Abstract:
A cleaning device for the shaving head of a dry shaving apparatus includes a receptacle formed in a housing of the cleaning device. The receptacle adapted to receive the shaving head for cleaning with a cleaning fluid. During the cleaning cycle, the dry shaving apparatus is lockable in the cleaning device by means of an interlock. The shaving head is exposed to heat from a heater for drying subsequent to cleaning. Following a drying cycle, release of the interlock is controlled by a control element provided in the cleaning device to prevent an operator&#39;s skin from being burned by an excessively hot shaving head in an immediately succeeding shaving operation.

Description:
TECHNICAL FIELD 
   This invention relates to a cleaning device for the shaving head of a dry shaving apparatus. 
   BACKGROUND 
   During a cleaning cycle, a cleaning device for electric-powered dry shaving apparatus can hold the dry shaving apparatus by means of an interlock device. The dry shaving apparatus cannot be removed until the interlock device is released and the electrical contact elements engaging the bottom end of the shaver housing are retracted from the housing. A fan driven by an electric motor can be used to dry the shaving head with an air stream being passed around the shaving head carried in the receptacle and drying the latter from both the outside and the inside. 
   Induction heaters can be used for heating the metal parts in the shaving head, e.g. the shaving foil and the undercutter. In this manner, the heated metal parts can heat the cleaning fluid during a cleaning cycle in addition to being able to dry the shaving head rapidly after the cleaning cycle. With a corresponding temperature increase of the metal parts in particular, it is also possible to produce sterile conditions without the evaporation of cleaning fluid. 
   SUMMARY 
   In one aspect, a cleaning device includes a control element responsive to the temperature of the shaving head and controlling an interlock device in dependence upon temperature. By virtue of the fact that the interlock device does not release the shaving apparatus for its removal from the cleaning device until a temperature suitable for shaving prevails on the metal shaving foil, skin burns are avoided when a shaving operation follows immediately afterwards. The control element may act on the interlock device directly or, alternatively, the control element may act on the interlock device mechanically, electrically or even hydraulically. 
   In this context it will be understood that a dry shaving apparatus also includes also electric-powered shaving apparatus that enable a shave to be performed also under water or a lotion to be supplied during a shave for improved shaving performance or enhanced operator comfort. Preferably, the shaving apparatus is equipped with outer cutter and undercutter sliding relative to each other, whether in a toothed configuration of both cutters or in a configuration involving a foil cooperating with an undercutter, and is powered electrically. 
   In some embodiments, a temperature-sensitive control element is exposed to the heat from the heater. The temperature-sensitive element is designed and spaced at a distance from the heater such that the interlock device is maintained in a locked condition as long as the temperature on the shaving head and, hence, on the shaving foil, is too high for contact with the skin. It will be understood that it would also be possible for the temperature-sensitive element to be arranged in the vicinity of the shaving head and to sense the temperature directly on the shaving head. An induction heater has proven to be advantageous because it is located underneath the receptacle, its magnetic fields penetrating the receptacle and the cleaning fluid held in the receptacle, thus reaching the metal parts in the shaving head and heating them. In this manner, the heater winding is protected from contact with liquid, thus increasing its service life. 
   A metal spring made from a memory metal has proven advantageous as a component that expands and contracts to a sufficient degree to serve as the temperature-sensitive control element as well as affording ease and economy of manufacture. However, the use of a bimetal in lieu of the memory metal is also contemplated. The spring may be either a leaf spring, a spiral spring or an otherwise bent sheet-metal element which expands or bends a particularly appreciable amount due to the effect of temperature. When such a temperature-sensitive element is heated and, hence, expands correspondingly, its expansion force can be introduced mechanically to a locking element to enable the locking element to engage with a recess, undercut, projection or some other engagement part formed on the dry shaving apparatus to lock the shaving apparatus into the cleaning device. 
   In some embodiments, the locking element can be configured to return to its initial position automatically. For example, when the heater has been on for a certain period of time, the temperature-sensitive element expands due to heat radiation and/or heat conduction—the latter only if contact exists between the locking element and the heater—and/or due to the heat developing in metal parts as the result of induced eddy currents, urging the locking element into engagement with a recess, projection or undercut of the dry shaving apparatus. At the same time, displacement of the locking element compresses a spring whose spring force is smaller than the force developed by expansion of the temperature-sensitive element. On cooling down, the temperature-sensitive element contracts again, its force diminishing. This enables the spring to disengage the locking element from its engagement with the recess, projection, or undercut. As this occurs, the locking element releases the dry shaving apparatus for removal. In this manner, an automatic locking device is obtained which, without operator intervention, locks the shaving apparatus in the cleaning device when the temperature on the shaving head is too high, and releases it again when the temperature on the shaving head has dropped to a sufficiently low value, preferably below 40° C. 
   In another embodiment, a manually actuatable actuating element which, when hand-operated by an operator, causes the locking element to be moved to its locking position when the cleaning device is turned on, is connected upstream of the control element. At the locking element is engaged, the electric control device of the cleaning device is activated to commence a cleaning cycle. Because the actuating element cannot be returned to its initial position until the temperature-sensitive element releases the shaving apparatus, the returning of the actuating element takes place likewise without operator intervention. In this embodiment, a vertical motion of the actuating element is converted into a horizontal motion of the locking element, which is accomplished by suitably arranged guide rails and a ramp, the latter cooperating in gliding fashion with a pin formed on the actuating element. It will be understood that other motion-converting mechanism using other transmission angles between the actuating element and the locking element may be employed. 
   In some embodiments, a mechanical switching device between the housing and the actuating element uses a cardioid slide arrangement which operates the electric switch of the cleaning device on actuation and subsequent release of the actuating element. Renewed actuation and release of the actuating element returns the slide arrangement to its initial position. Such an On-Off mechanism is particularly simple in terms of function and affords economy of manufacture. The switching mechanism can also provide a clearance space for movement of the temperature-sensitive element to enable it to initially expand freely due to the effect of temperature. 
   In some embodiments, a time-dependent control element (e.g. electronic or mechanical timers), upon termination of a cleaning cycle, moves the locking element from its locking position back to its initial position as a function of time. Only after a specified time period has elapsed can the dry shaving apparatus be removed from its receptacle. The cooling-off period upon termination of a cleaning cycle is selected to last until the temperature on the shaving head drops below a value limiting the risk of burns when the shaving foil subsequently contacts an operator&#39;s skin. 
   When a mechanical timer is used, it can be turned on with the commencement of a cleaning cycle, because the duration of a cleaning cycle is exactly known. Therefore, this time period plus a cooling period can be entered in the timer as the specified time period. The dry shaving apparatus is then released only when the temperature on the shaving head is likely to be sufficiently low. In embodiments where an electronic timer is used, preferably an electrically actuatable control element which is locked or unlocked electronically by the timer control signal is also used. 
   In some embodiments, an electric temperature sensor is arranged in the vicinity of the heater. In such embodiments, which however incur slightly higher cost, the electric temperature sensor may directly sense the surface of the shaving head. For example, water-protected temperature sensors can be used that have their electrical signals supplied to a control circuit via lines, said control circuit in turn operating in response to the temperature to release or lock the locking element via electromechanical devices as, for example, an electric solenoid switch. 
   The details of two embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims. 

   
     DESCRIPTION OF DRAWINGS 
       FIG. 1  is a schematic of an interlock and switch-on device as integrated in a cleaning device for a dry shaving apparatus, in unlocked condition, in which a dry shaving apparatus, of which only a fragment is shown, is inserted in a receptacle of the cleaning device for cleaning purposes. 
       FIG. 2  is a view similar to  FIG. 1  but showing the interlock and switch-on device in locked condition. 
       FIG. 3  is a sketch of an interlock device in accordance with a second embodiment as integrated in a cleaning device for a dry shaving apparatus, in unlocked condition, in which a dry shaving apparatus, of which only a fragment is shown, is inserted in a receptacle of the cleaning device for cleaning purposes. 
       FIG. 4  is a view similar to  FIG. 3  but showing the interlock device in locked condition. 
   

   Like reference symbols in the various drawings indicate like elements. 
   DETAILED DESCRIPTION 
   Referring now to  FIGS. 1 to 4 , an electric-powered cleaning device I is comprised of a receptacle  2  having a bowl-shaped receiving space  3  for accommodating a shaving head  6  and a cleaning fluid (not shown). The receiving space  3  is open in upward direction by means of the opening  4 . Directional references in this description are provided with reference to the orientation of the drawings rather than to imply an absolute orientation of the components described. The shaving head  6  of a dry shaving apparatus  7  extends through the opening  4  down to the bottom  5 . The shaving head  6  preferably includes two undercutters  8  and one long-hair trimmer  9  provided intermediate the undercutters  8 . The undercutters  8  are covered toward the outside by a shaving foil  10  to form the short-hair cutter unit. The shaving head  6  is pivotally mounted on the housing  11  (shown only in part) of the dry shaving apparatus  7 . Mounted in the housing  11  are a drive mechanism, an electronic switching device, storage batteries and other components, which are not shown in the drawings. 
   Underneath the receptacle, a coil  13  is wound around an iron core  12  and generates a magnetic field when electric current is passed through the coil. The magnetic field serves to heat the metal parts  8 ,  9 ,  10  as well as the entire shaving head  6  and the cleaning fluid (not shown) that is temporarily present in the receiving space  3  during a cleaning cycle. The iron core  12  and the coil  13  form the heater  56  of the cleaning device  1 . Arranged on the left side of the receptacle  2  at the level of the left-hand free end of the U-shaped and upwardly open iron core  12  is a control element  14  which, in this embodiment, is a spiral spring made from memory metal. The control element  14  is formed by a temperature-sensitive element through which a stud  15  extends. 
   Referring to  FIGS. 1 and 2 , the stud  15  widens in the form of a step  16 , forming an upper enlarged section  19  that is fixedly connected to a housing part  20  of the cleaning device  1 . The temperature-sensitive element  14  bears with its other end against an end surface  21  of an arm  17  formed integrally with an actuating element  18 . At the same time, the stud  15  extends through a bore  22  formed in the arm  17 . The arm  17  is shown cut away for better clarity of illustration of the bore  22 . The stud  15  passes through the bore  22  and projects beyond the arm  17  downwardly, its other end being likewise fixed to a component  23  of the cleaning device  1  formed fast with the housing. In this manner, the actuating element  18  has its lower region guided in the longitudinal direction of the vertical axis  24  of the stud  15 . The temperature-sensitive element  14  is thus solidly seated between the step  16  and the end surface  21 . 
   Referring to  FIGS. 1 and 2 , a compression spring  26  in the form of a spiral spring bears with one end against the lower outer end surface  25  formed in the transition region between the lower free end of the arm  17  and the actuating element  18 , while its other end rests against a stop  27  formed fast with the housing. The actuating element  18  is constructed as an essentially rectangular flat injection molded part guided in an up and down direction parallel to the vertical axis  24  in lateral guides  28  formed fast with the housing. Provided on the upper free end of the actuating element  18  is a shoulder  29  forming the control button. 
   Arranged on the front surface  30  of the actuating element  18  of  FIGS. 1 and 2  is a heart-shaped recess  31  having an adjoining central slot  32  in the lower region thereof. Extending centrally in the recess  31  at a slight upward inclination from left to right is a rib  33 . On another housing part  34 , a horizontally displaceable sliding block having a pin  36  fastened to it is guided in a groove  35 , said pin cooperating with the recess  31  to form a two-position mechanical switching device  55 . 
   Referring to  FIGS. 1 and 2 , underneath actuating device  36 , a pin  37  engaging a ramp  38  extending from bottom to top right is fastened to the actuating element  18 . The ramp is part of a locking element  39  shaped in an essentially rectangular configuration and having at its bottom right end a recess  40  which in the locked position of the dry shaving apparatus  7  shown in  FIG. 2  engages behind the lower left edge  41  of the shaving head  6  from above. 
   Referring to  FIGS. 1 and 2 , the lower left end of the actuating element  18  has a bevel  42  opposite to which is a bent sheet-metal blade  43  that is fixed to a stop  44  formed fast with the housing. Fixed to a lower stop  46  formed fast with the housing is a second sheet-metal blade  45  level with the first blade  43 . The two sheet-metal blades are spaced from each other by a small distance, being brought together by the bevel  42  and hence making contact on displacement of the actuating element  18  in the On-direction (X). 
   An actuating element  18  as represented in  FIGS. 1 and 2  is not shown in  FIGS. 3 and 4  for the sake of simplicity. Adjoining the upper left section of the receptacle  2  is a cup-shaped receiving socket  57  having a cylindrical recess  47  in which the temperature-sensitive element  14  is located. Towards the other side, the recess  47  is open by means of the opening  48  to enable the locking element to exit from the opening  48 . The step  49  formed on the locking element  39  provides the stop for the one end of the temperature-sensitive element  14 . On its other end, the temperature-sensitive element  14  bears against an end surface  16  formed on the bottom  52  of the receiving socket  57 . The bottom  52  has a central bore  50  that extends concentrically with the temperature-sensitive element  14 . The stud  15  connected to the locking element penetrates the bottom  52  through the bore  50 , terminating at an enlarged abutment stop  51 . Seated between the abutment stop  51  and the bottom  52 , the compression spring  26  bears against the receiving socket  57  from outside. 
   Referring to  FIGS. 1 and 2 , the mode of operation of the cleaning device  1  of the invention is as follows: 
   After the dry shaving apparatus  7  is inserted into the receiving space  3  of the receptacle  2  with its shaving head  6  pointing down, the control button  29  is pressed down by hand in the direction X to activate the cleaning device  1 . As this occurs, the actuating element  18  moves downwards in the vertical guide  28 , whereby the locking pin  36  slides along the underside  58  of the rib  33  upwards and enters the upper section of the recess  31  where it is moved along the upper wall  53  to the left inside the groove  35 . 
