Title:
Pneumatic ball thrower with constriction formed vacuum for drawing balls from ball feed thereof
United States Patent 3911888
Abstract:
A ball thrower has a blower connected to a discharge barrel from which balls are blown. A timing tube leads into the barrel in front of a constriction which causes a suction in the timing tube. Balls roll or are drawn through a ball feed tube to the base of the timing tube which branches at the end of the feed tube to form a suction bypass which is also connected to the barrel. A stop prevents a first ball from entering the suction bypass so that the first ball leaving the feed tube is drawn up the timing tube by greater suction therein. The first ball in the timing tube reduces its suction at the branching of the suction bypass so that a second ball is held against the stop by the now greater suction of the suction bypass. When the first ball is drawn into the barrel from the timing tube to be expelled therefrom, back pressure builds up in the timing tube and the suction bypass forcing the second ball against a third ball which jams in a jamming chamber while the first ball is expelled. Balls are successively expelled at intervals which are determined by adjusting the constriction in front of the barrel. While shown for table tennis balls, this invention may be adapted for tennis balls, baseballs, toy plastic balls, marbles, metal shot, and the like.
US Patent References:
Pneumatic gun
Hale - September 1944 - 2357951
Apparatus for practicing ping-pong and the like
Lemon - May 1950 - 2508461
AUTOMATIC BALL THROWER
Horvath - June 1971 - 3584614
TARGET LAUNCHER
Brandt - April 1973 - 3724438
Pneumatic gun
Hale - September 1944 - 2357951
Apparatus for practicing ping-pong and the like
Lemon - May 1950 - 2508461
AUTOMATIC BALL THROWER
Horvath - June 1971 - 3584614
TARGET LAUNCHER
Brandt - April 1973 - 3724438
Application Number:
05/495373
Publication Date:
10/14/1975
Filing Date:
08/07/1974
View Patent Images:
Export Citation:
Primary Class:
Other Classes:
124/53.500
International Classes:
A63B69/40; A63B47/02; A63B47/00; A63B65/12; F41F1/04
Field of Search:
124/11R,51A 273/30 302/2R 221/278 243/3,5
Primary Examiner:
Pinkham, Richard C.
Assistant Examiner:
Stouffer R. T.
Attorney, Agent or Firm:
Tailer, Peter L.
Claims:
I claim
1. A ball thrower to successively throw balls at timed intervals comprising, in combination, a barrel, an air supply, means connecting said air supply to one end of said barrel, a constriction in said means connecting said air supply to said barrel forming a vacuum between said constriction and said barrel, a timing tube communicating with said barrel between said constriction and said barrel, said barrel and said timing tube receiving balls therethrough with slight clearance, a suction bypass tube communicating with said barrel between said constriction and said barrel, ball feed means connected to said timing tube and said suction bypass tube, said suction bypass tube and said timing tube forming a branching at said ball feed means, said suction bypass tube restricting air flow therethrough so that said constriction draws a greater vacuum through said timing tube than through said suction bypass tube at said branching, and ball jamming means associated with said ball feed means preventing the expulsion of balls backward into said ball feed means, said constriction forming a vacuum to successively draw a first ball from said ball feed means into said timing tube past said suction bypass tube at said branching, the first ball reducing the vacuum of said timing tube at said branching while the first ball is within said timing tube so that said suction bypass tube holds a second ball at said branching, said jamming means limiting backward movement of the second ball while the first ball is in said barrel being expelled therefrom producing a backpressure in said timing tube and said suction bypass tube.
2. The combination according to claim 1 wherein said timing tube has a greater flow therethrough than said suction bypass tube providing the greater vacuum of said timing tube at said branching.
3. The combination according to claim 2 wherein said ball jamming means is a jamming chamber at the end of said ball feed means, a third ball successively entering said jamming chamber jamming the backward passage of a second ball while a first ball is being expelled from said barrel.
4. The combination according to claim 3 wherein said ball feed means has at least an end slightly larger in diameter than said balls, said second ball being jammed within the end of said ball feed means blocking the escape of air while a first ball is being expelled from said barrel.
5. The combination according to claim 4 with the addition of a Y connection at the end of said ball feed means passing balls therethrough, said jamming chamber being one leg of said Y connection having a ball stop therein.
6. The combination according to claim 4 wherein said jamming chamber is at right angles to the end of said ball feed means and has an entrance forming the end of said ball feed means that leads at right angles into said branching of said timing tube and said suction bypass tube, said jamming chamber having an end wall against which a third ball is forced by a second ball while a first ball is being expelled from said barrel, said second ball blocking the entrance of said jamming chamber preventing the escape of air.
