GB2174499A - Speed determination from exhaust note - Google Patents
Speed determination from exhaust note Download PDFInfo
- Publication number
- GB2174499A GB2174499A GB08510972A GB8510972A GB2174499A GB 2174499 A GB2174499 A GB 2174499A GB 08510972 A GB08510972 A GB 08510972A GB 8510972 A GB8510972 A GB 8510972A GB 2174499 A GB2174499 A GB 2174499A
- Authority
- GB
- United Kingdom
- Prior art keywords
- speed
- motor
- signal representing
- signal
- actual speed
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
- G01P3/00—Measuring linear or angular speed; Measuring differences of linear or angular speeds
- G01P3/42—Devices characterised by the use of electric or magnetic means
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Control Of Electric Motors In General (AREA)
Abstract
A method for determining the speed of operation of a pneumatic motor is provided which includes sensing air pressure variations produced from its exhaust and converting these to a signal representing the speed. A speed determination system comprises a transducer 4 for sensing air pressure variations produced from the exhaust 3 of a pneumatic motor 2 driving a device 1 and produces an electrical signal proportional to the frequency of the variations thereby representing the speed of operation of the motor. This signal may be used to operate means for controlling the speed of the motor. The system is particularly useful in dirty or dangerous environments, for example for determining the speed of rotation of an atomisation disc in a paint plant, since it does not require a direct physical connection to the machinery. <IMAGE>
Description
SPECIFICATION
Speed determination from exhaust note
This invention relates to measurement of the speed of a device driven by a pneumatic motor. It is particularly applicable for use in dirty or dangerous environments since it does not require a direct physical connection to the machinery.
In the following description, the term 'pneumatic motor' will be used to mean any air turbine or motor, including an internal combustion engine, which creates air pressure variations of a frequency proportional to motor speed. In particular the term is used to apply to a rotary vaned air motor. A pulse of air is produced from the exhaust of such a motor each time a vane passes the exhaust.
The invention is especially useful for determining the normal operating speed of a rotating atomisation disc, driven by a pneumatic powered motor, used in a paint coating process. This measurement is important as the speed of the disc is one of the major factors determining the evenness of the final coating of paint.
For several years, attempts have been made to find an accurate method of measuring the speed of operation of a paint atomisation disc. It has been found to be an extremely awkward measurement to make, not least because the disc and associated apparatus are always coated with paint and, in addition to this, the disc traverses vertically at high speed whilst rotating in a horizontal plane. The disc is also held at a potential of several tens of thousands of volts. The hostile environment makes conventional techniques of measurement barely adequate.
One method previously used to determine the speed of the disc involves the use of a stroboscope, but this may be used only when the normal vertical traversal of the disc has been inhibited and the paint supply to the disc stopped. The value thus obtained is only a rough indication of the normal operating speed since the speed of the unloaded disc is higher than the normal operating speed.
In another known method, a slotted disc is attached to the drive spindle and a fibre optic cable is used to direct light onto the slotted disc. The resulting pulses of light have a frequency proportional to the speed of rotation of the disc. This method does however require modification to the drive motor either by the addition of a suitable slotted disc or, for example, by the application of reflective coatings to existing cooling fins. Great cleanliness is needed with this approach, especially when changing the drive motor, so that the fibres are not contaminated, and the air supply must also be filtered.
An object of the invention is to provide a system for determining the speed of a device which is particularly useful in dirty environments.
According to the invention there is provided a speed determination system comprising transducer means for receiving air pressure variations produced from the exhaust of a pneumatic motor driving a device and producing an electrical signal proportional to the frequency of said air pressure variations thereby representing the actual speed of operation of the motor.
The electrical signal representing the speed of operation of the motor may be displayed, and means may be included to convert the signal representing the actual speed of operation of the motor into a signal representing the actual speed of operation of the device. This is necessary especially if there is gearing between the motor shaft and the device driven by it so that their speeds of operation are different. The electrical signal representing the speed of operation of the device driven may also be displayed.
