an output signal from the sensor when said test means is in its second operating condition for causing said alarm means to produce a fault indication, whereby a fault indication is produced in response to operation of said test means when the sensitivity of the sensor is outside the predetermined range.

Claim 16

In a combustion products detector (10) having a sensor (12) for producing an output signal in response to the presence of an amount of combustion products in excess of a threshold amount, wherein the threshold amount varies inversely with the sensitivity of the sensor, and wherein the desired sensitivity is in a predetermined range between minimum and maximum sensitivities, the improvement comprising: test means (35-40) having first and second operating conditions, said test means in the first operating condition thereof simulating the presence of a first amount of combustion products slightly less than the amount corresponding to the maximum sensitivity, said test means in the second operating condition thereof simulating the presence of a second amount of combustion products slightly greater than the amount corresponding to the minimum sensitivity, control means (32) for operating said test means in the first and second operating conditions thereof, and alarm means (24) coupled to the sensor and to said control means and operative for producing a fault indication, said control means including means (33) responsive to an output signal from the sensor when said test means is in its first operating condition for causing said alarm means to produce a fault indication, said control means including means (34) responsive to the absence of an output signal from the sensor when said test means is in its second operating condition for causing said alarm means to produce a fault indication, whereby a fault indication is produced in response to operation of said test means when the sensitivity of the sensor is outside the predetermined range.

Claim 17

The combustion products detector of claim 13, wherein said control means includes means for automatically periodically operating said test means sequentially in its first and second operating conditions.

Claim 18

The combustion products detector of claim 13, wherein said control means includes means (32) for operating said test means for a predetermined time interval during which said test means is operated sequentially in its first and second operating conditions, and means (44) for delaying the production of a fault indication by said alarm means until after the expiration of said predetermined time interval.

Claim 19

The combustion products detector of claim 13, wherein said alarm means includes annunciator means coupled to the sensor and responsive to an output signal therefrom for producing an alarm indication, and means (44) for inhibiting the operation of said annunciator means during said predetermined time interval.

Claim 20

The combustion products detector of claim 13, wherein said test means (35-40) includes first (36) and second (39) electronic switch means, said control means includes timing means (32) for periodically operating said test means for a predetermined time interval during which said test means is sequentially operated in its first and second operating conditions, first register means (33) responsive to the existence of an output signal from the sensor when said test means is operating its first operating condition for producing a first failure signal, second register means (34) responsive to the absence of an output signal from the sensor when said test means is operating in its second operating condition for producing a second failure signal, means (44) for inhibiting the operation of said alarm means during said predetermined time interval, and means (41) responsive to either of said first and second failure signals for causing said alarm means to produce a fault indication after the expiration of said predetermined time interval.