CA1154844A - Motor speed control - Google Patents
Motor speed controlInfo
- Publication number
- CA1154844A CA1154844A CA000368687A CA368687A CA1154844A CA 1154844 A CA1154844 A CA 1154844A CA 000368687 A CA000368687 A CA 000368687A CA 368687 A CA368687 A CA 368687A CA 1154844 A CA1154844 A CA 1154844A
- 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
- 239000012530 fluid Substances 0.000 claims abstract description 87
- 230000003287 optical effect Effects 0.000 claims abstract description 72
- 239000003550 marker Substances 0.000 claims abstract description 14
- 238000012545 processing Methods 0.000 claims abstract description 7
- 230000008878 coupling Effects 0.000 claims description 55
- 238000010168 coupling process Methods 0.000 claims description 55
- 238000005859 coupling reaction Methods 0.000 claims description 55
- 239000000463 material Substances 0.000 claims description 43
- 239000011248 coating agent Substances 0.000 claims description 41
- 238000000576 coating method Methods 0.000 claims description 41
- 239000004020 conductor Substances 0.000 claims description 22
- 230000001276 controlling effect Effects 0.000 claims description 15
- 239000000835 fiber Substances 0.000 claims description 15
- 230000004044 response Effects 0.000 claims description 6
- 238000000889 atomisation Methods 0.000 claims description 3
- 238000012544 monitoring process Methods 0.000 claims description 3
- 230000000007 visual effect Effects 0.000 claims description 2
- 238000010292 electrical insulation Methods 0.000 claims 3
- 238000000034 method Methods 0.000 claims 1
- 230000003334 potential effect Effects 0.000 claims 1
- 230000001702 transmitter Effects 0.000 claims 1
- 239000005002 finish coating Substances 0.000 description 3
- 230000003595 spectral effect Effects 0.000 description 3
- 238000005421 electrostatic potential Methods 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 230000007246 mechanism Effects 0.000 description 2
- 239000013307 optical fiber Substances 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- 230000009471 action Effects 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 230000000875 corresponding effect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- 231100001261 hazardous Toxicity 0.000 description 1
- 238000009413 insulation Methods 0.000 description 1
- 230000005012 migration Effects 0.000 description 1
- 238000013508 migration Methods 0.000 description 1
- 230000001681 protective effect Effects 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
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
-
- 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
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Electrostatic Spraying Apparatus (AREA)
- Nozzles (AREA)
- Spray Control Apparatus (AREA)
- Control Of Turbines (AREA)
- Fluid-Pressure Circuits (AREA)
Abstract
A feedback system for controlling the speed of a fluid motor includes an optical-signal transmitter, an optical-signal receiver, and an optically sensitive marker on the motor output shaft. The marker selectively couples the optical-signal transmitter to the optical-signal receiver to provide an optical-signal indicative of motor speed. This selectively coupled optical output signal is fed to a converter which converts the signal to a fluid signal. A processor is coupled to the converter for processing the fluid signal to provide a processed fluid signal which is coupled to the input of the fluid motor to control it.
Description
8L3~4 This invention relates to motor-speed controls, and specifically to a feedback speed-control system for a fluid motor such as that described in, for example, United States Patent Application Serial No. 13,125, now United States Patent No. ~ which issued ~ r~e 3~ / 7 ~ / , and assigned to the same assignee as this application.
Various types of coating material atomizing device drive mechanisms are known. There are, for example, the drive mechanisms of the following United States Patents: Juvinall et al, United States Patent 2,759,764;
Juvinall, United States Patent 2,754,226; Simmons, United States Reissue Patent 24,602~ Wirth, United States 3,358,931; Hechenbleikner, United States Patent 1,853,682; and Kent et al, United States Patent 3,011,472q Many coating devices are known which are adapted to be driven by fluid motors, such as air motors.
There are, for example, the systems of the following United States Patents:
Sigvardsson et al, United States Patent 3~067J949; Wampler et al, United States Patent 3,121,024; and Allander, United States Patent 2,711,926. The increasing use of such fluid motors is attributable, in part, to the ease with which the rotational speeds of atomizing devices driven by such motors can be varied by varying the fluid pressures to the inputs of such motors.
However, an undesirable characteristic of such fluid motors is that changes in certain characteristics of coating materials being dispensed from the atomizing devices coupled to such fluid motors can cause significant vari-ations in the rotational speeds of such atomizing devices by changing the loads of such fluid motors~ This is particularly true of very low horsepower (e.g.J
fractional horsepower) fluid motors, such as the turbine-air motor described in the above-identi-fied United States Patent No.
Generally, such changing characteristics of the coatin~ materials which are being atomized include changes in viscosities, solids contents, - 1 - :
. . ~ . , ~ : "i .
, ;~..
