Spark plug cleaner with improved grit recycling

A spark plug cleaner is constructed as an upright canister with outwardly directed openings into which spark plugs are inserted. A vertically mounted motor driven impeller sucks grit from an axial center of the canister and flings it toward the spark plug sockets. A grit recovery floor is provided below the impeller and sockets and is configured concave upward. A suction guide fits coaxially over the collection floor and also slopes concave upward toward the center of the impeller. An annular vacuum channel is formed between the collection floor and the suction guide to concentrate impeller suction on spent grit as it falls to said collection floor and to increase grit velocity and density to the impeller.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to spark plug cleaners designed for workshop 
use for amateur internal combustion engine maintenance. 
2. Description of the Prior Art 
A number of different types of internal combustion engine spark plug 
cleaners are commercially available for use by amateur mechanics. Some 
commercially available embodiments are designed for a plurality of spark 
plugs, while others accomodate but a single plug at a time. Virtually all 
conventional embodiments of such spark plug cleaners employ an impeller 
which rotates at a high speed and sucks grit axially toward the impeller 
near its center and flings the grit outwardly toward a spark plug socket 
or a plurality of sockets. 
The spark plug sockets in conventional plug cleaners may be either 
horizontally disposed, vertically disposed, or disposed at an angle 
between the horizontal and vertical. In those spark plug cleaners in which 
the plug sockets are mounted horizontally, the impeller rotates about a 
vertically disposed shaft. In such conventional devices, there has been a 
consistent problem in recycling the grit to the impeller for reuse. Once 
the grit has inpinged upon the spark plug electrode to effectuate 
cleaning, its momentum is quickly spent and it falls to the floor of the 
confining container. 
The principal difficulty in conventional systems arises in returning the 
spent grit to the impeller for reuse. In conventional devices with 
impellers mounted about vertical axes a suction is created to draw the 
grit upwardly for this purpose. However, in conventional devices it has 
been extremely difficult to recycle grit to any significant degree because 
of the low suction that is normally produced by the motors and impellers 
utilized. In one commercially available device, a helical or spiral ramp 
is defined about a vertical axis coaxial with the impeller axis. The 
spiral about the vertical axis is intended to slope siginficantly to allow 
the grit to reach the impeller quickly. Nevertheless, the vertical spiral 
configuration necessarily forces the grit against the outer cylindrical 
confines of the spiral channel and as a consequence, the grit arrives at 
the impeller intake at a relatively low velocity. The rotation of the 
impeller imparts additional velocity to the grit to increase its momentum 
to impinge upon the spark plug electrodes. However, since the grit has 
very little momentum entering the impeller, its momentum as it strikes the 
spark plug electrodes is developed almost entirely within the impeller. 
Other spark plug cleaners have sought to enhance suction by providing 
relatively narrow cylindrical tubes leading from the impeller inlet to the 
collection floor of the plug cleaning chamber. In this fashion, suction is 
applied over a smaller cross sectional area, and hence a greater vacuum is 
produced. However, because suction is applied over a small area there is a 
tendency for the grit at the collection floor in the immediate vicinity of 
the suction tube to be quickly depleted, and hence the density of grit 
passed through the impeller is reduced. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to improve both the concentration 
and momentum of grit discharged through an impeller to impinge against the 
spark plug electrodes to be cleaned in a spark plug cleaner. This is 
achieved by an improved construction which more rapidly recycles the grit. 
The spark plug cleaner of the invention employs a canister having one or 
more horizontally disposed spark plug sockets or ports and an impeller 
mounted about a vertical axis for directing grit toward these ports. The 
spark plug cleaner is provided with a concave annular collection floor 
located within the canister beneath the level of the sockets and the 
impeller. The collection floor slopes upwardly toward the interior of the 
confining canister walls, and also upward toward the impeller axis. A 
generally cone shaped convex suction guide fits coaxially over the 
collection floor where it slopes upward toward the impeller. The narrow 
annular space between the suction guide and collection floor forms a 
narrow annular vacuum channel leading from the collection floor to the 
impeller to supply the impeller with grit to fling centrifically outward 
against the electrodes of spark plugs positioned in the sockets. 
Thereafter, the spent grit sinks again to the collection floor. Because 
the floor slopes upward toward the canister walls, the spent grit slides 
downwardly and inwardly toward the mouth of the annular vacuum channel 
between the collection floor and the suction guide. This maximizes the 
concentration of grit at the suction inlet. 
