US3145930A

US3145930A - Electrostatic paint spraying apparatus for changing liquids

Info

Publication number: US3145930A
Application number: US80944A
Authority: US
Inventors: Herklotz Helmut; Leichtle Walter; Otto Louis; Platz Walter; Wiegelmann Herbert
Original assignee: Metallgesellschaft AG
Current assignee: GEA Group AG
Priority date: 1961-01-05
Filing date: 1961-01-05
Publication date: 1964-08-25
Anticipated expiration: 1981-08-25

Description

Aug. 25, 1964 H. HERKLOTZ ETAL 3,145,930

APPARATUS FOR CHANGING ELECTROSTATIC PAINT SPRAYING LIQUIDS Filed Jan. 5, 1961 5 Sheets-Sheet 1 HEL MUT HER/(072, LOU/5 arm, WAL TER LE/CHTLE, WALT'R PLATZ, HEKBERT W/EGELMA/V/V W :tarney:

Aug. 25, 1964 H. HERKLOTZ ETAL 3,145,930

APPARATUS FOR CHANGING ELECTROSTATIC PAINT SPRAYING LIQUIDS 5 Sheets-Sheet 2 Filed Jan. 5, 1961 .[nVe/nm l/E'L/Ml/Tf/EKKZOTZ, 0015 0770, WAL TER LE/CH 7/. E, WAL 76/? PZATZ B Y HERBERT W/EGEL MAN V f M Aitarne'y Aug. 25, 1964 H. HERKLOTZ ETAL APPARATUS FOR CHANGING ELECTROSTATIC PAINT SPRAYING LIQUIDS Filed Jan. 5, 1961 5 Sheets-Sheet 5 .[I7VE/7L0/S z, LOU/S 0770 75? LE/CHTLL-j. WALTERPtATZ, HEABEKT W lEGELM/l/V N I Attorney HELMUT HER/(107' WA 25, 1964 H. HERKLOTZ ETAL 3,

" APPARATUS FOR CHANGING ELECTROSTATIC PAINT SPRAYING LIQUIDS Filed Jan. 5, 1961 5 Sheets-Sheet 4 J n v en in rs HELMUT HERKLOTZ, LOU/5 OT T 0 WALTER LE/CHTLE, WALTER PLATZ HERBERT W/EGELMANN BY A 7ORNE 5 Aug. 25, 1964 H. HERKLOTZ ETAL 3,145,930

APPARATUS FOR CHANGING ELECTROSTATIC PAINT SPRAYING LIQUIDS 5 Sheets-Sheet 5 Filed Jan. 5, 1961 Invemors HELMUT HER/(L0 TZ, LOU/S arm, WALTER 15/0 n 72,

Y 7 Attorneys E, WALTER PLA HERBER T W/EGEL MA MA BY United States Patent "ice 3,145,930 ELECTROSTATIC PAINT SPRAYING APPARATUS FOR CHANGING LIQUIDS Helmut Herklotz and Walter Leichtle, Neu-Isenburg, and Louis Otto, Walter Platz, and Herbert Wiegelmann, Frankfurt am Main, Germany, assignors to Metallgesellschaft Aktiengesellschaft, Frankfurt, Germany Filed Jan. 5, 1961, Ser. No. 80,944 Claims. (Cl. 239-15) This invention relates to a device for changing or switching liquids. In particular, the invention is directed to the changing of a liquid in a paint or lacquer spraying device in order to change the color being sprayed.

In paint spraying apparatuses, it is desirable to spray various colors one after the other from the same spray nozzle. Such a change in the color of the liquid entails the necessity of cleaning the pipe lines between each color change. Existing devices utilize switching devices or multichannel feeders for changing from one color to another. Such devices are complicated and have angular passages which are difficult to clean. The instant invention has for its object the changing of the color of the paint or the like by a rapid and automatic switching means. According to this invention, the change from one color to another is carried out, including the flushing or the rinsing of the pipe lines, within one minute. The invention provides for the cleaning of the pump, pipes and hoses and the spray nozzles by rinsing them after one color has been sprayed and in preparation for spraying a different color. The apparatus of this invention has the advantage in that it can be installed in existing apparatuses because it requires very little space.