7. The combination according to claim 4 wherein said timing tube and said suction bypass tube are the same diameter, and with the addition of a stop in said suction bypass tube at said branching preventing the entrance of balls into said suction bypass tube, said stop reducing flow through and thereby the vacuum of said suction bypass tube at said branching.
8. The combination according to claim 4 wherein said jamming chamber contains at least one air inlet disposed behind a second ball jammed therein against a third ball.
9. The combination according to claim 1 wherein said constriction is adjustably moveable relative to the communicating of said timing tube and said suction bypass tube with said barrel to vary air flow through said timing tube and the time intervals at which balls are expelled.
10. The combination according to claim 9 with the addition of adjustably opened ports at the base of said barrel, said ports bleeding air from said barrel adjusting the velocity of balls expelled therefrom.
1. A ball thrower to successively throw balls at timed intervals comprising, in combination, a barrel, an air supply, means connecting said air supply to one end of said barrel, a constriction in said means connecting said air supply to said barrel forming a vacuum between said constriction and said barrel, a timing tube communicating with said barrel between said constriction and said barrel, said barrel and said timing tube receiving balls therethrough with slight clearance, a suction bypass tube communicating with said barrel between said constriction and said barrel, ball feed means connected to said timing tube and said suction bypass tube, said suction bypass tube and said timing tube forming a branching at said ball feed means, said suction bypass tube restricting air flow therethrough so that said constriction draws a greater vacuum through said timing tube than through said suction bypass tube at said branching, and ball jamming means associated with said ball feed means preventing the expulsion of balls backward into said ball feed means, said constriction forming a vacuum to successively draw a first ball from said ball feed means into said timing tube past said suction bypass tube at said branching, the first ball reducing the vacuum of said timing tube at said branching while the first ball is within said timing tube so that said suction bypass tube holds a second ball at said branching, said jamming means limiting backward movement of the second ball while the first ball is in said barrel being expelled therefrom producing a backpressure in said timing tube and said suction bypass tube.
2. The combination according to claim 1 wherein said timing tube has a greater flow therethrough than said suction bypass tube providing the greater vacuum of said timing tube at said branching.
3. The combination according to claim 2 wherein said ball jamming means is a jamming chamber at the end of said ball feed means, a third ball successively entering said jamming chamber jamming the backward passage of a second ball while a first ball is being expelled from said barrel.
4. The combination according to claim 3 wherein said ball feed means has at least an end slightly larger in diameter than said balls, said second ball being jammed within the end of said ball feed means blocking the escape of air while a first ball is being expelled from said barrel.
5. The combination according to claim 4 with the addition of a Y connection at the end of said ball feed means passing balls therethrough, said jamming chamber being one leg of said Y connection having a ball stop therein.
6. The combination according to claim 4 wherein said jamming chamber is at right angles to the end of said ball feed means and has an entrance forming the end of said ball feed means that leads at right angles into said branching of said timing tube and said suction bypass tube, said jamming chamber having an end wall against which a third ball is forced by a second ball while a first ball is being expelled from said barrel, said second ball blocking the entrance of said jamming chamber preventing the escape of air.
7. The combination according to claim 4 wherein said timing tube and said suction bypass tube are the same diameter, and with the addition of a stop in said suction bypass tube at said branching preventing the entrance of balls into said suction bypass tube, said stop reducing flow through and thereby the vacuum of said suction bypass tube at said branching.
8. The combination according to claim 4 wherein said jamming chamber contains at least one air inlet disposed behind a second ball jammed therein against a third ball.
9. The combination according to claim 1 wherein said constriction is adjustably moveable relative to the communicating of said timing tube and said suction bypass tube with said barrel to vary air flow through said timing tube and the time intervals at which balls are expelled.
10. The combination according to claim 9 with the addition of adjustably opened ports at the base of said barrel, said ports bleeding air from said barrel adjusting the velocity of balls expelled therefrom.
Description:
FIELD OF THE INVENTION
1. Background of the Invention
Ball throwing machines are now finding a wide acceptance as tennis practice devices. There is a need for an inexpensive and more reliable ball thrower for table tennis, tennis, and baseball as well as for toy, amusements operated by coins, and other applications.
