Abstract:
A liquid dispenser has a liquid filled container which is attached to a pump for dispensing. The pump has at least two sensors, a first sensor that identifies whether a person&#39;s hand is present and activates the pump, and a second sensor that identifies when the pump has been fully actuated which then switches the direction of the pump&#39;s actuation back to its starting point. The dispensing nozzle serves as the pump&#39;s actuator and is moved by a motor powered gear system and a toothed rack to move the nozzle.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority of Taiwanese Application No. 097215858, filed on Sep. 3, 2008. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a liquid dispenser, more particularly to a liquid dispenser including a part-driving unit that has a gear set and a rack driven by the gear set to drive movement of a liquid-driving unit for discharging an amount of a liquid from a liquid container. 
     2. Description of the Related Art 
     As shown in  FIG. 1 , Taiwanese Patent Utility Model No. M328853 discloses a conventional liquid soap dispenser including an automatic liquid discharging mechanism  11  mounted in a housing  12 . The automatic liquid discharging mechanism  11  includes a base  111 , a motor  112  mounted on the base  111 , a gear set  113  mounted on the base  111  and driven by the motor  112 , a pressing member  114  connected pivotably to the base  111 , a liquid container  117  receiving a liquid soap therein, and an elastic deformable conduit  115  connected to and in liquid communication with the liquid container  117 . A pushing member  116  is driven by the gear set  113  and is in contact with the pressing member  114  such that when the motor  112  is actuated, the gear set  113  drives the pushing member  116  to rotate, which, in turn, results in pivoting of the pressing member  114  to a position to squeeze the deformable conduit  115 , thereby discharging the liquid soap from an outlet of the deformable conduit  115 . The pushing member  116  and the pressing member  114  subsequently return to their original positions and the deformable conduit  115  returns to its original shape after discharging. The deformable conduit  115  is likely to suffer from material fatigue after a period of use due to repeated deformation. 
     U.S. Pat. No. 6,536,629 discloses an aerosol device including a liquid pump that defines a passage therein and that has a plunger extending into the passage and an actuating head connected to the plunger for driving movement of the plunger between closed and opened positions. The passage has an inlet adapted to be in liquid communication with a liquid container, and an outlet opposite to the liquid inlet. The actuating head is pressable such that when the actuating head is pressed by the user, the plunger is driven to move from the closed position to the opened position for drawing a liquid from the liquid container to pass through the inlet and outlet of the passage. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide a liquid dispenser that includes a part-driving unit which can be applied to different types of conventional liquid-driving units for discharging a constant amount of a liquid from a liquid container. 
     Accordingly, a liquid dispenser of the present invention comprises: a liquid container defining a liquid-storing space that is adapted to store a liquid therein; a liquid-driving unit defining a liquid passage and having a movable part, the liquid passage having an inlet that is in liquid communication with the liquid-storing space, and an outlet that is disposed outwardly of the liquid container, the movable part being movable between first and second positions for driving an amount of the liquid from the liquid-storing space to pass through the inlet and the outlet; and a part-driving unit including a power-driven gear set, and a rack engaging and driven by the gear set and connected to the movable part for driving movement of the movable part between the first and second positions. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other features and advantages of the present invention will become apparent in the following detailed description of the preferred embodiment with reference to the accompanying drawings, of which: 
         FIG. 1  is a fragmentary schematic view of a conventional liquid dispenser; 
         FIG. 2  is an exploded perspective view of the preferred embodiment of a liquid dispenser according to the present invention; 
         FIG. 3  is a perspective view to illustrate the configuration of a part-driving unit and a position of a sensor of the preferred embodiment; 
         FIG. 4  is an exploded perspective view to illustrate the configuration of a liquid-driving unit and a mounting casing of the preferred embodiment; 
         FIG. 5  is an exploded perspective view to illustrate the configuration of a rack of the preferred embodiment; 
         FIG. 6  is an assembled perspective view to illustrate the configuration of the rack and the liquid-driving unit of the preferred embodiment; 
         FIG. 7  is an assembled sectional view to illustrate a state where the rack together with a plunger of the preferred embodiment is disposed at a first position; and 
         FIG. 8  is an assembled sectional view to illustrate another state where the rack together with the plunger of the preferred embodiment is disposed at a second position. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to  FIGS. 2 to 4 , the preferred embodiment of a liquid dispenser according to the present invention is shown to include: a liquid container  6  defining a liquid-storing space  62  that is adapted to store a liquid  8 , such as a cleaning liquid, therein; a liquid-driving unit  7  (see  FIGS. 6 and 7 ) defining a liquid passage  70  and having a movable part  73 , the liquid passage  70  having an inlet  725  that is in liquid communication with the liquid-storing space  62 , and an outlet  726  that is disposed outwardly of the liquid container  6 , the movable part  73  being movable between first and second positions (see  FIGS. 7 and 8 ) for driving an amount of the liquid  8  from the liquid-storing space  62  to pass through the inlet  725  and the outlet  726 ; and a part-driving unit  5  including a power-driven gear set  53 , and a rack  56  engaging and driven by the gear set  53  and connected to the movable part  73  for driving movement of the movable part  73  between the first and second positions. 
     In this embodiment, the gear set  53  includes a pinion  533  (see  FIGS. 2 ,  3  and  7 ). The rack  56  has a toothed plate  561  (see  FIG. 5 ) that engages the pinion  533 , and a holding arm  562  that extends from the toothed plate  561  and that defines a retaining recess  560 . The movable part  73  includes a coupling sleeve  723  that extends in a first direction (X), and a flange  724  that radiates outwardly from the coupling sleeve  723  into the retaining recess  560  (see  FIG. 6 ). The holding arm  562  has an enlarged C-shaped end  5621  that defines the retaining recess  560 . 
