CA1154126A - Motor speed control - Google Patents
Motor speed controlInfo
- Publication number
- CA1154126A CA1154126A CA000368728A CA368728A CA1154126A CA 1154126 A CA1154126 A CA 1154126A CA 000368728 A CA000368728 A CA 000368728A CA 368728 A CA368728 A CA 368728A CA 1154126 A CA1154126 A CA 1154126A
- Authority
- CA
- Canada
- Prior art keywords
- motor
- signal
- optical
- fluid
- coupling
- 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.)
- Expired
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
- B05B3/00—Spraying or sprinkling apparatus with moving outlet elements or moving deflecting elements
- B05B3/02—Spraying or sprinkling apparatus with moving outlet elements or moving deflecting elements with rotating elements
- B05B3/10—Spraying or sprinkling apparatus with moving outlet elements or moving deflecting elements with rotating elements discharging over substantially the whole periphery of the rotating member, i.e. the spraying being effected by centrifugal forces
- B05B3/1064—Spraying or sprinkling apparatus with moving outlet elements or moving deflecting elements with rotating elements discharging over substantially the whole periphery of the rotating member, i.e. the spraying being effected by centrifugal forces the liquid or other fluent material to be sprayed being axially supplied to the rotating member through a hollow rotating shaft
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
- B05B5/00—Electrostatic spraying apparatus; Spraying apparatus with means for charging the spray electrically; Apparatus for spraying liquids or other fluent materials by other electric means
- B05B5/025—Discharge apparatus, e.g. electrostatic spray guns
- B05B5/04—Discharge apparatus, e.g. electrostatic spray guns characterised by having rotary outlet or deflecting elements, i.e. spraying being also effected by centrifugal forces
- B05B5/0415—Driving means; Parts thereof, e.g. turbine, shaft, bearings
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
- B05B5/00—Electrostatic spraying apparatus; Spraying apparatus with means for charging the spray electrically; Apparatus for spraying liquids or other fluent materials by other electric means
- B05B5/025—Discharge apparatus, e.g. electrostatic spray guns
- B05B5/04—Discharge apparatus, e.g. electrostatic spray guns characterised by having rotary outlet or deflecting elements, i.e. spraying being also effected by centrifugal forces
- B05B5/0422—Discharge apparatus, e.g. electrostatic spray guns characterised by having rotary outlet or deflecting elements, i.e. spraying being also effected by centrifugal forces comprising means for controlling speed of rotation
-
- 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
- G01P3/44—Devices characterised by the use of electric or magnetic means for measuring angular speed
- G01P3/48—Devices characterised by the use of electric or magnetic means for measuring angular speed by measuring frequency of generated current or voltage
- G01P3/481—Devices characterised by the use of electric or magnetic means for measuring angular speed by measuring frequency of generated current or voltage of pulse signals
- G01P3/486—Devices characterised by the use of electric or magnetic means for measuring angular speed by measuring frequency of generated current or voltage of pulse signals delivered by photo-electric detectors
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P23/00—Arrangements or methods for the control of AC motors characterised by a control method other than vector control
- H02P23/16—Controlling the angular speed of one shaft
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Electrostatic Spraying Apparatus (AREA)
- Control Of Velocity Or Acceleration (AREA)
- Nozzles (AREA)
Abstract
A feedback system, for controlling the speed of a fluid motor having a fluid motor input, includes an optical-signal transmitter, an optical-signal receiver, an optically sensitive marker provided on the motor to couple the transmitter to the receiver intermittently as the motor rotates and provide an output signal indicative of motor rotation. A converter processes the output signal to provide a fluid signal which is fed back to the motor input. A mechanism is provided for braking the motor from an overspeed condition when the output signal exceeds a preselected value.
Description
---`` 1154~1.2~
The invention concerns an electrostatic enameling system with a revolving spray bell supported by a spray head, a spray bell drive, an enamel line through which the enamel can be fed, facultatively separate lines for feediny compressed air and solvent, and with a voltage supply serving to apply voltage across the spray bell.
Revolving spray disks or spray bells supported by a spray head which carries high voltage have been used for a long time in electrostatic enameling. For enameling, the enamel to be sprayed is fed to the spray disks or spray bells continuously. The spray~dlsks or spray bells were mostly driven by electromotors at ground potential, but also by slow-running electromotors on high~voltage potential. In addition, pneumatic motors were employed, which were mostly at high voltage potential.
While previously speeds~of ~rotation of 1,000 to 3,000 RPM were customary, rotational speeds from 10,000 to 30,000 RPM have been used recently,~ especially due to newer enamel materials. To achieve such rotational speeds with electromotors on ground~ potential, gearing and/or V-belt drives connected to~high voltage potential were used at the proper ratio. While pneumatic motors were usable on the high voltage side, lubrication problems arose in conjunction with these motors and~the useful life of their ball bearlngs.
Newly developed enamel materials, such as water .
enamel or so-called solventless enamel, require still greater speeds of rotation of approximately 40,000 to 70,000 RPM for which so-called turbodrives, con~ected to high voltage, are used. The turbodrives consist usually of a compressed air nozzle and an impeller wheel at which the compressed air from ,..
~,, ,,, , . . ... ~ ~ -1 , :,, ,. . .
, ~. . , 1~41~6 the nozzle is directed. ~he spray bells used at such high speeds of rotation have usually a relatively small diameter, about between 20 and 80 mm. Depending on diameter, the operational peripheral speeds of these spray bells range from 100 to 250 m/s. One problem of this drive type is constituted by the adjustment of the individually most favorable speed of rotation and by keeping it constant. In idling, with no enamel being fed, the speed of rotation is very high while under load, when enamel is being fed for spraying, it drops considerably. As a result, bearing wear is high in idling. When no spray bell is mounted, even higher and dangerous speeds of rotation are reached. In addition, an excessive speed of rotation produces a spray which is too dry and has an adverse effect on the finish. At a low speed of rotationj a high degree of atomization is not achieved, and thus no optimum enameling results either.
.
~ Based on these problems, the invention attempts, among other things, to advance an electrostatic enamel application system of the initially named type in a fashion such that an exact control of the speed of rotation of the turbodrive for the spray disk or spray bell (herein always referred to as spray bell for convenience) is accomplished without incurring problems in connection with the high voltage.
These problems are solved in the invention by providing a rotational speed sensor for sensing the speed of rotation of the spray bell, which sensor features an electrically insulating signal-transmission device which extends a sufficient insulation distance between a point connected to high voltage potential and a point connected to .. . .
" , , ~154~26 ground potential, in that the output signal of the rotational speed sensor is transmitted via signal-processing and signal-forming stages to a comparator to which a set value is fed by a set value emitter, and in that the output signal of the comparator is passed by way of further signal-processing stages to a control component. --A desired speed of rotation can accurately beachieved and kept constant at any operating conditions with the above characteristics. The constancy of the desired speed of rotation can be achieved also in the case of changes of the amount of enamel supplied or of the temperature or other parameters which usually have an influence upon the speed of rotation. With a varying size of the enameling surfaces, e.g., enamel quantity changes are preprogrammed in electrostatic enameling systems used in automotive facilities, which quantity changes require likewlse corresponding rotational speed changes for optimization which, according to the invention, can be preprogrammed as well.