2. Description of the Prior Art
Ball throwers which use air to expel a ball are well known. Heretofore, such machines have required complex breech or ball feeding mechanisms to introduce balls into a barrel to be blown out of it. These breech mechanisms, which regulate the frequency at which balls are expelled, require many moving parts which makes them costly and failure prone.
SUMMARY OF THE INVENTION
The ball thrower of this invention, except for a blower, requires no moving parts as balls themselves successively function as valves. A blower constantly forces air through a barrel. A constriction immediately in front of the barrel causes a suction in a timing tube which leads into the barrel in front of the constriction. The timing tube branches into a suction bypass tube which rejoins the timing tube at the entrance of a ball feed tube. A ball stop is placed where the suction bypass and the timing tube branch from the feed tube so balls can't enter the suction bypass. A first ball rolling from and/or being drawn through the feed tube encounters the stop and is drawn into the timing tube which permits a greater flow of air therethrough than the suction bypass. The resistance of the first ball in the timing tube reduces its suction and increases it in the bypass so that a second ball is held against the stop by the now greater flow of air into the suction bypass while the first ball is being drawn through the timing tube. When the first ball enters the barrel to be blown therefrom, back pressure in the timing tube and the suction bypass force the second ball back against a third ball which enters a jamming chamber to arrest the second ball. The arrested second ball blocks the loss of air from the back pressure so balls can be expelled at maximum velocity. The ball thrower then repeats the process to successively throw balls at given intervals. The constriction is adjusted to vary the suction and the air flow through the timing tube to set the intervals at which balls are successively discharged.
With light balls, such as table tennis balls, the timing tube may be vertical as the weight of the balls is negligible compared to the suction in a close fitting timing tube. With tennis or baseballs, the timing tube may be substantially horizontal so that the ball weight will not affect the suction drawing them through a timing tube. The ball thrower of this invention may be used with metal shot for simulated gunfire amusements or with marbles in a toy. It can be used to throw any spherical objects at high or low velocity at any desired intervals. This invention provides a more inexpensive, versatile, and reliable ball thrower. Blower pressure and capacity can be varied or pressure and air flow can be bled off to set the velocity at which balls are expelled.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a perspective view of a ball thrower according to this invention mounted on a table tennis table with a net to serve as a table tennis robot;
FIG. 2 is a section taken on line 2--2 of FIG. 1 showing a ball in the process of being blown from the barrel;
FIG. 3 is a section taken on line 3--3 of FIG. 2 with a central portion of a timing tube and a vacuum bypass tube broken away;
FIG. 4 is a section taken on a portion of line 3--3 of FIG. 2 showing a feed tube leading to the lower ends of the timing tube and the vacuum bypass tube with a first ball shown being drawn through the timing tube;
FIG. 5 is a bottom view of the table tennis table taken on line 5--5 of FIG. 2 showing a hinged attachment of the ball thrower to the table;
FIG. 6 is a vertical, longitudinal section through the table tennis table showing an attached ball thrower folded thereunder when not in use;
FIG. 7 is a vertical section through a fragment of a table tennis table showing a net supporting rod;
FIG. 8 is a plan view of a spread out table tennis table net;
FIG. 9 is a perspective view of an assembled net with a portion broken away;
FIG. 10 is a perspective view of a modified table tennis ball thrower;
FIG. 11 is a horizontal section taken on line 11--11 of FIG. 10;
FIG. 12 is a vertical section taken on line 12--12 of FIG. 11;
FIG. 13 is a perspective view of a feed tube and a jamming chamber with fragments of a timing tube and a vacuum bypass tube connected thereto according to a second embodiment of this invention;
FIG. 14 is a longitudinal section through a feed tube and a jamming chamber, and through a timing tube and a suction bypass tube with a barrel attached, the timing tube and the bypass tube being rotated 90° about the axis of the barrel, a first ball being shown being drawn through the timing tube; and
FIG. 15 is a section similar to that shown in FIG. 14 showing a ball being expelled from the barrel while a second ball forces a third ball into a jamming chamber.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
As shown in FIG. 1, the ball thrower of this invention is generally designated by the reference numeral 6. It is held to a table tennis table 7 by a hinged arm 8 and rests on a single foot 9. A net 10 surrounds one end of table 7 and contains a slit 11 through which barrel 12 of ball thrower 6 extends. A blower 13 is connected to barrel 12 by a flexible tube 14. A foot switch 15, or any other control, can start or stop the ball thrower 6 which shoots balls as a robot player through barrel 12.
