A tack-off system for cleaning vehicular bodies eliminates the presence of exposed, flexible conduit at locations above the path of travel of the vehicle therethrough. Additionally, the apparatus includes a positioning system which allows the tack-off brushes to be moved in relation to the vehicular bodies, without changing the positional orientation of the brush assembly with regard thereto. Also, the system includes a vortex enhanced plenum utilized to evacuate ambient air and contaminant particles.

FIELD OF THE INVENTION 
This invention relates generally to a cleaning apparatus for the removal of 
dust, lint and other particulate matter from surfaces prior the painting, 
lacquering or other coating thereof. In particular, the present invention 
relates to an automated tacking machine for cleaning motor vehicle bodies 
prior to painting. 
BACKGROUND OF THE INVENTION 
It is very important to remove dust, lint and other such particulate matter 
from surfaces prior to their painting, since such contaminants can produce 
a variety of blemishes in the final painted finish. Cleaning is 
particularly important in those instance where it is desirable to achieve 
large area, high quality painted finishes, as for example in the 
manufacture of motor vehicles. It is essential that any pre-painting 
cleaning process not mar the vehicle or introduce any new contaminants. 
Furthermore, it is desirable that any cleaning process be compatible with 
high volume automated manufacturing techniques. 
Originally, pre-painting cleaning was carried out by wiping the surfaces 
with cloths impregnated with a tacky material, and hence, all such 
cleaning processes are generally referred to as "tacking" or "tack-off" 
processes. Cloth based processes have been found to be generally 
unsatisfactory, and the art has turned to various brush based systems. 
Apparatus of this type generally comprises a rotating brush which is swept 
across the surface to be cleaned. The brush removes dust particles which 
are collected by a vacuum. One such prior art system particularly adapted 
for cleaning motor vehicle bodies is shown in U.S. Pat. No. 4,689,749. 
A number of problems have been encountered with prior art tack-off systems, 
particularly as applicable to the manufacture of motor vehicles. Brush 
positioning and control is critical, since it is necessary that the brush 
sweep the entire vehicle surface. However, it is important to avoid 
inadvertent collision of the brush with the vehicle. The brushes are 
typically manufactured from ostrich feathers and are expensive and 
fragile; furthermore, an inadvertent collision can also mar the vehicle 
surface. Problems of brush control are further complicated by the fact 
that most vehicular bodies are of fairly complicated design, and in most 
instances, a particular tack-off system will be employed to prepare a 
number of different vehicular body types. It is also most important that 
any tack-off machine not introduce any new contaminants to the cleaned 
vehicle surface. In many prior art tack-off machines, the vacuum 
collection system includes a number of flexible conduits, and these 
conduits are frequently disposed in a location above the path of travel of 
the vehicle being cleaned, and one such prior art system having overhead 
conduits is shown in U.S. Pat. No. 4,689,749. In accord with the present 
invention, it has been found that these conduits can become a significant 
source of contamination. The present invention recognizes that it is 
important to properly position, and eliminate the number of conduits in a 
tack-off system in order to prevent recontamination of the cleaned 
surfaces. 
As will be described in greater detail hereinbelow, the present invention 
provides an improved tack-off machine which accurately controls brush 
position to maximize cleaning effect while minimizing the possibility of 
marring the vehicular surface. The machine of the present invention also 
provides improved cleaning efficiency and prevents recontamination of the 
cleaned surface by optimizing the configuration of collection conduits. 
These and other advantages of the present invention will be readily 
apparent from the drawings, discussion and description which follow. 
BRIEF DESCRIPTION OF THE INVENTION 
There is disclosed herein a tack-off machine which includes a cylindrical 
tack-off brush rotatable about an axis thereof, an exhaust hood 
surrounding a portion of the circumference of the brush and an exhaust 
plenum in communication with the hood. The plenum is a vortex moderated 
exhaust plenum having a top wall with an exhaust port defined therein, a 
bottom wall having an exhaust slit defined therein, and first side wall 
and a second side wall. The walls are configured and disposed in 
cooperation to define an interior volume which is tapered along three 
mutually perpendicular axes so that the narrowest width dimension and the 
greatest length dimension of the interior volume are closest to the bottom 
wall, and the greatest width dimension and the shortest length dimension 
of the interior volume are closest to the top wall. The plenum is 
configured so that when air is drawn through the exhaust slot and out of 
the exhaust port, a variable region of turbulent flow is created in the 
interior volume. The turbulent flow has a maximum value proximate the 
exhaust port and a minimum value distal the exhaust port. This turbulent 
flow creates a variable choke effect along the length of the slot so that 
the velocity of the air flowing therethrough is constant along the length. 