The system may also inciude means operated by the signal representing the actual speed of operation of the motor or device for controlling the actual speed of operation of the motor driving the device.
Means may be included for producing a signal corresponding to a desired speed of operation of the motor together with comparator means for comparing this signal with the signal representing the actual speed of operation of the motor and producing an output signal representing the difference. Means may also be included for controlling the speed of the motor in response to this output signal.
According to a further aspect of the invention there is provided a method for determining the speed of operation of apparatus driven by a pneumatic motor including sensing air pressure variations produced from the exhaust of the motor and converting these to a signal representing the actual speed of operation of the motor.
The signal representing the speed of operation of the motor may further be converted to a signal representing the speed of operation of the apparatus driven by it and either of these signals may be used to control the actual speed of the motor.
In the particular example of use of the invention to measure the speed of rotation of the atomisation disc in a paint plant there are advantages over the prior art previously mentioned in that the speed may be measured under normal operating conditions even though the environment is dirty and dangerous, modifications to the drive motor or other associated apparatus are not required and the method is not affected by contaminants in the air supply.
US Patent 3,908,167 describes a method of determining engine speed in r.p.m. by optically monitoring puffs of exhaust gases resulting from ignitions in cylinders in an internal combustion engine but this would not be applicable, as the present invention is, to pneumatic motors.
In order that the invention may be clearly understood and readily carried into effect, it will be described by way of example with reference to the accompanying drawings, of which:
Figure 1 is an example of a circuit to give a display of operational speed for a device driven by a pneumatic motor, and
Figure 2 shows a circuit simiiar to that of Figure 1 adapted to correct the speed of the device in response to the speed measured.
Referring first to Figure 1, paint atomisation disc 1 is driven by drive motor 2. The motor is driven by a compressed air supply 16 as indicated. The motor exhaust 3 emits a note, the frequency of which is proportional to the speed of the motor due to air pressure variations produced by the motor. The note is detected by a transducer 4. The transducer may be a microphone or any other air pressure sensor capable of operating over the required frequency range and it may be located anywhere provided that it is sensitive enough to detect the air pressure variations and that other noise sources do not interfere. The transducer converts the air pressure variations into an electrical signal which is fed to an amplifier 5. The output signal from the amplifier is filtered by a low pass filter 6 to remove any high frequency noise.The filtered signal 11 corresponding to the actual speed of operation of the motor may be displayed using means such as an oscilloscope 7 and it may be fed to a phase locked loop 8 which acts as a discriminator to filter unwanted signals. The signal from the phase locked loop is then fed to a counter 9 which counts the number of cycles in a given time period and scales the signal (taking gearing ratios between the motor and device into account) so that the signal corresponding to the actual speed of operation of the motor is converted into an eiectrical signal representing the actual speed of operation of the device driven by it. This may be displayed at 10 as, for example, a value of the number of revolutions per minute of the disc.The display may be in analogue or digital form and the means for displaying the signal may be, for example, an oscilloscope, a meter or a digital display.
The atomisation disc is merely an example of the type of device which could be driven and the invention is applicable to the determination of the speed of any type of machinery driven by a pneumatic motor, the operating speed of which depends on that of the motor.
Figure 2 shows the circuit in Figure 1 adapted so that the signal 17, corresponding to the actual speed of operation of the device, obtained from the counter 9 is fed to one input of a comparator 13. A signal 12 corresponding to a desired speed of operation of the device is fed to the other input of the comparator which compares the signals and produces an output signal representing the difference (the error signal 14) which is fed to a speed control device 15. The speed control device is used for controlling the speed of operation of the drive motor by regulating the pressure of the compressed air supply to the motor in response to the output of the comparator means.
The desired speed may be input as an analogue value from a potentiometer or as a digital value from binary coded decimal (B.C.D.) switches. It is also possible to use an oscillator to input a signal corresponding to the desired speed.
If the desired speed value is greater than the actual speed value, the error signal produced from the comparator will cause the speed control device to increase the motor speed. Conversely, if the desired speed is lower than the actual speed, the speed control device will be caused to decrease the speed of the motor. This is a simple feedback system.