Experiments have shown that any enamel material, ,, even enamel materials of the same type but with different shades can be optimally applied only at a specific speed of rotation which varies from the optimum RP~ for other enamel materials and other shades. The invention makes it possible to adjust a specific speed of rotation which is governed by the enameling material and the selected shade which, in the case of multicolor systems, can be handled automatically, e.g., with every paint change according to previous programming.
When the rotational speed is measured on a part connected to high voltage, for instance either the spray bell . .
.
,:
1154~Z6 or a spray bell drive connected to high voltage, a problem arises: that is, transmitting khe signal obtained through rot;ational speed measuring, for further processing by the Gontrol circuitry, from the high voltage side to a point which is approximately at ground potential. For that purpose, the `
invention provides a rotational speed sensor which features an electrically insulating signal transmission device with a signal transmission path which, with a sufficient insulating length, extends between a point connected to high voltage potential and a point connected to ground potential.
According to one broad aspect of the present inve~tion, there is provided a speed control system for a fluid motor having a motor fluid input, the system comprising a rotational speed sensor which derives an output signal indicative of the rotational speed of the motor, means for converting the output signal to a fluid signal, means for coupling the converting means to the motor input and means for braking the motor, the converter and braking means controlling motor speed.
According to another broad aspect of the present invention, there ;
is provided a feedback system for controlling the speed of a fluid motor having a motor fluid input, the system including an optical-signal trans-mitter, an optical-signal receiver, means`providing an optically sensitive marker, means for coupling the marker to the motor in driven engagement, the marker selectively coupling the optical-transmitter signal to the optical-signal receiver to provide an optical output signal indicative of motor rotation, means for converting the optical output signal to a fluid signal, means for coupling the converter to the motor input, and means or braking the motor, the converter and braking means controlling motor speed.
According to a further broad aspect of the present invention, there is provided a method for controlling rotation rate of a fluid motor, comprising the steps of establishing a desired rotation rate, monitoring the actual rotation rate, comparing the actual rotation rate to the desired rotation rate, generating a driving fluid error signal in response to such l~LS4~ 6 comparison, and supplying said error signal to the motor to correct the ~ctual rotation rate toward the desired rotation rate, the motor being a motor for rotating a rotary atomi~ing device of a coating material atomizing and dispensing system including means for feeding a selected coating material from a selected one of a plurality of sources for such coating materials to the atomizing device, supplying highrmagnitude electrical potential to the rotary atomizing device, the step of monitoring the actual rotatlon rate comprising the step of generating a light signal, coupling the light signal through a fiber optical conductor to a member which rotates with the rotary atomizing device, detecting reflections of the light signal from the member through a fiber optical conductor to maintain the electrically insulated integrity of the atomizing device from the return of the source of high-magnitude electrical potential while permitting the feedback of motor speed-related signals for motor and atomizer speed control, and processing the reflected signal coupled through the fiber optical conduGtor to an optical signal receiver, and processing the refIected light signal received by the optical signal receiver to obtain the actual rotation rate.
According to a particularly favorable embodiment, the speed sensor comprises the following components: an optical marking located in the high voltage area and revolving at a speed of rotation which is proportional to the speed of rotation of the spray bell, a light source, a photoelectric receiver connected to approximately ground potential and capable of emitting ~;
an electrical signal corresponding to the incident light, and a light-transmission segment with a first light-transmission section between the light source and the marking, and a second light-transmission section between the marking and the photoelectric receiver, with each light-transmission section possessing a sufficient insulating length between any points connected to high voltage and approximately ground potential. This rotation-al speed sensor design avoids conductive signal transmission devices, such as electrical lines and cables. By using, for the transmission of the signal - 5a -r~
: ~ . . . . ~ , :
~llS4~6 proportional to the speed of rotation, a light which is modulated in accord- :
ance with the rotational speed of the spray bell, insulation problems are ' ~.
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- 5b -~54~
precluded. The marking must be provided on a component which revolves together with the spray bell, for instance on the turbine wheel of a turbodrive or on some other wheel. The -wheel may be provided with a single marking or with a number of markings. When using only a single marking, signals corresponding to the speed of rotation are obtained. When using several markings in the peripheral direction on the wheel, a signal is obtained which equals an appropriate multiple of the rotational speed of the spray bell. The length of the light transmission sections must be selected at least large enough to ensure that, contingent on the high voltage applied, no arc-over to components at ground potential can occur, for instance to the light source and the photoelectric receiver.
The optical marking may favorably be ~ashionedj e~g., as a mirror wheel with a plurality of mirror segment surfaces. Owing to the good reflection of the mirror segment sarfaces, a weaker llght source can be employed.
~ In order to eliminate outside Iight lnfluences and, on the other hand, to make do with a relatively weak light soarce, a glass fiber OptlC transmitter (glass fiber light conductor~ is favorably provided as a light-transmission section between the light source and the marking and as a light-transmission section between the marking and the photoelectric component.
According to another suitable embodiment, the rotational speed sensor comprises the following components:
an electric signal generator coupled with the spray bell, for instance a revolving tachometer generator which emits intermittent signals at a frequency which is proportional to .
~. ~ . .... . .
~154~26 the speed of rotation of the spray bell, a light source capable of emitting at a high frequency intermittent light signals with the signals being supplied to the light source by the signal generator, facultatively by way of a pulse-forming circuit, and a light-transmission section, favorably with optical fibers and su~ficient insulation gap which passes the light signals from the light source to a photoelectric receiver which approximately carries ground potential. This embodiment has the advantage that the light transmission path from the light source via the optical fibers and to the photoelectric receiver can be completely encapsulated so that the path is practically not exposed to any outside influences, and specifically not to contamination and any deterioration of transmission properties caused thereby. Generally, it can be pointed out that by transmitting digital signals the transmission path of the light signals is at a rate less sensitlve than when transmltting analog light signals.
The light source is suitably a light-emitting diode, especially for reason of utility life and heat generatlon. According to a preferred embodiment, the spray head is attached to the end of an insulated support tube whose other end is fastened to a point of the enameling system which is connected to ground potential, with the optical fiber light conductors being run through the interior of the insulating tube. This makes for a particularly protected arrangement of the optical fibers. Besides, they are not subjected to bending stress when the spray head is moved to and fro. This design permits a practically complete elimination of oatside light influences. A still more rugged .
1~541~6 and operationally safe design of the rotational speed sensor according to the invention is obtained by molding the light source, the photoelectric receiver, their electrical leads, and the optical fiber parts terminating at them, in pressure-resistant fashion in a housing which favorably is fastened to the insulating tube.
According to another suitable embodiment, a compressed air generator driven by the spray bell is coupled with it as a rotational speed sensor, which compressed air generator is capable of producing in a compressed air line constructed from insulating material a static air pressure which is a function of the speed of rotatian of the bell, with a transducer, preferably a pressure-electric transducer, being provided on the other end of the pressure line in order to generate an output signal proportional to the speed of rotation of the spray bell. Again, the compressed air generator may be a turbine coup~ed with the shaft of the spray bell, but acting as ~a pressure generator. A rotational speed generator of such design permits extreme simplicity and operational dependability.