In accord with another aspect of the invention tack-off machines for 
cleaning vehicles which pass along the path of travel therethrough 
includes a support frame defining an opening configured to permit the 
vehicle to pass therethrough, a generally cylindrical top, tack-off brush 
supported on the frame for rotation about an axis transverse to the path 
of travel of the vehicle, a drive system for rotating the brush and an 
exhaust hood disposed so as to surround a portion of the circumference of 
the brush. The system further includes an exhaust blower and a flexible, 
expansible, exhaust conduit disposed to convey an exhaust stream from the 
hood to the blower. The conduit is supported and enclosed within the frame 
so that the conduit does not pass over the vehicle as the vehicle passes 
through the tack-off machine. 
In accord with another aspect of the present invention the tack-off machine 
includes a support linkage for pivotably attaching an exhaust hood 
associated with a cylindrical brush to the frame. The support linkage 
includes a first and a second arm disposed in a spaced apart relationship. 
Each arm has a first end pivotably connected to the frame and a second end 
pivotally connected to the hood. The linkage further includes an actuator 
in mechanical communication with the hood for pivoting the hood on the 
frame. In this linkage, the first and second arm cause the hood and frame 
to maintain a fixed angular relationship as the hood is pivoted so that 
the contact point of the brush with a vehicle passing there past, does not 
change.

DETAILED DESCRIPTION THE INVENTION 
Referring now to FIG. 1, there is shown a perspective view of a tack-off 
machine 10 of the present invention looking in a direction along the path 
of travel which a motor vehicle would follow through the machine. 
Typically, the vehicle would be traveling through the machine in a 
direction toward the viewer. The machine 10 of FIG. 1 includes a support 
frame 12 configured as a cross member supported by a pair of pillars so as 
to define an opening large enough for a vehicle to pass through. A 
generally cylindrical top tack-off brush 14 is supported on the frame 12 
for rotation about an axis which is generally transverse to the path of 
travel a vehicle would take through the machine 10. In the context of the 
present disclosure, the top brush 14, as well other brushes in the machine 
are described as being generally cylindrical, and it is to be understood 
that in some instances, the diameter of the brush may vary along its 
length, and such tapered or stepped cylindrical brushes are also included 
within the designation of generally cylindrical brushes. The brushes 
employed in the present invention will typically be conventionally 
employed tack-off brushes, such as ostrich feather brushes, although it is 
to be understood that the present invention is not limited to the use of 
such brushes and can be employed in combination with a variety of brush 
materials. 
The top brush 14 is supported on the frame 12 in a pair of tracks 16, 18 
which guide the brush along a path of travel which is generally inclined 
at an acute angle relative to the path of travel of the vehicle. As 
illustrated, the tracks 16, 18 slope forwardly along the path of travel of 
the vehicle. In this manner, the brush 14 may be raised and lowered so as 
to contact various portions of the vehicle body, and the forward 
inclination permits the brush 14 to follow the vehicle as it travels 
through the support frame 12, thereby allowing for efficient cleaning of 
the vehicle's back surface. 
The machine of FIG. 1 also includes two sets of side brushes. The first set 
of brushes 20, 22 are disposed with their axes of rotation in a generally 
vertical direction and are positioned to contact the lower side portions 
of the vehicle. It will be noted that these brushes 20, 22 are tapered 
cylindrical brushes. As will be described in greater detail hereinbelow, 
the brushes 20, 22 are each partially surrounded by an exhaust hood 24, 
and are pivotally mounted to allow for optimum contact with the vehicle. A 
second set of side mounted brushes 26, 28 are disposed with their axes of 
rotation inclined relative to the vertical and are positioned to permit 
cleaning of the upper side surfaces of the vehicle. These brushes are also 
disposed within exhaust hoods 24 and are pivotally mounted as previously 
described. 
Referring now to FIG. 2, there is shown a side view of the machine 10 of 
FIG. 1 with the end panel of the support frame 12 cut away. FIG. 2 
specifically illustrates the manner in which the top brush 14 is supported 
by the inclined track 18 so as to be movable along a path of travel which 
slopes downwardly and forwardly in relation to the path of travel of the 
motor vehicle through the apparatus, which path is generally indicated by 
arrow A. 
The top brush 14 has a portion of its circumference enclosed by an exhaust 
hood 30, and this hood has an exhaust plenum 32 extending therealong. The 
plenum 32 extends into a housing as defined by the upright pillar of the 
support frame 12 and therein couples to a flexible, expansible conduit 34. 
