192 clutches and power-stop control – Clutch and brake – Automatic check and release
Patent
1987-03-16
1989-04-04
Bonck, Rodney H.
192 clutches and power-stop control
Clutch and brake
Automatic check and release
192 12BA, 192 17D, 192 36, 192 81C, F16D 1308, F16D 6702
Patent
active
048177717
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a spring clutch having a driving hub and a driven hub, the driven hub being rotated by the driving hub only when the clutch is engaged, and also including a spring coaxially fitted between the two hubs for torque transmission, and a clutch sleeve for the operation of the transmission.
Spring clutches are most frequently used as shifting clutches which, as a rule, are engaged and disengaged by way of an electromagnetically or mechanically-activated lever and a cam sleeve which interacts with the lever. Mostly, a transmission link is briefly interrupted when the clutch spring is opened by immobilizing the cam sleeve, thereby interrupting the transmission link between the driving hub and the driven hub. For this type of spring clutch with driving hub and driven hub normally standing in constant transmission link, the use of a helical spring results in a very simple construction. If, however, the opposite is the case and the transmission link is supposed to be present only when the clutch is activated, one can no longer make do with the simple constructional principle for such a spring clutch.
The present invention has to do with a spring clutch of the latter-named type, in which the transmission link is realized only during activation.
From GB-PS No. 898,183 a spring clutch is known which has a clutch sleeve surrounding the helical clutch spring, this sleeve, when the transmission link of the spring clutch is separated, being rotated by means of the helical clutch spring, which is applied with a segment with pre-loading against the drive hub and with another segment applied on the inside against the clutch sleeve. On the exterior circumference of this sleeve a helical control spring is fitted which rotates with the clutch sleeve, this control spring including an angled end which runs up against a radially displaceable activation lever so that by means of the clutch sleeve, which is held back by the control helical spring, the helical clutch spring is closed and the transmission link is established. The decisive disadvantage of this construction, however, consists in the fact that due to the form-closure between the spring and the clutch sleeve, friction and therefore wear-and-tear result between the sleeve and the control helical spring which sits on its perimeter while being held firmly by the activation lever during the starting phase, so that normally disengaged type spring clutch is suitable only for short starting phases and certainly not for high rates of revolution.
SUMMARY OF THE PRESENT INVENTION
The object of the present application therefore consisted in creating a spring clutch which would be suitable for long starting phases without the incidence of abrasion due to friction, and which therefore would also be suitable for high rates of revolution. Moreover, a goal to be achieved at the same time was one where, when the transmission link is de-coupled, the driven hub and the mass set into rotation by it becomes slowed down by braking action--which, namely, is not possible with the prior art spring clutch. This is achieved in the transmission according to the invention by means of a helical clutch spring which consists of two segments with diameters of different sizes, a partial length of one segment being in gripping contact with preloading when the clutch is disengaged, its external circumference being applied on the inside surface of a housing bore.
The advantage of the spring clutch according to the invention consists in the fact that engagement of the clutch is not achieved by immobilizing an additional spring by means of an abutment, but that an additional spring which is present likewise is secured with pre-loading to turn with the drive hub, and is constantly rotating, and is only opened for a short time during the starting phase of engagement by running up against the carrier piece of the clutch sleeve, thereby slipping through until the fixed friction torque of the slipping-through action succeeds in achieving full entrainmen
REFERENCES:
patent: 1932000 (1933-10-01), Starkey
patent: 1934790 (1933-11-01), Brownlee
patent: 2302312 (1942-11-01), Greenlee et al.
patent: 2336757 (1943-12-01), Starkey
patent: 2878914 (1959-03-01), Worst
patent: 2951568 (1960-09-01), Hungerford et al.
patent: 2971394 (1961-02-01), Christensen
patent: 3048050 (1962-08-01), Perryman
patent: 3529703 (1970-09-01), Kroeker
patent: 4418811 (1983-12-01), MacDonald
Baumann & Cie AG
Bonck Rodney H.
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