FIGS. 5-9 show details of the net 10 and of the attachment of the ball thrower 6 to a table tennis table 7. The attachment shown enables the ball thrower 6 to be swung under table 7 when not in use. The net 10 and its removable supports are easily removed and set up. These and other elements of this invention will be the subject of additional related patent applications.
Referring now to FIGS. 2-4, blower 13 sends a constant stream of air through tube 14 to exhaust through barrel 12. Balls 16 roll in net 10 to a hopper 17 which includes baffles or inclined surfaces 18 and 19 to prevent balls 16 from jamming therein. Hopper 17 feeds balls 16 to feed tube 20. Feed tube 20 is connected to barrel 12 by timing tube 22 and vacuum bypass 23 in front of a constriction 26 which draws a vacuum in timing tube 22, bypass tube 23, and feed tube 20.
As may be seen in FIG. 4 and referring also to FIG. 2 for the orientation of elements in a vertical plane, first, second, and third balls 16a, 16b, and 16c roll or are sucked through feed tube 20 over jamming chamber 21 to the branching of timing tube 22 and vacuum bypass tube 23. A T connection 24 connects the jamming bed or chamber 21 at the end of feed tube 20 to the timing tube 22 and the vacuum bypass tube 23 which terminate in lower 90° bends 22a and 23a. A stop 25 prevents first ball 16a from entering bypass tube 23. Since there is a greater air flow through timing tube 22, the first ball 16a is drawn into it. Timing tube 22 is slightly larger in diameter than the balls 16 so balls 16 may be drawn through it with a small clearance. The weight and resistance of the first ball 16a in timing tube 22 causes a greater air flow past stop 25 through vacuum bypass 23. Stop 25 is a partial blockage of suction bypass 23 so that there is a greater air flow through the timing tube as the first ball 16a reaches T fitting or connection 24. The first ball entering timing tube 22 changes this relative air flow so that greater suction is exerted on the second ball 16b by the bypass tube 23 to hold it against stop 25 while ball 16a is in the timing tube 22. The third ball 16c and subsequent balls 16 are stopped by ball 16b.
As shown in FIGS. 2 and 3, ball 16a is drawn through timing tube 22 to enter barrel 12. The upper ends of timing tube 22 and suction bypass tube 23 terminate in the 90° bends 22b and 23b which are connected to the cross fitting 28 as are barrel 12 and air supply hose 14. As ball 16a enter cross fitting 28 and barrel 12, pressure builds up behind ball 16a to expel it. This sudden pressure would force balls 16b and 16c back in feed tube 20, but ball 16b forces ball 16c down into jamming chamber 21 which is essentially one leg of a Y connection contining a stop 31. Ball 16c checks ball 16b in the close fitting shank of T connection 24 in front of the air inlet slot 29. A second air inlet opening 30 is formed in jamming chamber 21 behind ball 16c, but ball 16b acts as a valve in the shank of fitting 24 so that pressure can't escape through these openings or through the feed tube 20.
After ball 16a is expelled from barrel 12, vacuum is again drawn in timing tube 22 and bypass tube 23 by the flow of air out of barrel 12 in front of constriction 26. Air entering inlets 30 and 29 moves balls 16b and 16c into T fitting 24 to repeat the successive throwing of balls 16. The degree of vacuum drawn or the rate at which air is drawn through timing tube 22 determines the time interval between the throwing of balls 16. As shown in FIG. 2, this rate is adjusted by moving the tubular constriction 26 further into or out of cross fitting 28. Moving the constriction away from the entrance of timing tube 22 and bypass tube 23 reduces vacuum or air flow and the time intervals at which balls are expelled are lengthened. In the case of table tennis balls 16, this interval between the ejection of balls 16 can be varied from a small fraction of a second to several seconds in one working model.
The velocity at which a ball 16 is thrown is controlled by a port 32 at the base of barrel 12 which may be adjustably opened to bleed expulsion pressure from barrel 12 as a ball 16 is being expelled. Thus the ball thrower of this invention allows balls 16 to be thrown at any set velocity at any repeated time interval. Barrel 12 can have its elevation set as desired. A modification of barrel 12 (not shown) allows it to aim down the center of table 7 while directing balls 16 right or left as set or at random. Thus the device of this invention provides a table tennis robot that will play a game at any pre-set level of skill from beginner to beyond expert. All return shots including spinning balls can be practiced.