The expansible conduit 34 connects to an exhaust duct 36, which in turn 
connects to an exhaust manifold 38 coupled to a blower or other such 
device, not shown, which evacuates ambient air from the manifold 38, duct 
36, conduit 34, plenum 32 and hood 30. The flexible conduit 34 permits the 
brush 14 to move along the inclined rail 18 while maintaining air flow 
through the system. 
It is notable that the flexible conduit 34 is disposed within the support 
pillar and is not at any location above the path of travel of a vehicle 
through the support frame. It has been found that the flexible conduit can 
be a significant source of secondary contamination. The conduit can 
attract and retain contaminant particles from the ambient atmosphere onto 
its exterior surface, and these particles will then be released as the 
conduit flexes. Additionally, the conduit material itself can be a source 
of contamination. In many instances, the conduit is fabricated from a wire 
reinforced body of coated fabric, which degrades to produce particulate 
contamination. The present invention significantly reduces secondary 
contamination by reducing the amount of flexible conduit employed in the 
machine and by eliminating the presence of any flexible conduit which is 
disposed immediately above a vehicle passing therethrough. 
Various modifications of the FIG. 2 system may be implemented in accord 
with the present invention. The manifold 38 may be expanded so as to 
project into the upright pillar of the support frame 12, and in this 
manner replace the top exhaust duct 36 as well as a large portion of the 
side exhaust duct 40. Other corresponding modifications will be readily 
available to one of skill in the art. 
FIG. 2 further illustrates the lower side brush hood 24a and the upper side 
brush hood 24c together with their respective support linkages 42a, 42c 
which pivotally mount them to the support frame 12, and which will be 
described in greater detail hereinbelow. Each brush assembly includes a 
motor 44 and associated drive belt 46 for rotating the associated brush. 
The lower side brush hood 24a is in communication with the evacuation 
manifold 38 via a duct 40 through a communication established by a short 
length of flexible conduit extending therebetween. In the FIG. 2 
illustration, the conduit has been omitted for the sake of clarity. In a 
similar manner, the upper side brush hood 24c communicates with the 
manifold 38 via a duct 48 and a length of flexible conduit, also omitted. 
As mentioned above, it is important to properly position the brushes in a 
tack-off apparatus so as to optimize the cleaning process and to prevent 
damage to the vehicle or to the brush from inadvertent collisions. In 
accord with another aspect of the present invention, there is provided a 
linkage mechanism which controls and directs brush assemblies, 
particularly the side brush assemblies of the tack-off machine. Referring 
now to FIGS. 3 and 4, there are shown top, and side views respectively of 
a brush assembly of the present invention illustrating the positioning 
linkage therefor. 
Shown in FIG. 3 is a brush assembly including an exhaust hood 24 which as 
previously described, is configured to extend along the length of a 
cylindrical brush 22 and enclose a portion of the circumference thereof. 
The hood 24 is pivotally supported upon the frame 12 by means of a support 
linkage. The support linkage includes a first arm 50 which has a first one 
of its ends pivotally connected to the frame 12 and a second one of its 
ends pivotally connected to the hood 24, in this instance through a 
support bracket 52; although, it is to be understood that connection may 
be directly to the hood or otherwise. The support linkage also includes a 
second arm 54 which is spaced from the first arm 50 and which also has its 
first end connected to the support frame 12 and its second end connected 
to the hood 24 through the bracket 52. The brush assembly further includes 
an actuator 56, which in this instance is an electrically powered linear 
actuator, coupled to the second arm 54, for moving the hood 24 and brush 
22. 
The support linkage permits the hood to pivot back and forth with relation 
to the path of travel of a motor vehicle through the tack-off machine, 
while maintaining a fixed angular relationship between the hood 24 and 
support frame 12. As will be explained in further detail hereinbelow, the 
retention of the fixed angular relationship assures that the contact point 
of the brush 22 and the vehicle remains constant as the brush is 
repositioned; furthermore, the positional relationship of the hood 24 and 
vehicle is also unchanged thereby assuring optimum operation of the 
tack-off system and preventing damage to the vehicle. 