5~
specific gravities, and the like, of the coating materials. Unfortunately, in many situations, for example where color changes are carried out between the finish coating of successive articles on a production line, the very act of changing the color of the coating material results in a substantial change in these characteristics. This occurs simply because it is not always possible to match every pertinent characteristic of every different coating material which is being used on the line. This results unavoidably in changes in the loads on the fluid motors which are atomizing these various coating materials with many of the changes in coating material color.
As an exampleJ on an automobile finish-coating line, each car to pass along the finish-coating line will typically be coated with a finish having a different color from the color applied to the next preceding car, and from the color to be applied to the next succeeding car. Several systems for controlling such color changes which take into account, and adjust for, many aspects of coating material variation from color to color have been proposed.
It is an object of the present invention to provide a system for con-trolling the speed of a drive motor for an atomizing device associated with such a production line, with the motor speed being controlled to account for variations in the characteristics of coating materials which are being atomized by the atomizing device. With respect to "variations of coating material char-acteristics" from coating material to coating material, what is meant is that the load on the motor which drives the atomizing device from which the atomized coating material is dispensed changes with such coating material characteristic variations. Accordingly, the motor input must be changed to maintain the motor speed constant under such changing load conditions.
According to one broad aspect of the present invention, there is pro-vided a feedback system for controlling the speed of a motor having a motor , `:
:
~ ~ 5 ~ 8~ ~
drive signal input, the system including an optical-signal transmitter, an op-tical-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 re-ceiver to provide an optical output signal indicative of motor rotation, means for converting the optical output signal to a motor drive signal~ and means for coupling the converter to the motor drive signal input to control 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 transmitter, an op-tical-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 pro-vide an optical output signal indicative of motor rotation, means for convert-ing the optical output signal to a fluid signal, and means for coupling the con-verter to the motor input to control motor speed.
According to an illustrative embodiment of the invention, the means for coupling the converting means to the motor input includes means for proces-sing the fluid signal to develop a processed fluid signal. The processed fluid signal is fed to the motor input.
According to an illustrative embodiment of the invention, the motor includes an output shaft and the means providing the optically sensitive marker includes a wheel, the means for coupling the marker to the motor includes means for mounting the wheel on the motor output shaft, and the wheel further in-cludes means for providing a pattern on one of its surfaces. The optical-signal transmitter includes means for directing an optical signal onto the pattern.
The optical-signal receiver includes means for detecting reflections of the ~ . , :: `:, "` :' ` ~:
1 1 54 ~
transmitted optical signal from the pattern ~o provide the optical output signal.
According to an illustrative embodiment, the means for converting the optical output signal to a fluid signal includes an optical pulse counter for counting optical-output signals to generate electrical signals indicative of motor revolutions, a clock for generating a time base, a signal processor, and means for coupling the optical pulse counter and clock to the signal processor to generate a signal indicative of motor revolutions per unit time. The con-verter means further includes means for displaying motor revolutions per unit time, and means for coupling the display means to the signal processor to pro-vide a visual indication of motor speed.
Additionally, in an illustrative embodiment, the signal processor in-cludes a control input for permitting selective adjustment of the motor speed.
Such selective adjustment can be provided either by an analog signal or by a digital signal, depending upon the specific requirements of the processor. The illustrative signal processor further includes a comparator for comparing the signal indicative of motor revolutions per unit time with the control input and for generating a comparator output signal.
The system further includes means for converting the comparator out-put signal into the fluid signal and means for coupling the converter to the comparator. The converter is also coupled to a source of fluid in the illustra-tive system, the converter acting to convert the comparator output signal to the fluid signal. In the illustrative system, a fluid-signal amplifier is pro-vided~ along with means for coupling the fluid-signal amplifier to a source of driving fluid for the motor, to the fluid-motor input, and to the converter.
The fluid-signal amplifier acts under the influence of the fluid signal from the converter to control the flo~ of motor driving fluid from the driving fluid source to the motor input to control motor speed.
:. . . .
. , .
' , , ~ ' ., ' :,' ,:
1 1 5~L8~ 4 The system may best be understood by referring to the following de-tailed description and accompanying drawing which is a block and schematic diagram of a feedback system constructed according to the present invention for controlling motor speed.
In the drawing~ a fluid motor 10 of the type described in the above-~identified United States Patent No. ~,27S~ 83 g includes an output shaft 12 uponwhich is mounted an atomizing device 14. Device 14 may be any of several suit-able types such as, for example, the type described in United States Patent 4,148,932. A feed tube 16 feeds a coating material from a selected one of a number of sources ~not shown) through a source control (not shown) to the inte-rior of atomizing device 14, from which the coating material is atomized in a pattern 18 and deposited onto a target 20, an article to be coated by the mate-rial. It is to be understood that the target 20 can be moving, for example, along an assembly line, and that motor 10 need not necessarily be stationary.