The invention may be constructed to accomodate either one or a plurality of 
spark plug sockets mounted in horizontal disposition. The impeller is 
formed with a plurality of radial or inclined vanes with openings 
therebetween through which grit is expelled. The grit travels in generally 
horizontal tangential paths from approximately the impeller periphery 
under the influence of the centrifugal force applied thereto by the 
impeller. The spark plug sockets are preferably aligned with the 
tangential paths of travel of the grit so as to maximize the direct impact 
of the grit on the spark plug electrodes to be cleaned. It is advantageous 
to provide the impeller with a cylindrical shield with a single outwardly 
directed opening therein through which grit can pass. The purpose of the 
shield is to maximize air flow with grit thru the suction channel leading 
to it and to minimize air flow from the larger portion of the chamber 
immediately under the impeller. 
The invention may be described with greater clarity and particularity by 
reference to the accompanying drawings.

DESCRIPTION OF THE EMBODIMENTS 
FIG. 4 depicts a spark plug cleaner formed as a generally cylindrical 
canister 10 having an upright cylindrical wall 12 closed at its ends by a 
generally disk-shaped top 14 and a generally disk shaped bottom 16. A 
plurality of tubular spark plug sockets 18 are defined in the upper 
portion of the wall 12, all disposed in a common horizontal plane just 
below the top 14. Within the canister 10 a disk-shaped impeller 20 is 
mounted horizontally in the same plane as the sockets 18. The impeller 20 
is mounted for rotation about a vertical axle 22, located at the center of 
the device. The impeller 20 is driven in rotation by a small electric 
motor 24, located in the lower portion of the canister 10. Within the 
canister 10 there is a concave upward annular collection floor depicted at 
26. The collection floor 26 slopes upwardly and outwardly, in a surface 28 
toward the upright wall 12, and upwardly and inwardly toward the impeller 
in an opposing surface 30 as depicted in FIG. 4. 
A generally truncated, cone shaped suction guide 32 fits coaxially over the 
collection floor 26 directly above the upwardly and inwardly sloping 
surface 30. The sloping surface 30 of the collection floor 26 and the 
suction guide 32 define therebetween an annular vacuum channel denoted at 
34. The channel 34 leads from the collection floor 26 to the impeller 20 
to supply the impeller 20 with grit 36. The grit 36 is comprised of small 
particles of sand or other abrasive which are sucked through the vacuum 
channel 34 and into the impeller 20 and are flung against the electrodes 
38 and 40 of spark plugs located in the sockets 18, such as the spark plug 
42 depicted in FIG. 4. 
The canister 10 is formed of plastic. The upper section of the canister 10 
is a generally cup-shaped structure disposed in inverted fashion and from 
the outer wall of which sockets 18 protrude. The sockets 18 are tubular 
structures integrally formed with the canister 10. At the mouths of the 
sockets 18 there are rubber disk shaped inserts 44 inset and glued into 
shoulders defined at the mouths of the sockets 18. The rubber gaskets 44 
have a generally star-shaped configuration of cuts therein, as depicted in 
FIGS. 1 and 2. The star-shaped cuts divide the gaskets 44 into a plurality 
of sector shaped flaps. These flaps may be forced aside by a spark plug 42 
which is manually pushed into a socket 18. When the gasket flaps are 
forced aside by a spark plug, they leave the electrodes 38 and 40 of a 
spark plug 42 in the path of grit flung centrifugally from the impeller 
20. 
The lower portion of the canister 10 is also of a generally cup-shaped 
configuration. Near the bottom of the lower section there is a molded 
annular power cord port defined by a collar 46 and a circular aperture 
within which an electrical switch 48 is restrained. The electrical switch 
48 is locked in position by threaded bushings 50 and 52, on the inside and 
outside respectively of the wall 12. The bushings 50 and 52 engage an 
annular threaded sleeve 54 within which a spring biased push button 56 
resides. 
