192 clutches and power-stop control – Clutches – Torque responsive
Patent
1985-10-22
1987-08-18
Friedman, Carl D.
192 clutches and power-stop control
Clutches
Torque responsive
192 56R, F16D 700
Patent
active
046870822
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a torque-sensing clutch, arranged to transmit a torque between two shafts or other rotating components. The one shaft has a sleeve-shaped portion surrounding the other shaft and one of them has means which, in their activated state, engage recesses in the other clutch part. When the transmitted torque exceeds a predetermined limit value the positions of said means are changed whereby the clutch engagement is released.
Prior art shaft clutches of the type above referred to are described in e.g. CH A No. 541 739 and DE B No. 2 729 775. It is a common feature to both those prior art designs that the coupling means are constituted by rigid metal bodies, more specifically steel balls, which are in radially directed grooves displaceable between an activated position and a released position. They are retained in their activated positions by an elastic force generated by pressure springs which act directly or via hydraulic plungers. Consequently, such clutches are relatively complicated from a structural point of view. They also suffer from the functional limitation that the value of the transmitted torque at which this engagement occurs is fixed and cannot conveniently by changed.
SUMMARY OF THE INVENTION
The object of the invention is to provide a torque-sensing shaft clutch which is of simple design, has low manufacturing costs and permits east variation of said limit value. The main characteristic of the invention is that the clutch comprises rigid means secured in and partly projecting from an elastic carrier permitting them, upon passage of the desired release value, to assume position in which their engagement with the recesses ceases.
This structure is in two essential respects different from the prior art. The one difference is that the engagement means are not radially displaceable. The second structural difference, that the engagement means are carried by an elastic and not by a rigid material, results in an important functional difference. The tangentially oriented forces acting on the engagement means, together with the effective lever arm length defining the torque transmitted during operation, deform the elastic material. This deformation causes the engagement means to deviate from the, suitably radial, position they assume when the clutch is not in operation. When the angular deviation reaches such a value that the engagement ceases the clutch will start slipping. This structural layout makes it possible in a relatively simple way to vary the torque limit value, namely by changing the dimensions of the engagement means, their radial and/or axial extension, their width, their profile or the properties of the elastic material in which they are secured. Those possibilities will below be referred to in greater detail.
It is per se known in the prior art to provide a clutch with a central rubber core having wing-like projections cooperating with recesses in a surrounding sleeve forming the other half of the clutch. However, in those prior art devices the radial projections are integral with the central core and consists of the same elastic material. As is at once understood, such a clutch is unable to transmit any significant torque and, for that reason, the use of those clutches has been restricted to toys and similar articles only. The invention will now be described with reference to the drawing.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a transverse cross-section through a shaft clutch illustrating the general principle of the invention.
FIG. 2, on a larger scale, shows a part of an engagement means and adjacent portions of the two clutch halves. This drawing figure illustrates a possibility to make the clutch operate with different torque limit values for each of the two rotational directions.
FIG. 3 is a perspective view illustrating an embodiment of the invention permitting variation of the torque limit value also during operation.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
On the drawing reference numeral 1 designates a tubul
REFERENCES:
patent: 680170 (1901-08-01), Oldfield
patent: 2758457 (1956-08-01), Meyer et al.
patent: 3515249 (1970-06-01), King, Jr.
patent: 4261453 (1981-04-01), Kunze
patent: 4346749 (1982-08-01), Singletary et al.
patent: 4417650 (1983-11-01), Geisthoff
Friedman Carl D.
Z-Lyften Produktion AB
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