That is, motor 10 can be mounted, for example, on a ram associated with a fluid cylinder which projects the motor 10 and atomizing device 14 into close proximi-ty to the target 20 before coating material is dispensed. Typically, the sys-tem also includes a source 24 of electrical potential for electrostatically charging and aiding in the atomization of particles of coating material in the pattern 18. In such a system, the target 20 will be maintained at a potential, here ground 26, to promote migration of the charged particles of coating mate-rial in pattern 18 toward ~he target 20. This greatly enhances the efficiency of coating of the target 20 and reduces coating material waste.
A wheel 30 is mounted on the output shaft 12, for example, on the inside of the motor 10 housing 32, as shown. It is to be understood that wheel 30 need not be a component which is added to motor 10. In fact, the wheel 30 can be the turbine wheel of the motor 10 itself. A marker pattern 36 is pro-',,~
:~lS4~
vided on wheel 30. Pattern 36 includes areas 38, 40 readily distinguishable from one another by an optical-signal transmit-receive head 42.
Head 42 includes an optical transmitter 44, provided, for example, as the finished and dressed end of an optical fiber 45 which conducts light from a light source, and an optical-signal receiver 46 mounted within housing 32 in close proximity to the finished and dressed end and in an orientation such that the receiver 46 detects movement of the pattern 36 as areas 38, 40 move beneath the optical-signal transmit-receive head 42. The pattern 36 can consist simply of light and dark areas 38, 40, respectivelyJ which, respectively, reflect and absorb light from transmitter 44 to provide a received ~reflected) signal on optical receiver 46 once each rotation of shaft 12.
The optical-signal transmit-receive head 42 provides at receiver 46 an output optical-signal which is transmitted along an optical fiber 49 in a fiber-optic cable 50 coupled to a light source and receiver 52. The cable 50 in the illustrative embodiment includes fiber 45 which transmits light "down"
the cable 50 to transmitter 44, and fiber 49 which transmits received light "up" cable 50 from receiver 46 to the light source and receiver 52. The head 42 and fiber-optic cable 50 are of a type such as the Spectral Dynamics Fiber-optic Cable Model 13134-GPT-l available from Spectral Dynamics Corporation of San Diego, P. 0. Box 671, San Diego, California 92112. ::
Light source and receiver 52 includes electric circuits responsive to the received light from receiver 46 to generate electrical pulses correspond-ing to the optical output signal from receiver 46. These electrical pulses are coupled, as shown, through conductors 56 to a clock, or time-base generator 58, which generates a time base against which occurrences of shaft 12 rotation (as represented by the signal on conductors 56) are compared. A signal indica-tive of motor 10 revolutions per unit time results cn conductors 60. The light '~' - '`~; ~ ;' ', ':
115~84~1 source and receiver 52 and clock 58 are available as a unit in, for example, the Spectral Dynamics Corporation of San Diego Model 13135. Conductors 60 couple the signal indicative of motor revolutions per unit time to a feedback comparator and servo drive system 62. The feedback comparator and servo drive system 62 includes an input 64 coupled by a suitable conductor 66 to a control input device 68. Device 68 produces an output signal which is selectively vari-able in accordance with the desired motor 10 speed. The output signal produced by device 68 on conductor 66 can be either analog or digital, depending upon the nature of device 68, and the nature and requirements of the feedback com-parator and servo driver 62. Feedback comparator and servo driver 62 includes an output 72 which is coupled by conductors 74 to a digital display 76 on which is displayed shaft 12 rotations per unit time (e.g., r.p.m.). Feedback compara-tor and servo driver 62, control input device 68, and digital display 76 are of commercially available types, such as, for example, the Ransburg Corporation Part Number 20370 Servo Driver; the Beckman 7360 Potentiometer, available from Beckman Instruments Incorporated, Helipot Division, 2500 Harbor Boulevard, Fullerton, California 92634; and the Weston 1230 Digital Panel Meter, available from Weston Instruments Division, Sangamo Weston Incorporated, 614 FrelinghuysenAvenue, Newark, New Jersey 07114, respectively.
An output 78 from the feedback comparator and servo driver 62 is coupled through conductors 80 to an input 82 of a converter, or transducer 84, which converts the signal on conductors 80 to a fluid signal at output 88 of transducer 84. A fluid source, such as a source of compressed air 90, is coupledthrough a conduit 94 to an input 96 of transducer 84. The transducer 84 acts to convert the signal at input 82 to a fluid signal at output 88 by controlling -the flow of fluid from source 90 in response to the input signal at 82.