   At the same time, axial displacement of the actuating element  18  in the direction X causes displacement of the locking bar  39  by means of the pin-and-ramp guide  37 ,  38  to the right, so that the recess  40  engages behind the edge  41  of the shaving head  6  from above. On displacement of the actuating element  18 , the sheet-metal blade  43  is elastically bent to the left by means of the bevel  42  until its free end contacts the sheet-metal blade  45 , whereby electric current is supplied to the cleaning device enabling the cleaning cycle to be started. Displacement of the actuating element  18  simultaneously compresses the spring  26 . The temperature-sensitive element  14  retains the contracted position as shown in  FIG. 1 , so that the downward movement of the actuating element  18  produces a clearance space between the step  16  and the upper free end of the temperature-sensitive element, which however is not shown in  FIG. 2  of the drawings because there the spring is already expanded due to the effect of the temperature of the heater  12 ,  13 . After the control button  29  is released, the locking pin  36  abuts against the upper left wall  53  of the heart-shaped recess  31 , holding the actuating element  18  in the On-position shown in  FIG. 2 . 
   As soon as electric current is supplied to the heater  56 , a magnetic field is produced on the coil  13  and the iron core  12 , causing heating of the metal parts lying in the vicinity of the heater  56 , which include the shaving foil  10  and the metal parts provided in the interior of the shaving head  6 , the temperature-sensitive element  14  and the stud  15 . The temperature-sensitive element  14  expands in the process until its upper free end abuts against the step  16 . Continued expansion of the temperature-sensitive element  14  compresses it because a further longitudinal expansion is not possible due to the spring  26  having previously been compressed to its solid length. This position is now maintained for the duration of the On-state of the cleaning device  1 . 
   If an attempt is made to remove the dry shaving apparatus  7  from the cleaning device  1  during or directly subsequent to a cleaning cycle, this is not possible because the locking element  39  holds the shaver captive in the receptacle  2  due to the still expanded temperature-sensitive element  14 . Even if an attempt is made to move the actuating element  18  back to its initial position shown in  FIG. 1  by depressing the control button  29  in the direction X, removal is not possible, because the force of expansion of the temperature-sensitive element  14  is greater than the force of the spring  26  due to the heat. This means that the force of the temperature-sensitive element  14 , which acts downwards onto the actuating element  18 , is greater than the force of the spring  26  acting upwards onto the actuating element  18 . Hence, the actuating element  18  is prevented from moving upwards into the initial position of shown in  FIG. 1 . 
   With the temperature-sensitive element  14  cooling off slowly, its force diminishes and the force of the spring  26  predominates, compressing the temperature-sensitive element  14  and urging the actuating element  18  upwards in opposition to the On-direction X. As this occurs, the locking pin  36  slides on the left side downwards past the rib  33  to resume the lower initial position illustrated in  FIG. 1 . At the same time, the movement of the actuating element  18  in opposition to the direction X causes displacement of the locking element  39  to the left by means of the pin-and-ramp arrangement  37 ,  38 , and the dry shaving apparatus  7  is released for removal from the receptacle  2 . 
   The mode of operation of the embodiment of  FIGS. 3 and 4  is similar to the embodiment of  FIGS. 1 and 2  so that only the differences will be discussed. A significant difference from the embodiment of  FIG. 1  is that control of the locking element  39  is exclusively by the temperature-sensitive element  14  and the spring  26 . In the presence of an excessive temperature on the shaving head  6 , the temperature-sensitive element  14  of  FIG. 4  is expanded and moves the locking element  39  in opposition to the force of the spring  26  out of the recess  47  until it engages behind the edge  41  of the shaving head  6  from above. This engagement prevents the dry shaving apparatus  7  from being removed from the receptacle  2 . 
   Also in this embodiment, induction or heat radiation from another source of heat causes heating of the metal parts in the shaving head  6  as well as the locking element  39  and the stud  15  connected therewith and the abutment stop  51 , provided they are also made from metal. When the heater  56  cools off after a cleaning cycle, the temperature-sensitive element  14  also cools and retracts into the position shown in  FIG. 3 . This enables the spring  26  to bias, through the abutment stop  51 , the stud  15  together with the locking element  39  back into the recess  47 . This releases the edge  41  of the shaving head  6  and the dry shaving apparatus  7  is ready for removal from the receptacle  2  and hence from the cleaning device  1 . The temperature-sensitive element is configured such that this occurs when the shaving foil  10  has reached a temperature that will not cause burns if placed in contact with a user&#39;s skin. 
   A number of embodiments of the invention have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the invention. For example, the control element  14  can be a time-dependent element rather than a temperature-dependent element. Accordingly, other embodiments are within the scope of the following claims.