Abstract:
A device for the linear drive of a pumping member in a soap-type dispenser includes a crank mechanism with a crank disc and a push rod transmitting a linear movement to a piston rod. Disengageable coupling members are located between the push rod and the piston rod to disengage the piston rod when an actuating signal is not present. The coupling members can be re-engaged upon further movement of the crank disc. The device may be employed in conjunction with a motor driven pumping member and a sensor with a control circuit to detect the presence of a hand to be supplied with the soap and generate the actuating signal.

Description:
The present invention relates to a device for the linear drive of a pumping member in a media dispenser and is a Continuation of PCT/CH 00/00028 filed Jan. 19, 2000. 
    
    
     BACKGROUND OF THE INVENTION 
     Electrically operated soap and/or foam dispensers for hand washing are generally activated in a contactless manner by a sensor, i.e. a hand held out at a suitable distance sets a pump mechanism in action, so a portion of soap or foam is dispensed. If the hand is withdrawn prematurely or if someone wishes to “test” the action of the dispenser by passing the hand underneath quickly, the dispensed portion falls on parts of the wash basin and/or soils the floor. 
     This drawback has been recognised and an attempt made to eliminate it by reversing the direction of rotation of the drive motor as set forth in DE-A1-198 05 304. Here the presence of the hand to be provided with soap is monitored during the is pumping process. The necessary change in the drive and the subsequent mechanism from a forward direction to a reverse direction represents a complete reversal in the flow of energy and causes motor currents which are a multiple of the nominal current. Repeated successive actuation of the change in the direction of rotation can overheat and damage a small motor. In addition, the control circuit has to be equipped with components (transistors/thyristors, passive elements) which can process the maximum resulting high currents and are correspondingly expensive. 
     The object of the present invention is therefore to create a device which manages dispensation without the reversal of a drive motor, is economical and yet satisfies the requirements in service. The subject of the invention should stop the drive when the hand to be provided with soap is not removed at the correct time such that there is no soiling of the dispenser and its surroundings. In addition, the dispenser should be ready for use again after a short time and must not incur any damage even after repeated incorrect triggering of the metering process. 
     This object is achieved by the use of switchable coupling members between the drive motor and a piston rod of the pump member. A sensor controls the operation of the coupling members, which disengage the pump from the motor when a hand is not in the proper position for receipt of the pumped media. 
     Owing to the uncoupling of the piston rod the flow of power to the pumping member is interrupted so the flow of medium is stopped immediately. The relief applied to the pumping member and corresponding elastic components is sufficient in most devices to cause minimum backlash, preventing dripping of the medium. 
     The switchable members may be located between a push rod and the piston rod. The push rod converts the rotational movement of the motor into an oscillating movement in a compact manner. Transmission of the movement of the push rod to a coupling link facilitates the interruption and the subsequent restoration of the flow of power. 
     Inclusion of a locking cam and a spring-loaded locking lever on the push rod is particularly advantageous for quick unlocking and locking, i.e. for connection to the coupling link with an interlocking fit. Electromagnetic disengagement of the locking lever can also be provided. 
     A connecting link can be utilized to actuate the locking lever. Rotational loading of the connecting link through a joint head construction allows virtually any arrangement of the electromagnet and requires only small forces for uncoupling. Such a construction also allows the use of commercially available actuating magnets. 
     The joint head also allows an oscillating movement of the push rod to be converted into a linear pumping movement. 
     A leaf spring can be used to act on the connecting link and ensures reliable disengagement thereof. 