Output signal 88 is supplied ~hrough a conduit 100 to the input 102 , . , : : . , ~, , ~5g8~
of an on-off solenoid valve 104. The output 106 of valve 104 is coupled through a conduit 108 to the input 110 of a fluid signal amplifier, or volume booster 112. An additional input 114 of volume booster 112 is coupled through a con-duit 116 to a source 118 of driving fluid for motor 10. The output 120 of vol-ume booster 112 is coupled through a conduit 122 to the driving fluid inlet 124 of motor lO.
Transducer 84, solenoid valve 104, and volume booster 112 are o-f com-mercially available types such as, for example, Fairchild Model 5109 Transducer, available from Fairchild Industrial Products Division, 1501 Fairchild Drive, Winston-Salem, North Carolina 27105; Skinner N.C. Solenoid V53DA2020 24VDC
Coil, available from Skinner Electric Valve Division, Skinner Precision Indus-tries Incorporated, 95 Edgewood Avenue, New Britain, Connecticut 06050; and Fairchild Model 20 #205103 1:6 Volume Booster, also available from Fairchild lndustrial Products Division.
The design of the instant invention is advantageous over other types of feedback control systems for fluid motors in that the element 42 for sensing motor 10 speed does not come into contact with rotating portionsJ e.g., shaft 12 and wheel 30, of the motor 10. Thus, the system of the present invention does not consume part of the motor 10 horsepower output to sense motor 10 speed.
Again, this is particularly significant where low- or fractional-horsepower mo-tors are used to rotate atomizing devices or for other purposes.
Further, by using the fiber-optic cable 50 in the sensing system, it is possible for the device to operate in a hazardous location (e.g., high sol-vents content atmosphere) without the need for protective sheathing, insulation, or the like. Specifically, the fiber-optic cable 50 permits the monitoring and control of the speed of motor 10, even when the motor 10 is at a high electro-static potential, e.g., 100 KV, as a result of the action of the electrostatic potential supply 24.
, - ~
:
-; . , : .,
Various types of coating material atomizing device drive mechanisms are known. There are, for example, the drive mechanisms of the following United States Patents: Juvinall et al, United States Patent 2,759,764;
Juvinall, United States Patent 2,754,226; Simmons, United States Reissue Patent 24,602~ Wirth, United States 3,358,931; Hechenbleikner, United States Patent 1,853,682; and Kent et al, United States Patent 3,011,472q Many coating devices are known which are adapted to be driven by fluid motors, such as air motors.
There are, for example, the systems of the following United States Patents:
Sigvardsson et al, United States Patent 3~067J949; Wampler et al, United States Patent 3,121,024; and Allander, United States Patent 2,711,926. The increasing use of such fluid motors is attributable, in part, to the ease with which the rotational speeds of atomizing devices driven by such motors can be varied by varying the fluid pressures to the inputs of such motors.
However, an undesirable characteristic of such fluid motors is that changes in certain characteristics of coating materials being dispensed from the atomizing devices coupled to such fluid motors can cause significant vari-ations in the rotational speeds of such atomizing devices by changing the loads of such fluid motors~ This is particularly true of very low horsepower (e.g.J
fractional horsepower) fluid motors, such as the turbine-air motor described in the above-identi-fied United States Patent No.
Generally, such changing characteristics of the coatin~ materials which are being atomized include changes in viscosities, solids contents, - 1 - :
. . ~ . , ~ : "i .
, ;~..
5~
specific gravities, and the like, of the coating materials. Unfortunately, in many situations, for example where color changes are carried out between the finish coating of successive articles on a production line, the very act of changing the color of the coating material results in a substantial change in these characteristics. This occurs simply because it is not always possible to match every pertinent characteristic of every different coating material which is being used on the line. This results unavoidably in changes in the loads on the fluid motors which are atomizing these various coating materials with many of the changes in coating material color.
As an exampleJ on an automobile finish-coating line, each car to pass along the finish-coating line will typically be coated with a finish having a different color from the color applied to the next preceding car, and from the color to be applied to the next succeeding car. Several systems for controlling such color changes which take into account, and adjust for, many aspects of coating material variation from color to color have been proposed.
It is an object of the present invention to provide a system for con-trolling the speed of a drive motor for an atomizing device associated with such a production line, with the motor speed being controlled to account for variations in the characteristics of coating materials which are being atomized by the atomizing device. With respect to "variations of coating material char-acteristics" from coating material to coating material, what is meant is that the load on the motor which drives the atomizing device from which the atomized coating material is dispensed changes with such coating material characteristic variations. Accordingly, the motor input must be changed to maintain the motor speed constant under such changing load conditions.