While bypass 23 is shown to be the same size as timing tube 22, it can be of smaller diameter if desired. The actual balance of relative air flows through the timing tube and the bypass is not important, only the stronger suction acting to draw a first ball 16a into the timing tube and the stronger suction of the bypass tube acting to hold a second ball 16b against the entrance to the bypass while a first ball 16a is in the timing tube is important.
FIGS. 10-12 show a modification of this invention in which a ball thrower 6' is mounted on a tripod 5 independently of any table or the like. A hopper 17' leads to feed tube 20' which terminates in a jamming chamber 21'. A blower 13' is connected to barrel 12' by a flexible tube 14'. A bypass tube 23' and a timing tube 22' lead from a T fitting 24' to a second upper T fitting 40 which leads to a third T fitting 41 connected between air supply tube 14' and barrel 12' in front of a vacuum forming constriction 26'.
As shown in FIG. 11, a ball guide 42 deflects balls 16 into fitting 41 while allowing a vacuum to be drawn in bypass 23'. As shown in FIG. 12 constriction 26' has a lower transverse partition 43 to draw a vacuum in fitting 41. A port 44 covered by a slide 45 may be opened to vary vacuum and thus the time intervals for the throwing of balls. A port 48 may be uncovered to adjustably bleed air from the barrel 12' to set the velocity at which balls are expelled. This modification of the invention allows vertical and horizontal aiming of barrel 12' as the fittings 40 and 41 are joined by firm press fits that may be turned at their connections.
FIGS. 13-15 show a second embodiment of this invention. A barrel 12" is connected to a blower 13" by a flexible air supply tube 14" which terminates in a constriction 26". A timing tube 22" and a vacuum bypass tube 23" lead into barrel 12" in front of constriction 26". At right angles to the bottom juncture 60 of tubes 22" and 23", there extends feed tube 20" which leads to jamming chamber 61. A hopper 17" feeds balls 16 into feed tube 20". Jamming chamber 61 extends upward from bottom juncture 60 to terminate in a top wall 62 below which feed tube 20" leads into jamming chamber 61 at right angles to its axis.
As shown in FIGS. 13 and 14, a stop and partial blockage 25" causes the initial greater suction in timing tube 22" to draw a first ball 16a into it. A second ball 16b is then held against stop 25" by the resulting greater suction in suction bypass tube 23" while ball 16a is in timing tube 22". When ball 16a enters barrel 12" as shown in FIG. 15, back pressure forces ball 16b upward into jamming chamber 61 to force ball 16c against top wall 62. Ball 16b then blocks the entrance to jamming chamber 61 so air can't escape to reduce pressure in barrel 12" during ball expulsion therefrom.
After a ball 16 is expelled from barrel 12", vent opening 64 allows air to enter the jamming chamber and push ball 16b downward from its position shown in FIG. 15 to than shown in FIG. 14. In the position shown in FIG. 14, suction or gravity will force balls 16 in feed tube 20" to jam against ball 16c. As the greater suction in timing tube 22" draws ball 16b from under ball 16c (first ball 16a having been expelled from barrel 12"), the bottom of ball 16b will be held to the bottom of juncture 60 at 65 by friction and its top will move as it rolls toward timing tube 22". Ball 16c can't jam ball 16b as it will rotate on the axis of feed tube 20" held by point contact with the first following ball 16d and the side wall of jamming chamber 61. A slot 66 communicates between the top of jamming chamber 61 and feed tube 20" to enable suction to draw ball 16c from the top of jamming chamber 61 after first ball 16 a has been expelled from barrel 12".
The second embodiment of this invention has ports 67 at the base of barrel 12" to be adjustably uncovered by a slide 68 to bleed air from barrel 12" during ball expulsion to adjust ball velocity. Although barrel 12" is shown pointing vertically, the elements of the second embodiment of my invention could be curved or connected to direct balls 16 of any type in any direction.
While the ball thrower of this invention has been shown and described for table tennis balls, the principle of the invention can be applied directly to tennis balls, marbles, metal shot, baseballs, etc. Heavier balls or balls that can't fit with small clearance in a timing tube 22 and a barrel can still be drawn through a timing tube 22 if it is inclined from the vertical. As shown in FIG. 13, the tubes 22" and 23" could be swiveled to the horizontal to throw heavy balls.
While this invention has been shown and described in the best form known, it will nevertheless be understood that this is purely exemplary and that modifications may be made without departing from the spirit of the invention.
1. Background of the Invention
Ball throwing machines are now finding a wide acceptance as tennis practice devices. There is a need for an inexpensive and more reliable ball thrower for table tennis, tennis, and baseball as well as for toy, amusements operated by coins, and other applications.