     An additional restoring force f applied to the piston increases the inherent backlash in the pumping member and prevents subsequent dripping, in particular if soap flakes undergo an expansion at an inner face next to the delivery aperture. The force should be as small as possible to conserve energy. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Embodiments of the invention will be described hereinafter with reference to drawings, in which: 
     FIG. 1 is a perspective view of a drive mechanism for a hose pump in a soap dispenser in accordance with the invention; 
     FIG. 2 shows the device from FIG. 1 in readiness for operation, in a lateral plan view; 
     FIG. 3 shows the device of FIG. 2 in the pumping position (end position); 
     FIG. 4 shows the device according to FIGS. 1 to  3  with temporary interruption of the metering process; 
     FIG. 5 shows the drive mechanism with its battery current supply, installed in a soap dispenser to be operated in a contactless manner; and 
     FIG. 6 is an enlarged diagram similar to FIG. 5 using an example of a foam dispenser. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     A drive mechanism designated  1  as used in soap and foam dispensers can be seen in FIG.  1 . 
     A commercially available electric motor M, a battery-operated d.c. motor, is inserted in a flange  2 . The housing of the motor M is held by a resiliently configured carrier  3  with holding flanges  4 . A drive pinion  5  (not shown) is located in the flange  2  and acts on a spur gear  6  placed on a gearing flange  7 . An assembly angle  31  is arranged integrally and at a right angle on the gearing flange  7 . The spur gear  6  is covered by a cover (not shown) held via clips  8  on the gearing flange  7 . 
     A crank mechanism  9  with crank pin  10  projecting from a crank disc  11  and engaging in a guide groove  13  of a push rod  12  is located on the side facing the observer. The push rod  12  is mounted at one end on a swivel pin  14  and has a locking cam  12 ′ at its opposing end. A coupling link  15  pivotal about a bearing journal  40  is connected with an interlocking fit at one end to the push rod  12 , a latching pawl  16  locking the two components  12  and  15  in the position shown so the pawl rests with a locking lever  17  on the locking cam  12 ′ of the push rod  12 . The latching pawl  16  is in turn mounted at its lower end on a swivel pin  18 . A cam-like spring mount  19 , on which a flat coil spring  20  is supported and presses the locking lever  17  against the push rod  12  and the locking cam  12 ′ in this case, is located at the lower end of the coupling link  15 . A joint head  21  in which lateral cams  23  of a piston rod  43  are engaged is located next to and beneath the flat coil spring  20 . The piston rod  43  carries a pump piston  25  and is centered on a trailing piston guide  41 , the piston  25  actuating in a manner known per se as a hose pump for a soap solution. In addition, lateral cheeks  24  providing parallel guidance with a suitable flat part (not shown) engaging therein, are located beneath the joint head  21 . 
     An elevation in which a pivotal cam disc  32  is mounted in a shaft  33  can be seen on the upper part of the assembly angle  31 . A fixing piece  34  holding an upper support  29  of a connecting link  26  in the position shown is located behind the cam disc  32 . This connecting link  26  is guided laterally by means of a lateral guide  27  next to which a leaf spring  28  is inserted and engages with its upper end in a recess of the connecting link  26  and biases the latter in the tilting direction K. A journal bearing  30  let into a further elevation of the assembly angle  31  serves as a pivot point for the possible tilting process in the direction K. 
     A magnet carrier  35  projects from the assembly angle  31 , on which carrier an electromagnet  36  is positioned parallel to the assembly angle  31 , in the solenoid  37  of which a vertically displaceably mounted armature  38  acts via a stud  39  on the components  32  and  34 . In addition, wedge-shaped supports  42  project from the gearing flange  7 . These serve as assembly aids in the dispenser. 
     In the figures hereinafter, identical functional parts are provided with identical reference numerals. 
     FIG. 2 corresponds to FIG. 1, wherein the connecting link  26  present in FIG. 1 has been omitted for illustrative reasons or is shown only by a dot-dash line in this plan view. The power transmission from crank pin  10 , rotating in the direction of the arrow D, via the coupling link  15  and a concave pressure face  22  present in the joint head  21  to the trailing end of the piston rod  43  can clearly be seen in this figure. 
     The diagram of FIG. 3 similar to FIG. 2 shows the pump piston  25  in its extended end position in which the crank pin  10  also assumes an extreme position. 