According to one broad aspect of the present invention, there is pro-vided a feedback system for controlling the speed of a motor having a motor , `:
:
~ ~ 5 ~ 8~ ~
drive signal input, the system including an optical-signal transmitter, an op-tical-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 re-ceiver to provide an optical output signal indicative of motor rotation, means for converting the optical output signal to a motor drive signal~ and means for coupling the converter to the motor drive signal input to control 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 transmitter, an op-tical-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 pro-vide an optical output signal indicative of motor rotation, means for convert-ing the optical output signal to a fluid signal, and means for coupling the con-verter to the motor input to control motor speed.
According to an illustrative embodiment of the invention, the means for coupling the converting means to the motor input includes means for proces-sing the fluid signal to develop a processed fluid signal. The processed fluid signal is fed to the motor input.
According to an illustrative embodiment of the invention, the motor includes an output shaft and the means providing the optically sensitive marker includes a wheel, the means for coupling the marker to the motor includes means for mounting the wheel on the motor output shaft, and the wheel further in-cludes means for providing a pattern on one of its surfaces. The optical-signal transmitter includes means for directing an optical signal onto the pattern.
The optical-signal receiver includes means for detecting reflections of the ~ . , :: `:, "` :' ` ~:
1 1 54 ~
transmitted optical signal from the pattern ~o provide the optical output signal.
According to an illustrative embodiment, the means for converting the optical output signal to a fluid signal includes an optical pulse counter for counting optical-output signals to generate electrical signals indicative of motor revolutions, a clock for generating a time base, a signal processor, and means for coupling the optical pulse counter and clock to the signal processor to generate a signal indicative of motor revolutions per unit time. The con-verter means further includes means for displaying motor revolutions per unit time, and means for coupling the display means to the signal processor to pro-vide a visual indication of motor speed.
Additionally, in an illustrative embodiment, the signal processor in-cludes a control input for permitting selective adjustment of the motor speed.
Such selective adjustment can be provided either by an analog signal or by a digital signal, depending upon the specific requirements of the processor. The illustrative signal processor further includes a comparator for comparing the signal indicative of motor revolutions per unit time with the control input and for generating a comparator output signal.
The system further includes means for converting the comparator out-put signal into the fluid signal and means for coupling the converter to the comparator. The converter is also coupled to a source of fluid in the illustra-tive system, the converter acting to convert the comparator output signal to the fluid signal. In the illustrative system, a fluid-signal amplifier is pro-vided~ along with means for coupling the fluid-signal amplifier to a source of driving fluid for the motor, to the fluid-motor input, and to the converter.
The fluid-signal amplifier acts under the influence of the fluid signal from the converter to control the flo~ of motor driving fluid from the driving fluid source to the motor input to control motor speed.
:. . . .
. , .
' , , ~ ' ., ' :,' ,:
1 1 5~L8~ 4 The system may best be understood by referring to the following de-tailed description and accompanying drawing which is a block and schematic diagram of a feedback system constructed according to the present invention for controlling motor speed.
In the drawing~ a fluid motor 10 of the type described in the above-~identified United States Patent No. ~,27S~ 83 g includes an output shaft 12 uponwhich is mounted an atomizing device 14. Device 14 may be any of several suit-able types such as, for example, the type described in United States Patent 4,148,932. A feed tube 16 feeds a coating material from a selected one of a number of sources ~not shown) through a source control (not shown) to the inte-rior of atomizing device 14, from which the coating material is atomized in a pattern 18 and deposited onto a target 20, an article to be coated by the mate-rial. It is to be understood that the target 20 can be moving, for example, along an assembly line, and that motor 10 need not necessarily be stationary.
That is, motor 10 can be mounted, for example, on a ram associated with a fluid cylinder which projects the motor 10 and atomizing device 14 into close proximi-ty to the target 20 before coating material is dispensed. Typically, the sys-tem also includes a source 24 of electrical potential for electrostatically charging and aiding in the atomization of particles of coating material in the pattern 18. In such a system, the target 20 will be maintained at a potential, here ground 26, to promote migration of the charged particles of coating mate-rial in pattern 18 toward ~he target 20. This greatly enhances the efficiency of coating of the target 20 and reduces coating material waste.
A wheel 30 is mounted on the output shaft 12, for example, on the inside of the motor 10 housing 32, as shown. It is to be understood that wheel 30 need not be a component which is added to motor 10. In fact, the wheel 30 can be the turbine wheel of the motor 10 itself. A marker pattern 36 is pro-',,~
:~lS4~
vided on wheel 30. Pattern 36 includes areas 38, 40 readily distinguishable from one another by an optical-signal transmit-receive head 42.
Head 42 includes an optical transmitter 44, provided, for example, as the finished and dressed end of an optical fiber 45 which conducts light from a light source, and an optical-signal receiver 46 mounted within housing 32 in close proximity to the finished and dressed end and in an orientation such that the receiver 46 detects movement of the pattern 36 as areas 38, 40 move beneath the optical-signal transmit-receive head 42. The pattern 36 can consist simply of light and dark areas 38, 40, respectivelyJ which, respectively, reflect and absorb light from transmitter 44 to provide a received ~reflected) signal on optical receiver 46 once each rotation of shaft 12.