2. Description of the Prior Art
Ball throwers which use air to expel a ball are well known. Heretofore, such machines have required complex breech or ball feeding mechanisms to introduce balls into a barrel to be blown out of it. These breech mechanisms, which regulate the frequency at which balls are expelled, require many moving parts which makes them costly and failure prone.
SUMMARY OF THE INVENTION
The ball thrower of this invention, except for a blower, requires no moving parts as balls themselves successively function as valves. A blower constantly forces air through a barrel. A constriction immediately in front of the barrel causes a suction in a timing tube which leads into the barrel in front of the constriction. The timing tube branches into a suction bypass tube which rejoins the timing tube at the entrance of a ball feed tube. A ball stop is placed where the suction bypass and the timing tube branch from the feed tube so balls can't enter the suction bypass. A first ball rolling from and/or being drawn through the feed tube encounters the stop and is drawn into the timing tube which permits a greater flow of air therethrough than the suction bypass. The resistance of the first ball in the timing tube reduces its suction and increases it in the bypass so that a second ball is held against the stop by the now greater flow of air into the suction bypass while the first ball is being drawn through the timing tube. When the first ball enters the barrel to be blown therefrom, back pressure in the timing tube and the suction bypass force the second ball back against a third ball which enters a jamming chamber to arrest the second ball. The arrested second ball blocks the loss of air from the back pressure so balls can be expelled at maximum velocity. The ball thrower then repeats the process to successively throw balls at given intervals. The constriction is adjusted to vary the suction and the air flow through the timing tube to set the intervals at which balls are successively discharged.
With light balls, such as table tennis balls, the timing tube may be vertical as the weight of the balls is negligible compared to the suction in a close fitting timing tube. With tennis or baseballs, the timing tube may be substantially horizontal so that the ball weight will not affect the suction drawing them through a timing tube. The ball thrower of this invention may be used with metal shot for simulated gunfire amusements or with marbles in a toy. It can be used to throw any spherical objects at high or low velocity at any desired intervals. This invention provides a more inexpensive, versatile, and reliable ball thrower. Blower pressure and capacity can be varied or pressure and air flow can be bled off to set the velocity at which balls are expelled.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a perspective view of a ball thrower according to this invention mounted on a table tennis table with a net to serve as a table tennis robot;
FIG. 2 is a section taken on line 2--2 of FIG. 1 showing a ball in the process of being blown from the barrel;
FIG. 3 is a section taken on line 3--3 of FIG. 2 with a central portion of a timing tube and a vacuum bypass tube broken away;
FIG. 4 is a section taken on a portion of line 3--3 of FIG. 2 showing a feed tube leading to the lower ends of the timing tube and the vacuum bypass tube with a first ball shown being drawn through the timing tube;
FIG. 5 is a bottom view of the table tennis table taken on line 5--5 of FIG. 2 showing a hinged attachment of the ball thrower to the table;
FIG. 6 is a vertical, longitudinal section through the table tennis table showing an attached ball thrower folded thereunder when not in use;
FIG. 7 is a vertical section through a fragment of a table tennis table showing a net supporting rod;
FIG. 8 is a plan view of a spread out table tennis table net;
FIG. 9 is a perspective view of an assembled net with a portion broken away;
FIG. 10 is a perspective view of a modified table tennis ball thrower;
FIG. 11 is a horizontal section taken on line 11--11 of FIG. 10;
FIG. 12 is a vertical section taken on line 12--12 of FIG. 11;
FIG. 13 is a perspective view of a feed tube and a jamming chamber with fragments of a timing tube and a vacuum bypass tube connected thereto according to a second embodiment of this invention;
FIG. 14 is a longitudinal section through a feed tube and a jamming chamber, and through a timing tube and a suction bypass tube with a barrel attached, the timing tube and the bypass tube being rotated 90° about the axis of the barrel, a first ball being shown being drawn through the timing tube; and
FIG. 15 is a section similar to that shown in FIG. 14 showing a ball being expelled from the barrel while a second ball forces a third ball into a jamming chamber.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
As shown in FIG. 1, the ball thrower of this invention is generally designated by the reference numeral 6. It is held to a table tennis table 7 by a hinged arm 8 and rests on a single foot 9. A net 10 surrounds one end of table 7 and contains a slit 11 through which barrel 12 of ball thrower 6 extends. A blower 13 is connected to barrel 12 by a flexible tube 14. A foot switch 15, or any other control, can start or stop the ball thrower 6 which shoots balls as a robot player through barrel 12.
