CA1124819A - Power control for vibratory feeder - Google Patents
Power control for vibratory feederInfo
- Publication number
- CA1124819A CA1124819A CA354,460A CA354460A CA1124819A CA 1124819 A CA1124819 A CA 1124819A CA 354460 A CA354460 A CA 354460A CA 1124819 A CA1124819 A CA 1124819A
- Authority
- CA
- Canada
- Prior art keywords
- capacitor
- feeder
- power
- charging path
- power source
- 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
- 239000003990 capacitor Substances 0.000 claims abstract description 34
- 230000001960 triggered effect Effects 0.000 claims abstract 2
- 230000008878 coupling Effects 0.000 claims 1
- 238000010168 coupling process Methods 0.000 claims 1
- 238000005859 coupling reaction Methods 0.000 claims 1
- 230000001939 inductive effect Effects 0.000 description 3
- 230000007423 decrease Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 244000228957 Ferula foetida Species 0.000 description 1
- 230000001174 ascending effect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000010304 firing Methods 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 230000002085 persistent effect Effects 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03K—PULSE TECHNIQUE
- H03K17/00—Electronic switching or gating, i.e. not by contact-making and –breaking
- H03K17/51—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used
- H03K17/56—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used by the use, as active elements, of semiconductor devices
- H03K17/72—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used by the use, as active elements, of semiconductor devices having more than two PN junctions; having more than three electrodes; having more than one electrode connected to the same conductivity region
- H03K17/725—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used by the use, as active elements, of semiconductor devices having more than two PN junctions; having more than three electrodes; having more than one electrode connected to the same conductivity region for ac voltages or currents
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B06—GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS IN GENERAL
- B06B—METHODS OR APPARATUS FOR GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS OF INFRASONIC, SONIC, OR ULTRASONIC FREQUENCY, e.g. FOR PERFORMING MECHANICAL WORK IN GENERAL
- B06B1/00—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency
- B06B1/02—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy
- B06B1/0207—Driving circuits
- B06B1/0223—Driving circuits for generating signals continuous in time
- B06B1/0238—Driving circuits for generating signals continuous in time of a single frequency, e.g. a sine-wave
- B06B1/0246—Driving circuits for generating signals continuous in time of a single frequency, e.g. a sine-wave with a feedback signal
- B06B1/0261—Driving circuits for generating signals continuous in time of a single frequency, e.g. a sine-wave with a feedback signal taken from a transducer or electrode connected to the driving transducer
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K33/00—Motors with reciprocating, oscillating or vibrating magnet, armature or coil system
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B06—GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS IN GENERAL
- B06B—METHODS OR APPARATUS FOR GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS OF INFRASONIC, SONIC, OR ULTRASONIC FREQUENCY, e.g. FOR PERFORMING MECHANICAL WORK IN GENERAL
- B06B2201/00—Indexing scheme associated with B06B1/0207 for details covered by B06B1/0207 but not provided for in any of its subgroups
- B06B2201/70—Specific application
Abstract
ABSTRACT OF THE DISCLOSURE
A power control for a vibratory feeder of parts and the like which includes a low current remote switching capability.
The control circuit includes a gate controlled thyristor which is triggered by a voltage on a capacitor which charges through a charging path from an AC power source. The remote controlled switch is placed in the charging path of the capacitor so that opening and closing the switch controls the application of power to the vibratory feeder, with the switching taking place in the low current charging path.
A power control for a vibratory feeder of parts and the like which includes a low current remote switching capability.
The control circuit includes a gate controlled thyristor which is triggered by a voltage on a capacitor which charges through a charging path from an AC power source. The remote controlled switch is placed in the charging path of the capacitor so that opening and closing the switch controls the application of power to the vibratory feeder, with the switching taking place in the low current charging path.
Description
' 1124~9 DESCRIPTION OF THE INVENTION
This invention relates generally to controls for vibratory feeders and more particularly concerns such controls which include a low current turn-off capability.
Vibratory feeders for small parts such as screws, nuts, plastic pieces and so on are generally AC powered and electro~lechanically tuned to either a 60 or 120 cycle per second frequency. For bowl-type feeders, a bowl for the parts which includes a spirally ascending track interiorly about its circumference is mounted on an intermediate portion which rests on a base. The intermediate portion is coupled to an AC power source through a power control and is electromagnetically tuned to vibrate the bowl. Vibration of the bowl causes the parts to move upwardly along the spiral track.