The optical-signal transmit-receive head 42 provides at receiver 46 an output optical-signal which is transmitted along an optical fiber 49 in a fiber-optic cable 50 coupled to a light source and receiver 52. The cable 50 in the illustrative embodiment includes fiber 45 which transmits light "down"
the cable 50 to transmitter 44, and fiber 49 which transmits received light "up" cable 50 from receiver 46 to the light source and receiver 52. The head 42 and fiber-optic cable 50 are of a type such as the Spectral Dynamics Fiber-optic Cable Model 13134-GPT-l available from Spectral Dynamics Corporation of San Diego, P. 0. Box 671, San Diego, California 92112. ::
Light source and receiver 52 includes electric circuits responsive to the received light from receiver 46 to generate electrical pulses correspond-ing to the optical output signal from receiver 46. These electrical pulses are coupled, as shown, through conductors 56 to a clock, or time-base generator 58, which generates a time base against which occurrences of shaft 12 rotation (as represented by the signal on conductors 56) are compared. A signal indica-tive of motor 10 revolutions per unit time results cn conductors 60. The light '~' - '`~; ~ ;' ', ':
115~84~1 source and receiver 52 and clock 58 are available as a unit in, for example, the Spectral Dynamics Corporation of San Diego Model 13135. Conductors 60 couple the signal indicative of motor revolutions per unit time to a feedback comparator and servo drive system 62. The feedback comparator and servo drive system 62 includes an input 64 coupled by a suitable conductor 66 to a control input device 68. Device 68 produces an output signal which is selectively vari-able in accordance with the desired motor 10 speed. The output signal produced by device 68 on conductor 66 can be either analog or digital, depending upon the nature of device 68, and the nature and requirements of the feedback com-parator and servo driver 62. Feedback comparator and servo driver 62 includes an output 72 which is coupled by conductors 74 to a digital display 76 on which is displayed shaft 12 rotations per unit time (e.g., r.p.m.). Feedback compara-tor and servo driver 62, control input device 68, and digital display 76 are of commercially available types, such as, for example, the Ransburg Corporation Part Number 20370 Servo Driver; the Beckman 7360 Potentiometer, available from Beckman Instruments Incorporated, Helipot Division, 2500 Harbor Boulevard, Fullerton, California 92634; and the Weston 1230 Digital Panel Meter, available from Weston Instruments Division, Sangamo Weston Incorporated, 614 FrelinghuysenAvenue, Newark, New Jersey 07114, respectively.
An output 78 from the feedback comparator and servo driver 62 is coupled through conductors 80 to an input 82 of a converter, or transducer 84, which converts the signal on conductors 80 to a fluid signal at output 88 of transducer 84. A fluid source, such as a source of compressed air 90, is coupledthrough a conduit 94 to an input 96 of transducer 84. The transducer 84 acts to convert the signal at input 82 to a fluid signal at output 88 by controlling -the flow of fluid from source 90 in response to the input signal at 82.
Output signal 88 is supplied ~hrough a conduit 100 to the input 102 , . , : : . , ~, , ~5g8~
of an on-off solenoid valve 104. The output 106 of valve 104 is coupled through a conduit 108 to the input 110 of a fluid signal amplifier, or volume booster 112. An additional input 114 of volume booster 112 is coupled through a con-duit 116 to a source 118 of driving fluid for motor 10. The output 120 of vol-ume booster 112 is coupled through a conduit 122 to the driving fluid inlet 124 of motor lO.
Transducer 84, solenoid valve 104, and volume booster 112 are o-f com-mercially available types such as, for example, Fairchild Model 5109 Transducer, available from Fairchild Industrial Products Division, 1501 Fairchild Drive, Winston-Salem, North Carolina 27105; Skinner N.C. Solenoid V53DA2020 24VDC
Coil, available from Skinner Electric Valve Division, Skinner Precision Indus-tries Incorporated, 95 Edgewood Avenue, New Britain, Connecticut 06050; and Fairchild Model 20 #205103 1:6 Volume Booster, also available from Fairchild lndustrial Products Division.
The design of the instant invention is advantageous over other types of feedback control systems for fluid motors in that the element 42 for sensing motor 10 speed does not come into contact with rotating portionsJ e.g., shaft 12 and wheel 30, of the motor 10. Thus, the system of the present invention does not consume part of the motor 10 horsepower output to sense motor 10 speed.
Again, this is particularly significant where low- or fractional-horsepower mo-tors are used to rotate atomizing devices or for other purposes.
