Environmental conditioning devices such as heaters, humidifiers, dehumidifiers, air conditioners and air cleaners are used extensively to create comfortable environmental conditions in residential and commercial enclosures. The electrical controls of such devices are very attractive to curious children whom delight in experimental manipulation of the controls. Such activity can result in either unsafe operations or damage-to the electrical controls.

Latchable controls have been proposed and employed previously to avert undesirable operation of electrical equipment. Such a control mechanism is disclosed, for example, in U. S. Patent No. 3,994,636. However, prior latchable controls have been subject to contravention by innovative, dexterous children.

The object of this invention therefore, is to provide an improved tamper resistant environmental conditioning device.

SUMMARY OF THE INVENTION The invention is a portable electric appliance including a housing defining an air inlet, an air outlet and an air flow path therebetween; a conditioner disposed in the air flow path and operable to condition air in the air flow path; a power source; and an electrical switch connected between the conditioner and the power source and having an actuator movable between an inactive position and at least one active position, the switch in its one active position transmitting power from the source to the conditioner, and in its inactive position preventing power transmission therebetween. Also included is a lock mechanism including a release element adapted for predetermined movement between a locked position and an unlocked position the actuator and release element being shaped and arranged to require independent manipulation by, respectively, first and second body parts; and wherein in its locked position the element prevents the given movement of the actuator, and in its unlocked position allows the given movement of the actuator.

The lock mechanism can be employed to inhibit operation of the electrical switch by children.

According to one feature of the invention, the given movement is of one sense and the predetermined movement is of another sense different than the one sense. The requirement for different senses of movement inhibits contravention of the lock mechanism.

According to another feature of the invention, the actuator is a rotatable knob defining at least one notch, the release element is a push button defining a tab ; and wherein in the inactive position of the actuator the tab is aligned for reciprocal movement in and out of the one notch, and in its locked position the tab is latched in the one notch, and in its unlocked position the tab is removed from the one notch. This featured structure efficiently provides the desired prevention of operation of the appliance by children.

According to a further feature of the invention, the housing defines a plurality of outer wall surfaces, the actuator projects from one surface and the element projects from a different wall surface. This structural feature complicates release of the lock mechanism to inhibit further activation of the switch by children.

According to an additional feature of the invention, the one surface is a side surface and the different surface is a top surface. The side and top surfaces are conveniently located to facilitate desired operation of the appliance.

According to yet another feature of the invention, the actuator is movable into a plurality of active positions and in each active position the switch activates the condi- tioner to provide a different level of conditioning to air in the air flow path. This feature provides the appliance with desired multiple modes of operation.

According to still additional features of the invention, the actuator is a rotatable knob defining a plurality of additional notches each associated with a different active position, the release element is a push button defining a tab; and wherein in each active position of the actuator, the tab. is aligned for reciprocal movement in and out of the associated additional notch, and in the locked position the tab is latched in the associated notch, and in the unlocked position said tab is removed from the associated notch. This feature inhibits alteration by children of a selected operational mode of operation.

DESCRIPTION OF THE DRAWINGS These and other objects and features of the invention will become more apparent upon a perusal of the following description taken in conjunction with the accompanying drawings wherein: Fig. 1 is a front perspective view of a portable heater according to the invention; Fig. 2 is a rear perspective view of the heater shown in Fig. 1 ; Fig. 3 is a top view of the heater shown in Figs. 1 and 2; Fig. 4 is an exploded view showing certain components of the heater shown in Figs. 1-3 ; Fig,. 5 is a perspective view of an electrical control assembly of the heater; Fig. 6 is an exploded view of the electrical control assembly shown in Fig. 5; Fig. 7 is a top view of a switch assembly portion of the control assembly shown in Figs. 5 and 6; Fig. 8 is a cross-sectional view taken along lines 8-8 of Fig. 6; Fig. 9 is a cross-sectional view taken along lines 9-9 of Fig. 6 ; and Fig. 10 is a cross-sectional view taken along lines 10-10 of Fig. 8.

DESCRIPTION OF THE PREFERRED EMBODIMENT An electric heater appliance 11 has a portable housing 12 formed by a semi-cylindrical front wall 13, a semi-cylindrical rear wall 14, a bottom wall 16, and a top wall 18. Defined by the rear wall 14 is an air inlet 21 covered by an inlet grill 22 while an air outlet 23 is defined by the front wall 13 and covered by an outlet grill 24. A pair of rotatable actuator knobs 25 and 26 project out of slots 27,28, respectively, in the rear wall 14. Formed in the rear wall 14 is a recess which functions as a handle 29.

A locking push button 30 projects out of an opening 20 in the top wall 18. The button 30 and actuator knobs 25 and 26 are components of an electrical control assembly 31 shown in Figs. 4-10 and described hereinafter.

As illustrated in Fig. 4, the housing 12 defines an enclosure 32 defining an air flow path 33 extending between the air inlet 21 and the air outlet 23. The enclosure 32 encloses a shroud 34 retaining an environmental conditioner assembly 36 including a heating element 37 and fan (not shown) aligned with the air flow path 33. Structural details of the conditioner assembly 36 are disclosed in U. S. Patent Applications Serial Nos. 09/456,623 and 09/457,468. During use of the heater 11, the control assembly 31 is used to energize and control the conditioner assembly 36 producing, through the path 33, air flow which is heated by the heater element 37.

The control assembly 31 (Figs. 4-6) includes a base 39 which supports the actuator knob 26 and a switch assembly 41 including the actuator knob 25 and the push-button 30. Defined by the base 39 is a semi-cylindrical recess 42 retaining the actuator knob 26 and forming and registered with the opening 28 in the rear wall 14 and a semi-cylindrical recess 43 retaining the actuator knob 25 and registered with the opening 27. A bracket 45 on the base 39 is secured to a mounting assembly 46 which in turn is secured to the top wall 18 of the housing 12. Supported by the base 39 below the recess 42 is a thermostatic control 48 having a shaft 49 keyed for rotation with the actuator knob 26.

The. switch assembly 41 (Figs. 6-10) includes a rotary electrical switch 51 mounted to a bottom wall portion 52 of the base 39 below the recess 43. Operatively connected to the rotary switch 51 by conventional circuit means (not shown) is a power source cord (not shown) and the conditioner assembly 36. Also encompassed by the switch assembly 41 is the actuator knob 25 and a locking mechanism 54 including the button 30. Defined by the button 30 is an upwardly projecting annular cavity 55 and an outwardly projecting collar 56 that moves between the top wall 18 of the housing 12 and a top surface 57. An annular compression spring 59 is retained within the annular cavity 55. Also defined at a-bottom portion. of the button 30 is an outwardly projecting locking tab 61.

The knob 25 has an inverted cup shape defined by the top wall 57 and a downwardly opening, annular side wall 64 (Fig. 9). Extending between an inner surface of the side wall 64 and a central hub 67 of the actuator 25 are a plurality of ribs 68. The hub 67 receives and is rotatably keyed to a shaft 69 of the switch 51. Also formed by the actuator knob 25 is a downwardly projecting wall portion 71 having an inner surface 72 which defines an arcuate cavity 73 extending between the top wall 63 of the knob 25 and location above the base 39. A plurality of spaced apart notches 74-77 (Fig. 9) are formed in a bottom edge 78 of the wall 71 which edge is above lower edges 79 of the ribs 68 as shown in Fig. 8.

A. wall portion 81 of the base 39 projects upwardly into the actuator knob 25. Defined by the wall portion 81 is an open upper ended cylindrical cavity 82 projecting into the arcuate cavity 73 and an open upper ended, transversely rectangular cavity 83 intersecting the cylindrical cavity 82.

The transverse cavity 83 is disposed below and registers vertically with forming the notches 74-77 in the wall 72 during rotation of the actuator knob 25. The compression spring 59 normally maintains the button 30 in an upper position (Fig. 10) in which the tab 61 can sequentially engage each of the notches 74-77 to prevent rotary movement of the actuator knob 25. Thus, with the button 30 in its upward position, control of the conditioner assembly 36 by rotation of the rotary switch 51 is prevented.

When operation of the heater 11 is desired, the button 30 is depressed rectilinearly against the bias force exerted by the spring member 59 into a lower position within the cylindrical and transverse cavities 82,83 as shown by dashed lines in Fig. 10. Depression of the button 30 can be accomplished, for example, with a single finger of a user.

With the button 30 held in its lower position, the tab 61 thereon is disposed below the bottom edge 78 of the wall portion 71 of the actuator knob 25. Thus, the knob 25 can be rotated by one or more other fingers into a plurality of operating positions in each of which the tab 61 is vertically registered with a different one of the notches 74-77. In each operating position, a release of downward pressure on the push button 30 allows the spring member 59 to move the tab 61 upwardly into one of the registered notches 74-77 and thereby prevent movement out of that position. A desired heater operational mode is, therefore, maintained by locking the switch assembly 41 into a selected position. For example, with the tab 61 engaged in the notch 74, the corresponding rotary position of the switch 51 de. energizes the conditioner assembly 36; with the tab 61 engaged in the notch 75, the corresponding rotary position of the switch 51 energizes only a fan (not shown) to produce ambient air flow through the air flow path 33; with the. tab 61 engaged in the notch 76, the corresponding rotary position of the switch 51 provides actuation of the fan and a portion of the heater element 37 to produce a low level flow of heated air through the air flow path 33; and with the tab 61 engaged in the notch 77 the corresponding rotary position of the switch 51 produces energization of the fan and the full heating element 37 to provide a high level of heated air flow through the path 33. Because each such change of operating mode entails the simultaneous application of differently directed forces to the separate and distinct locking button 30 and actuator knob 25 by different body parts, the change requires specific manipulation and dexterity not easily mastered by children.

Accordingly, unwanted and possible unsafe operation of the heater 11 by children is prevented.

Obviously, many modifications and variations of the present invention are possible in light of the above teachings. It is to be understood, therefore, that the invention can be practiced otherwise than as specifically described.