The tuned intermediate portion of the vibratory feeder presents a generally large damped inductive load to the power source. Various controls have been used to vary the amount of power coupled from an AC power source to a vibratory feeder. These power controls operate in a half wave or full wave mode depending upon whether the vibratory feeder is tuned to 60 or 120 hertz, respectively. In operation the power control couples a portion of each power source cycle (or half cycle for 120 hertz operation) to the vibratory feeder.
- One way to control the amount of power coupled to the feeder is to divide down the power source voltage through an impedance divider network. Another more common approach lS
to couple the AC power source voltage to the feeder for a portion of each cycle or half cycle of the AC wa~eform.
Solid state gate controlled thyristor circuits may be used in such controls wherein, for a full wave system, the thyristor
This invention relates generally to controls for vibratory feeders and more particularly concerns such controls which include a low current turn-off capability.
Vibratory feeders for small parts such as screws, nuts, plastic pieces and so on are generally AC powered and electro~lechanically tuned to either a 60 or 120 cycle per second frequency. For bowl-type feeders, a bowl for the parts which includes a spirally ascending track interiorly about its circumference is mounted on an intermediate portion which rests on a base. The intermediate portion is coupled to an AC power source through a power control and is electromagnetically tuned to vibrate the bowl. Vibration of the bowl causes the parts to move upwardly along the spiral track.
The tuned intermediate portion of the vibratory feeder presents a generally large damped inductive load to the power source. Various controls have been used to vary the amount of power coupled from an AC power source to a vibratory feeder. These power controls operate in a half wave or full wave mode depending upon whether the vibratory feeder is tuned to 60 or 120 hertz, respectively. In operation the power control couples a portion of each power source cycle (or half cycle for 120 hertz operation) to the vibratory feeder.
- One way to control the amount of power coupled to the feeder is to divide down the power source voltage through an impedance divider network. Another more common approach lS
to couple the AC power source voltage to the feeder for a portion of each cycle or half cycle of the AC wa~eform.
Solid state gate controlled thyristor circuits may be used in such controls wherein, for a full wave system, the thyristor
-2-is gated on at a point along each half cycle of the AC power source sine wave voltage to couple the feeder to the power source for the remainder of the half cycle.
With all such vibratory parts feeder and control arrangements, there is a need to turn off the power to the feeder for temporary periods during operation such as when there is a parts jam along the track leading from the feeder to the parts-using operation. In the past, sensors have been placed along feeder tracks to determine if there is a parts blockage on the feeder track, and high current switches in the power line have been controlled to turn off the power coupled through the control circuit to the vibratory feeder.
These switches have been placed directly in the connection from the AC power line which carries the full feeder load current, which is of an order of magnitude of amperes.
Controlling currents of this magnitude calls for large relays and the like, and the contacts of such high current switches frequently wear out, necessitating replacement of the switch.
It is consequently an object of the present invention to provide a control in a vibratory feeder arrangement which includes a low current turn off swit¢hing capability.
Other objects and advantages of the invention will become apparent upon reading the following detailed description and upon reference to the drawings in which:
Figure 1 is a diagrammatic illustration of a vibratory -feeder and control arrangement;
Figure 2 is a circuit diagram of the control of Figure l; and Figure 3 a-e is a series of voltage waveforms taken at various points in the circuit of Fig. 2.
~ 1124819 While the invention is susceptible to various modifications and alternative forms, a specific embDdiment thereof has been shown by way of example in the drawings and will iherein be described in detail. It should be understood, however, that it is not intended to limit the invention to the particular form disclosed, but, on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims.
In Figure 1 a vibratory feeder 11 has a parts-bearing bowl 12, an intermediate bowl-vibrating portion 15, and a base 13. Vibration of the bowl 12 moves the parts 14 along.an interior circumferential track 16 and out of the bowl 12 onto a straight feeder track 17. The parts move along the track 17 to a subsequent location such as for a machine operation (not shown).
