Patent Document

BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to an automatic ice maker and, more particularly, relates to an automatic ice maker for household refrigerators. 
     2. Description of the Prior Art 
     FIG.  16  and FIG. 17 show a conventional automatic ice maker disclosed in the U.S. Pat. No. 5,010,738, wherein a reference numeral  1  denotes a tray for making ice cubes,  2  denotes an array of stationary fingers mounted on one side of an upper surface of the tray  1 ,  3  denotes a rotary shaft extending along the center line of the upper surface of the tray  1  and to be rotated by a motor (not shown),  4  denotes an array of ejector fingers fixed to the rotary shaft  3  for rotation therewith so as to interleave with the stationary fingers  2  and cooperate therewith to cause the ice cubes to be deposited in a bin  8  arranged below the tray  1 . A reference numeral  5  denotes a control box,  6  denotes a water supply box,  7  denotes an ice cube detecting device for detecting whether a sufficient ice cubes are located within the bin  8  or not, and  9  denotes a freezer compartment of a refrigerator  10 . 
     In the tray  1 , a thermostat and a heater are installed. The heater and the motor are energized when the water is frozen in the tray  1  and the thermostat is turned ON, so that a surface of the ice cubes attached to the tray  1  are molten and that the ice cubes in the tray  1  is ejected to the bin  8  by the ejector fingers  4  when the motor is rotated. The water supply to the tray  1  is started and a quantity of water determined according to the angular position of the motor is supplied to the tray  1  to make ice cubes, again. The above cycle is repeated. 
     When the ice cube detecting device  7  detects a sufficient quantity of ice cubes located within the bin  8 , the automatic operation of the ice maker is stopped temporarily. The automatic operation of the ice maker is restarted when the quantity of the ice cubes located within the bin  8  is reduced. The ice cube detecting device  7  comprises a stop arm in the form of a wire and swings along an arc above the bin  8  to detect the upper surface of the ice cubes located within the bin  8 . However, the above-mentioned conventional automatic ice maker has many problems and defects. The stop arm is sometimes broken when it is brought into contact with the ice cubes. The ice cubes stored in the bin  8  positioned below the bottom surface of the tray  1  are liable to melt by a heat radiation from the tray  1 , when the heater is energized. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to solve the above problems. 
     Another object of the present invention is to provide an automatic ice maker for use in household refrigerators comprising a water supply device, a tray for making ice cubes, an ice cube ejector device, a heater for separating ice cubes from the tray, a sensor for sensing a temperature of the tray, a bin for storing therein ice cubes, an ice cube detecting device for detecting ice cubes located within the bin, and an electronic control circuit for controlling the ice making operation, wherein said components other than the water supply device are arranged in a freezer compartment of the refrigerator, and the ice cube detecting device is formed of a planar stop arm movable to a position between the tray and the bin according to the energization and deenergization of the heater. 
     Said stop arm has an upper surface inclined downwards gradually from a tray side to an opposite side. 
     Said stop arm is supported through a spring and rotated by a drive shaft. 
     Said stop arm can be moved horizontally. Said electronic control circuit comprises an original point hole IC and a magnet faced to each other with a gap therebetween, and said magnet is composed of N and S poles superposed to each other. 
    