FIGS. 5-9 show details of the net 10 and of the attachment of the ball thrower 6 to a table tennis table 7. The attachment shown enables the ball thrower 6 to be swung under table 7 when not in use. The net 10 and its removable supports are easily removed and set up. These and other elements of this invention will be the subject of additional related patent applications.
Referring now to FIGS. 2-4, blower 13 sends a constant stream of air through tube 14 to exhaust through barrel 12. Balls 16 roll in net 10 to a hopper 17 which includes baffles or inclined surfaces 18 and 19 to prevent balls 16 from jamming therein. Hopper 17 feeds balls 16 to feed tube 20. Feed tube 20 is connected to barrel 12 by timing tube 22 and vacuum bypass 23 in front of a constriction 26 which draws a vacuum in timing tube 22, bypass tube 23, and feed tube 20.
As may be seen in FIG. 4 and referring also to FIG. 2 for the orientation of elements in a vertical plane, first, second, and third balls 16a, 16b, and 16c roll or are sucked through feed tube 20 over jamming chamber 21 to the branching of timing tube 22 and vacuum bypass tube 23. A T connection 24 connects the jamming bed or chamber 21 at the end of feed tube 20 to the timing tube 22 and the vacuum bypass tube 23 which terminate in lower 90° bends 22a and 23a. A stop 25 prevents first ball 16a from entering bypass tube 23. Since there is a greater air flow through timing tube 22, the first ball 16a is drawn into it. Timing tube 22 is slightly larger in diameter than the balls 16 so balls 16 may be drawn through it with a small clearance. The weight and resistance of the first ball 16a in timing tube 22 causes a greater air flow past stop 25 through vacuum bypass 23. Stop 25 is a partial blockage of suction bypass 23 so that there is a greater air flow through the timing tube as the first ball 16a reaches T fitting or connection 24. The first ball entering timing tube 22 changes this relative air flow so that greater suction is exerted on the second ball 16b by the bypass tube 23 to hold it against stop 25 while ball 16a is in the timing tube 22. The third ball 16c and subsequent balls 16 are stopped by ball 16b.
As shown in FIGS. 2 and 3, ball 16a is drawn through timing tube 22 to enter barrel 12. The upper ends of timing tube 22 and suction bypass tube 23 terminate in the 90° bends 22b and 23b which are connected to the cross fitting 28 as are barrel 12 and air supply hose 14. As ball 16a enter cross fitting 28 and barrel 12, pressure builds up behind ball 16a to expel it. This sudden pressure would force balls 16b and 16c back in feed tube 20, but ball 16b forces ball 16c down into jamming chamber 21 which is essentially one leg of a Y connection contining a stop 31. Ball 16c checks ball 16b in the close fitting shank of T connection 24 in front of the air inlet slot 29. A second air inlet opening 30 is formed in jamming chamber 21 behind ball 16c, but ball 16b acts as a valve in the shank of fitting 24 so that pressure can't escape through these openings or through the feed tube 20.
After ball 16a is expelled from barrel 12, vacuum is again drawn in timing tube 22 and bypass tube 23 by the flow of air out of barrel 12 in front of constriction 26. Air entering inlets 30 and 29 moves balls 16b and 16c into T fitting 24 to repeat the successive throwing of balls 16. The degree of vacuum drawn or the rate at which air is drawn through timing tube 22 determines the time interval between the throwing of balls 16. As shown in FIG. 2, this rate is adjusted by moving the tubular constriction 26 further into or out of cross fitting 28. Moving the constriction away from the entrance of timing tube 22 and bypass tube 23 reduces vacuum or air flow and the time intervals at which balls are expelled are lengthened. In the case of table tennis balls 16, this interval between the ejection of balls 16 can be varied from a small fraction of a second to several seconds in one working model.
The velocity at which a ball 16 is thrown is controlled by a port 32 at the base of barrel 12 which may be adjustably opened to bleed expulsion pressure from barrel 12 as a ball 16 is being expelled. Thus the ball thrower of this invention allows balls 16 to be thrown at any set velocity at any repeated time interval. Barrel 12 can have its elevation set as desired. A modification of barrel 12 (not shown) allows it to aim down the center of table 7 while directing balls 16 right or left as set or at random. Thus the device of this invention provides a table tennis robot that will play a game at any pre-set level of skill from beginner to beyond expert. All return shots including spinning balls can be practiced.