This invention is especially adapted for paint and lacquer changes in an electrostatic spraying apparatus and is distinguished in that the distributor or color selector head for the liquid paint or lacquer and the paint pump are mutually mounted upon a bracket which is spaced from a supporting frame or stand by means of insulators, and with the head and pump being driven through insulating shafts. The stand or frame supports a gear unit, a potentiometer, and a selector head brush-shifting drive motor, which drives the gear unit, and a drive motor for the pump.

In the spraying booth, the selector head should be located as closely as possible to the spray nozzle. The pump is driven through an insulated shaft by a tightly coupled polyphase induction motor running at about 1500 rpm. Also, the pump can be driven by a conventional driving motor having a low variable speed. When driven at a low variable speed, the armature of the high speed motor is dead and rotates idly. When the high speed motor is activated, then the low speed motor is cut off by means of a freely overrunning clutch with which the two motors are coupled. During spraying time, the low variable speed motor drives the pump by itself. During change-over from one color to another, the use of the high speed motor results in a shortened pumping time during the flushing or rinsing of the pipe lines and the advancing of a fresh paint to the spray nozzle. The high speed motor is then cut out and the low variable speed motor actuated to drive the pump.

The selector or control distributor head is composed of a cylindrical housing having radially extending openings therethrough with pipe connection fittings and a valve plug body rotatably mounted in the housing. This body has an axially extending passage which communicates with a radially extending passage, with the latter being adapted to be aligned with one of the radial openings in the housing. The selector head is coupled to an electric potentiometer driven by a motor. The selec- 3 ,145,930 Patented Aug. 25, 1964 tor head is connected by tubes joined to the pipe fittings with the various paint holding tanks.

The apparatus is remotely controlled from a switching system. This system contains the elements for automatically switching from one color to another through a complete cycle. The manner of operating the switching system is as follows:

A new color is selected by pressing a color selection switch on the electric control panel upon which the following functions are automatically performed: The color selector head is turned to the passage to which the cleaning agent, such as a solvent or thinner, is joined and the high speed pump motor is activated, upon which the solvent is rapidly pumped through the selector head and spray nozzle to clean the same. After a predetermined flushing time, the selector head is turned automatically to the passage connected to the new color supply. The high speed motor rapidly pumps the new color liquid through the pipe system until all of the solvent in the pipes has been pushed out and the pipe system filled with the new color liquid. Then the high speed motor cuts off and the low speed variable motor is activated to pump the new color liquid through the spray nozzle. The switching system has the further feature of having a follow-up control for adjusting the selector head and the time sequence control for completing the liquid changing process, so that these steps are automatically performed by one and the same control means.

The means by which the objects of the invention are obtained are described more fully with reference to the accompanying drawings, in which:

FIGURE 1 is a front elevational view of the apparatus;

FIGURE 2 is a plan view of FIGURE 1;

FIGURE 3 is a cross-sectional view through the selector head;

FIGURE 4 is a cross-sectional view taken on the line 4-4 of FIGURE 3;

FIGURE 5 is a circuit diagram of the switching system; and

FIGURE 6 is a circuit diagram for the entire apparatus.

As shown in FIGURES 1 and 2, a variable low speed motor 1 through a transmission gear 2 is connected by a coupling 3 and a free-Wheel overrunning clutch 4 to the high speed scavenging or rinsing pump motor 5. An insulating shaft 6 is connected by joints 7 to a pump 8 having a liquid feed inlet 9 and an outlet 10. Pump 8 is mounted upon a bracket 11 which is suspended by means of a pair of insulators 12 from a stand or frame 13. A flange connection 14 secures selector head 16 upon bracket 11. Selector head 16 is provided with a plurality of pipe fittings 21 to which tubes are adapted to be attached, which tubes lead to the various paint color tanks 21a respectively. Selector head 16 is driven through an insulating shaft 23 connected through joints 24 to a gear unit 25 to which is coupled a potentiometer P1. The gear unit is driven by a belt or chain drive 27 connected to an electric motor 28.