According to a modified embodiment, an ultrasonic generator coupLed with the spray bell may suitabIy be provided as a rotational speed sensor, generating ultrasonic pulses of a frequency which is proportional to the speed of rotation of the spray bell, with the ultrasonic pulses being transmitted via an insulating transmission line with sufficient insulation length to a signal transformer which lies at approximately ground potential and emits an electrical output signal. This embodiment may as well be designed extremely simple, rugged, and resistant to outside interference.
., 115~126 A pneumatic drive is suitably provided for the spray bell while the comparator is coupled, facultatively through the intermediary of an amplifier and an adaptor circuit, by an electric-pneumatic transducer whose output signal is transmitted to a pressure amplifier for the drive air of the pneumatic drive of the spray bell. According to a preferred embodiment, the signal-processing and forming stages arranged after the rotational speed sensor comprise a flip-flop ampl~ifier and, following the latter, a pulse-voltage~transducer, while with a suitably modified embodiment, the signal-processing and forming stages arranged after the rotational speed sensor ~eature a flip-flop amplifier, a frequency meter, and a digital-analog converter.
Thus, the actual signal processing is han~dled electrically.
For insulation reasons and because of the high speed of rotation, however, a pneumatic~system is preferred for the spray bell drive. Favorably provided is an enameling control where, in the case of changing from one color to another, a new set value is stored in the comparator and, if the actual speed of rotation is greater than the new set value, a switching amplifier will cause a valve to open and feed braking air to the pneumatic drive of the spray bell. If, upon changing from one enamel color to another, a rotational speed lower than the one used before is selected, a long time will pass upon shutoff of the compressed air used for the drive until the rotational speed of the spray bell drops to the new value. Therefore, the braking process is suitably accelerated in the simplest fashion by an additional nozzle which acts on the turbine wheel in a braking direction.
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Emb~diments of the invention will be explained hereafter with reference to the attached drawings, in which contextexpress re~erence is made to the drawings withi~regard to the teaching of the invention, due to the simplicity and clarity of the drawings.
Figure loshows a schematic of a first embodiment according to the invention;
Figure 2 shows a~lschematic of a modified part of Figure l; and Figure 3 shows a rotational speed curve of two electrostatic -enamel~ng systems with a revolving spray beIl, one operating controlled and one operating uncontrolled.
To begin with~ reference is made to Figure 1. A spray head 1 supports a spray bell 2 and is mounted on a support tube la constructed from insulating material. One end oflthe insulating tube la supports the spray head l~ and the other end of the insulating tube la is fastened to an enameling system point which is connected to ground potential. The enamel to be atomized is fed to the spray bell 2 via an enamel line (not shown). Other llnes~referred to below) make it possible to feed to the spray bell com-pressed air for improving the spray pattern and a solvent for cleaning the , spray bell in the case of color changes. The spray head is kept at high voltage potential (100 to 150 KV direct voltage) by a high voltage supply not illustrated in detail.
~ The spray bell 1 is driven by a turbodrive which, while not il-lustrated in detaill~ is connected with the spray bell 2 in non rotating fashion and features an impeller whbel 3~ and a compressed air nozzle ~not shown). Compressed air is fed via a compressed air line ~ to the compressed air nozzle.
Arranged on the back of the impeller wheel 3 is a mirror wheel 5 :-with n segment faces, with the mirror wheel 5 revolving past a reflection head 6. Light from a light-emltting diode 8~en~ergi~ed ~ya voltage source 8 is transmitted via an optical fiber conductor 7 and the reflection head 6 to ,! -lo-, . . .
' ~ ! ~ '. ! ...........
~154i2S
the mirror wheel 5. The bright segments of the mirror wheel 5 reflect the light back to the reflection head 6 and pass it via another fiber optics conductor 9 to a photoelectric receiver 10, for instance a photoelectric resistor. A potential separation is accomplished through the two light con-d~ctors 7, 9 between the spray head connected to high voltage and the emitter-receiver electronics connected to ground potential.
In order to keep the light conductors 7 and 9 as short as pos-sible and provide mechanical protection for them, they are run through the interior of the insulating support tube la. The light conductors Z, 9, as well as the light-emitting diode 8a and the photoelectric receiver 10 and their leads, are molded in a pressure-resistant manner in a PTB-tested~
housing. This housing is mounted at the rear end of the insulating support tube la.
Another possibility would be to arrange the light-emitting diade `
and ~he photoelectric receiver outside the hazardous area (indicated by the broken double lines in Figure 1) and the use of longer llght conductors.
However, these light conductors must be run from the turbodrive to the wall of the enameling booth. In the case of a~vertically moving spray head, they ~ must be capable of withstanding flexing. In addition, with such an arrange-- ment, an increased light loss may have to be tolerated. This loss can be compensated for by increased transmitting power of the light-emitting diode andlor by more sensitive photoelectric receivers.
The light pulses ~rotational speed multiplied by number of mirror~
wheel segments) received by the photoelectric receiver 10 are amplified by a flip-flop amplifier 11 (Schmitt trigger) and so processed that they can be passed to a frequency-to-voltage converter 12. Ihe output of this converter 12 is a voltage proportional to the speed of rotation and permits indication, for instance by means o~ a digital voltmeter 13. Alternatively, a frequency -~
meter 14 may as well be connected before the transducer 12, as is indicated by broken lines in Figure 1.
The voltage signal proportional to the speed of rotation is passed as an actual value to the comparator 15 which, contingent on the set l~llS~
value of a manually adjustable set value potentiometer 16 and/or of the set value output signal of a computer 17, transmits a control voltage to an am-plifier 18. Adjusted on this amplifier 18 are the zero point and the limit for a voltage-pressure ~V/P) transducer 19. The output signal of 0.2 to 1 bar of transducer 19 is amplified by a pressure amplifier 20 to a value of approximately 1 to 6 bars. The air flow to the turbodrive can be shut off completely by means of a solenoid valve 21.
In order to enable a quick rotational speed drop when changing an enamel which is applied with a spray head 1, the turbine is equipped with an additional braking air connection which is supplied by a braking air line 22. The air line 22 is connected to an appropriate braking nozzle (not shown) which is disposed to direct air on to the turbine wheel in a hraking direction.
A control command "rotational speed reduction" is given by the overriding enameling control to the electronic control circuitry of the tur-bine. This control command stores by way of the computer 17 a new set value ;
in the comparator 15. As long as the actual value exceeds this new set val-ue9 the braking valve 24 is opened by the switching amplifier 23 and the tur-bodrive slowed down briefly by the braking air supplied by way of the braking air line 22 to the braking nozzle. Instead of using a separate braking line 22 and braking nozzle a similar effect could be achieved by venting the drive line to atmosphere to stop drive air from passing to the turbodrive.
In the operational shutoff of the turbodrive by way of the solenoid valve 21, the braking valve 24 is inactive; the turbine comes gradually to a standstill.
A modification of Figure 1 is illustrated in Figure 2. Instead of the frequency-to-voltage converter 12 and the digital voltmeter 13 be-tween flip-flop amplifier 11 and comparator 15, a frequency meter 25 is .
coupled to the output of the frequency-to-voltage transducer 1~ and the digi-tal value of the frequency meter 25 is trcmsmitted to a digital-to-analog converter 26 which, for instance~ transforms a BCD-coded number ~` an ana-log voltage and feeds it as actual value to the comparator 15.
