Broadband vibration sensor apparatus

• US 6,205,872 B1
• Filed: 12/29/1998
• Issued: 03/27/2001
• Est. Priority Date: 12/29/1998
• Status: Expired due to Term

• Current Assignee: Growth Finance AG
• Original Assignee: Montronix
• Inventors: Pflueg, Christian
• Primary Examiner(s): MOLLER, RICHARD ALAN
• Application Number:
  US09/222,451
• Time in Patent Office: 819 Days
• Field of Search: 735/10, 735/140.1, 735/143.4, 735/93, 735/70, 734/31, 738/665, 736/49, 736/58
• US Class Current: 73/866.5
• CPC Class Codes: G01H 11/08 using piezoelectric devices

Abstract

A broadband vibration sensor apparatus includes a single housing having at least two vibration sensors disposed in signal communication with a machine contact surface of the housing and a machine on which the housing is mounted. One of the sensors is a piezoelectric element capable of detecting high frequency vibrations and the other sensor is an accelerometer capable of detecting low frequency vibrations. A low impedance transducer is mounted in the housing to convert the output of the piezoelectric element to a low impedance output. An amplifier is connected to the output of the low impedance modified first sensor and the output of the second sensor for amplifying both outputs. A single cable connects the housing to an amplifier housing. Select jumpers are provided for converting the amplifier between a one input, two or four channel amplifier and a two input, two channel amplifier. Bandpass filters with different frequency ranges are replaceably mountable in the amplifier housing to select the bandpass frequency range of each sensor. An RMS to DC converter is coupled to the amplified sensor output.

Claims

1. A vibration sensor apparatus for sensing low frequency vibrations emitted by a machine or a machine tool and high frequency acoustic emissions from deformation in a machine or a machine tool and transmitted as high frequency sound comprising:

a housing having a machine tool contact surface;

first and second sensors mounted in the housing for sensing vibrations emitted by the machine and machine tool, each first and second sensor generating an output proportional to a sensed vibration, the first sensor responsive to low frequency machine and machine tool vibrations, the second sensor responsive to high frequency acoustic emissions from a machine and a machine tool; and

amplifier means, mounted in the housing and responsive to outputs of the first and second sensors, for amplifying the outputs of the first and second sensors.

2. The vibration sensor apparatus of claim 1 wherein the first sensor is an accelerometer.

3. The vibration sensor apparatus of claim 2 wherein the accelerometer senses vibration frequencies between about 0.1 Hz to about 600 Hz.

4. The vibration sensor apparatus of claim 1 wherein the second sensor is a piezoelectric element.

5. The vibration sensor apparatus of claim 4 wherein the piezoelectric element senses vibration frequencies between about 50 KHz and about 500 KHz.

6. The vibration sensor apparatus of claim 1 further comprising:

a single multi-conductor cable connected to and extending from the housing for carrying the outputs of the first and second sensors.

7. The vibration sensor apparatus of claim 1 further comprising:

means for converting both of the first and second sensor outputs into separate pairs of first and second parallel channels.

8. The vibration sensor apparatus of claim 1 further comprising:

means for converting at least one of the first and second sensor outputs into first and second parallel channels.

9. The vibration sensor apparatus of claim 8 further comprising:

means for coupling a bandpass filter to each of the first and second channels.

10. The vibration sensor apparatus of claim 9 wherein each bandpass filter comprises:

a plurality of filters, each having a different bandpass frequency range.

11. The vibration sensor apparatus of claim 1 further comprising:

means for fixedly mounting each of the first and second sensors in signal communication with the machine contact surface of the housing.

12. The vibration sensor apparatus of claim 11 wherein:

the first sensor is an accelerometer; and

the second sensor is piezoceramic sensor.

13. The vibration sensor apparatus of claim 1 further comprising:

an impedance transducer mounted in the housing and coupled to the output of the second sensor for converting the output of the second sensor to a low impedance output.

14. The vibration sensor apparatus of claim 1 further comprising:

a cavity formed in the housing; and

the first and second sensors mounted in the cavity in vibration signal communication with the machine contact surface of the housing.

15. The vibration sensor apparatus of claim 14 wherein the first and second sensors are adhesively fixedly mounted in signal communication with the machine contact surface of the housing.

16. The vibration sensor apparatus of claim 15 wherein the adhesive is an epoxy.

17. The vibration sensor apparatus of claim 14 further comprising:

a recess formed in the housing for receiving one of the first and second sensors.

18. The vibration sensor apparatus of claim 17 further comprising:

an adhesive bonding one of the first and second sensors in the recess in the housing.

19. The vibration sensor apparatus of claim 1 wherein the first sensor senses vibration frequencies between about 0.1 Hz to about 600 Hz.

20. The vibration sensor apparatus of claim 1 wherein the second sensor senses vibration frequencies between about 50 KHz and about 500 KHz.