JPH03532B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a viscous shear clutch that can be varied by an electrical device.

Viscous shear clutches that use a viscous fluid, such as silicone oil, to transmit rotational drive from a drive shaft to a driven shaft through a suitable coupling piece are well known. Such clutches have the disadvantage that they rely on mechanical adjustment of each joint piece to vary the torque delivered by the fluid, making it difficult to achieve conditions of total disengagement and rigid engagement. This drawback arises from the Newtonian flow properties of viscous fluids, i.e., the fluid deforms in shear at a rate directly proportional to the applied shear stress. Therefore, whatever stress is applied by each joint piece, some shearing deformation of the fluid will always occur.

Compositions whose flow properties change when subjected to an electric field are well known. These compositions, formerly called electrorheological fluids but now even better known as electrorheological fluids, consist of a slurry of finely divided hydrophilic solids in a hydrophobic liquid. In the absence of an electric field, these fluids follow Newtonian flow characteristics. However, when an electric field is applied, the fluid behaves more or less like Bingham plastic. Even if no shear action occurs, the shear stress reaches a maximum value known as the yield point. The value of this yield point depends on the composition of the fluid and the applied electric field. For a given fluid, the breakdown point is typically directly proportional to the voltage gradient applied above a threshold and can be defined as k(E-E ₀ ).
In this equation, E and E ₀ are the applied voltage gradient and threshold voltage gradient, respectively, and k is a proportionality constant. When a shear stress above the yield point is applied to a fluid, the shear action occurs at a rate proportional to the difference between the yield point and the stress.

The advantages of electrical control provided by the use of electrorheological fluids in viscous shear clutches were first described in U.S. Pat. No. 2,417,850 to WMWinslow. This patent describes a simple disc-shaped clutch in which each disc is isolated from each other by an electrorheological fluid. This kind of clutch is
When an appropriate voltage is applied between each disc, it is possible to lock the discs into a nearly solid state of connection against voltages below the yield point. However, as with all viscous shear clutches, the natural viscosity of the fluid still prevents any uncoupling when all applied voltage is removed.

The present invention adds electrorheological fluid flow characteristics to a viscous shear clutch to provide an electrically controllable clutch with a fuller transmission range from completely uncoupled to fixedly engaged.

The present invention provides a viscous shear clutch having a housing 40, including: (a) an input shaft 46 rotatably mounted within the housing; and (b) two shafts rotatably connected to the input shaft. a set of a plurality of conductive input drive plates 4;
7, 48; 50, 51 and (c) For each of these one set of input side drive plates, two sets are arranged in such a relationship that they are inserted at equal intervals without contacting each other. a plurality of electrically conductive output side driven plates 53, 54; 56, 57; (d) rotatably mounted within the housing;
an output shaft 58 rotatably connected to the output side driven plate; (e) an electrorheological fluid 63 filling a space in the housing; One set 47, 48 is mutually rotated in the same direction as one shaft 46 of the input shaft and output shaft, and the other set 50, 51 of the input side drive plates is rotated with respect to the one shaft 46. Said one shaft is connected to a gear 4 so as to rotate each other in opposite directions.
5, 49, each set of input side drive plate 47,
48; connected to 50, 51, each of the output side driven plates 53, 54, 56, 57
The other shaft 58 of the input shaft and the output shaft is configured to rotate the input shaft and the output shaft relative to each other in the same direction.
, directly to each of the output side driven plates 53, 54;
6,57, a viscous shear clutch is connected thereto.

Preferably, the input side driving plate and the output side driven plate have a cylindrical shape and are arranged concentrically so as to rotate around their mutual axes.

Differential rotation between output driven plates connected to one output shaft can reduce the effects of the inherent viscous resistance of the electrorheological fluid.

Embodiments of the viscous shear clutch of the present invention will now be described in detail with reference to the accompanying drawings.

A cylindrical housing 40 having a sealed bearing 41 at one end and coaxial inner bearings 42 and outer bearings 43 at the other end is located mid-longitudinal and has an idler gear 45 attached thereto. Two short shafts 44, 44 facing each other along the inside are provided.

An input shaft 46 mounted on a bearing 41 is attached to driving cylindrical bodies 47 and 48 which are concentric with each other. Cylindrical body 47
has a toothed end surface 49 (or gear ring) that meshes with the idler gear 45.

Similar mutually concentric drive cylinders 50, 51 extend on a short hollow shaft 52 in mesh with the idler gear 45. The hollow shaft 52 is mounted on an outer bearing 43.

The driven cylinders 53 and 54 concentrically combined with each of the driving cylinders 47 and 48 have short axes 44 facing each other and second cylinders angularly displaced by 90° from each short axis 44.
It is attached to one end face of a non-conductive pulley 55 which is rotatably positioned between a similar pair of short shafts (not shown). Or 3 separated by 120° from each other
A set consisting of a book shaft 44 and an idler gear 45 may also be used. The other end surface of the pulley 55 supports a second pair of driven cylinders 56, 57 concentrically assembled with each drive cylinder 50, 51. The driven cylindrical body 57 is
It is hollow and extends through the inner bearing 42 and is connected to the output shaft 58 via a non-conductive sleeve 59 fitted with two slip rings 60,61.