Figure 3 shows clearly that, when the turbodrive is adjusted to a specific idling speed and a speed regulation is not provided, the RPM
will drop with the amount of enamel fed to the spray bell per unit of time.
On the other hand, with the speed control system .according to 10the invention it is possible to keep a rotational speed adjusted in idling condition constant,`even when the spray bell is supplied with increasing amounts of enamel.
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The invention concerns an electrostatic enameling system with a revolving spray bell supported by a spray head, a spray bell drive, an enamel line through which the enamel can be fed, facultatively separate lines for feediny compressed air and solvent, and with a voltage supply serving to apply voltage across the spray bell.
Revolving spray disks or spray bells supported by a spray head which carries high voltage have been used for a long time in electrostatic enameling. For enameling, the enamel to be sprayed is fed to the spray disks or spray bells continuously. The spray~dlsks or spray bells were mostly driven by electromotors at ground potential, but also by slow-running electromotors on high~voltage potential. In addition, pneumatic motors were employed, which were mostly at high voltage potential.
While previously speeds~of ~rotation of 1,000 to 3,000 RPM were customary, rotational speeds from 10,000 to 30,000 RPM have been used recently,~ especially due to newer enamel materials. To achieve such rotational speeds with electromotors on ground~ potential, gearing and/or V-belt drives connected to~high voltage potential were used at the proper ratio. While pneumatic motors were usable on the high voltage side, lubrication problems arose in conjunction with these motors and~the useful life of their ball bearlngs.
Newly developed enamel materials, such as water .
enamel or so-called solventless enamel, require still greater speeds of rotation of approximately 40,000 to 70,000 RPM for which so-called turbodrives, con~ected to high voltage, are used. The turbodrives consist usually of a compressed air nozzle and an impeller wheel at which the compressed air from ,..
~,, ,,, , . . ... ~ ~ -1 , :,, ,. . .
, ~. . , 1~41~6 the nozzle is directed. ~he spray bells used at such high speeds of rotation have usually a relatively small diameter, about between 20 and 80 mm. Depending on diameter, the operational peripheral speeds of these spray bells range from 100 to 250 m/s. One problem of this drive type is constituted by the adjustment of the individually most favorable speed of rotation and by keeping it constant. In idling, with no enamel being fed, the speed of rotation is very high while under load, when enamel is being fed for spraying, it drops considerably. As a result, bearing wear is high in idling. When no spray bell is mounted, even higher and dangerous speeds of rotation are reached. In addition, an excessive speed of rotation produces a spray which is too dry and has an adverse effect on the finish. At a low speed of rotationj a high degree of atomization is not achieved, and thus no optimum enameling results either.
.
~ Based on these problems, the invention attempts, among other things, to advance an electrostatic enamel application system of the initially named type in a fashion such that an exact control of the speed of rotation of the turbodrive for the spray disk or spray bell (herein always referred to as spray bell for convenience) is accomplished without incurring problems in connection with the high voltage.
These problems are solved in the invention by providing a rotational speed sensor for sensing the speed of rotation of the spray bell, which sensor features an electrically insulating signal-transmission device which extends a sufficient insulation distance between a point connected to high voltage potential and a point connected to .. . .
" , , ~154~26 ground potential, in that the output signal of the rotational speed sensor is transmitted via signal-processing and signal-forming stages to a comparator to which a set value is fed by a set value emitter, and in that the output signal of the comparator is passed by way of further signal-processing stages to a control component. --A desired speed of rotation can accurately beachieved and kept constant at any operating conditions with the above characteristics. The constancy of the desired speed of rotation can be achieved also in the case of changes of the amount of enamel supplied or of the temperature or other parameters which usually have an influence upon the speed of rotation. With a varying size of the enameling surfaces, e.g., enamel quantity changes are preprogrammed in electrostatic enameling systems used in automotive facilities, which quantity changes require likewlse corresponding rotational speed changes for optimization which, according to the invention, can be preprogrammed as well.
Experiments have shown that any enamel material, ,, even enamel materials of the same type but with different shades can be optimally applied only at a specific speed of rotation which varies from the optimum RP~ for other enamel materials and other shades. The invention makes it possible to adjust a specific speed of rotation which is governed by the enameling material and the selected shade which, in the case of multicolor systems, can be handled automatically, e.g., with every paint change according to previous programming.
When the rotational speed is measured on a part connected to high voltage, for instance either the spray bell . .
.
,:
1154~Z6 or a spray bell drive connected to high voltage, a problem arises: that is, transmitting khe signal obtained through rot;ational speed measuring, for further processing by the Gontrol circuitry, from the high voltage side to a point which is approximately at ground potential. For that purpose, the `
invention provides a rotational speed sensor which features an electrically insulating signal transmission device with a signal transmission path which, with a sufficient insulating length, extends between a point connected to high voltage potential and a point connected to ground potential.
According to one broad aspect of the present inve~tion, there is provided a speed control system for a fluid motor having a motor fluid input, the system comprising a rotational speed sensor which derives an output signal indicative of the rotational speed of the motor, means for converting the output signal to a fluid signal, means for coupling the converting means to the motor input and means for braking the motor, the converter and braking means controlling motor speed.
According to another broad aspect of the present invention, there ;
is provided a feedback system for controlling the speed of a fluid motor having a motor fluid input, the system including an optical-signal trans-mitter, an optical-signal receiver, means`providing an optically sensitive marker, means for coupling the marker to the motor in driven engagement, the marker selectively coupling the optical-transmitter signal to the optical-signal receiver to provide an optical output signal indicative of motor rotation, means for converting the optical output signal to a fluid signal, means for coupling the converter to the motor input, and means or braking the motor, the converter and braking means controlling motor speed.
According to a further broad aspect of the present invention, there is provided a method for controlling rotation rate of a fluid motor, comprising the steps of establishing a desired rotation rate, monitoring the actual rotation rate, comparing the actual rotation rate to the desired rotation rate, generating a driving fluid error signal in response to such l~LS4~ 6 comparison, and supplying said error signal to the motor to correct the ~ctual rotation rate toward the desired rotation rate, the motor being a motor for rotating a rotary atomi~ing device of a coating material atomizing and dispensing system including means for feeding a selected coating material from a selected one of a plurality of sources for such coating materials to the atomizing device, supplying highrmagnitude electrical potential to the rotary atomizing device, the step of monitoring the actual rotatlon rate comprising the step of generating a light signal, coupling the light signal through a fiber optical conductor to a member which rotates with the rotary atomizing device, detecting reflections of the light signal from the member through a fiber optical conductor to maintain the electrically insulated integrity of the atomizing device from the return of the source of high-magnitude electrical potential while permitting the feedback of motor speed-related signals for motor and atomizer speed control, and processing the reflected signal coupled through the fiber optical conduGtor to an optical signal receiver, and processing the refIected light signal received by the optical signal receiver to obtain the actual rotation rate.