Further, by using the fiber-optic cable 50 in the sensing system, it is possible for the device to operate in a hazardous location (e.g., high sol-vents content atmosphere) without the need for protective sheathing, insulation, or the like. Specifically, the fiber-optic cable 50 permits the monitoring and control of the speed of motor 10, even when the motor 10 is at a high electro-static potential, e.g., 100 KV, as a result of the action of the electrostatic potential supply 24.
, - ~
:
-; . , : .,
Claims (22)
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 transmitter, an op-tical-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 pro-vide an optical output signal indicative of motor rotation, means for convert-ing the optical output signal to a fluid signal, and means for coupling the con-verter to the motor input to control motor speed.
2. The apparatus of claim 1 wherein the means for coupling the converter to the motor input comprises means for processing the fluid signal to provide a processed fluid signal.
3. The apparatus of claim 2 wherein the motor includes a motor output shaft and the means providing an optically sensitive marker includes a wheel, the means for coupling the marker to the motor includes means for mounting the wheel on the motor output shaft, the wheel further includes means providing a pattern on one of its surfaces.
4. The apparatus of claim 3 wherein the optical-signal transmitter in-cludes means for directing a beam of light onto the pattern.
5. The apparatus of claim 4 wherein the optical-signal receiver includes means for detecting reflections of the light beam from the pattern to provide the optical output signal.
6. The apparatus of claim 5 wherein the means for converting the optical output signal to a fluid signal includes an optical pulse counter for counting optical output signals and for generating electrical signals indicative of mo-tor revolutions, a clock for generating a time base, a signal processor, and means for coupling the optical pulse counter and clock to the processor to gen-erate a signal indicative of motor revolutions per unit time.
7. The apparatus of claim 6 and further comprising means for displaying motor revolutions per unit time, and means for coupling the display means to the signal processor to provide a visual indication of motor speed.
8. The apparatus of claim 7 wherein the signal processor includes a con-trol input for permitting selective adjustment of motor speed.
9. The apparatus of claim 8 wherein the signal processor includes a com-parator for comparing the signal indicative of motor revolutions per unit time with the control input and for generating a comparator output signal.
10. The apparatus of claim 9 wherein the means for converting the optical output signal to a fluid signal comprises means for converting said comparator output signal into the fluid signal, and means for coupling the converter to the comparator.
11. The apparatus of claim 10 and further comprising means for coupling the converter to a source of fluid, the converter acting to convert the compara-tor output signal to a signal in the fluid flow from the fluid source to gener-ate the fluid signal.
12. The apparatus of claim 11 wherein the means for processing the fluid signal comprises a fluid signal amplifier, means coupling the fluid signal amplifer, to a source of driving fluid for the motor, means coupling the fluid signal amplifier to the fluid mo-tor input, and means coupling the fluid signal amplifier to the converter, the fluid signal amplifier acting under the influence of the fluid signal from the converter to control the flow of motor driving fluid from the driving fluid source to the motor input to control motor speed.
13. A feedback system for controlling the speed of a motor having a motor drive signal input, the system including an optical-signal transmitter, an op-tical-signal receiver, means providing an optical coupler, means for coupling the optical coupler to the motor in driven engagement, the optical coupler se-lectively coupling the optical-transmitter signal to the optical-signal receiver to provide an optical output signal indicative of motor rotation, means for con-verting the optical output signal to a motor drive signal, and means for cou-pling the converter to the motor drive signal input to control motor speed.
14. The apparatus of claim 13 wherein the motor is a fluid motor, the mo-tor drive signal input is a motor driving fluid input, and the drive signal is a fluid signal.
15. The apparatus of claim 14 wherein the motor includes a motor output shaft and the means providing an optical coupler includes a wheel having an op-tically sensitive marker provided thereon, and the means for coupling the op-tical coupler to the motor includes means for mounting the wheel on the motor output shaft.
16. In a coating material atomizing and dispensing system including a rotary atomizing device and means for feeding a selected coating material from a selected one of a plurality of sources for such coating materials to the atomizing device, and a motor for rotating the atomizing device, 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 op-tical output signal indicative of motor operation, means for converting the op-tical output signal to a motor drive signal, and means for coupling the convert-er to the motor input to control motor speed.
17. A motor, 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 opera-tion, means for converting the optical output signal to a motor control signal, and means for coupling the converter to the motor input to control 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 poten-tial, 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 elec-trically 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.
18. A fluid motor having a driving fluid input, a feedback system for con-trolling the rate of rotation of the fluid motor, the system including means providing an optically reflective pattern on the motor, an optical-signal trans-mitter 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 rotaty 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 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.
19. 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 por-tion, 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 permit-ting the feedback of motor speed-related signals for motor and atomizing device speed control.
20. 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 to maintain the desired rate of rotation, 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 atomiza-tion 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 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.