As shown in FIGURES 3 and 4, the selector head 16 is composed of a cylindrical housing 36 having a plurality of radially extending passages 37 into which the pipe couplings 21 are fitted. Rotatably mounted in the housing is a valve plug body 39 in the shape of a truncated cone. This body is rotated by a stub shaft 40 connected to insulating shaft 23. The opposite side of body 39 is extended by means of a shaft having an axial bore 41. The shaft terminates in a fitting 42 adapted to be connected to the inlet 9 of pump 8. This turnable extension is provided with a flanged collar 43 against which the spring 44 is pressed, with the other end of the spring being held against spring seat 45. Plug body 39 contains an axial passage 46 which communicates with a radial passage 47 adapted to be aligned with one of the openings 37. Of the thirteen radial openings 37 which are shown, one is always connected to the tank holding the flushing or rinsing fluid, while the other openings are connected to the various paint or lacquer tanks of diffierent colors, respectively. By turning plug 39, the passage 47 is lined up with the desired opening 37.

As shown in FIGURE I, paint of a chosen color or rinsing fluid flows from tank 21a through fitting 21, radial passage 47, axial passage 46, bore 41, and pipe 42a to pump inlet 9. The fluid leaves the pump 8 through pipe 421) and is led to paint nozzle 58, from which the paint is sprayed on an object such as the vehicle 59.

The wiring diagrams represented in FIGURES 5 and 6 contain the following essential control element groups:

The follow-up control for adjusting selector head 16 (paint distributor) and the time-sequence control for handling the paint-changing cycle.

The function of the individual control elements becomes evident from the following description of the wiring diagrams of FIGURES 5 and 6:

If a paint change is desired, then the paint selector switch LS is set on the paint color to be selected, such amounting to the switching of contact LS to the variable resistor which goes with same. Paint changing key T1 is pressed by hand and cuts in relay D, FIGURE 5. By closing contact d relay I is energized. The auxiliary contacts through jg are hereby activated; cuts out paint selector switch LS; j switches fixed tap for flushing fluid, W1, a potentiometer, in conjunction with paint selector switch setting means, to polarized relay A. Contact 1' switches on paint change pilot lamp MLl. Relay responds simultaneously; contact 0 is opened, and in doing so, the high-voltage that is placed on the terminals 56, 56 from the painting apparatus is switched off. The closing of contact 0 causes the controlling mechanisms which are connected to terminals 57, 57' to set off switching processes by means of which the spray nozzle 58 is brought to a definite position, for example, pointed into a waste tank. Contact 1' opens, and switches off relay D once more. Contact is closed and thus paves the way for the tripping process of the time circuit P3-C4 and contact trips the delayed cut-in relay F. Contact i bridges key T3, and contact j7 de-energizes relay N. According to the way P1 is positioned, relay A will cause relay B or C to respond via contact a Motor switches G or H are switched in via b or 0 for the selector head motor 28. The field coils of motor 28 are connected to

terminals

50, 50 and the armature windings to 51, 51'. Capacitor C2 or C3 is switched in parallel fashion to relay B or C by contact h or 0 (delayed release). By virtue of the full transformer voltage, motor 28 runs at high speed via contact i which is closed in the normal position. Transformer Tr is energized via the terminals 49, 49' with an alternating voltage of 220 volts.