According to a particularly favorable embodiment, the speed sensor comprises the following components: an optical marking located in the high voltage area and revolving at a speed of rotation which is proportional to the speed of rotation of the spray bell, a light source, a photoelectric receiver connected to approximately ground potential and capable of emitting ~;
an electrical signal corresponding to the incident light, and a light-transmission segment with a first light-transmission section between the light source and the marking, and a second light-transmission section between the marking and the photoelectric receiver, with each light-transmission section possessing a sufficient insulating length between any points connected to high voltage and approximately ground potential. This rotation-al speed sensor design avoids conductive signal transmission devices, such as electrical lines and cables. By using, for the transmission of the signal - 5a -r~
: ~ . . . . ~ , :
~llS4~6 proportional to the speed of rotation, a light which is modulated in accord- :
ance with the rotational speed of the spray bell, insulation problems are ' ~.
~ ' ' ' '' : : , "'~
- 5b -~54~
precluded. The marking must be provided on a component which revolves together with the spray bell, for instance on the turbine wheel of a turbodrive or on some other wheel. The -wheel may be provided with a single marking or with a number of markings. When using only a single marking, signals corresponding to the speed of rotation are obtained. When using several markings in the peripheral direction on the wheel, a signal is obtained which equals an appropriate multiple of the rotational speed of the spray bell. The length of the light transmission sections must be selected at least large enough to ensure that, contingent on the high voltage applied, no arc-over to components at ground potential can occur, for instance to the light source and the photoelectric receiver.
The optical marking may favorably be ~ashionedj e~g., as a mirror wheel with a plurality of mirror segment surfaces. Owing to the good reflection of the mirror segment sarfaces, a weaker llght source can be employed.
~ In order to eliminate outside Iight lnfluences and, on the other hand, to make do with a relatively weak light soarce, a glass fiber OptlC transmitter (glass fiber light conductor~ is favorably provided as a light-transmission section between the light source and the marking and as a light-transmission section between the marking and the photoelectric component.
According to another suitable embodiment, the rotational speed sensor comprises the following components:
an electric signal generator coupled with the spray bell, for instance a revolving tachometer generator which emits intermittent signals at a frequency which is proportional to .
~. ~ . .... . .
~154~26 the speed of rotation of the spray bell, a light source capable of emitting at a high frequency intermittent light signals with the signals being supplied to the light source by the signal generator, facultatively by way of a pulse-forming circuit, and a light-transmission section, favorably with optical fibers and su~ficient insulation gap which passes the light signals from the light source to a photoelectric receiver which approximately carries ground potential. This embodiment has the advantage that the light transmission path from the light source via the optical fibers and to the photoelectric receiver can be completely encapsulated so that the path is practically not exposed to any outside influences, and specifically not to contamination and any deterioration of transmission properties caused thereby. Generally, it can be pointed out that by transmitting digital signals the transmission path of the light signals is at a rate less sensitlve than when transmltting analog light signals.
The light source is suitably a light-emitting diode, especially for reason of utility life and heat generatlon. According to a preferred embodiment, the spray head is attached to the end of an insulated support tube whose other end is fastened to a point of the enameling system which is connected to ground potential, with the optical fiber light conductors being run through the interior of the insulating tube. This makes for a particularly protected arrangement of the optical fibers. Besides, they are not subjected to bending stress when the spray head is moved to and fro. This design permits a practically complete elimination of oatside light influences. A still more rugged .
1~541~6 and operationally safe design of the rotational speed sensor according to the invention is obtained by molding the light source, the photoelectric receiver, their electrical leads, and the optical fiber parts terminating at them, in pressure-resistant fashion in a housing which favorably is fastened to the insulating tube.
According to another suitable embodiment, a compressed air generator driven by the spray bell is coupled with it as a rotational speed sensor, which compressed air generator is capable of producing in a compressed air line constructed from insulating material a static air pressure which is a function of the speed of rotatian of the bell, with a transducer, preferably a pressure-electric transducer, being provided on the other end of the pressure line in order to generate an output signal proportional to the speed of rotation of the spray bell. Again, the compressed air generator may be a turbine coup~ed with the shaft of the spray bell, but acting as ~a pressure generator. A rotational speed generator of such design permits extreme simplicity and operational dependability.
According to a modified embodiment, an ultrasonic generator coupLed with the spray bell may suitabIy be provided as a rotational speed sensor, generating ultrasonic pulses of a frequency which is proportional to the speed of rotation of the spray bell, with the ultrasonic pulses being transmitted via an insulating transmission line with sufficient insulation length to a signal transformer which lies at approximately ground potential and emits an electrical output signal. This embodiment may as well be designed extremely simple, rugged, and resistant to outside interference.
., 115~126 A pneumatic drive is suitably provided for the spray bell while the comparator is coupled, facultatively through the intermediary of an amplifier and an adaptor circuit, by an electric-pneumatic transducer whose output signal is transmitted to a pressure amplifier for the drive air of the pneumatic drive of the spray bell. According to a preferred embodiment, the signal-processing and forming stages arranged after the rotational speed sensor comprise a flip-flop ampl~ifier and, following the latter, a pulse-voltage~transducer, while with a suitably modified embodiment, the signal-processing and forming stages arranged after the rotational speed sensor ~eature a flip-flop amplifier, a frequency meter, and a digital-analog converter.
Thus, the actual signal processing is han~dled electrically.
For insulation reasons and because of the high speed of rotation, however, a pneumatic~system is preferred for the spray bell drive. Favorably provided is an enameling control where, in the case of changing from one color to another, a new set value is stored in the comparator and, if the actual speed of rotation is greater than the new set value, a switching amplifier will cause a valve to open and feed braking air to the pneumatic drive of the spray bell. If, upon changing from one enamel color to another, a rotational speed lower than the one used before is selected, a long time will pass upon shutoff of the compressed air used for the drive until the rotational speed of the spray bell drops to the new value. Therefore, the braking process is suitably accelerated in the simplest fashion by an additional nozzle which acts on the turbine wheel in a braking direction.
,...................................... .
_g_ :. ,......... . : - ~
.
~lS4~
Emb~diments of the invention will be explained hereafter with reference to the attached drawings, in which contextexpress re~erence is made to the drawings withi~regard to the teaching of the invention, due to the simplicity and clarity of the drawings.
Figure loshows a schematic of a first embodiment according to the invention;
Figure 2 shows a~lschematic of a modified part of Figure l; and Figure 3 shows a rotational speed curve of two electrostatic -enamel~ng systems with a revolving spray beIl, one operating controlled and one operating uncontrolled.
To begin with~ reference is made to Figure 1. A spray head 1 supports a spray bell 2 and is mounted on a support tube la constructed from insulating material. One end oflthe insulating tube la supports the spray head l~ and the other end of the insulating tube la is fastened to an enameling system point which is connected to ground potential. The enamel to be atomized is fed to the spray bell 2 via an enamel line (not shown). Other llnes~referred to below) make it possible to feed to the spray bell com-pressed air for improving the spray pattern and a solvent for cleaning the , spray bell in the case of color changes. The spray head is kept at high voltage potential (100 to 150 KV direct voltage) by a high voltage supply not illustrated in detail.