The upper extremity of the lower section of the canister 10 is bounded by 
the collection floor 26, which is a molded plastic structure facing 
concave upward and convex downward, as depicted in FIG. 4. At the inner 
extremity of the sloping surface 30 of the collection floor 26 there is a 
thickened section 60 with a mounting tab 61. A mounting screw 62 extends 
through the mounting tab 61 and into a tapped hole in the upper end of the 
motor 24 to mount the motor in the canister 10. A fiber or felt washer 63 
serves as a protective device for the motor 24 under the thickened section 
60 and above a motor bearing 65. One of the electrical leads of the 
connector cord 58 is connected to one power input contact of the motor 24, 
while the other is connected to the other power contact through the switch 
48. The circuit is completed to drive the motor 24 during the time that 
the pushbutton 56 is in the depressed condition. The electrical switch 48 
closed by the pushbutton 56 remains on until depressed again to turn the 
spark plug cleaner off. This allows the operator to use both hands to 
rotate the plug 42 within the sockets 18 for more thorough cleaning. 
Mounted atop the motor shaft 64 is an enlarged axle 22 of sufficient 
diameter to power the impeller 20. The upper end 66 of the impeller 20 is 
a circular disk, while the lower end 68 is an annular disk. The impeller 
20 includes a number of vanes 68 which are directed outwardly from the 
axle 22 and are integrally formed therewith. The vanes 68 are either 
radial or they may be curved. With either construction, the vanes 68 
define openings therebetween through which grit is expelled centrifugally 
through tangential paths toward the cylindrical wall 12 of the canister 
10. As is apparent from FIG. 3, the spark plug sockets 18 are offset from 
radial alignment with the canister 10, and are instead aligned with a 
tangential path of travel of the grit 36 from the impeller 20. 
At the underside of the annular bottom 68 of the impeller 20 there is an 
axially extending annular collar 72 that extends downward outside of the 
suction guide 32. The collar 72 forms a shield at the upper extremity of 
the vacuum channel 34 to maximize air flow with grit through the vacuum 
channel 34 and to minimize air flow from the larger area of the chamber 
outside the suction guide 32. 
The upper and lower sections of the canister 10 fit snugly together as 
depicted in FIG. 2, to create a relatively smooth surface at the interior 
upright wall 12, so that spent grit is not caught between the upper and 
lower sections, but rather flows smoothly down the interior surface of the 
wall 12 to the curved surface 28 of the collection floor 26. 
In the operation of the invention, spent grit tends to collect in the 
lowest area of the collection floor 26 between the oppositely sloping 
surfaces 28 and 30. Since the lower extremity of the suction guide 32 
terminates directly above this area, a narrow annular vacuum channel 34 is 
formed at the mouth of the suction guide 32 and between the suction guide 
32 and the collection floor 26. Since the vacuum produced as a result of 
rotation of the impeller 20 by the motor 24 is concentrated in this small 
area, the particles of grit are swept swiftly upward through the vacuum 
channel 34 toward the axle 22 and toward the impeller 20. Because of the 
tendency of the grit to collect at the mouth of the suction channel 34, a 
high density of grit is continuously supplied to the impeller 20. Because 
of the narrow dimensions of the vacuum channel 34, and because of the 
smooth arcuate curves of the suction guide 32 and the sloping surface 30, 
the grit 36 arrives at the impeller 20 with a great deal of momentum. 
Further momentum is imparted to the grit 36 by the impeller 20 with the 
result that the grit 36 achieves a greater velocity in impingment upon the 
electrodes 38 and 40 of the spark plug 42. 
With the enhanced grit concentration and the increase in grit velocity, the 
present invention is able to more effectively clean spark plug electrodes 
in a significantly shorter time, as contrasted with prior art devices. 
This is true both with respect to the embodiment designed to clean a 
single spark plug, depicted at 10' in FIG. 2, and also in the multiple 
spark plug cleaner 10 depicted in FIG. 1. 
Both embodiments of the spark plug cleaner of the invention may be driven 
from an automotive vehicle battery. Power is transmitted through the power 
cord 58 from color coded clamps 76 and 78, depicted in FIG. 1. 
Accordingly, the spark plug cleaner of the invention can be utilized 
outside, and is not dependent upon the availability of commercial a.c. 
power. 
It should be understood that numerous variations and modifications of the 
invention are possible. The spark plug cleaner can be used not only to 
clean the spark plugs of automotive vehicles, but also spark plugs 
employed in connection with other devices, such as boat motors, 
snowblowers and lawn mowers. Moreover, various alternative motor mounting 
arrangements, canister constructions and spark plug socket configurations 
are possible. Accordingly, the scope of the invention should not be 
limited to the specific embodiments depicted in the drawings, but rather 
is defined in the claims appended hereto.