Also in Figure 1 a power control 18 has a connection 19 to a conventional 60 hertz AC power source. The power from the AC source is coupled through the control 18 and a connection 21 to the vibratory feeder 11 to provide the power to vibrate the feeder. The control 18 includes an on-off switch 22 and a power control knob 23 for setting the amount of power to be coupled to the feeder 11.
A switch 26 is connected by lines 24 to the control 18 and is operable to turn off the power coupled to the feeder 11 through the connection 21, as shall be explained in more detail hereinafter. The switch 26 is controlled by a sensor 27 which detects the presence of a backlog of the parts 14 at a transducer location such as 28. Such a parts backlog may be due to difficulties with the subsequent machine which is using the parts or may be the result o~ a parts jam ¢- llZ4819 downstream in the track 17. When a parts bac~log is detected by the sensor 27 the switch 26 is actuated to provide a low current turnoff for the feeder 11, as shall be described more particularly hereinafter.
In Figure 2 there is illustrated a preferred embodiment for the circuitry of the control 18 of Figure 1 and its connections to the vibratory feeder 11, switch 26, and the lines l9 to an AC power source. The feeder 11 presents a large su~stantially inductive load impedance and is connected in parallel with a resistor 31 which provides a minimum re-sistive load. This combined load is connected in series with a triac 32, and the series combination of the triac and ! load is connected across the incoming AC power source lines 19. The on-off power switch 22 is connected in series with one of the incoming AC power source lines 19 in order to control the application of AC power to the control circuit.
When the triac 32 is nonconductive, there is a minimal current flow through the feeder 11, and the feeder is substantially turned off. When the triac 32 is conductive, the feeder is connected across the AC power source and for , the period of time that the triac is conductive the feeder is fully energized. The triac 32 is gated, during normal operation, to be conductive for part of each cycle, or half cycle, of the AC power source voltage, with the lengt~ of timé that the triac is conductive determining the amount of power coupled to the feeder 11.
In order to provide timed gating for the triac 32 to obtain the desired power for the feeder 11, a capacitor 33 is charged through two charging paths, and the capacitor voltage is used to produce pulses for the gate of the triac 32.
When the voltaye on the capaci~or 33 reaches the breakover r 11248~9 voltage of a diac 34, a trigger pulse is produced at the gate at the triac 32, and the triac becomes conductive. For full wave, i20 hertz, operation, a jumper 36 is connected in parallel-with a diode 37 so that both polarities of voltage on the capacitor 33 are coupled to the diac 34. This produces two gating pulses, one positive and one negative, for the triac 32 on each full cycle of the power source voltage waveform. The voltage at the gate of the triac 32 is shown in Figure 3 as voltage Ve. If the jumper 36 is not connected in parallel with the diode 37, only the positive (relative to a common node 40) voltage on the capacitor 33 is coupled through the diode 37 to the diac 34. In this case only the positive gating pulse on the ~e waveform of Figure 3 is produced.
In order to provide the positive and negative voltages on the capacitor 33, two charging paths from the AC source are provided for the capacitor. A first charging path is from a node 50 through either a ~umper 38 or the switch 26, a potentiometer 3g and a resistor 41. The node 50 is separated from one of the AC power source input lines 19 by the relatively small minimum load resistor 31 and the parallel damped inductive feeder load. The node 50 is also connected to one of the main terminals of the triac 32 and is therefore connected to the common node 40 when the triac is conductive.
When the triac 32 is nonconductive, the node 50 is substantially at the AC power source line voltage, and the capacitor 33 charges through the potentiometer 39 and the resistor 41.
The range of times during a voltage waveform cycle for the firing of the triac 32 i5 enhanced by the provision of a second charging path from the node 45 which is connected through the on-off switch 22 to one of the AC power source lines 19. The voltage at the node 45 is substantially unaffected by the condition of the triac 32 and charges a capacitor 42 through a resistor 43 from the AC power ~ource voltage. The voltage on the capacitor 42 charges the capacitor 33 through a potentiometer 44.
The operation of the circuit, beginning with a positive half cycle (taking the voltage at the node 45 with reference to that at the node 40), will now be described. The line voltage is initially applied across the feeder 11 with the triac 32 conductive, the feeder voltage Va being shown in Figure 3a. The voltage across the triac 32 is shown as Vb in Figure 3b; and the sum of Va and Vb, of course, equals the power source voltage from node 45 to the node 40. From the beginning of the positive-going half cycle until the time t3, the input voltage is applied across the feeder 11.