In the illustrated embodiment, the first arm 50 is configured so that its 
length may be adjusted, and toward that end, the first arm comprises an 
internally threaded sleeve portion 51 and a threaded shaft 53. The shaft 
53 engages the sleeve 51, and it will be appreciated that the overall 
length of the arm 50 may be adjusted by disconnecting one of the ends of 
the arm 50 from the support 12 or the bracket 52 and unscrewing the shaft 
51 and sleeve 53 relative to one another. In this manner, the angular 
relationship of the hood 24 and support 12 may be adjusted to accommodate 
varying ranges of vehicular dimensions. Once adjusted, the angular 
relationship is maintained as the hood 24 and brush 22 are pivoted by the 
support linkage. 
As will be noted from FIG. 3, the hood 24 further includes an exhaust 
plenum 58 having a flexible conduit 60 attached thereto, and in the 
illustration, only a portion of the conduit 60 is shown. The hood 24 
further includes an ionization source 62, which in this embodiment 
comprises an electrically energized ion source. The ion source 62 
neutralizes static electrical charges on the brush and/or automotive 
vehicle to thereby control the collection of dust particles and prevent 
their redeposition upon the vehicle. A variety of ion sources are known in 
the art and may be employed in the practice of the present invention. 
Referring now to FIG. 4, there is shown a side elevational view of the 
brush assembly depicted in FIG. 3. It should be noted that in FIG. 4, the 
brush has been removed from the hood 24 although the brush mounting shaft 
64 is shown in the hood 24. Also visible in the FIG. 4 drawing is an 
exhaust slot 66 disposed in the hood. The slot leads to the exhaust plenum 
58 and provides for withdrawal of ambient air and entrained contaminant 
particles from the hood 24. 
FIG. 4 also depicts the first arm 50 and better shows the manner in which 
it is pivotally attached to the support 12 and mounting bracket 52. It 
will be noted from the Figure that the second arm 54 is not only laterally 
spaced from the first arm 50, but is vertically displaced therefrom, and 
the support linkage also includes a third arm 68 which is vertically 
displaced from, but rigidly affixed to, the second arm 54. The third arm 
68 and second arm 54 cooperate to provide rigid support for the hood, and 
essentially operate as a single arm, and in view thereof it will be 
appreciated that other linkages may be similarly employed. For example, 
additional arms, aligned with arm 54 and arm 68 may be employed, or the 
two arms may be replaced by a single member. FIG. 4 further depicts a 
drive motor 44 which operates to rotate the brush through a drive belt 46 
and a pair of drive pulleys 70, 72. 
The operation and advantage of the pivoting linkage of the present 
invention will be better illustrated by reference to FIGS. 5A and 5B. FIG. 
5A depicts a tack-off brush 22 and hood 24 mounted in accord with the 
present invention. The brush and hood assembly is shown in a first 
position depicted in phantom outline and a second position in solid 
outline. It will be noted as the assembly is pivoted, the relationship of 
the hood 24 and support 12 is unchanged; and accordingly, the relationship 
thereof to the path of travel of a vehicle there past, indicated by arrow 
A, is also unchanged. Similarly, the contact point 74 of the brush 22, 
that is to say the point on the brush which is tangent to a vehicle 
passing there past along the path of travel A, is unchanged as the brush 
moves from the first to the second position. Thus it will be appreciated 
that the linkage of the present invention preserves the positional 
geometry of the brush system thereby allowing optimized conditions to be 
maintained throughout the operation of the machine. 
FIG. 5B depicts a prior art mounting system in which a brush 22 and hood 24 
simply pivot about a support 12. In the FIG. 5B embodiment, the brush 22 
and hood 24 are shown in a first position in phantom outline and in a 
second position in solid outline, as disposed with regard to the path of 
travel A of a vehicle there past. It will be noted that as the brush 
pivots to the second position the contact point shifts from location 76 to 
location 78. It is also significant that the orientation of the hood 24 
changes greatly, and the ionization source 62 is positioned far 
differently with regard to the brush 22 and path of travel A as the 
assembly pivots. This change in geometry can result in damage to the 
vehicle from the hood 24. Additionally, the geometric relationship of the 
ionization source 62, brush 22, hood 24 and vehicle also changes thereby 
compromising the operation of the tack-off system. 
In the operation of any tack-off system, it is essential that there be 
provided an exhaust for withdrawing collected particulate matter from the 
brush and hence from the region of the vehicle. A number of approaches 
have been implemented in the prior art in an effort to obtain a uniform 
and consistent air flow. U.S. Pat. No. 4,689,749 depicts a tack-off system 
which employs plural exhaust conduits associated with each tack-off brush. 