It should be noted that a phase locked loop is not the only method of removing unwanted signals. It is however particularly suitable due to its ability to remove noise. It is also convenient since it may be a single chip. Other means such as digital filtering may be used to remove unwanted signals.
Claims (18)
1. A speed determination system comprising transducer means for receiving air pressure variations produced from the exhaust of a pneumatic motor driving a device and producing an electrical signal proportional to the frequency of said air pressure variations thereby representing the actual speed of operation of the motor.
2. A speed determination system according to
Claim 1 further including means for converting said electrical signal into a signal representing the actual speed of operation of the device.
3. A speed determination system according to
Claim 1 or Claim 2 further including means for using said signal representing the actual speed of operation of the motor for controlling the speed of operation of the motor.
4. A speed determination system according to any one of the preceding claims including means for producing a signal corresponding to a desired speed of operation of the motor and comparator means for comparing said signal with the signal representing the actual speed of operation of the motor and producing an output signal representing the difference.
5. A speed determination system according to
Claim 4 including means for controlling the speed of the motor in response to said output signal of said comparator means.
6. A speed determination system according to Clalm 2 further including means operated by said signal representing the actual speed of operation of the device for controlling the actual speed of operation of the motor driving the device.
7. A speed determination system according to
Claim 2 or Claim 6 further including means for producing a signal corresponding to a desired speed of operation of the device and comparator means for comparing said signal with the signal representing the actual speed of operation of the device and producing an output signal representing the difference.
8. A speed determination system according to
Claim 7 including means for controlling the speed of operation of the motor in response to said output signal of said comparator means.
9. A speed determination system according to any one of the preceding claims including means for displaying the signal representing the actual speed of operation of the motor.
10. A speed determination system according to
Claim 2 or any one of Claims 6 to 9 including means for displaying the signal representing the actual speed of operation of the device.
11. A speed determination system substantially as herein described with reference to either of Figures 1 and 2 of the accompanying drawings.
12. A method for determining the speed of operation of apparatus driven by a pneumatic motor including sensing air pressure variations produced from the exhaust of the motor and converting these to a signal representing the actual speed of operation of the motor.
13. A method according to Claim 12 including the step of converting the signal representing the actual speed of operation of the motor into a signal representing the actual speed of operation of the apparatus.
14. A method according to Claim 12 or Claim 13 including using the signal representing the actual speed of operation of the motor for controlling the speed of the motor.
15. A method according to any one of Claims 12 to 14 including comparing the signal representing the actual speed of operation of the motor with a signal corresponding to a desired speed of operation of the motor, producing an output signal representing the difference and controlling the speed of operation of the motor in response to said difference signal.
16. A method according to Claim 13 including using the signal representing the actual speed of operation of the apparatus for controlling the speed of operation of the motor driving the apparatus.
17. A method according to Claim 13 or Claim 16 including comparing the signal representing the actual speed of operation of the apparatus with a signal corresponding to a desired speed of operation of the apparatus, producing a signal representing the difference and controlling the speed of operation of the motor in response to said difference signal.