The triac 32 remains conductive during this initial portion of the positive-going half cycle of the input voltage due to a persisting reverse current through the triac and the feeder because of the large inductance of the feeder. When the triac 32 becomes nonconductive at the time t3, the feeder 11 is no longer energized and the source voltage appears across the triac 32. In full wave operation the time t4 in the negative half cycle corresponds to the time t3 in the positive half cycle.
During the beginning of the positive half cycle of the source voltage waveform, the voltage Vc on the capacitor 42 becomes pcsitive, charging from the node 45 through the resistor 43, and serves to charge the gate triqger timing capacitor 33 through the potentiometer 44. Once the triac 32 has become nonconductive, the capacitor 33 is also charged through the charging path from the node 50 through the f- llZ4819 potentiometer 39 and the resistor 41. When the voltage on the capacitor 33 reaches the breakover voltage of the diac 34, the triac 32 is gated and once again becomes conductive, at the time tl in Figure 3.
At this time the triac voltage Vb returns to zero and the source voltage is reapplied across the feeder 11. Also at tl there is a slight drop in the capacitor 42 voltage Vc and a more significant drop in the capacitor 33 voltage Vd.
As indicated above, the gate pulse Ve establishes the time tl. The charging time for the capacitor 33 to reach the breakover voltage of the diac 34 and produce a gating pulse is determined by the settings of the potentiometers 39 and 44. The smaller the resistance of each potentiometer, the more quickly the capacitor 33 charges on each half cycle, and the sooner the triac is turned on. It should be noted that as less power is coupled to the feeder not only does the turn-on time tl or the triac 32 move to the right in FIgure 3 toward the y-axis, but also the turn-off time t3 of the triac moves to the left toward the beginning of the positive half cycle of the power source voltage waveform.
This earlier turn-off time of the triac occurs because the residual current in the feeder decreases as the turn-on time at the end of the previous half cycle decreases. Consequently, substantially full continuous feeder power adjustment is possible with the control circuit 18.
The sooner the triac is turned on and becomes conductive, the more power is coupled to the feeder. The potentiometer 44 is preferably set to an initial value through a calibration procedure, and the potentiometer 39 is controlled by the power control knob 23 for adjustment of the level of power cou~led to the feeder 11. In calibrating the control 18, -~ 11248~9 the potentiometer 39 is set to its maximum resistance value, to provide the lowest amount of charging current to the capacitor 33 through this charging path. Then the potentiometer 44 is adjusted until tl corresponds to approximately tO, the crossover point of the source voltage waveform at the y-axis, so that a minimum amount of power is coupled to the feeder 11. In full wave operation, with the adjustment of the potentiometer 44, t2 is at the next source voltage crossover point. With this setting for the potentiometer 44, subsequent adjustment of the potentiometer 39 to lower resistance values increases the charging current to the capacitor 33 so that the triac 32 fires sooner. The desired amount of power may be coupled to the feeder ll by adjusting the potentiometer 39 to fire the triac 32 in each cycle or half cycle a~ the appropriate time.
In accordance with the invention, the switch 26 is connected in series with the charging path through the potentiometer 39 and the resistor 41 to the capacitor 33.
With the switch 26 connected in the charging path, the jumper 38 is omitted. As shown in Figure l, the switch 26 is externally connected to the control 18 and is responsive to a sensor such as one which can detect a backlog of parts on the feeder track 17. When the switch 26 is opened, this opens the charging path through the potentiometer 39 and the resistor 41, and the control 18 couples a minimum amount of power to the feeder. It can ~e seen that placing the switch in this charging path eliminates the need for high current switching in series with the feeder 11. In fact, the current in the charging path through the switch 26 is less than the entire charging current for the triac gate timing capacitor 33 since there is a second charging path through the resistor ~,. 1124819 43 and the potentiometer 44. Generally, the charging path current is on the order of milliamperes and the feeder current is on the order of amperes.
In the control circuit 18 there are additionally two varistors 46 and 47 to limit the amplitude of voltage transients across the voltage source input lines 19 and across the triac 32. There is also a snubber network, connected across the triac 32, consisting of a resistor 48 in series with a capacitor 49 for limiting the rate of rise of voltage across the triac.