As noted above, conduits themselves can be a source of contamination and 
it is desirable to minimize their number. The present invention includes 
an exhaust plenum having a unique configuration which provides for 
establishment of a highly uniform flow of air through elongated slot via a 
single exhaust conduit. The plenum of the present invention is configured 
so as to establish a specifically shaped vortex region therewithin. This 
vortex functions as a variable choke which selectively restricts air flow 
through the exhaust slot to a greater degree proximate the exhaust conduit 
than at locations on the slot remote from the conduit. 
Referring now to FIG. 6, there is shown a perspective view of one 
configuration of plenum 80 of the present invention. The plenum 80 
includes a top wall which includes a first top wall segment 82, a second 
top wall segment 84 and a central segment 86 which is disposed between the 
first 82 and the second 84 segment and is contiguous with an edge of each. 
The central segment 86 includes an exhaust port 88 therein and in this 
embodiment, the exhaust port 88 is surrounded by a flange 90 which is 
coupled to a conduit, not shown. The plenum 80 includes a pair of side 
walls, one of which is indicated by reference numeral 92 and the other of 
which is not visible in this drawing. The plenum 80 also includes a bottom 
wall 94, a portion of which is visible in this drawing through the exhaust 
port 88. FIG. 7 provides a better depiction of the bottom wall 94, and it 
will be noted that the wall 94 includes an exhaust slot 96 defined 
therethrough. As illustrated, the bottom wall 94 may also include a set of 
adjustable baffles, which in this instance are segmented baffles 98a, 98b. 
The baffles may be employed to adjust the width of the slit and thereby 
control the velocity of the airflow therethrough. 
The plenum of the present invention is particularly configured so that the 
walls thereof define an interior volume which is tapered along three 
mutually perpendicular axes so that the narrowest width dimension and the 
greatest length dimension of the interior volume are closest to the bottom 
wall and so that the greatest width dimension and the shortest length 
dimension are closest to the top wall. 
The configuration of the plenum of the present invention will better be 
understood by reference to FIGS. 8A-8E which correspond to cross sectional 
views of the plenum of FIG. 6 taken along section lines 1--1, 3--3, 5--5, 
7--7 and 9--9 respectively. It will be noted from the Figures that the 
side walls 92, 93 are inwardly tapered so as to form an obtuse interior 
angle with the bottom wall 94. Within the context of the present 
disclosure, an interior angle is defined as an angle formed by the walls 
of the plenum as measured therebetween within the interior volume enclosed 
thereby. 
The first segment 82 and second segment 84 of the top wall are each tapered 
so that the width thereof varies from a maximum proximate the central 
segment, as shown in cross sectional view of FIG. 8C, to a minimum at a 
point distal the central segment, as shown in FIG. 8A. The first and 
second segments each are disposed so as to form an acute interior angle 
with the bottom wall 94 at their respective second ends. 
This multiple taper geometry defines an interior volume and creates a 
region of turbulent flow therewithin, when air is drawn through the slot 
94 in the bottom wall and out the exhaust port. 
FIG. 9 is a top view of the plenum with the top wall removed. The figure 
depicts the air flow in the interior volume. As will be apparent from the 
drawings of FIG. 8A-8E and 9, the turbulent flow region is greatest 
proximate the exhaust port and decreases toward the opposite ends of the 
plenum. The turbulent flow region creates an impedance to the direct flow 
of air therethrough and functions as a choke. It has been found, in accord 
with the present invention, that this particular geometry produces a choke 
effect which varies along the length of the slot of the plenum so as to 
provide an air flow having a uniform velocity therealong. In this manner, 
the present invention eliminates the need encountered in the prior art, to 
utilize multiple conduits in order to achieve a uniform flow of air 
through the hood of a tack-off brush. 
The present invention provides a significantly improved tack-off machine. 
The machine of the present invention is highly efficient at removing and 
collecting particulate contaminants from a vehicle. Additionally, the 
system of the present invention can readily adjust for varying vehicular 
sizes and shapes without compromising its operational parameters. 
Additionally, the system of the present invention is particularly 
configured to minimize secondary contamination of the cleaned vehicle 
resultant from the system itself. These features are a result of the 
interaction of the various individual features of the present invention 
namely the minimization of conduits, the enclosure of conduits, the 
improved positioning system and the vortex enhanced plenum. These various 
features interact synergistically; however, may also be employed with some 
advantage individually. Additionally, these features may be incorporated 
in other apparatus with equal advantage. Therefore, it is to be understood 
that the invention may be practiced in combinations and embodiments other 
than those specifically shown herein. The discussion, description, and 
drawings herein are illustrative of the present invention, and are not 
limitations upon the practice thereof. It is the following claims, 
including all equivalents, which define the scope of the invention.