~ The spray bell 1 is driven by a turbodrive which, while not il-lustrated in detaill~ is connected with the spray bell 2 in non rotating fashion and features an impeller whbel 3~ and a compressed air nozzle ~not shown). Compressed air is fed via a compressed air line ~ to the compressed air nozzle.
Arranged on the back of the impeller wheel 3 is a mirror wheel 5 :-with n segment faces, with the mirror wheel 5 revolving past a reflection head 6. Light from a light-emltting diode 8~en~ergi~ed ~ya voltage source 8 is transmitted via an optical fiber conductor 7 and the reflection head 6 to ,! -lo-, . . .
' ~ ! ~ '. ! ...........
~154i2S
the mirror wheel 5. The bright segments of the mirror wheel 5 reflect the light back to the reflection head 6 and pass it via another fiber optics conductor 9 to a photoelectric receiver 10, for instance a photoelectric resistor. A potential separation is accomplished through the two light con-d~ctors 7, 9 between the spray head connected to high voltage and the emitter-receiver electronics connected to ground potential.
In order to keep the light conductors 7 and 9 as short as pos-sible and provide mechanical protection for them, they are run through the interior of the insulating support tube la. The light conductors Z, 9, as well as the light-emitting diode 8a and the photoelectric receiver 10 and their leads, are molded in a pressure-resistant manner in a PTB-tested~
housing. This housing is mounted at the rear end of the insulating support tube la.
Another possibility would be to arrange the light-emitting diade `
and ~he photoelectric receiver outside the hazardous area (indicated by the broken double lines in Figure 1) and the use of longer llght conductors.
However, these light conductors must be run from the turbodrive to the wall of the enameling booth. In the case of a~vertically moving spray head, they ~ must be capable of withstanding flexing. In addition, with such an arrange-- ment, an increased light loss may have to be tolerated. This loss can be compensated for by increased transmitting power of the light-emitting diode andlor by more sensitive photoelectric receivers.
The light pulses ~rotational speed multiplied by number of mirror~
wheel segments) received by the photoelectric receiver 10 are amplified by a flip-flop amplifier 11 (Schmitt trigger) and so processed that they can be passed to a frequency-to-voltage converter 12. Ihe output of this converter 12 is a voltage proportional to the speed of rotation and permits indication, for instance by means o~ a digital voltmeter 13. Alternatively, a frequency -~
meter 14 may as well be connected before the transducer 12, as is indicated by broken lines in Figure 1.
The voltage signal proportional to the speed of rotation is passed as an actual value to the comparator 15 which, contingent on the set l~llS~
value of a manually adjustable set value potentiometer 16 and/or of the set value output signal of a computer 17, transmits a control voltage to an am-plifier 18. Adjusted on this amplifier 18 are the zero point and the limit for a voltage-pressure ~V/P) transducer 19. The output signal of 0.2 to 1 bar of transducer 19 is amplified by a pressure amplifier 20 to a value of approximately 1 to 6 bars. The air flow to the turbodrive can be shut off completely by means of a solenoid valve 21.
In order to enable a quick rotational speed drop when changing an enamel which is applied with a spray head 1, the turbine is equipped with an additional braking air connection which is supplied by a braking air line 22. The air line 22 is connected to an appropriate braking nozzle (not shown) which is disposed to direct air on to the turbine wheel in a hraking direction.
A control command "rotational speed reduction" is given by the overriding enameling control to the electronic control circuitry of the tur-bine. This control command stores by way of the computer 17 a new set value ;
in the comparator 15. As long as the actual value exceeds this new set val-ue9 the braking valve 24 is opened by the switching amplifier 23 and the tur-bodrive slowed down briefly by the braking air supplied by way of the braking air line 22 to the braking nozzle. Instead of using a separate braking line 22 and braking nozzle a similar effect could be achieved by venting the drive line to atmosphere to stop drive air from passing to the turbodrive.
In the operational shutoff of the turbodrive by way of the solenoid valve 21, the braking valve 24 is inactive; the turbine comes gradually to a standstill.
A modification of Figure 1 is illustrated in Figure 2. Instead of the frequency-to-voltage converter 12 and the digital voltmeter 13 be-tween flip-flop amplifier 11 and comparator 15, a frequency meter 25 is .
coupled to the output of the frequency-to-voltage transducer 1~ and the digi-tal value of the frequency meter 25 is trcmsmitted to a digital-to-analog converter 26 which, for instance~ transforms a BCD-coded number ~` an ana-log voltage and feeds it as actual value to the comparator 15.
Figure 3 shows clearly that, when the turbodrive is adjusted to a specific idling speed and a speed regulation is not provided, the RPM
will drop with the amount of enamel fed to the spray bell per unit of time.
On the other hand, with the speed control system .according to 10the invention it is possible to keep a rotational speed adjusted in idling condition constant,`even when the spray bell is supplied with increasing amounts of enamel.
' ~.:
~, ,~
, ~ '~
-13- ::
:-
Claims (14)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A feedback system for controlling the speed of a fluid motor having a motor fluid input, the system including an optical-signal trans-mitter, an optical-signal receiver, means providing an optically sensitive marker, means for coupling the marker to the motor in driven engagement, the marker selectively coupling the optical-transmitter signal to the optical-signal receiver to provide an optical output signal indicative of motor rotation, means for converting the optical output signal to a fluid signal, means for coupling the converter to the motor input, and means for braking the motor, the converter and braking means controlling motor speed.
2. The apparatus of claim 1 wherein the braking means includes means for comparing motor speed to desired motor speed, and valve means responsive to the comparing means for controlling braking fluid flow in the motor.
3. The apparatus of claim 2 wherein the valve means includes means for venting fluid from the motor when motor speed is excessive.
4. The apparatus of claim 2 wherein the valve means includes means for restricting the flow of fluid from the motor fluid input into the motor.
5. The apparatus of claim 2 wherein the valve means includes a noz-zle for directing braking fluid against motor components to effect braking of the motor.
6. A speed control system for a fluid motor having a motor fluid in-put, the system comprising a rotational speed sensor which derives an output signal indicative of the rotational speed of the motor, means for converting the output signal to a fluid signal, means for coupling the converting means to the motor input and means for braking the motor, the converter and braking means controlling motor speed.
7. A feedback system for controlling the speed of a fluid motor which drives a rotary atomizing device for atomizing a coating material, means for providing a high electrostatic potential difference between the device and a target to be coated by coating material dispensed from the device, the fluid motor being subject to load variations which otherwise would adversely affect the rate of rotation of the device, the fluid motor having a motor fluid input, the system including an optical-signal transmitter, an optical-signal receiver electrically insulated from the electrostatic potential on the atomizing device, means providing an optically sensitive marker, means for coupling the marker to the motor in driven engagement, the marker selectively coupling the optical-transmitter signal to the optical-signal receiver to provide an optical output signal indicative of motor rotation, means for converting the optical output signal to a fluid signal, means for coupling the converter to the motor input, and means for braking the motor, the converter and braking means controlling motor speed.