21. A fluid motor having a driving fluid input for rotating a rotary por-tion of the motor, a feedback system for controlling the rate of rotation of the fluid motor, the system including means providng an optically reflective pattern on the motor rotary portion, an optical-signal transmitter for direct-ing 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, and 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 to maintain the desired rate of rotation, 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.
22. A method for controlling rotation rate of a 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, genera-ting an 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 (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US11322180A | 1980-01-18 | 1980-01-18 | |
| US113,221 | 1980-01-18 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1154844A true CA1154844A (en) | 1983-10-04 |
Family
ID=22348240
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000368687A Expired CA1154844A (en) | 1980-01-18 | 1981-01-16 | Motor speed control |
Country Status (7)
| Country | Link |
|---|---|
| JP (1) | JPS56121654A (en) |
| BE (1) | BE886934A (en) |
| CA (1) | CA1154844A (en) |
| DE (1) | DE3101193C2 (en) |
| GB (1) | GB2068150B (en) |
| HK (1) | HK28588A (en) |
| IT (1) | IT1143276B (en) |
Families Citing this family (15)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2087264A (en) * | 1980-11-19 | 1982-05-26 | Graco Inc | A speed control apparatus for operating a centrifugal atomiser |
| AU526982B2 (en) * | 1981-04-16 | 1983-02-10 | Ransburg Corp. | Coating material atomizing and dispensing system |
| JPS58124254U (en) * | 1982-02-17 | 1983-08-24 | トヨタ自動車株式会社 | Rotary atomization electrostatic coating equipment |
| US4936507A (en) * | 1986-06-26 | 1990-06-26 | The Devilbiss Company | Rotary atomizer with high voltage isolating speed measurement |
| US4997130A (en) * | 1986-06-26 | 1991-03-05 | Illinois Tool Works, Inc. | Air bearing rotary atomizer |
| US4965444A (en) * | 1988-08-17 | 1990-10-23 | Ransburg Corporation | Automatic gain control fiber optica-to-electrical transceiver |
| US4878454A (en) * | 1988-09-16 | 1989-11-07 | Behr Industrial Equipment Inc. | Electrostatic painting apparatus having optically sensed flow meter |
| JPH0389963A (en) * | 1989-09-02 | 1991-04-15 | Nippon Paint Co Ltd | Apparatus and method for forming pattern |
| FR2809334B1 (en) * | 2000-05-29 | 2003-02-28 | Eisenmann Sarl | SPRAYING DEVICE FOR SPRAYING A COATING PRODUCT |
| NL1022128C2 (en) * | 2002-12-10 | 2004-07-05 | Hytop B V | Measuring method for determining the displacement of a movable part of an actuator and device for applying the measuring method. |
| JP4327846B2 (en) * | 2004-02-23 | 2009-09-09 | Ａｂｂ株式会社 | Rotary atomizing head type coating equipment |
| 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 |
| 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 (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE1013907B (en) * | 1953-11-16 | 1957-08-14 | Samson Appbau Aktien Ges | Pressure medium operated regulator with feedback |
| US3757128A (en) * | 1972-03-20 | 1973-09-04 | Ibm | Multiphase tachometer |
| US4016723A (en) * | 1975-10-21 | 1977-04-12 | Westinghouse Electric Corporation | Speed measurement system for turbine power plant |
| JPS5444385A (en) * | 1977-09-13 | 1979-04-07 | Yoshida Seisakusho Kk | Air motor that drive dental cutting tool |
| DE2755343A1 (en) * | 1977-12-12 | 1979-06-13 | Papst Motoren Kg | SPEED CONTROL ARRANGEMENT |
-
1980
- 1980-10-24 GB GB8034305A patent/GB2068150B/en not_active Expired
- 1980-12-31 BE BE0/203377A patent/BE886934A/en not_active IP Right Cessation
-
1981
- 1981-01-14 JP JP331581A patent/JPS56121654A/en active Pending
- 1981-01-16 DE DE3101193A patent/DE3101193C2/en not_active Expired
- 1981-01-16 IT IT67049/81A patent/IT1143276B/en active
- 1981-01-16 CA CA000368687A patent/CA1154844A/en not_active Expired
-
1988
- 1988-04-21 HK HK285/88A patent/HK28588A/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| GB2068150A (en) | 1981-08-05 |
| BE886934A (en) | 1981-04-16 |
| HK28588A (en) | 1988-04-29 |
| DE3101193C2 (en) | 1984-07-05 |
| DE3101193A1 (en) | 1981-11-26 |
| IT1143276B (en) | 1986-10-22 |
| IT8167049A0 (en) | 1981-01-16 |
| JPS56121654A (en) | 1981-09-24 |
| GB2068150B (en) | 1984-07-25 |
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