Piezo-electric seed-flow monitor

• US 4,079,362 A
• Filed: 07/02/1976
• Issued: 03/14/1978
• Est. Priority Date: 07/02/1976
• Status: Expired due to Term

• Current Assignee: University Of Saskatchewan
• Original Assignee: Canadian Patents and Development Limited
• Inventors: Paulson, Garry E., Grimm, Edward A.
• Primary Examiner(s): Swann, III, Glen R.
• Application Number:
  US05/702,059
• Time in Patent Office: 620 Days
• Field of Search: 340/259, 340/261, 340/267 R, 310/9.1, 310/8.1, 310/326, 310/321
• US Class Current: 340/684
• CPC Class Codes: A01C 7/105 Seed sensors
• CPC Class Codes: G07C 3/00 Registering or indicating the condition or the working of machines or other apparatus, other than vehicles
• CPC Class Codes: Y10S 111/902 Pasture renovation
• CPC Class Codes: Y10S 111/903 Monitor

Abstract

The monitor is used with seeder equipment having one or more seeder hopper sections wherein each hopper section has a number of metering assemblies for feeding the seed from each hopper section to the soil. The monitoring apparatus includes at least one sensor consisting of a piezoelectric transducer which provides an output signal in response to being struck by a seed, a vibration isolating mounting structure to position the sensor in the seed flow path between the metering assembly and the soil, and a circuit for receiving the sensor electronic response and providing an indication of seed flow condition. The mounting structure includes an elongated member such as a metal tubing, to one end of which is fixed a cushion made of a material such as a closed cell foam and to the other end of which is fixed a securing member to secure the structure to the seeder. The sensor is positioned on the cushion and a pair of leads connected across the sensor, pass through the tube and are connected to twin conductors at the other end. The circuit for each sensor includes a control circuit which processes the sensor signal and which provides an output control signal representing a flow condition such as the no flow condition. The circuit further includes visual and audio alarm circuits which indicate the flow condition for each sensor.

Claims

1. Monitoring apparatus for seeder equipment having one or more seed hopper sections and a number of metering assemblies for feeding the seed from each hopper to the soil, comprising:

one or more sensor means, each of said sensor means including a piezo-electric crystal fixed to a metal disc for providing an electronic output signal when the disc is struck by seed;

mounting means for each of said sensor means to mount the sensor means in the path of seed flow between a metering assembly and the soil, said mounting means including an elongated member having securing means fixed to one end for securing the mounting means to the seeder and cushion means fixed to the other end of the elongated member on which the sensor means is fixed thereby isolating the sensor means for spurious vibrations of the seeder and electrically insulating the sensor means from the mounting means; and

circuit means coupled to the sensor means for receiving the electronic signals and for indicating a predetermined seed flow condition.

2. Monitoring apparatus as claimed in claim 1 wherein the cushion means consists of a closed cell foam.

3. Monitoring apparatus as claimed in claim 2 wherein the elongated member consists of a metal tubing having a pair of leads therein, the leads being connected to said sensor means at said other end of said member and to a pair of conductors at said one end of said member.

4. Monitoring apparatus as claimed in claim 3 wherein said circuit means includes:

control circuit means coupled to said pair of conductors from each sensor means to receive the sensor means output signal and to provide an output control signal representing a predetermined seed flow condition; and

alarm circuit means coupled to said control circuit means to receive the output control signal and to provide a visual alarm signal indicating the predetermined seed flow condition.

5. Monitoring apparatus as claimed in claim 4 wherein the control circuit means includes:

differential amplifier means having a bandpass characteristic centered at the predetermined resonant frequency of the sensor means for amplifying the signal difference across the sensor means;

threshold detector means coupled to the amplifier means for providing output pulses in response to amplified sensor signals exceeding a predetermined amplitude; and

charging circuit means having a charging capacitor connected to a reference source to charge said capacitor, amplifier means coupled to said capacitor to provide an output control signal in response to a predetermined voltage across said capacitor, and switch means connected across said capacitor to discharge said capacitor in response to pulses from said threshold detector.

6. A monitoring apparatus as claimed in claim 5 wherein said alarm circuit means includes a normally open alarm switch means connected in series with lamp means and a voltage source, said alarm switch means being coupled to the amplifier means of said charging circuit to close in response to said output control signal thereby illuminating said lamp means to indicate a no flow condition.

7. A monitoring apparatus as claimed in claim 6 wherein said alarm circuit further includes audible alarm means and a second voltage source in series with said alarm switch means to activate the audible alarm means in response to said output control signal.

8. A monitoring apparatus as claimed in claim 7 wherein the first-recited and second voltage sources consist of square wave voltage generators.

9. A monitoring apparatus as claimed in claim 7 wherein the second voltage source includes means for deactivating the second voltage in response to a no flow condition on all of the sensor means.

10. Monitoring apparatus as claimed in claim 3 wherein the sensor means has a resonant frequency above 16 kHz.

11. Monitoring apparatus for seeder equipment having one or more seed hopper sections and metering assemblies for feeding the seed from the hoppers to the soil comprising:

one or more sensor means having an impact sensitive transducer mounted on a metal disc for providing an electronic output signal when the disc is struck by seed;

means for mounting the sensor means between the metering assembly and the soil in the path of seed flow;

control circuit means coupled to each sensor means to receive the sensor means output signal and to provide an output control signal representing a predetermined seed flow condition, said control circuit means including differential amplifier means having a bandpass characteristic centered at the predetermined resonant frequency of the sensor means for amplifying the signal difference across the sensor means, threshold detector means coupled to the amplifier means for providing output pulses in response to amplified sensor signals exceeding a predetermined amplitude, and charging circuit means having a charging capacitor connected to a reference source to charge said capacitor, amplifier means coupled to said capacitor to provide an output control signal in response to a predetermined voltage across said capacitor, and switch means connected across said capacitor to discharge said capacitor in response to pulses from said threshold detector; and

alarm circuit means including a normally open alarm switch means connected in series with lamp means and a first voltage source, said alarm switch means being coupled to the amplifier means of said charging circuit means to close in response to said output control signal thereby illuminating said lamp means to indicate a no flow condition, audible alarm means and a second voltage source in series with said alarm switch means to activate the audible alarm means in response to said output control signal, wherein said second voltage source includes means for deactivating the second voltage source in response to a no flow condition on all of the sensor means.