Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05C—APPARATUS FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05C11/00—Component parts, details or accessories not specifically provided for in groups B05C1/00 - B05C9/00
  • B05C11/10—Storage, supply or control of liquid or other fluent material; Recovery of excess liquid or other fluent material
  • B05C11/1002—Means for controlling supply, i.e. flow or pressure, of liquid or other fluent material to the applying apparatus, e.g. valves
  • B05C11/1034—Means for controlling supply, i.e. flow or pressure, of liquid or other fluent material to the applying apparatus, e.g. valves specially designed for conducting intermittent application of small quantities, e.g. drops, of coating material
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05C—APPARATUS FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05C5/00—Apparatus in which liquid or other fluent material is projected, poured or allowed to flow on to the surface of the work
  • B05C5/001—Apparatus in which liquid or other fluent material is projected, poured or allowed to flow on to the surface of the work incorporating means for heating or cooling the liquid or other fluent material
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05C—APPARATUS FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05C5/00—Apparatus in which liquid or other fluent material is projected, poured or allowed to flow on to the surface of the work
  • B05C5/02—Apparatus in which liquid or other fluent material is projected, poured or allowed to flow on to the surface of the work the liquid or other fluent material being discharged through an outlet orifice by pressure, e.g. from an outlet device in contact or almost in contact, with the work
  • B05C5/0225—Apparatus in which liquid or other fluent material is projected, poured or allowed to flow on to the surface of the work the liquid or other fluent material being discharged through an outlet orifice by pressure, e.g. from an outlet device in contact or almost in contact, with the work characterised by flow controlling means, e.g. valves, located proximate the outlet

Definitions

• the invention relates to a metering system for a metering substance comprising a nozzle, a feed channel for the metering substance, an ejection element, an actuator unit coupled to the ejection element and/or the nozzle with a piezoelectric actuator, and a cooling device.
• the invention further relates to a method for operating and a method for manufacturing such a metering system.
• Dispensing systems of the type mentioned above are typically used to precisely dispense a medium, usually a liquid to viscous substance.
• a medium usually a liquid to viscous substance.
• micro-dispensing technology it is often necessary to apply very small quantities of a substance to a target surface with pinpoint accuracy and without contact, i.e., without direct contact between the dispensing system and the target surface.
• Such a non-contact method is frequently referred to as a “jet dispensing method.”
• a typical example is the dispensing of adhesive dots, solder pastes, etc., during the assembly of printed circuit boards or other electronic components, or the application of converter materials for LEDs.
• a key requirement is the highly precise delivery of the dosing agents to the target surface – that is, at the right time, in the right place, and in a precisely measured quantity. This can be achieved, for example, by dispensing the dosing agent drop by drop through a nozzle of the dosing system. In this process, the medium only comes into contact with the interior of the nozzle and a section, usually the front, of the ejection element of the dosing system.
• a preferred method is the ejection of individual droplets in a type of "inkjet" process, as used, for example, in inkjet printers.
• the droplet size, or the amount of medium per droplet can be predetermined as precisely as possible through the design and control of the nozzle, as well as the resulting effect.
• the dosing agent can also be sprayed in a jet.
• a movable ejector element (usually a plunger) can be arranged in the nozzle of the dosing system.
• the ejector element can be pushed forward at a relatively high speed inside the nozzle towards a nozzle opening or outlet, thereby ejecting a droplet of the medium, which is then retracted.
• the nozzle of the metering system itself can be moved in an ejection or retraction direction.
• the nozzle and an ejection element located inside the nozzle are moved relative to each other. This relative movement can be achieved either solely by moving the outlet or nozzle, or at least partially by moving the ejection element.
• the ejector element can typically be moved into a closed position by firmly engaging a sealing seat in the nozzle opening and remaining there temporarily. With more viscous metering media, it may also be sufficient for the ejector element to simply remain in the retracted position, i.e., removed from the sealing seat, without any drop of the medium escaping.
• the present invention can be used in all the aforementioned variants regardless of the specific ejection principle, i.e., in a jet process, an open ink-jet process, a classic closure element or a movable nozzle.
• the movement of the ejector and/or nozzle is typically achieved using an actuator system within the metering system.
• the metering system typically includes a motion mechanism coupled to both the actuator system and the ejector.
• This motion mechanism can be implemented, for example, by means of a lever upon which the actuator system is mounted. The lever itself can rest on a lever bearing and be tiltable about a pivot axis so that the movement of the actuator system is transmitted to the ejector via a contact surface of the lever.
• the motion mechanism can also be designed to transmit the force generated by the actuator system to move the nozzle.
• the actuator system can be implemented in various ways, with piezo actuators being particularly preferred in applications requiring highly precise dosing resolution.
• Piezo actuators also known as piezoelectric actuators, offer the advantage of very precise and, above all, fast controllability compared to other types of actuators, such as hydraulically, pneumatically, and/or electromagnetically operated actuators.
• piezo actuators are characterized by...
• Piezo actuators are characterized by extremely short reaction and response times, which are typically significantly lower than those of other actuator principles.
• Another advantage is that piezo actuators require comparatively little installation space within a dispensing system compared to other types of actuators. Therefore, piezo actuators offer an efficient solution for operating dispensing systems, especially for highly precise dosing requirements.
• piezoelectric actuators are components that dissipate significant power, which can cause substantial heating of the piezoelectric material. Since piezoelectric actuators exhibit temperature-dependent behavior, heating of the actuator material can affect both the longitudinal expansion of the piezoelectric actuator in its resting (unexpanded) state and its displacement under voltage. In addition to the piezoelectric actuator itself, the components of the dispensing system's movement mechanism can also heat up due to frictional heat, especially under high-frequency dispensing requirements.
• Thermally induced expansion of one or more of the aforementioned components can lead to an undesirable change in the stroke process of the ejector element, causing the dispensed quantity of material to increasingly deviate from the target value during operation of the dosing system. Consequently, the temperatures of the piezoelectric actuator and the movement mechanism can have a direct impact on the precision of the dosing system.
• the entire actuator can be surrounded by compressed air, as compressed air is already available in most dosing systems.
• the movement mechanism is not directly exposed to the airflow but is simply surrounded by the exhaust air from the piezoelectric actuator.
• a disadvantage of this approach is that as the ambient temperature of the dosing system increases, the compressed air is no longer sufficient to dissipate enough heat from the piezoelectric actuator to keep it and other temperature-sensitive components of the system consistently below a critical temperature for precise operation.
• a cooling fluid e.g., air
• US 2016/0339470 A1 A dosing system is described in which air can be introduced into a housing of the dosing system to cool a piezo actuator.
• US 2016/0136661 A1 A dosing system is described, wherein two piezo actuators They can be cooled in a housing of the dosing system using a cooling fluid.
• KR 101 150 139 B1 A dosing system is described in which heat can be drawn off from a piezoelectric element by means of a heat pipe.
• a metering system for a liquid to viscous metering substance comprises at least one nozzle, a feed channel for the metering substance, an ejection element, an actuator unit coupled to the ejection element and/or the nozzle with at least one piezoelectric actuator for moving the ejection element and/or the nozzle, and a cooling device.
• the term plunger is used synonymously with an ejection element, without limiting the invention thereto.
• the dispensing of the metering agent from the metering system according to the invention can be carried out in any of the ways described above; that is, the metering system is not limited to a specific ejection or operating principle. Accordingly, as is usually the case, a ejection element movable at a relatively high speed can be arranged in the nozzle of the metering system (particularly in the area of the nozzle, e.g., shortly before the outlet opening) to eject the metering agent from the nozzle. Alternatively or additionally, as mentioned, an outlet opening of the metering system according to the invention can be designed to be movable.
• the metering agent is dispensed by means of a movable ejection element, e.g., a plunger.
• a movable ejection element e.g., a plunger.
• the invention is not intended to be limited to this.
• the actuator unit's movement mechanism is designed to functionally couple the ejector element with the at least one piezoelectric actuator of the metering system. This coupling is achieved by transmitting the forces and movements exerted by the piezoelectric actuator, resulting in the desired movement of the ejector element to release the metering material from the nozzle.
• the movement mechanism thus represents a force-transmitting, preferably multi-part, coupling that is at least temporary, to convert the deflection of the piezoelectric actuator into a movement of the ejector element, preferably vertical.
• the coupling between the movement mechanism and the ejector element is not a fixed coupling. This means that the two components are preferably not screwed, welded, glued, etc., together for coupling purposes.
• the dosing system comprises a cooling device with a feed device for supplying a pre-cooled cooling medium into a housing of the dosing system, in particular into a housing of the actuator unit.
• the housing of the actuator unit encloses the actuator unit from the ambient atmosphere of the dosing system, i.e., it forms an enclosure for the actuator unit, and therefore comprises at least one piezo actuator and the movement mechanism of the dosing system.
• the feed device has a number of connection or coupling points for an (external) cooling medium supply line in a region of the housing, as well as a feed channel arrangement adjoining the (respective) coupling point and extending into an interior space of the housing.
• the feed device can further comprise a number of components for regulating a volume flow and/or pressure of the cooling medium flowing into the housing, e.g., a pump or a proportional valve, and optionally other components.
• the cooling device is designed for the direct, predominantly selective cooling of at least a partial area of the piezo actuator and/or the movement mechanism of the actuator unit coupled to the piezo actuator by means of the pre-cooled cooling medium.
• "Direct" cooling of a partial area means that the respective partial area, in particular its surface, is the focus of the cooling.
• the respective partial area can be directly exposed to the pre-cooled cooling medium.
• the cooling of a partial area takes place within the housing itself, i.e., directly "on site”. The cooling is therefore not “indirect” by cooling the housing or parts thereof from the outside (e.g., by conduction).
• the cooling device allows only a single sub-area, i.e., a limited area or section of the surface of the piezo actuator or the movement mechanism, to be selectively and predominantly exposed to the cooling medium. Therefore, the cooling device can include flow-directing elements within the housing, such as separately controllable flow channels, guide vanes, fans, etc., to direct the cooling medium to a specific sub-area. Accordingly, there can be areas of the surface of the piezo actuator or movement mechanism that are not included in the sub-area to be cooled and are therefore excluded from direct cooling.
• sub-areas i.e., one or more sub-areas which together comprise essentially the entire surface of the piezo actuator or the components of the movement mechanism, are directly exposed to the cooling medium. Therefore, the invention will be described below, without limitation, using this embodiment.
• the invention does not cover the mere flow of the cooling medium to areas of the dosing system other than (partial) areas of the piezo actuator or the movement mechanism, e.g., an outer surface of the housing.
• areas located inside the housing e.g., the walls forming a chamber surrounding the piezo actuator (actuator chamber) and a chamber surrounding the movement mechanism, are not the target of direct cooling.
• These areas or surfaces of the dosing system which are not encompassed by a section to be cooled, are therefore not specifically targeted by the cooling medium, but merely "passed by" it. This means that the cooling medium necessarily passes through these areas on its way from the feed device to an outlet opening in the housing, but the areas themselves are not the focus of direct cooling by the cooling device.
• the cooling device can be configured to selectively cool only a number of sub-areas of one or more piezoelectric actuators. This means that the movement mechanism would not be affected by the direct cooling.
• the direct cooling could also be directed only at one or more sub-areas of the movement mechanism, whereby the piezoelectric actuator would not be included in the direct cooling.
• the piezoelectric actuator and the movement mechanism can thus be cooled separately by means of the cooling device according to the invention.
• the cooling device can also be configured to directly cool a number of sub-areas of the piezoelectric actuator and the movement mechanism as a single unit, as will be explained later.
• the dosing system can operate at maximum dosing frequency even at high ambient temperatures.
• the cooling unit allows for the targeted and selective cooling of temperature-sensitive components within the dosing system, eliminating the need to cool the other components or the housing itself. This reduces the consumption of pre-cooled coolant.
• control is used synonymously with “control” and/or “regulation” in the following. This means that even when referring to “control,” the control process can encompass at least one regulation process.
• a controlled variable actual value
• setpoint a reference variable
• Regulation typically occurs in such a way that the controlled variable is adjusted to match the reference variable. This means that the controlled variable (actual value) continuously influences itself within the control loop.
• a state parameter can be, for example, a (surface) temperature in at least a sub-area of the piezo actuator and/or a (surface) temperature in at least a sub-area of the movement mechanism coupled to the piezo actuator and/or a temperature in at least a sub-area of an outer surface of the housing ("external temperature").
• the dosing system can comprise one or more temperature sensors, which are preferably coupled to a control unit of the dosing system.
• multiple temperature sensors can be implemented along a longitudinal axis on the actuator surface. If the piezoelectric actuator has an actuator housing in which a piezoelectric stack is encapsulated, multiple temperature sensors can also be arranged in different areas of an inner and/or outer wall of the actuator housing. Alternatively or additionally, a number of temperature sensors can also be arranged in direct contact with at least one component of the movement mechanism, e.g., the lever.
• a number of temperature sensors can be mounted on or in the housing in close proximity to a respective component to estimate or extrapolate the component's temperature.
• the temperature sensors can also be designed to determine the temperature of a specific sub-area of the movement mechanism or the piezo actuator from a certain distance, e.g., using infrared temperature sensors.
• a relevant state parameter, upon which the control is dependent (“control state parameter"), can correspond to a mean temperature or a maximum temperature of a number of sub-areas of the piezo actuator and/or movement mechanism.
• Another state parameter can be the length of at least a portion of the piezoelectric actuator.
• piezoelectric actuators or rather the individual piezoelectric elements, can exhibit temperature-dependent expansion behavior. Therefore, to monitor the (operating) state of the piezoelectric actuator, at least one strain gauge can be attached to the actuator surface to monitor the absolute length and/or the dynamic change in length of the piezoelectric actuator.
• the strain gauge can be used to monitor the longitudinal strain of the entire actuator as well as a section thereof.
• the strain gauge can also be located inside the actuator. an actuator housing (e.g. in the area of an inner wall) and/or on an outer surface of the actuator housing.
• the distance between the ejection element, preferably a plunger tip, and the nozzle or nozzle seat of the metering system in the open state can also be used as a state parameter to control the cooling.
• wear can occur, particularly in the area of the plunger tip, which can cause the plunger to shorten.
• the individual components of the movement mechanism can heat up and expand due to friction. A thermally induced change in the actuator's length, resulting from its coupling with the movement mechanism, can also cause the actual position of the plunger tip to deviate from the target position.
• the dosing system can include at least one motion sensor, e.g., a magnetic sensor, for measuring the displacement of a moving component.
• at least one thermally compensated Hall sensor can be arranged in a region of the housing such that the sensor can interact with a magnet of the plunger and/or the lever to perform a preferably vertical displacement measurement of the plunger or lever.
• the position of the plunger tip in the closed state of the dosing system can be compared with a position in the open state to determine the actual movement of the plunger or plunger tip for dispensing the metering material.

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• Reciprocating Pumps (AREA)
• Coating Apparatus (AREA)
• Fuel-Injection Apparatus (AREA)
• Micromachines (AREA)
• Cooling Or The Like Of Electrical Apparatus (AREA)

Applications Claiming Priority (2)

Publications (3)

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Family Applications (1)

Country Status (9)

Families Citing this family (12)

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• 2018
  • 2018-10-05 DE DE102018124662.5A patent/DE102018124662A1/de active Pending
• 2019
  • 2019-09-24 SG SG11202102551QA patent/SG11202102551QA/en unknown
  • 2019-09-24 US US17/278,608 patent/US11498092B2/en active Active
  • 2019-09-24 MY MYPI2021001469A patent/MY200279A/en unknown
  • 2019-09-24 WO PCT/EP2019/075644 patent/WO2020069909A1/de not_active Ceased
  • 2019-09-24 JP JP2021515577A patent/JP2022501184A/ja not_active Withdrawn
  • 2019-09-24 KR KR1020217008205A patent/KR102871540B1/ko active Active
  • 2019-09-24 CN CN201980062163.3A patent/CN112770845B/zh active Active
  • 2019-09-24 EP EP19782925.2A patent/EP3860771B1/de active Active

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