Potentiometer P1 goes beyond the equalization with LS, and in so doing switches over relay A. Again, through this, contact al switches from relay B to C, or else from C to B; correspondingly contacts b and 6 cause contactor G or H to operate. Due to the delayed release of B or, as the case may be, C, relays B and C are both energized for a short timeand even the motor contactors G and H as well-by way of contacts b and c Auxiliary contacts g and 11 short-circuit the armature winding of the motor 28 during this time, and by this means bring about the braking of the motor 28. contacts g and 11 cause switch-over contactor S for the motors fast-slow speed to respond, whereby contact s cuts out the slow-acting capacitors C2 and C3. One of the two relays, B and C, releases, and in so doing release G and H as well. Contactor S is held by way of contacts s and g or, as the case may be, I1 Contact s opens and switches off the motor 28 so that the latter no longer runs at high speed, and contact s (transformer partial voltage) switches the brush-shifting motor 28 to slow speed. Potentiometer P1 returns to balance position; relay A becomes de-energized through this, and hence, so do contactors B, or else C, and G, or else H. In doing such, contacts g or else 11 cut out contactor S. Contacts g and h close simultaneously, and delayed cut-in relay F begins to act via m and 0 Contacts g and I1 close simultaneosuly, and delayed cut-in relay F begins to act via m and 0 Contacts g and 12.; close and brake the motor 28 by short-circuiting the armature winding. Contact 1, closes and applies voltage to the exciting electrode of cathode tube Z803U via potentiometer P2, contact 11; and capacitor C4 (timelimit relay switching). The voltage is decreased by rectifier G11 on which an alternating voltage of 220 volts has been placed by way of

terminals

48, 48. Contact f closes and causes scavenging motor 5 to start up via switch M. The poly-phase motor is hooked up to terminals 55, 55', 55" as a scavenging motor, and at

terminals

54, 54, 54" a three-phase voltage is drawn from the power supply. After contactor M breaks, the threephase windings are short-circuited, and the motor braked.

After a specified period of time (setting at potentiometer P2) tube Z803U lights up and relay E begins to act. This causes contact 6 to cut in relay D, and contact e discharges capacitor C4 via resistor R10. By opening contact d relay J functions and hence, so do relays F and M due to the opening of contacts and 11;. Switch d causes contactor K to respond; contact k switches the preselected tap of paint selector switch LS to relay A; contactor k continues to keep the circuit to pilot lamp MLl closed and holds the circuit for contactor 0. Contact k de-energizes relay D due to its opening, and contact k prepares the cut-in of the time-base circuit P3-C4 (timing at P3). Contact k cuts in slow-acting relay F; contact k bridges key T3, and contact k cuts out relay N. Change-over contact a switches to relay B or C according to the Way the operation is set up, and auxiliary contact of sameb or c causes selector head motor 28 to start up via motor contactor G or, as the case may be, H. Switch b switches capacitor C2 in parallel fashion to relay B or, as the case may be, contact c switches capacitor C3 in parallel fashion to relay C (releasing delay). The motor again runs at high speed.

Motor 28 is now shifted from high to low speed through the circuitry heretofore described and stopped.

Following the fixed time P3C4, relay E begins to act via the electron tube Z803U. This causes contact e to cut in relay D which produces a shift on the part of selector switch LS. Contact e again discharges capacitor C4. Contacts d and m cause contactor relay L to respond for normal paint pumping operation, in which case contact l causes the pilot lamp ML2 to light up; contact closes and bridges contact m so that relay L itself is held. The lacquer pump motor 1 is hooked up to terminals 53, 53, 53". The connections to the threephase line are at

terminals

52, 52, 52". By cutting out relay D, relay K is released-as are also relays F, M, O via contacts k k and k7; pilot lamp MLl is also extinguished.

The switching operation for general flushing, rinsing or cleaning is as follows:

Key T2 (general cleaning) is pushed by hand and causes contactor N to respond. This causes a series of switching operations to be triggered once again. Contact 12 switches the flushing switch at W1 to relay A. Due to the opening of contact 11 the possibility of a switching from T1 is avoided, as is likewise a further switching of relay D. Contact 11 cuts out relay E, and contact 11.; energizes delayed cut-in relay F. Contact n cuts out contactor L, and contact 11 holds contactor N itself. Contact 11 causes contactor O to take effect again which shuts off the high voltage and causes the sprayer to be protected. in which case contact It breaks the power supply to pilot lamp MLl. In place of this, pilot lamp ML3, general cleaning, lights up via contact u According to the way in which potentiometer P1 is positioned, contact a again cuts in relay B or C, and it cuts in contactor G or H via contact b or else Contact b or provides for a delayed release of relay B or C again via capacitor C2 or C3. The additional switching operations proceed as heretofore described.