     In this embodiment, the liquid dispenser further includes a mounting casing  4 , a motor  52  mounted on the mounting casing  4 , a control circuit  54  coupled to the motor  52  for controlling operation of the control circuit  54  to control activation of the motor  52 , and a pair of first sensors  541  mounted on the mounting casing  4  and coupled to the control circuit  54  for controlling circuit states of the motor  52 . 
     Each of the first sensors  541  is a light sensor. The mounting casing  4  has a bottom wall  42  (see  FIG. 4 ) that is formed with a pair of through-holes  421 . The first sensors  541  are respectively aligned with the through-holes  421  in the first direction (X). 
     In this embodiment, the liquid dispenser further includes a second sensor  542  mounted on the mounting casing  4  (see  FIG. 3 ) and coupled to the control circuit  54  for controlling operating of the control circuit  54  to control direction of rotation of the motor  52 . 
     The second sensor  542  is a light sensor. The movable part  73  is movable together with the rack  56  in the first direction (X) between the first and second positions. The rack  56  further has a light-blocking plate  563  (see  FIG. 5 ) that extends from an end of the toothed plate  561  in a transverse direction (Y) relative to the toothed plate  561  and that is formed with upper and lower holes  565 ,  566  which are aligned in the first direction (X). The second sensor  542  is aligned with the upper hole  565  in a second direction (Z) transverse to the first direction (X) when the movable part  73  is disposed at the first position, and is aligned with the lower hole  566  in the second direction (Z) when the movable part  73  is disposed at the second position. 
     The movable part  73  further includes a plunger  731  extending in the first direction (X) into the liquid passage  70 . The coupling sleeve  723  is coupled to and is sleeved around the plunger  731 . The liquid-driving unit  7  further has an annular outer surrounding wall  721  sleeved around and coupled to the coupling sleeve  723 . The movable part  73  is movable relative to the outer surrounding wall  721  in the first direction (X). The outer surrounding wall  721  is formed with first and second inserting protrusions  727 ,  728  (see  FIG. 6 ). The mounting casing  4  defines an accommodating recess  46  defined by a recess-defining wall  46 ′ that is formed with first and second retaining holes  461 ,  462 . The outer surrounding wall  721  and the coupling sleeve  723  are received in the accommodating recess  46 . The first and second inserting protrusions  727 ,  728  of the outer surrounding wall  721  extend fittingly into the first and second retaining holes  461 ,  462 , respectively. 
     In this embodiment, the recess-defining wall  46 ′ is further formed with an elongate guiding slot  463  that extends in the first direction (X). The holding arm  562  of the rack  56  extends from the toothed plate  561  through the elongate guiding slot  463  such that the enlarged C-shaped end  5621  is disposed in the accommodating recess  46 . 
     In this embodiment, the liquid dispenser further includes a housing  3 . The liquid container  6 , the liquid-driving unit  7 , and the part-driving unit  5  are mounted in the housing  3 . The housing  3  has a bottom wall  31  that is formed with a bottom opening  312  registered with the outlet  726  of the liquid passage  70  for passage of the liquid  8  therethrough. The bottom wall  31  of the housing  3  is further formed with a sensor-detecting opening (not shown) registered with the through-holes  421  in the bottom wall  42  of the mounting casing  4 . 
     Referring to  FIG. 2 , a battery unit  55  is mounted in a chamber  431  in the mounting casing  4 . The gear set  53  further includes a reduction gear unit driven by the motor  52 , engaging the pinion  533 , and having a plurality of transmission gears  531  and reduction gears  532  for reducing the speed to be transmitted to the rack  56 . 
     In this embodiment, the liquid driving unit  7  is a pump having a structure similar to that of the liquid pump disclosed in U.S. Pat. No. 6,536,629. Details of the structure and operation of the pump can be found in the aforesaid patent. 
     In operation, when the hand of the user is placed at a position underneath the through-holes  421  in the bottom wall  42  of the mounting casing  4 , the first sensors  541  detect the hand of the user and enable the control circuit  54  to actuate the motor  52  to rotate in a first rotational direction (note that the second sensor  542  is aligned with the upper hole  565  in the light-blocking plate  563  in the second direction (Z) at this time), which results in rotation of the gear set  53  and movement of the movable part  73  together with the rack  56  in the first direction (X) from the first position to the second position. When the movable part  73  reaches the second position, the second sensor  542  is aligned with the lower hole  566  in the light-blocking plate  563  and enables the motor  52  to rotate in a second rotational direction opposite to the first rotational direction until the movable part  73  reaches the first position. 
     With the inclusion of the rack  56  in the part-driving unit  5  of the liquid dispenser of this invention, the liquid dispenser can be applied to different types of the liquid-driving units. Moreover, combination of the part-driving unit  5 , the liquid-driving unit  7  having the plunger  731  as driving means, the second sensor  542 , and the upper and lower holes  565 ,  566  in the light-blocking plate  563  permits a regulated amount of the liquid  8  to be discharged from the liquid container  6  during every dispensing operation. 
     While the present invention has been described in connection with what is considered the most practical and preferred embodiment, it is understood that this invention is not limited to the disclosed embodiment but is intended to cover various arrangements included within the spirit and scope of the broadest interpretation so as to encompass all such modifications and equivalent arrangements.