While the control circuit has been illustrated in combination with a bowl type of vibratory feeder, it should ,- be understood that other types of vibratory parts feeding apparatus might also be employed with the control circuit 18. Such apparatus includes, for example, in-line drive parts feeders and vibrating storage hoppers.
From the foregoing it can be seen that a power control for a vibratory feeder type of apparatus has been provided which permits low current switching of the power to the apparatus in response to externally sensed conditions. The external switching of the power control may be in response to parts flow conditions as shown in the illustrated embodiment or in response to other system conditions requiring turn-off of the vibrating apparatus.
With all such vibratory parts feeder and control arrangements, there is a need to turn off the power to the feeder for temporary periods during operation such as when there is a parts jam along the track leading from the feeder to the parts-using operation. In the past, sensors have been placed along feeder tracks to determine if there is a parts blockage on the feeder track, and high current switches in the power line have been controlled to turn off the power coupled through the control circuit to the vibratory feeder.
These switches have been placed directly in the connection from the AC power line which carries the full feeder load current, which is of an order of magnitude of amperes.
Controlling currents of this magnitude calls for large relays and the like, and the contacts of such high current switches frequently wear out, necessitating replacement of the switch.
It is consequently an object of the present invention to provide a control in a vibratory feeder arrangement which includes a low current turn off swit¢hing capability.
Other objects and advantages of the invention will become apparent upon reading the following detailed description and upon reference to the drawings in which:
Figure 1 is a diagrammatic illustration of a vibratory -feeder and control arrangement;
Figure 2 is a circuit diagram of the control of Figure l; and Figure 3 a-e is a series of voltage waveforms taken at various points in the circuit of Fig. 2.
~ 1124819 While the invention is susceptible to various modifications and alternative forms, a specific embDdiment thereof has been shown by way of example in the drawings and will iherein be described in detail. It should be understood, however, that it is not intended to limit the invention to the particular form disclosed, but, on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims.
In Figure 1 a vibratory feeder 11 has a parts-bearing bowl 12, an intermediate bowl-vibrating portion 15, and a base 13. Vibration of the bowl 12 moves the parts 14 along.an interior circumferential track 16 and out of the bowl 12 onto a straight feeder track 17. The parts move along the track 17 to a subsequent location such as for a machine operation (not shown).
Also in Figure 1 a power control 18 has a connection 19 to a conventional 60 hertz AC power source. The power from the AC source is coupled through the control 18 and a connection 21 to the vibratory feeder 11 to provide the power to vibrate the feeder. The control 18 includes an on-off switch 22 and a power control knob 23 for setting the amount of power to be coupled to the feeder 11.
A switch 26 is connected by lines 24 to the control 18 and is operable to turn off the power coupled to the feeder 11 through the connection 21, as shall be explained in more detail hereinafter. The switch 26 is controlled by a sensor 27 which detects the presence of a backlog of the parts 14 at a transducer location such as 28. Such a parts backlog may be due to difficulties with the subsequent machine which is using the parts or may be the result o~ a parts jam ¢- llZ4819 downstream in the track 17. When a parts bac~log is detected by the sensor 27 the switch 26 is actuated to provide a low current turnoff for the feeder 11, as shall be described more particularly hereinafter.
In Figure 2 there is illustrated a preferred embodiment for the circuitry of the control 18 of Figure 1 and its connections to the vibratory feeder 11, switch 26, and the lines l9 to an AC power source. The feeder 11 presents a large su~stantially inductive load impedance and is connected in parallel with a resistor 31 which provides a minimum re-sistive load. This combined load is connected in series with a triac 32, and the series combination of the triac and ! load is connected across the incoming AC power source lines 19. The on-off power switch 22 is connected in series with one of the incoming AC power source lines 19 in order to control the application of AC power to the control circuit.
When the triac 32 is nonconductive, there is a minimal current flow through the feeder 11, and the feeder is substantially turned off. When the triac 32 is conductive, the feeder is connected across the AC power source and for , the period of time that the triac is conductive the feeder is fully energized. The triac 32 is gated, during normal operation, to be conductive for part of each cycle, or half cycle, of the AC power source voltage, with the lengt~ of timé that the triac is conductive determining the amount of power coupled to the feeder 11.