After potentiometer P1 has gone to the balance position, relay A cuts out, and in doing so, relay B or C follows suit. Even relay S cuts out as well, provided that G and H were energized as a result of the delayed re lease of B and C. As rest contacts, contacts g and h cause relay F to take effect by Way of the tripping delay, and contacts g and k short-circuit the armature Windings from

terminals

51, 51 of the selector head motor 28. Contact f causes scavenging motor 5 to start up via contactor M. The flushing operation can be interrupted by pressing key T3, general cleaning, (switch-01f). By doing such, contactors M and N are cut out and relay F along with pilot lamp ML3 become de-energized.

Rectifiers G12 and G13 of a known design are still needed besides rectifier G11. R11 is a current-limiting series resistor for transformer Tr.

Having now described the means by which the objects of the invention are obtained, we claim:

1. In an electrostatic paint spraying apparatus, means for changing from one spray liquid to another comprising a bracket, a liquid selector head and a liquid pump mounted upon said bracket, a spray nozzle adapted to be electrically energized connected through said pump to said selector head, insulators for holding said bracket, a high speed motor connected by an insulated shaft to said liquid pump for driving said pump to pump rinsing liquid to said selector head, an overrunning clutch joined to said high speed motor, a slow variable speed motor connected through said clutch to said high speed motor for driving said liquid pump while spraying paint, and a selector head insulated drive shaft joined to said selector head.

2. In an apparatus as in claim 1, a supporting frame joined to said insulators, a selector drive motor coupled to the selector head shaft through a gear unit and a potentiometer and being mounted on said frame, and both the high and the slow speed pump drive motors being mounted on said frame.

3. In an apparatus as in claim 2, said selector head comprising a cylindrical housing adapted to be connected to a high voltage source, a plurality of radially extending openings through said housing, a valve plug body rotatably mounted in said housing and joined to said selector head drive shaft, an axial passage in said body, and a radial passage in said body communicating with said axial passage and being adapted to be aligned with one of said openings.

4. In an apparatus as in claim 3, said potentiometer being connected to said gear unit as an actual value transmitter of a follow-up control.

5. In an apparatus as in claim 1, said selector head and said liquid pump with their respective associated drives, being vertically separated.

References Cited in the file of this patent UNITED STATES PATENTS 1,857,084 Goetz May 3, 1932 2,178,559 Cohen Nov. 7, 1939 2,189,950 Gump Feb. 13, 1940 2,250,507 Thomas July 29, 1941 2,257,004 Fleming Sept. 23, 1941 2,272,544 Cederstrom Feb. 10, 1942 2,770,248 Audia Nov. 13, 1956 2,834,376 Hughes May 13, 1958 2,920,635 Wilson Jan. 12, 1960 2,921,599 Fleischman Jan. 19, 1960 FOREIGN PATENTS 1,162,056 France Mar. 31, 1958

Claims

1. IN AN ELECTROSTATIC PAINT SPRAYING APPARATUS, MEANS FOR CHANGING FROM ONE SPRAY LIQUID TO ANOTHER COMPRISING A BRACKET, A LIQUID SELECTOR HEAD AND A LIQUID PUMP MOUNTED UPON SAID BRACKET, A SPRAY NOZZLE ADAPTED TO BE ELECTRICALLY ENERGIZED CONNECTED THROUGH SAID PUMP TO SAID SELECTOR HEAD, INSULATORS FOR HOLDING SAID BRACKET, A HIGH SPEED MOTOR CONNECTED BY AN INSULATED SHAFT TO SAID LIQUID PUMP FOR DRIVING SAID PUMP TO PUMP RINSING LIQUID TO SAID SELECTOR HEAD, AN OVERRUNNING CLUTCH JOINED TO SAID HIGH SPEED MOTOR, A SLOW VARIABLE SPEED MOTOR CONNECTED THROUGH SAID CLUTCH TO SAID HIGH SPEED MOTOR FOR DRIVING SAID LIQUID PUMP WHILE SPRAYING PAINT, AND A SELECTOR HEAD INSULTED DRIVE SHAFT JOINED TO SAID SELECTOR HEAD.