Two sets of driven cylindrical bodies 56, 57 and driven cylindrical body 5
3 and 54 are electrically connected to slip rings 60 and 61, respectively. Terminals 62 provided in the housing 40 connect to each drive cylinder 47, 48, 50, 51.
are electrically connected to each other via a short shaft 44 and an idler gear 45. The internal cylindrical gap is filled with an electrorheological fluid 63.

In operation, when the input shaft 46 is rotating, each drive cylinder 50, 51 is rotated by the idler gear 45 at the same speed in a direction opposite to the direction in which each drive cylinder 47, 48 rotates. The viscous drags on the two corresponding sets of driven cylinders are therefore equal and opposite if the fluid viscosity is uniform throughout and therefore no net rotation is applied to the output shaft 58.
A control voltage applied between the terminal 62 and one or the other of the slip rings 60, 61 causes one of the sets of drive and driven cylinders to be switched to the other, i.e., the upper set of drive and driven cylinders, or The shear resistance of the fluid between both cylinders of the lower set increases,
Both cylinders of this set are locked and the output shaft 58 can be rotated in the corresponding forward or reverse direction.

That is, by increasing the control voltage of any one of the two pairs of the driving cylinder and the driven cylinder, until both the driving cylinder and the driven cylinder of that pair are securely locked. , the shear resistance of the set of electrorheological fluids can be continuously increased. As a result, it is possible to provide a joint that minimizes the generation of heat between the driving cylinder and the driven cylinder that are locked together and provides highly effective transmission. Needless to say, the other sets of uncoupled driving cylinders and driven cylinders are not locked to each other and rotate relative to each other at twice the speed of the input shaft 46.
Heat is generated by the viscous resistance of the electrorheological fluid. However, the multi-annular drive and driven cylinders provide a high surface-to-volume ratio that allows this heat to be easily dissipated, reducing the radius of the drive and driven cylinders to their lengths. By keeping the shear rate in the electrorheological fluid as low as possible to minimize thermal effects. For simplicity of illustration, the number of cylinders inserted into each other has been kept to a minimum, but it is clear that a larger number of cylinders could be used.

Although the above embodiment is a reversible clutch (a clutch in which the roles of the input shaft and the output shaft can be reversed), it is of course better to select the shaft with the minimum inertia as the output shaft in many applications. .

Although the present invention has been described above in detail with reference to its embodiments, it goes without saying that the embodiments can be modified in various ways without departing from the spirit of the invention.

[Brief explanation of the drawing]

The accompanying drawings show a rotatable drive plate assembly and
a rotatable driven plate assembly;
FIG. 3 is an axial cross-sectional view of a completely sealed viscous shear clutch of the present invention; 40...Housing, 45...Gear (idle gear), 46...Input shaft, 47, 48, 50, 51
... Drive plate (drive cylinder), 49 ... Gear (gear ring or toothed end surface), 53, 54, 56, 5
7... Driven plate (driven cylindrical body), 58... Output shaft,
63... Electrorheological fluid.

Claims (1)

[Scope of Claims] 1. A viscous shear clutch having a housing 40, including: (a) an input shaft 46 rotatably mounted within the housing; and (b) an input shaft rotatably connected to the input shaft. In addition, two sets of a plurality of conductive input side drive plates 4
7, 48; 50, 51 and (c) For each of these one set of input side drive plates, two sets are arranged in such a relationship that they are inserted at equal intervals without contacting each other. a plurality of electrically conductive output side driven plates 53, 54; 56, 57; (d) rotatably mounted within the housing;
an output shaft 58 rotatably connected to the output driven plate; (e) an electrorheological fluid 63 filling a space in the housing; One set 47, 48 is mutually rotated in the same direction as one shaft 46 of the input shaft and output shaft, while the other set 50, 51 of the input side drive plates is rotated with respect to the one shaft 46. Said one shaft is connected to a gear 4 so as to rotate each other in opposite directions.
5, 49, each set of input side drive plate 47,
48; connected to 50, 51, each of the output side driven plates 53, 54, 56, 57
The other shaft 58 of the input shaft and the output shaft is configured to rotate the input shaft and the output shaft relative to each other in the same direction.
, directly to each of the output side driven plates 53, 54;
A viscous shear clutch consisting of 6 and 57 connected to each other. 2. A viscous shear clutch as claimed in claim 1, wherein all said input drive plates and output driven plates are cylindrical so as to form a mutually coaxial assembly. 3. The viscous shear clutch according to claim 2, wherein the output shaft and the output side driven plate are mutually rotated in the same direction. 4. The output shaft is coaxially connected to the output side driven plate, and the input side drive plates 47 and 50 each have two
two gear rings 49, the two gear rings being opposed to each other via an idler gear 45, and the input shaft being coaxially connected to only one of the input drive plates. A viscous shear clutch according to claim 3.