8. A fluid motor having a motor fluid input, a feedback system for controlling the operating speed of the motor, the system including an optical-signal transmitter, an optical-signal receiver, means providing an optical coupler, means for coupling the optical coupler to the motor in driven engagement, the optical coupler selectively coupling the optical-transmitter signal to the optical-signal receiver as the motor operates to provide an optical output signal indicative of motor operation, means for converting the optical output signal to a motor fluid drive signal, means for coupling the converter to the motor fluid input of the motor, means for braking the motor, means for coupling the converter to the braking means, the control signal and braking means controlling the motor speed, the motor being a motor for rotating a rotary atomizing device of a coating material atomizing and dispensing system including means for feeding a selected coating material from a selected one of a plurality of sources for such coating materials to the atomizing device, a source of high-magnitude electrical potential, means for coupling the potential source to the motor, a fiber optical conductor for coupling the light signal from the optical signal transmitter to the optical coupler, and a fiber optical conductor for coupling the light signal from the optical coupler to the optical signal receiver to maintain the electrically insulated integrity of the atomizing device from the return of the source of high-magnitude electrical potential while permitting the feed-back of motor speed-related signals for motor and atomizer speed control.
9. A fluid motor having a driving fluid input, a feedback system for controlling the rate of rotation of the fluid motor, the system including means providing an optically reflective pattern on the motor, an optical-signal transmitter for directing a beam of light onto the pattern, an optical-signal receiver for detecting reflections of the light beam from the pattern to provide an optical output signal, first means for converting the optical output signal to a signal indicative of the actual rate of rotation of the rotary portion, the first converting means including a control input for selecting a desired rate of rotation of the rotary portion, means for comparing the signal indicative of the actual rate of rotation of the rotary portion to the control input and for generating an error signal in response to such comparison, second means for converting the error signal to a fluid signal, and means for coupling the second converting means to the fluid input of the motor to maintain the desired rate of rotation, the second converting means including means for braking the motor, the motor being a motor for rotating a rotary atomizer of a coating material atomizing and dispensing system including means for feeding a selected coating material from a selected one of a plurality of sources for such coating materials to the atomizer, a source of high-magnitude electrical potential and means for coupling the high-magnitude potential source to the rotary atomizer, a fiber optical conductor for coupling the beam of light from the optical-signal transmitter to the pattern and a fiber optical conductor for coupling reflections from the pattern to the optical signal receiver to preserve the electrically insulated integrity of the atomizing device from the return to the source of high-magnitude electrical potential while permitting the feedback of motor speed-related signals for motor and atomizer speed control.
10. A fluid motor having a driving fluid input and a rotary portion, a feedback system for controlling the rate of rotation of the fluid motor, the system including means providing an optically reflective pattern on the rotary portion, an optical-signal transmitter for directing a beam of light onto the pattern, an optical-signal receiver for detecting reflections of the light beam from the pattern to provide an optical output signal, first means for converting the optical output signal to a signal indicative of the actual rate of rotation of the rotary portion, the first converting means including a control input for selecting a desired rate of rotation of the rotary portion, means for comparing the signal indicative of the actual rate of rotation of the rotary portion to the control input and for generating an error signal in response to such comparison, second means for converting the error signal to a fluid signal, and means for coupling the second converting means to the fluid input of the motor to correct the actual rate of rotation of the rotary portion, the second converting means including means for braking the motor, the motor being a motor for rotating a rotary atomizer of a coating material atomizing and dispensing system including means for feeding a selected coating material from a selected one of a plurality of sources for such coating materials to the atomizing device, a source of high-magnitude electrical potential and means for coupling the high-magnitude potential source to the rotary atomizing device, a fiber optical conductor for coupling the beam of light from the optical-signal transmitter to the pattern and a fiber optical conductor for coupling reflections from the pattern to the optical signal receiver to maintain the electrical insulation of the atomizing device from the return to the source of high-magnitude electrical potential while permitting the feedback of motor speed-related signals for motor and atomizing device speed control.
11. A fluid motor having a driving fluid input for rotating the motor rotary portion, a feedback system for controlling the rate of rotation of the fluid motor, the system including means providing an optically reflective pattern on the rotary portion, an optical-signal transmitter for directing a beam of light onto the pattern, an optical-signal receiver for detecting reflections of the light beam from the pattern to provide an optical output signal, an optical pulse processor for processing optical output signals and for generating electrical signals indicative of motor revolutions, a clock for generating a time base, a signal processor, and means for coupling the optical pulse processor and clock to the signal processor to generate a signal indicative of motor revolutions per unit time, a comparator including a control input for selecting a desired rate of rotation of the rotary portion for comparing the processor output signal to the control input and for generating an error signal in response to such comparison, means for converting the error signal to a fluid signal, and means for coupling the converting means to the fluid input of the motor, the converting means including means for braking the motor, the motor being a motor for rotating a rotary atomizing device from which atomized material is dispensed, means for feeding a selected coating material from a selected one of a plurality of sources for such coating materials for atomization from the rotary atomizing device, a source of high-magnitude electrical potential and means for coupling the high-magnitude potential source to the rotary atomizing device, a fiber optical conductor for coupling the beam of light from the optical-signal transmitter to the pattern and a fiber optical conductor for coupling reflections from the pattern to the optical signal receiver to main-tain the electrical insulation of the rotary atomizing device from the return to the source of high-magnitude electrical potential while permitting the feedback of motor speed-related signals for motor and atomizing device speed control.
12. A fluid motor having a driving fluid input for rotating a rotary portion of the motor, a feedback system for controlling the rate of rotation of the fluid motor, the system including means providing an optically reflective pattern on the motor rotary portion, an optical-signal transmitter for directing a beam of light onto the pattern, an optical-signal receiver for detecting reflections of the light beam from the pattern to provide an optical output signal, first means for converting the optical output signal to a signal indicative of the actual rate of rotation of the rotary portion, the first converting means including a control input for selecting a desired rate of rotation of the rotary portion, means for comparing the signal indicative of the actual rate of rotation of the rotary portion to the control input and for generating an error signal in response to such comparison, second means for converting the error signal to a fluid signal, means for amplifying the fluid signal, means for coupling the fluid signal amplifier to a source of driving fluid for the motor, to the second converting means and to the fluid input of the motor, means for braking the motor, means for coupling the braking means to the motor, means for coupling the comparing means to the braking means, the motor being a motor for driving a rotary atomizing device from which atomized material is dispensed, means for feeding a selected coating material from a selected one of a plurality of sources for such coating materials for atomization from the rotary atomizing device, a source of high-magnitude electrical potential and means for coupling the high-magnitude potential source to the rotary portion, a fiber optical conductor for coupling the beam of light from the optical-signal transmitter to the pattern and a fiber optical conductor for coupling reflections from the pattern to the optical signal receiver to maintain the electrical insulation of the rotary atomizing device from the return to the source of high-magnitude electrical potential while permitting the feedback of motor speed-related signals for motor and atomizing device speed control.