     If a signal is now emitted by a optical sensor present in the dispenser, after which the hand to be provided with soap is withdrawn, the supply of current to the motor M is interrupted immediately and the solenoid  37  immediately experiences a current pulse so the stud  39  travels upward causing the components  32  and  34  to pivot into the position shown in FIG. 4 so the connecting link  26 , shown in dot-dash lines, has pivoted about the journal bearing  30  in the tilting direction K. 
     It is obvious that in this position shown in FIG. 4 there is no flow of power from the motor M via the drive mechanism to the piston rod  43 . The piston rod  43  is “freely switched” and owing to the inherent elasticity of the hose pump (not shown here) undergoes a shift back into the starting position. 
     The crank mechanism  9  used now proves to be advantageous: as soon as the motor M is again supplied with current the push rod  12  returns to its starting position connected to the coupling link  15 . The locking lever  17  engages again and is connected to the locking cam  12 ′. Consequently, a flow of power from motor M to piston  25  is again possible. The drive mechanism  1  is ready for operation again without further mechanical and/or electrical measures being necessary. 
     According to FIG. 5 a drive mechanism  1  according to the invention is placed on a back wall  130  in a soap dispenser  100  and provided with current by commercially available batteries B mounted in a well known battery compartment  50 . A sensor  51  (light barrier), also commercially available, detecting the presence of a hand is located on the bottom of the dispenser  100 . 
     FIG. 5 also shows a housing  120  with a window  121  at the front, behind which a level indicator known per se of the intermediate container  106  is arranged. 
     The soap dispenser  100  has a supply bottle  102  placed upside down in an adaptor  108  on a cap  107  of an intermediate container  106  serving as reservoir. The piston rod  43  issuing from the drive mechanism  1  acts with its pump piston  25  on a hose pump  118  and actuates (opens) the rubber lip of a soap outlet  117  during portioning of soap. 
     The inherent elasticity of the hose pump  118  is sufficient for the soap outlet  117  to close and the piston  25  to return as soon as the drive mechanism  1  arrives in the state described in FIG.  4 . The hose pump  118  therefore acts as a restoring spring. The restoring force resulting from the hose pump  118  is designated by f and acts directly on the pump piston  25 . 
     The same function is performed in a foam dispenser  101  according to FIG. 6, though this does not contain a restoring hose pump but a restoring spring in the pneumatic cylinder  182 . The soap solution is supplied in the same manner as in the soap dispenser in FIG. 5 albeit here via a passage pin  184  fed by a soap metering cylinder  183 . The soap exits in the form of fine pored foam via a delivery aperture  180 . 
     The disengagement of the piston rod  43  alone causes a return stroke owing to the gas bubbles present in the pneumatic/hydraulic system, so no soap foam and/or soap solution drips from the aperture  180  when the hand is withdrawn. In addition, there is a nozzle/expansion space  177  which allows foam possibly present in the delivery aperture  180  to expand so it disintegrates and foams again during the next pumping process. 
     The subject of the invention may be largely produced from conventional plastics materials and is accordingly inexpensive. The electric motor M used is commercially available (Mabuchi, Japan, FF-180PH-2852 type). The nominal speed is 6,500/min, the nominal power 1.3 W. The transmission ratio of the spur gear  6  is 200:1. The motor controller and the evaluation of the sensor signal are performed in a well known manner and are designed for minimal energy demand. 
     Calculations have shown that a dispenser can be operated with two monocells of 1.5 volt (BABY LR 14) for one year without battery change even in a frequently used washroom. 
     Of course the subject of the invention is not limited to the embodiment described, thus, for example, the commercially available electromagnet  36  used can be replaced by a smaller one acting directly on the locking lever  17 . As a result at least the connecting link  26  and the components  32  to  34  may be dispensed with. 
     The embodiments described are designed for delivery of a medium into a hand but they may also be extended by suitable sensors to a variation intended for delivery of the medium into both hands. 
     In general, functional dispensers operating in a contactless manner contribute to an improvement in hygiene and prevent the transmission of germs to unappealing operating members as exhibited by manually operated soap and foam dispensers.