In order to provide timed gating for the triac 32 to obtain the desired power for the feeder 11, a capacitor 33 is charged through two charging paths, and the capacitor voltage is used to produce pulses for the gate of the triac 32.
When the voltaye on the capaci~or 33 reaches the breakover r 11248~9 voltage of a diac 34, a trigger pulse is produced at the gate at the triac 32, and the triac becomes conductive. For full wave, i20 hertz, operation, a jumper 36 is connected in parallel-with a diode 37 so that both polarities of voltage on the capacitor 33 are coupled to the diac 34. This produces two gating pulses, one positive and one negative, for the triac 32 on each full cycle of the power source voltage waveform. The voltage at the gate of the triac 32 is shown in Figure 3 as voltage Ve. If the jumper 36 is not connected in parallel with the diode 37, only the positive (relative to a common node 40) voltage on the capacitor 33 is coupled through the diode 37 to the diac 34. In this case only the positive gating pulse on the ~e waveform of Figure 3 is produced.
In order to provide the positive and negative voltages on the capacitor 33, two charging paths from the AC source are provided for the capacitor. A first charging path is from a node 50 through either a ~umper 38 or the switch 26, a potentiometer 3g and a resistor 41. The node 50 is separated from one of the AC power source input lines 19 by the relatively small minimum load resistor 31 and the parallel damped inductive feeder load. The node 50 is also connected to one of the main terminals of the triac 32 and is therefore connected to the common node 40 when the triac is conductive.
When the triac 32 is nonconductive, the node 50 is substantially at the AC power source line voltage, and the capacitor 33 charges through the potentiometer 39 and the resistor 41.
The range of times during a voltage waveform cycle for the firing of the triac 32 i5 enhanced by the provision of a second charging path from the node 45 which is connected through the on-off switch 22 to one of the AC power source lines 19. The voltage at the node 45 is substantially unaffected by the condition of the triac 32 and charges a capacitor 42 through a resistor 43 from the AC power ~ource voltage. The voltage on the capacitor 42 charges the capacitor 33 through a potentiometer 44.
The operation of the circuit, beginning with a positive half cycle (taking the voltage at the node 45 with reference to that at the node 40), will now be described. The line voltage is initially applied across the feeder 11 with the triac 32 conductive, the feeder voltage Va being shown in Figure 3a. The voltage across the triac 32 is shown as Vb in Figure 3b; and the sum of Va and Vb, of course, equals the power source voltage from node 45 to the node 40. From the beginning of the positive-going half cycle until the time t3, the input voltage is applied across the feeder 11.
The triac 32 remains conductive during this initial portion of the positive-going half cycle of the input voltage due to a persisting reverse current through the triac and the feeder because of the large inductance of the feeder. When the triac 32 becomes nonconductive at the time t3, the feeder 11 is no longer energized and the source voltage appears across the triac 32. In full wave operation the time t4 in the negative half cycle corresponds to the time t3 in the positive half cycle.
During the beginning of the positive half cycle of the source voltage waveform, the voltage Vc on the capacitor 42 becomes pcsitive, charging from the node 45 through the resistor 43, and serves to charge the gate triqger timing capacitor 33 through the potentiometer 44. Once the triac 32 has become nonconductive, the capacitor 33 is also charged through the charging path from the node 50 through the f- llZ4819 potentiometer 39 and the resistor 41. When the voltage on the capacitor 33 reaches the breakover voltage of the diac 34, the triac 32 is gated and once again becomes conductive, at the time tl in Figure 3.
At this time the triac voltage Vb returns to zero and the source voltage is reapplied across the feeder 11. Also at tl there is a slight drop in the capacitor 42 voltage Vc and a more significant drop in the capacitor 33 voltage Vd.
As indicated above, the gate pulse Ve establishes the time tl. The charging time for the capacitor 33 to reach the breakover voltage of the diac 34 and produce a gating pulse is determined by the settings of the potentiometers 39 and 44. The smaller the resistance of each potentiometer, the more quickly the capacitor 33 charges on each half cycle, and the sooner the triac is turned on. It should be noted that as less power is coupled to the feeder not only does the turn-on time tl or the triac 32 move to the right in FIgure 3 toward the y-axis, but also the turn-off time t3 of the triac moves to the left toward the beginning of the positive half cycle of the power source voltage waveform.