    
     These and other objects and features of the present invention will become apparent from the following description in conjunction with the attached drawings. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a front view of an automatic ice maker according to the present invention; 
     FIG. 2 is a plan view of an automatic ice maker according to the present invention; 
     FIG. 3 is a bottom view of an automatic ice maker according to the present invention; 
     FIG. 4 is a schematic view of a stop arm drive portion of an automatic ice maker according to the present invention; 
     FIG. 5 is a schematic view of a stop arm operation of an automatic ice maker according to the present invention; 
     FIG. 6 is a schematic view of a stop arm operation of an automatic ice maker according to the present invention; 
     FIG. 7 is a schematic view of a stop arm operation of an automatic ice maker according to the present invention; 
     FIG. 8 is a schematic view of a stop arm operation of an automatic ice maker according to the present invention; 
     FIG. 9 is a schematic view of a stop arm operation of an automatic ice maker according to the present invention; 
     FIG. 10 is a schematic view of a stop arm operation of an automatic ice maker according to the present invention; 
     FIG. 11 is a schematic view of a stop arm operation of an automatic ice maker according to the present invention; 
     FIG. 12 is a cross section taken along line  12 — 12  of FIG. 2; 
     FIG. 13 is a schematic view of a magnet for an original point hole IC of an automatic ice maker according to the present invention; 
     FIG. 14 is a schematic view of a magnet for an original point hole IC of an automatic ice maker according to the present invention; 
     FIG. 15 is a schematic view of a magnet for an original point hole IC of an automatic ice maker according to the present invention; 
     FIG. 16 is an enlarged, perspective view illustrating a conventional automatic ice maker; and 
     FIG. 17 is a fragmentary, perspective view of a conventional automatic ice maker. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     As automatic ice maker according to the present invention will now be explained with reference to the attached drawings. 
     According to the present invention, an elongated stop arm  11  in the form of a triangular plate is used as shown in FIG. 1 to FIG. 3 instead of using the stop arm in the form of a wire as in the conventional automatic ice maker. The distal end of the stop arm  11  is supported through a coil spring  13  rotatably by a driving shaft  12  projected from the bottom surface of a control box  5  so that the stop arm  11  can be rotated with respect to the driving shaft  12  against the force of the coil spring  13  when the stop arm  11  is hit against an obstacle. As shown in FIG.  4  and FIG. 5, a rod shaped cam follower  16  is provided on the driving shaft  12  so as to extend radially therefrom so that the tip end of the cam follower  16  is brought into contact with a cam surface of a cam  15  fixed to an output shaft  14  to be rotated by a motor. The configuration of the cam surface of the cam  15  is so determined that the stop arm  11  is positioned below the tray  1  when the heater is energized and that the stop arm  11  swings horizontally on the bin  8  according to the rotation of the ejector fingers  4  when the heater is not energized. 
     A magnet  17  is mounted on the tip end of an arm extending radially from the driving shaft  12 , and an arm hole IC  19  is provided on a base plate  18  of the control box  5  facing the magnet  17  with a gap therebetween. 
     A magnet  20  is mounted on an end surface of the output shaft  14 , and an original point hole IC  21  is provided on the base plate  18  facing the magnet  20  with a gap therebetween. 
     According to the automatic ice maker of the present invention, the stop arm  11  is positioned below the tray  1  directly before or directly after the energization of the heater, or at the same time of the energization of the heater, after the water in the tray  1  has been frozen, so that the ice cubes in the bin  8  is prevented from being molten by the heat radiation from the heater. 
     FIG. 5 shows a state that the stop arm  11  is positioned above the bin  8  and outside of the tray  1 , the arm hole IC  19  is turned OFF, the original point hole IC  21  is turned ON, the water in the tray  1  is frozen, the thermostat is turned ON, and the heater is energized, but the ejector fingers  4  are not yet rotated. 
     FIG. 6 shows a state after about 90 seconds from the energization of the heater. The stop arm  11  is not yet moved to the below the tray  1 . The arm hole IC  19  and the original point hole IC  21  are turned OFF, and the ejector fingers  4  are rotated by 15°. 
     FIG. 7 shows a state that the stop arm  11  is swing and positioned below the tray  1 , the ejector fingers  4  are rotated by 195°, the arm hole IC  19  is turned ON, and the original point hole IC  21  is turned OFF. 
     In this state, the ice cubes stored in the bin  8  are prevented from being molten by the heat radiation from the heater, because the stop arm  11  is positioned below the tray  1 . 
     FIG. 8 shows a state that the stop arm  11  is not yet moved from below the tray  1  to the outside, but the ejector fingers  4  are rotated by 270°, the arm hole IC  19  is turned ON, and the original point hole IC  21  is turned OFF. 
     FIG. 9 shows a state that the stop arm  11  is not yet moved from below the tray  1  to the outside, but the ejector fingers  4  are rotated by 300°, the arm hole IC  19  is turned ON, and the original point hole IC  21  is turned OFF. 
     FIG. 10 shows a state that the stop arm  11  is swung and moved from below the tray  1  to the outside, the ejector fingers  4  are rotated by 330°, and the arm hole IC  19  and the original point hole IC  21  are turned OFF. 
     FIG. 11 shows a state that the stop arm  11  is positioned at the outside of the tray  1 , the ejector fingers  4  are returned to the original position, the arm hole IC  19  is turned OFF, and the original point hole IC  21  is turned ON. 
     FIG. 12 shows a cross section of the stop arm  11 . The upper surface of the stop arm  11  is inclined downwards gradually from the side of the tray  1  to the opposite side, so that the ice tips or water drops formed by the ejecting operation of the ejector fingers  4  are removed automatically when they are fallen on the stop arm  11 . 
     Further, conventionally, either one of N and S poles of the conventional single magnet is used as the magnet  17  or  20  for the hole IC. In this case, however, the relation between the relative distance and the magnetic flux density of the original point hole IC  21  and the magnet  20  is shown by a gentle curve as shown in FIG.  13 . The original point hole IC  21  is operated only when the distance between the original point hole IC  21  and the magnet  20  is changed to the large extent and the change of the magnetic flux density becomes a predetermined value, so that the precision of the operation of the original point hole IC  21  is deteriorated. 
     Accordingly, in the present invention, a magnet consisting of superposed N and S poles as shown in FIG. 14 is used as the magnet  20 . In this case, the relation between the relative distance and the magnetic flux density of the original point hole IC  21  and the magnet  20  is shown by a curve having a sharply inclined portion as shown in FIG.  15 . Accordingly, the original point hole IC  21  can be operated by a small change in distance if the above sharply inclined portion of the curve is used, so that the precision of the operation of the original point hole IC  21  can be enhanced. 
     As stated above, according to the present invention, the original point of rotation of the ejector fingers  4  can be detected by the original point hole IC  21 , and the stop arm  11  can be swung according to the output of the arm hole IC  19  only when the output shaft  14  is in the angular position between 15° to 330°. 
     Further, the stop arm  11  can be prevented from being damaged. The ice cubes can be prevented from being molten by the heat radiation from the heater, because the stop arm  11  can be positioned below the bottom surface of the tray  1 . 
     Furthermore, the operations of the ejector fingers  4  and the stop arm  11  can be controlled precisely by elevating the sensitivity of the original point hole IC  21 . 
     It should be understood that many changes and modifications may be made within the scope of the present invention without departing from the spirit thereof. The scope of these changes will become apparent from the attached claims.

Technology Category: 2