While bypass 23 is shown to be the same size as timing tube 22, it can be of smaller diameter if desired. The actual balance of relative air flows through the timing tube and the bypass is not important, only the stronger suction acting to draw a first ball 16a into the timing tube and the stronger suction of the bypass tube acting to hold a second ball 16b against the entrance to the bypass while a first ball 16a is in the timing tube is important.
FIGS. 10-12 show a modification of this invention in which a ball thrower 6' is mounted on a tripod 5 independently of any table or the like. A hopper 17' leads to feed tube 20' which terminates in a jamming chamber 21'. A blower 13' is connected to barrel 12' by a flexible tube 14'. A bypass tube 23' and a timing tube 22' lead from a T fitting 24' to a second upper T fitting 40 which leads to a third T fitting 41 connected between air supply tube 14' and barrel 12' in front of a vacuum forming constriction 26'.
As shown in FIG. 11, a ball guide 42 deflects balls 16 into fitting 41 while allowing a vacuum to be drawn in bypass 23'. As shown in FIG. 12 constriction 26' has a lower transverse partition 43 to draw a vacuum in fitting 41. A port 44 covered by a slide 45 may be opened to vary vacuum and thus the time intervals for the throwing of balls. A port 48 may be uncovered to adjustably bleed air from the barrel 12' to set the velocity at which balls are expelled. This modification of the invention allows vertical and horizontal aiming of barrel 12' as the fittings 40 and 41 are joined by firm press fits that may be turned at their connections.
FIGS. 13-15 show a second embodiment of this invention. A barrel 12" is connected to a blower 13" by a flexible air supply tube 14" which terminates in a constriction 26". A timing tube 22" and a vacuum bypass tube 23" lead into barrel 12" in front of constriction 26". At right angles to the bottom juncture 60 of tubes 22" and 23", there extends feed tube 20" which leads to jamming chamber 61. A hopper 17" feeds balls 16 into feed tube 20". Jamming chamber 61 extends upward from bottom juncture 60 to terminate in a top wall 62 below which feed tube 20" leads into jamming chamber 61 at right angles to its axis.
As shown in FIGS. 13 and 14, a stop and partial blockage 25" causes the initial greater suction in timing tube 22" to draw a first ball 16a into it. A second ball 16b is then held against stop 25" by the resulting greater suction in suction bypass tube 23" while ball 16a is in timing tube 22". When ball 16a enters barrel 12" as shown in FIG. 15, back pressure forces ball 16b upward into jamming chamber 61 to force ball 16c against top wall 62. Ball 16b then blocks the entrance to jamming chamber 61 so air can't escape to reduce pressure in barrel 12" during ball expulsion therefrom.
After a ball 16 is expelled from barrel 12", vent opening 64 allows air to enter the jamming chamber and push ball 16b downward from its position shown in FIG. 15 to than shown in FIG. 14. In the position shown in FIG. 14, suction or gravity will force balls 16 in feed tube 20" to jam against ball 16c. As the greater suction in timing tube 22" draws ball 16b from under ball 16c (first ball 16a having been expelled from barrel 12"), the bottom of ball 16b will be held to the bottom of juncture 60 at 65 by friction and its top will move as it rolls toward timing tube 22". Ball 16c can't jam ball 16b as it will rotate on the axis of feed tube 20" held by point contact with the first following ball 16d and the side wall of jamming chamber 61. A slot 66 communicates between the top of jamming chamber 61 and feed tube 20" to enable suction to draw ball 16c from the top of jamming chamber 61 after first ball 16 a has been expelled from barrel 12".
The second embodiment of this invention has ports 67 at the base of barrel 12" to be adjustably uncovered by a slide 68 to bleed air from barrel 12" during ball expulsion to adjust ball velocity. Although barrel 12" is shown pointing vertically, the elements of the second embodiment of my invention could be curved or connected to direct balls 16 of any type in any direction.
While the ball thrower of this invention has been shown and described for table tennis balls, the principle of the invention can be applied directly to tennis balls, marbles, metal shot, baseballs, etc. Heavier balls or balls that can't fit with small clearance in a timing tube 22 and a barrel can still be drawn through a timing tube 22 if it is inclined from the vertical. As shown in FIG. 13, the tubes 22" and 23" could be swiveled to the horizontal to throw heavy balls.
While this invention has been shown and described in the best form known, it will nevertheless be understood that this is purely exemplary and that modifications may be made without departing from the spirit of the invention.