18. A method for determining the speed of operation of apparatus driven by a pneumatic motor, the method being substantially as herein described with reference to Figures 1 and 2 of the accompanying drawings.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB08510972A GB2174499A (en) | 1985-04-30 | 1985-04-30 | Speed determination from exhaust note |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB08510972A GB2174499A (en) | 1985-04-30 | 1985-04-30 | Speed determination from exhaust note |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB8510972D0 GB8510972D0 (en) | 1985-06-05 |
| GB2174499A true GB2174499A (en) | 1986-11-05 |
Family
ID=10578443
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB08510972A Withdrawn GB2174499A (en) | 1985-04-30 | 1985-04-30 | Speed determination from exhaust note |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2174499A (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE4431720C1 (en) * | 1994-09-06 | 1996-02-29 | Sun Electric Deutschland Gmbh | Method and device for determining the rotational speed of internal combustion engines |
| DE19713182A1 (en) * | 1997-03-27 | 1998-10-01 | Siemens Ag | Method of determining engine revs. of motor vehicle for engine testing esp. exhaust gas testing |
| WO1999058984A1 (en) * | 1998-05-08 | 1999-11-18 | Josef Ott | Device for measuring the rotational speed of fluid-driven drive mechanisms |
| FR2844359A1 (en) * | 2002-09-11 | 2004-03-12 | Siemens Vdo Automotive | Palletization installation for use with fragile products, e.g. stacks of flat egg cartons, whereby a pushing mechanism is used to move rows of product stacks from a conveyor belt to a pallet support in layer by layer fashion |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3530672A (en) * | 1968-08-06 | 1970-09-29 | George D Wolff | Speed sensing device |
| US3538775A (en) * | 1968-07-29 | 1970-11-10 | Us Army | Rotational speed sensing method and apparatus |
| US3580086A (en) * | 1969-03-20 | 1971-05-25 | Gen Electric | Fluidic speed governor |
| GB1542476A (en) * | 1975-12-25 | 1979-03-21 | Nissan Motor | Method of and system for detecting misfire in internal combustion engine |
| EP0031806A2 (en) * | 1979-12-19 | 1981-07-08 | List, Hans | Apparatus for controlling the functioning of internal-combustion engine valves |
| US4328706A (en) * | 1979-07-27 | 1982-05-11 | Nippon Soken, Inc. | Tachometer suitable for use in engine maintenance |
-
1985
- 1985-04-30 GB GB08510972A patent/GB2174499A/en not_active Withdrawn
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3538775A (en) * | 1968-07-29 | 1970-11-10 | Us Army | Rotational speed sensing method and apparatus |
| US3530672A (en) * | 1968-08-06 | 1970-09-29 | George D Wolff | Speed sensing device |
| US3580086A (en) * | 1969-03-20 | 1971-05-25 | Gen Electric | Fluidic speed governor |
| GB1542476A (en) * | 1975-12-25 | 1979-03-21 | Nissan Motor | Method of and system for detecting misfire in internal combustion engine |
| US4328706A (en) * | 1979-07-27 | 1982-05-11 | Nippon Soken, Inc. | Tachometer suitable for use in engine maintenance |
| EP0031806A2 (en) * | 1979-12-19 | 1981-07-08 | List, Hans | Apparatus for controlling the functioning of internal-combustion engine valves |
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE4431720C1 (en) * | 1994-09-06 | 1996-02-29 | Sun Electric Deutschland Gmbh | Method and device for determining the rotational speed of internal combustion engines |
| US5640086A (en) * | 1994-09-06 | 1997-06-17 | Sun Electric Deutschland Gmbh | Tachometer based on electrical ripple and calibrated by mechanical engine signals |
| DE4431720C2 (en) * | 1994-09-06 | 2001-03-15 | Sun Electric Deutschland Gmbh | Method and device for determining the rotational speed of internal combustion engines |
| USRE38100E1 (en) | 1994-09-06 | 2003-04-29 | Sun Electric Deutschland Gmbh | Tachometer based on electrical ripple and calibrated by mechanical engine signals |
| DE19713182A1 (en) * | 1997-03-27 | 1998-10-01 | Siemens Ag | Method of determining engine revs. of motor vehicle for engine testing esp. exhaust gas testing |
| WO1999058984A1 (en) * | 1998-05-08 | 1999-11-18 | Josef Ott | Device for measuring the rotational speed of fluid-driven drive mechanisms |
| FR2844359A1 (en) * | 2002-09-11 | 2004-03-12 | Siemens Vdo Automotive | Palletization installation for use with fragile products, e.g. stacks of flat egg cartons, whereby a pushing mechanism is used to move rows of product stacks from a conveyor belt to a pallet support in layer by layer fashion |
Also Published As
| Publication number | Publication date |
|---|---|
| GB8510972D0 (en) | 1985-06-05 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |