Dispensing – With discharge assistant – Motor operated
Reexamination Certificate
2000-04-13
2001-08-14
Shaver, Kevin (Department: 3754)
Dispensing
With discharge assistant
Motor operated
Reexamination Certificate
active
06273302
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to motorized tools for extruding semi-dense materials such as sealants and similar materials.
In particular, the invention concerns such a motorized tool comprising a body in pistol form containing a screw and nut system driven by means of an electric motor to move a piston borne at one end of the screw, in which said motor is of the reversible type and is controlled by means of a trigger switch which can be pulled back to actuate the motor and in front of which is a switch for selecting the rotation direction of the motor.
Tools of this type are known: for example, German patent DE-C-3842767, European patent application EP-A0463990, U.S. Pat. No. 5,027,984 and, in particular, Italian application for registered utility model no. TO93U000049 in the name of Stefor Srl, assigned to the Applicant. In the motorized tool described in that document, which envisages a friction clutch device for releasing the screw of the actuating unit to rotate freely if the resistance to the movement of the piston is of a greater magnitude than a predetermined value, the selector switch governing the direction of rotation of the motor consists of a lever pointed towards either side of the tool to switch the rotation direction of the motor so as to correspond either to the forward or to the reverse movements of the screw with the piston.
This solution, while being relatively simple and effective, can lead to jamming and therefore to delays, particularly as far as the reverse movement of the piston at the end of the extrusion operation is concerned, with the consequence that it causes further undesired quantities of sealant or similar substance to come out of the tool.
A further problem with known motorized tools resides in the difficulty in setting the speed of flow of the sealant or similar substance from the tool with precision and its adjustment is entrusted to the sensitivity of the operator.
SUMMARY OF THE INVENTION
The object of this invention is to overcome these problems.
According to the invention, this object is achieved by the fact that, in a motorized tool of the type defined at the beginning, the abovementioned selector switch consists of the button of a microswitch which can be advanced to switch over the rotation direction of the motor alternatively, and the fact that connected to said trigger switch are an electronic variator for controlling the rotation speed of the motor, which depends on the length of the backward stroke of the trigger switch, and an adjustable stop device to select said length of the backward stroke of said trigger switch.
According to a particularly simple, economical and functional preferred embodiment of the invention, the adjustable stop is of mechanical type and is actuated manually. Furthermore, this adjustable stop can be advantageously set in an extreme position where it locks the trigger switch in the forward position.
REFERENCES:
patent: 3309484 (1967-03-01), Frenzel
patent: 3603757 (1971-09-01), Sahrbacker
patent: 3711666 (1973-01-01), Sahrbacker
patent: 3854629 (1974-12-01), Blieberger
B.X.T. Trading Marketing E Consultores LDA
Bui Thach H
Shaver Kevin
Sughrue Mion Zinn Macpeak & Seas, PLLC
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