Cutlery – Razors – With cooperating shearing blades
Reexamination Certificate
1998-12-21
2001-03-27
Watts, Douglas D. (Department: 3724)
Cutlery
Razors
With cooperating shearing blades
C030S346510
Reexamination Certificate
active
06205666
ABSTRACT:
This invention relates to a dry shaving apparatus.
A dry shaving apparatus of the type initially referred to is known from printed specification DE 33 02 610 A1. The exchangeable frame disposed in a shaving head frame sits, by means of a flange, on the ledge of the apparatus housing and is attached thereto by a positive-engagement latch mechanism which is formed by projections engaging within recesses and acts in both working directions of the cutter head.
A housing portion which is intended to receive and mount an exchangeable frame may be disposed on the housing of a dry shaving apparatus releasably—see DE 33 02 610 A1—or, alternatively, it may be solidly joined together with the housing, meaning that it constitutes part of the housing—see DE 44 105 43 (C1), FIG. 10.
Positive-engagement connections between an exchangeable frame and a housing portion of a dry shaving apparatus for the purpose of obtaining a vibration-free seat of the exchangeable frame require an engagement of cooperating positive-engagement elements that is free from relative movement, that is, a clearance-free positive engagement. This necessarily involves increased manufacturing expense, the more so since the components, such as the exchangeable frame and the housing portion, which are equipped with cooperating positive-engagement elements are manufactured in different dies needing to be matched with great precision. Considering that the exchangeable frame is removed from, and placed back onto, the housing portion after each shave in order to clean the cutting elements, abrasion and/or deformation necessarily occurs on the cooperating positive-engagement elements. In addition, sebum and hair dust settle on the positive-engagement elements, causing increased abrasion and deformation of the positive-engagement elements typically made of plastic. Then air gaps may occur between the positive-engagement elements in manufacture, particularly however later in operation of the dry shaving apparatus, and while these gaps are initially relatively small, they tend to become wider due to, for example, vibration of the housing, vibration of the cutting elements and other loads, eventually causing the exchangeable frame in the housing portion to covibrate correspondingly. Covibration of an exchangeable frame equipped with at least one cutting element is known to impair the cutting effect of the cooperating cutting elements provided, in addition to producing an undesired, relatively loud rattling noise.
It is an object of the present invention to ensure, in a dry shaving apparatus of the type initially referred to, a lasting vibration-free seat of the exchangeable frame in a housing portion.
This object is accomplished in a dry shaving apparatus embodying the invention.
A substantial advantage of the present invention resides in that the stop elements provided on both the exchangeable frame and the housing portion, under the action of the spring-loaded pressure elements, are moved automatically into abutting engagement with a sloping wall surface during the process of attaching the exchangeable frame to the housing portion and are maintained in engagement therewith, and the effect of the spring element acting through the pressure elements on the sloping wall surface is dimensioned such that a permanent engagement of the cooperating stop elements withstands any loads that may occur in operation of the dry shaving apparatus.
The present invention enables the manufacturing tolerances of the components governing the cooperative relationship of exchangeable frame to housing portion to be amply dimensioned, because it utilizes the range of action of a tensed spring element to compensate for any clearance—resulting, for example, from attrition and/or deformation among other causes—between the stop elements and the pressure elements, hence ensuring a clearance-free engagement of the stop elements at all times. This facilitates the manufacture of exchangeable frame and housing portion and, in consequence, reduces the manufacturing cost.
According to an embodiment of the present invention, at least one stop element is provided on a transverse wall of the housing portion. For the purpose of attaching the exchangeable frame to the housing portion, it is sufficient in accordance with an embodiment of the present invention to provide a stop element on at least one of the longitudinal sides of the exchangeable frame. In an embodiment of the invention it is, however, of particular advantage to arrange one stop element each on each of the two longitudinal sides of the exchangeable frame. This enables the exchangeable frame to be attached to the housing portion either way. A congruent arrangement of the stop elements on the longitudinal sides of the exchangeable frame and the longitudinal sides of the transverse walls of the housing portion ensures at least equally an attachment either way and, beyond that, a force-balanced engagement of the exchangeable frame with the housing portion.
In an embodiment of the present invention, the stop elements have abutment surfaces extending parallel to the direction of force of the spring element. In another aspect of this embodiment, provision is made for the direction of force of the spring element to be oriented parallel to the vertical center line M—direction of arrow A—of the dry shaving apparatus.
The direction in which the sloping wall surface extends relative to the direction of force of the spring element is determined by the angle &agr;. The smaller the angle &agr;, the greater the necessary range of action of the pressure element. A small angle &agr; enables a weaker dimensioning of the spring element, with the attendant advantage of a small overall size of the spring element and reduced demands on the stability of the abutment for the spring element. A low force of the spring element has the advantage that the additional energy to be expended by the arrangement of the invention is kept low as the exchangeable frame is seated down onto the housing portion.
In an embodiment of the present invention, the sloping wall surface extends at an angle &agr; of 3°-45° relative to the direction of force of the spring element—direction of arrow A. In a preferred embodiment of the present invention, the angle &agr; is provided in an angular range of 15°±5°. In this connection it is to be remembered that the use of an angle &agr; that lies below or in the range of the angle of friction dependent on the pairing of the materials of pressure element and sloping wall surface requires that the pressure element be constructed as a rolling element because otherwise jamming occurs when the exchangeable frame is seated in place.
In a preferred embodiment of the present invention, at least one pressure element acted upon by a spring element is provided in one of the walls of two adjacent wall surfaces of the exchangeable frame and the housing portion. In a further aspect of this embodiment, two pressure elements each acted upon by a spring element are provided in an end wall of the housing portion. In an embodiment of the present invention differing therefrom, two pressure elements acted upon by only one spring element are arranged in an end wall of the housing portion. In an alternative embodiment of the invention, at least one pressure element acted upon by a spring element is provided in a sloping wall surface of the exchangeable frame.
In a preferred embodiment of the present invention, the sloping wall surface is provided on the exchangeable frame. A particularly simple embodiment is characterized in that the sloping wall surface is formed by at least one end wall of the exchangeable frame. In another embodiment of the present invention, the sloping wall surface is provided on the housing portion. In a still further embodiment of the invention, at least one of the inner sides of the end walls of the housing portion is configured as a sloping wall surface. In a preferred embodiment of the invention, the opposite end walls of the exchangeable frame and the inner sides, extending parallel thereto, of the
Braun GmbH
Fish & Richardson P.C.
Watts Douglas D.
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