This earlier turn-off time of the triac occurs because the residual current in the feeder decreases as the turn-on time at the end of the previous half cycle decreases. Consequently, substantially full continuous feeder power adjustment is possible with the control circuit 18.
The sooner the triac is turned on and becomes conductive, the more power is coupled to the feeder. The potentiometer 44 is preferably set to an initial value through a calibration procedure, and the potentiometer 39 is controlled by the power control knob 23 for adjustment of the level of power cou~led to the feeder 11. In calibrating the control 18, -~ 11248~9 the potentiometer 39 is set to its maximum resistance value, to provide the lowest amount of charging current to the capacitor 33 through this charging path. Then the potentiometer 44 is adjusted until tl corresponds to approximately tO, the crossover point of the source voltage waveform at the y-axis, so that a minimum amount of power is coupled to the feeder 11. In full wave operation, with the adjustment of the potentiometer 44, t2 is at the next source voltage crossover point. With this setting for the potentiometer 44, subsequent adjustment of the potentiometer 39 to lower resistance values increases the charging current to the capacitor 33 so that the triac 32 fires sooner. The desired amount of power may be coupled to the feeder ll by adjusting the potentiometer 39 to fire the triac 32 in each cycle or half cycle a~ the appropriate time.
In accordance with the invention, the switch 26 is connected in series with the charging path through the potentiometer 39 and the resistor 41 to the capacitor 33.
With the switch 26 connected in the charging path, the jumper 38 is omitted. As shown in Figure l, the switch 26 is externally connected to the control 18 and is responsive to a sensor such as one which can detect a backlog of parts on the feeder track 17. When the switch 26 is opened, this opens the charging path through the potentiometer 39 and the resistor 41, and the control 18 couples a minimum amount of power to the feeder. It can ~e seen that placing the switch in this charging path eliminates the need for high current switching in series with the feeder 11. In fact, the current in the charging path through the switch 26 is less than the entire charging current for the triac gate timing capacitor 33 since there is a second charging path through the resistor ~,. 1124819 43 and the potentiometer 44. Generally, the charging path current is on the order of milliamperes and the feeder current is on the order of amperes.
In the control circuit 18 there are additionally two varistors 46 and 47 to limit the amplitude of voltage transients across the voltage source input lines 19 and across the triac 32. There is also a snubber network, connected across the triac 32, consisting of a resistor 48 in series with a capacitor 49 for limiting the rate of rise of voltage across the triac.
While the control circuit has been illustrated in combination with a bowl type of vibratory feeder, it should ,- be understood that other types of vibratory parts feeding apparatus might also be employed with the control circuit 18. Such apparatus includes, for example, in-line drive parts feeders and vibrating storage hoppers.
From the foregoing it can be seen that a power control for a vibratory feeder type of apparatus has been provided which permits low current switching of the power to the apparatus in response to externally sensed conditions. The external switching of the power control may be in response to parts flow conditions as shown in the illustrated embodiment or in response to other system conditions requiring turn-off of the vibrating apparatus.
Claims (3)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. An electrical power control for coupling power from an AC power source to a vibratory parts feeder having load terminals which comprises a gate-controlled thyristor having main terminals and a gate terminal, the thyristor being trig-gered through its gate terminal and having a conductive state and a nonconductive state and being operable such that in one state power is coupled from the AC power source to the vibra-tory parts feeder and in the other state power is not coupled from the AC power source to the vibratory parts feeder, at least one of the main terminals being coupled to one load terminal of the vibratory feeder and at least one of the main terminals being coupled to the AC power source, a capacitor operable to trigger the thyristor coupled between the gate terminal and one of the main terminals of the thyristor, a charging path from the AC power source to the capacitor, said capacitor having a current path to said one main terminal of the thyristor connected to said load terminal, and a switch associated with the charging path which is operable to alter the impedance of the charging path, said control further including a second capacitor coupled through a charging path to the AC power source and connected to the other load terminal of the vibratory feeder, and coupled through another charging path to the first capacitor.
2. The control of claim 1 which further comprises a sensor, remote from the electrical power control, controlling the switch associated with the charging path from the AC
power source to the first capacitor.
- Page One of Claims -
power source to the first capacitor.