13. An electrostatic coating material application system comprising a rotary atomizer supported by a fluid motor for rotating the atomizer, the fluid motor having a driving fluid input and fluid braking means, a coating material delivery line through which coating material can be fed, faculatively separate lines for supplying compressed air and solvent, and a high-voltage supply through which high voltage can be applied to the atomizing device, a rotary speed sensor for sensing the rotary speed of the atomizing device, the sensor including a fiber glass section for electrically insulating the atomizing device while providing a signal transmission path which extends with a sufficient insulating length between a point carrying the high voltage and essentially ground potential, an optical marker which revolves at a speed proportional to the speed of the atomizer, a light source and a photoelectric receiver capable of emitting an electrical signal in keeping with the impinging light, the output signal of the rotary speed sensor being passed through signal-processing and signal-forming stages to a comparator to which is supplied a set value through a desired rotational speed set value generator, and the comparator output signal being transmitted through further signal-processing stages, including means for converting the comparator out-put signal to a fluid signal, to the driving fluid input and the braking means for controlling the rotary speed of the atomizer.
14. A method for controlling rotation rate of a fluid motor, comprising the steps of establishing a desired rotation rate, monitoring the actual rotation rate, comparing the actual rotation rate to the desired rotation rate, generating a driving fluid error signal in response to such comparison, and supplying said error signal to the motor to correct the actual rotation rate toward the desired rotation rate, the motor being a motor for rotating a rotary atomizing device of a coating material atomizing and dispensing system including means for feeding a selected coating material from a selected one of a plurality of sources for such coating materials to the atomizing device, supplying high-magnitude electrical potential to the rotary atomizing device, the step of monitoring the actual rotation rate comprising the step of generating a light signal, coupling the light signal through a fiber optical conductor to a member which rotates with the rotary atomizing device, detecting reflections of the light signal from the member through a fiber optical conductor to maintain the electrically insulated integrity of the atomizing device from the return of the source of high-magnitude electrical potential while permitting the feedback of motor speed-related signals for motor and atomizer speed control, and processing the reflected signal coupled through the fiber optical conductor to an optical signal receiver, and processing the reflected light signal received by the optical signal receiver to obtain the actual rotation rate.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US11322180A | 1980-01-18 | 1980-01-18 | |
| DEP3002206.1 | 1980-01-22 | ||
| DE19803002206 DE3002206A1 (en) | 1980-01-18 | 1980-01-22 | Vehicle spray gun motor speed control device - utilises optical head assembly to detect rotational speed of patterned disc |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1154126A true CA1154126A (en) | 1983-09-20 |
Family
ID=25783313
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000368728A Expired CA1154126A (en) | 1980-01-18 | 1981-01-16 | Motor speed control |
Country Status (9)
| Country | Link |
|---|---|
| AU (1) | AU529910B2 (en) |
| BR (1) | BR8100252A (en) |
| CA (1) | CA1154126A (en) |
| DE (1) | DE3002206A1 (en) |
| FR (1) | FR2474192A1 (en) |
| GB (1) | GB2068152B (en) |
| HK (1) | HK28288A (en) |
| IT (1) | IT1143277B (en) |
| SE (1) | SE452209B (en) |
Families Citing this family (16)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5745357A (en) * | 1980-09-02 | 1982-03-15 | Champion Spark Plug Co | Rotary atomizing painting device |
| AU526982B2 (en) * | 1981-04-16 | 1983-02-10 | Ransburg Corp. | Coating material atomizing and dispensing system |
| US4997130A (en) * | 1986-06-26 | 1991-03-05 | Illinois Tool Works, Inc. | Air bearing rotary atomizer |
| US4936507A (en) * | 1986-06-26 | 1990-06-26 | The Devilbiss Company | Rotary atomizer with high voltage isolating speed measurement |
| DE3822835A1 (en) * | 1988-07-06 | 1990-03-08 | Josef Schucker | Process and arrangement for coating workpiece surfaces |
| US4965444A (en) * | 1988-08-17 | 1990-10-23 | Ransburg Corporation | Automatic gain control fiber optica-to-electrical transceiver |
| DE4306800C2 (en) * | 1993-03-04 | 1998-07-02 | Duerr Gmbh & Co | Coating device with a rotary atomizer |
| DE10053294C1 (en) * | 2000-10-27 | 2002-07-04 | Eisenmann Lacktechnik Kg | High-speed rotary atomizer for applying powder coating |
| FR2823855B1 (en) * | 2001-04-20 | 2003-07-25 | Eisenmann France Sarl | ROTATION SPEED READING DEVICE FOR ROTATING BOWL PAINT SPRAYER |
| DE10233005B4 (en) | 2002-07-20 | 2004-09-16 | Eisenmann Lacktechnik Kg | Device for supplying a sensor with high electrical potential in a paint shop with electrical energy |
| DE10237128B4 (en) * | 2002-08-13 | 2019-03-14 | Dürr Systems Ag | Operating method for a rotary atomizing turbine and corresponding arrangement |
| DE102007033892A1 (en) | 2007-07-20 | 2009-01-22 | Dürr Systems GmbH | Method for process diagnostics and rotary atomizer arrangement |
| SE532224C2 (en) * | 2008-02-15 | 2009-11-17 | Atlas Copco Tools Ab | Pneumatic power tool provided with indicator for working parameter values |
| FR2941877B1 (en) * | 2009-02-09 | 2011-04-08 | Sames Technologies | ELECTROSTATIC PROJECTOR HAVING A ROTATION SPEED DETECTION DEVICE |
| DE102016104655A1 (en) | 2016-03-14 | 2017-09-14 | Gema Switzerland Gmbh | Plant and method for refining and / or garnishing foodstuffs |
| DE102016006085A1 (en) * | 2016-05-20 | 2017-11-23 | Eisenmann Se | rotary atomizers |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2245950A1 (en) * | 1973-09-28 | 1975-04-25 | Peugeot & Renault | Angular speed measuring device - has optical sensor for use with printed circuit motor to sense printed pattern |
| DE2755343A1 (en) * | 1977-12-12 | 1979-06-13 | Papst Motoren Kg | SPEED CONTROL ARRANGEMENT |
-
1980
- 1980-01-22 DE DE19803002206 patent/DE3002206A1/en active Granted
-
1981
- 1981-01-14 AU AU66199/81A patent/AU529910B2/en not_active Ceased
- 1981-01-15 GB GB8101189A patent/GB2068152B/en not_active Expired
- 1981-01-15 SE SE8100214A patent/SE452209B/en not_active IP Right Cessation
- 1981-01-16 FR FR8100745A patent/FR2474192A1/en active Granted
- 1981-01-16 CA CA000368728A patent/CA1154126A/en not_active Expired
- 1981-01-16 IT IT67050/81A patent/IT1143277B/en active
- 1981-01-16 BR BR8100252A patent/BR8100252A/en unknown
-
1988
- 1988-04-21 HK HK282/88A patent/HK28288A/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| HK28288A (en) | 1988-04-29 |
| AU6619981A (en) | 1982-04-22 |
| GB2068152B (en) | 1984-08-30 |
| BR8100252A (en) | 1981-08-04 |
| IT8167050A0 (en) | 1981-01-16 |
| FR2474192B1 (en) | 1984-05-18 |
| FR2474192A1 (en) | 1981-07-24 |
| DE3002206A1 (en) | 1981-07-23 |
| SE8100214L (en) | 1981-07-19 |
| GB2068152A (en) | 1981-08-05 |
| AU529910B2 (en) | 1983-06-23 |
| IT1143277B (en) | 1986-10-22 |
| SE452209B (en) | 1987-11-16 |
| DE3002206C2 (en) | 1987-12-23 |
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