The present subject matter relates generally to the field of conveyors, and more particularly to an improved conveyor drive system for use in thin film deposition systems wherein a thin film layer, such as a semiconductor material layer, is deposited on a substrate conveyed through the module.
Thin film photovoltaic (PV) modules (also referred to as “solar panels”) are gaining wide acceptance and interest in the industry, particularly modules based on cadmium telluride (CdTe) paired with cadmium sulfide (CdS) as the photo-reactive components. Solar energy systems using CdTe PV modules are generally recognized as the most cost efficient of the commercially available systems in terms of cost per watt of power generated. However, the advantages of CdTe not withstanding, sustainable commercial exploitation and acceptance of solar power as a supplemental or primary source of industrial or residential power depends on the ability to produce efficient PV modules on a large scale and in a cost effective manner.
The ability to process relatively large substrates on an economically sensible commercial scale is thus a crucial consideration and, in this regard, down time of the deposition modules for maintenance and repair should be minimized. Maintenance on the module conveyor typically requires disconnecting the drives from the conveyors, which can be a tedious and timely exercise. Subsequent alignment of the drives with the conveyor components can also be problematic. Diagnosing problems with the module drives while the units are under operating temperature and vacuum conditions can also be difficult. In addition, the life of the conveyor drives can be significantly shortened by transmission of the tremendous heat generated in the deposition module to the externally mounted drive components, which also results in down time of the system to replace the components.
Accordingly, there exists an ongoing need for deposition modules with improved drive systems that reduce maintenance/repair down time, as well as address other disadvantages noted above.
Aspects and advantages of the invention will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the invention.
In accordance with aspects of the invention, a module is provided for a system wherein a sublimated source material is deposited as a thin film on a substrate conveyed through one or more of the modules. In a particular embodiment, the module is a vapor deposition module configured for deposition of a thin film of photo-reactive material on a PV substrate. The module may also be one or more of the modules in the system that conveys the substrate to and from the deposition module. The module includes a drive unit mounted on an exterior wall of the module, with the drive unit having a drive shaft that extends into the module. A conveyor is operably disposed within the module and is configured to be driven in a conveying path by the drive unit. For example, in a particular embodiment, the conveyor is driven in an endless loop path between opposite sprockets within the module. A releasable drive coupling is configured between the drive unit and a drive member of the conveyor, which may be a sprocket shaft. The drive coupling has a first end that releasably engages the drive shaft and a second end that releasably engages the conveyor drive member. The drive coupling includes a torque member and at least one thermal shield spaced concentrically around the torque and extending axially between the first and second ends.
In a particular embodiment, the torque member includes an innermost torque transmission tube and a plurality of the concentric thermal shields disposed around the torque transmission tube.
The drive coupling may be axially movable along at least one of the drive shaft or conveyor drive member for disconnecting and removal of the drive coupling. A releasable locking device may be provided for axially fixing the drive coupling relative to the drive shaft and conveyor drive member.
To accommodate some degree of misalignment between the drive unit and conveyor drive member, a particular embodiment may include a partially rounded interface between the first end of the drive coupling and the drive shaft and between the second end of the drive coupling and the conveyor drive member.
In an embodiment wherein the conveyor is driven in an endless loop path between opposite sprockets, a selectively actuatable clutch may be operably configured between the drive unit and drive shaft. Another respective drive unit with associated clutch and drive coupling may be configured with a shaft on the opposite sprocket. The clutches may be operably interfaced so that the clutches cannot be simultaneously engaged. For example, the clutches may be pneumatic clutches with a controllable three-way valve disposed between an air source and the clutches, wherein the valve permits actuating airflow to only one of clutch at a time.
In still another embodiment, a deposition module is provided wherein a sublimated source material is deposited as a thin film on a substrate conveyed through said module. The module includes a conveyor operably disposed within the module to be driven in an endless loop path between opposite sprockets, with at least one of the sprockets being a drive sprocket. A drive unit is mounted on an exterior wall of the module for each of the sprockets, with each of the drive units having a drive shaft that extends into the module. A releasable drive coupling is configured between each drive unit and respective sprocket. The drive coupling includes a first end that releasably engages the drive shaft and a second end that releasably engages the drive sprocket. A selectively actuatable clutch is configured between each drive unit and respective drive shaft, with the clutches operably interfaced so that the clutches cannot be simultaneously engaged.
In a unique embodiment, the deposition module includes a conveyor housing disposed within the module, with the conveyor and sprockets configured within the conveyor housing. The conveyor housing may be removable from the module upon disconnecting the drive coupling from the drive shafts and sprockets.
Variations and modifications to the embodiments of the deposition module discussed above are within the scope and spirit of the invention and may be further described herein.
These and other features, aspects and advantages of the present invention will become better understood with reference to the following description and appended claims.
A full and enabling disclosure of the present invention, including the best mode thereof, is set forth in the specification, which makes reference to the appended drawings, in which:
Reference now will be made in detail to embodiments of the invention, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. For instance, features illustrated or described as part of one embodiment, can be used with another embodiment to yield a still further embodiment. Thus, it is intended that the present invention encompass such modifications and variations as come within the scope of the appended claims and their equivalents.
For reference and an understanding of an environment in which the present modules 100 may be used, the system 10 of
Referring to
The vapor deposition module 60 may take on various configurations and operating principles within the scope and spirit of the invention, and is generally configured for vapor deposition of a source material, such as CdTe, as a thin film on the PV module substrates 14. In the embodiment of the system 10 illustrated in
The vacuum chamber 12 also includes a plurality of interconnected cool-down modules 20 within the vacuum chamber 12 downstream of the vapor deposition module 60. The cool-down modules 20 define a cool-down section within the vacuum chamber 12 in which the substrates 14 having the thin film of source material deposited thereon are allowed to cool at a controlled cool-down rate prior to the substrates 14 being removed from the system 10. Each of the modules 20 may include a forced cooling system wherein a cooling medium, such as chilled water, refrigerant, or other medium is pumped through cooling coils configured with the modules 20.
In the illustrated embodiment of system 10, at least one post-heat module 22 is located immediately downstream of the vapor deposition module 60 and before the cool-down modules 20. As the leading section of a substrate 14 is conveyed out of the vapor deposition module 60, it moves into the post-heat module 22, which maintains the temperature of the substrate 14 at essentially the same temperature as the remaining portion of the substrate 14 within the vapor deposition module 60. In this way, the leading section of the substrate 14 is not allowed to cool while the trailing section of the substrate 14 is still within the vapor deposition apparatus 60.
As diagrammatically illustrated in
Still referring to
An exit vacuum lock station is configured downstream of the last cool-down module 20, and operates essentially in reverse of the entry vacuum lock station described above. For example, the exit vacuum lock station may include an exit buffer module 42 and a downstream exit lock module 44. Sequentially operated valves 34 are disposed between the buffer module 42 and the last one of the cool-down modules 20, between the buffer module 42 and the exit lock module 44, and between the exit lock module 44 and an exit conveyor module 46. A fine vacuum pump 38 is configured with the exit buffer module 42, and a rough vacuum pump 32 is configured with the exit lock module 44. The pumps 32, 38 and valves 34 are sequentially operated to move the substrates 14 out of the vacuum chamber 12 in a step-wise fashion without loss of vacuum condition within the vacuum chamber 12.
System 10 also includes a coordinated conveyor system configured to move the substrates 14 into, through, and out of the vacuum chamber 12. In the illustrated embodiment, this conveyor system includes a plurality of individually controlled conveyor assemblies 48 within each of the various modules in the system 10. Although the releasable drive coupling of the present invention is particularly suited for the conveyor assembly in the vapor deposition module 60, it should be appreciated that the drive couplings are not limited in this regard. Any combination of the respective conveyor assemblies 48 within any of the modules in system 10 may include one or more of the drive units 102 with releasable couplings 120 as discussed in greater detail below.
As described, each of the various modules and respective conveyors in the system 10 are independently controlled to perform a particular function. For such control, each of the individual modules may have an associated independent controller 50 configured therewith to control the individual functions of the respective module, including the conveyance rate of the conveyor assemblies 48 (and thus the speed of the drive units 102). The plurality of controllers 50 may, in turn, be in communication with a central system controller 52, as illustrated in
Referring to
The drive units 102 include a motor 103 configured on a drive unit housing 109. Any configuration of gearing or other transmission means may be contained within the housing 109 for conveying rotational torque to a drive shaft 106 associated with the drive unit 102. A flange 107 may be provided with the housing 109 for mounting the drive unit 102 onto a mounting surface or flange configured on the exterior wall 104 of the module 100.
Referring to
In the illustrated embodiment, the releasable coupling 102 is axially movable relative to the respective shafts 106, 116 upon releasing the locking mechanism (e.g., removing the cotter pin 146) for relatively simple removal of the coupling 102 from between the shafts. For example, referring to
Referring particularly to
In order to accommodate relative axial misalignment between the respective shafts 106, 116, a partially rounded engagement interface may be defined between the ends of the shafts and the respective keyed hubs 130. For example, referring to
The drive units 102 provide motive force to any manner of conveyor within the module 100. A particular embodiment of a conveyor 108 is illustrated in
Referring to
Referring particularly to
The conveyor 108, particularly the housing 164, is configured for drop-in placement of the assembly 110 in the vapor deposition module 60. A plurality of braces 178 are attached to the side walls 168 and extend through slots in the top wall 170. These braces 178 define a plurality of lifting points for raising and lowering the conveyor assembly 108 into the vapor deposition module 60. When maintenance is required, the drive units 102 are disengaged from the conveyor assembly 108 by removing the drive couplings 120 as discussed above and the housing 164 is easily lifted from the module 60. A spare conveyor assembly 108 is readily dropped into the module 60 and engaged with the drive units 102 with the drive couplings 120. In this way, maintenance may be conducted on the removed assembly 108 while the processing line is returned to service. This keeps the vapor deposition line running in parallel with maintenance tasks.
The drive units 102 may be configured with a selectively actuatable clutch 154, as depicted in
The clutches 154 may also be torque limiting clutches that operate below a design maximum torque. If excess torque is produced, the clutches 154 slip, and may also trip an over-torque sensor. This safety feature prevents a jam from causing extensive damage to the conveyor 108.
When an enclosed module 100 is under high temperature and vacuum conditions, there is no easy means to evaluate the conditions of the conveyor 108 within the module. In this regard, it may be desired to include an externally accessible male driver configured on an end of the drive shaft 106, such as a hex head driver 162 depicted in
This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.