- Page One of Claims -
3. The control of claim 1 in which the charging path for the first capacitor includes a first adjustable potenti-ometer and the charging path between the first capacitor and the second capacitor includes a second adjustable potentio-meter.
- Page Two of Claims -
- Page Two of Claims -
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US089,352 | 1979-10-26 | ||
| US8935279A | 1979-10-30 | 1979-10-30 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1124819A true CA1124819A (en) | 1982-06-01 |
Family
ID=22217199
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA354,460A Expired CA1124819A (en) | 1979-10-26 | 1980-06-20 | Power control for vibratory feeder |
Country Status (6)
| Country | Link |
|---|---|
| JP (1) | JPS593364B2 (en) |
| CA (1) | CA1124819A (en) |
| DE (1) | DE3038685A1 (en) |
| FR (1) | FR2468527B1 (en) |
| GB (1) | GB2065388B (en) |
| IT (1) | IT1131996B (en) |
Families Citing this family (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3139724A1 (en) * | 1981-10-06 | 1983-04-21 | J. Wagner Gmbh, 7990 Friedrichshafen | ELECTRICAL FEED AND CONTROL CIRCUIT FOR THE PUMP PISTON OF A SPRAY GUN |
| US4456822A (en) * | 1981-11-17 | 1984-06-26 | Dixon Automatic Tool, Inc. | Self-contained multi-mode vibratory feeder control with unitary delay adjustment |
| GB8316441D0 (en) * | 1983-06-16 | 1983-07-20 | Limitorque Ltd | Electrical circuit |
| DE3503688A1 (en) * | 1985-02-04 | 1986-08-07 | Siemens AG, 1000 Berlin und 8000 München | SAFETY DEVICE FOR A SHOCK SHAFT GENERATOR |
| EP0213234B1 (en) * | 1985-09-06 | 1989-03-15 | Wagner International Ag | Airless spraygun |
| JPH0798567B2 (en) * | 1988-11-21 | 1995-10-25 | 神鋼電機株式会社 | Method for removing parts clogging in a vibrating parts carrier |
| US4965509A (en) * | 1989-02-13 | 1990-10-23 | Lutron Electronics Co., Inc. | Quasi-constant gate drive circuit |
| JPH0672532A (en) * | 1992-08-24 | 1994-03-15 | Yoshida Kogyo Kk <Ykk> | Part feeder control device |
| US6116408A (en) * | 1998-07-30 | 2000-09-12 | Fmc Corporation | Apparatus and system for controlling the operating frequency of an electromagnetic vibratory feeder at a submultiple of the power line frequency |
| US6471040B1 (en) * | 2000-09-01 | 2002-10-29 | Fmc Technologies, Inc. | Vibratory feeder embodying self-contained control |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1146977A (en) * | 1965-05-18 | 1969-03-26 | Mullard Ltd | Circuit arrangement for controlling the speed of a d.c. commutator motor |
| US3814888A (en) * | 1971-11-19 | 1974-06-04 | Gen Electric | Solid state induction cooking appliance |
| DE2806223A1 (en) * | 1978-02-14 | 1979-08-16 | Sortimat Creuz & Co Gmbh | CONTROL FOR VIBRATION DRIVES |
-
1980
- 1980-06-20 CA CA354,460A patent/CA1124819A/en not_active Expired
- 1980-07-21 JP JP55098828A patent/JPS593364B2/en not_active Expired
- 1980-07-25 IT IT23729/80A patent/IT1131996B/en active
- 1980-08-11 FR FR8017673A patent/FR2468527B1/en not_active Expired
- 1980-10-13 GB GB8033000A patent/GB2065388B/en not_active Expired
- 1980-10-14 DE DE19803038685 patent/DE3038685A1/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| FR2468527A1 (en) | 1981-05-08 |
| IT1131996B (en) | 1986-06-25 |
| GB2065388B (en) | 1983-10-05 |
| FR2468527B1 (en) | 1986-03-07 |
| IT8023729A0 (en) | 1980-07-25 |
| DE3038685A1 (en) | 1981-05-14 |
| DE3038685C2 (en) | 1987-07-02 |
| JPS5665706A (en) | 1981-06-03 |
| GB2065388A (en) | 1981-06-24 |
| JPS593364B2 (en) | 1984-01-24 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |