Eddy Current Rotary Machine Having Torque Transmission Arrangement

Abstract

The eddy-current element in a torque transmitting device is formed from two concentric radially spaced apart drums. An annular array of inductor members is inserted in the space between the drums from one end and a magnetic field generating yoke is inserted between the drums from the other end. The drums, consisting of magnetic material, are supported in spaced relation by nonmagnetic means interposed between the drums intermediate the ends between the inductor members on the one hand and the yoke on the other hand. Efficient cooling is afforded by a series of holes in the drums and the provision of fan blades for impelling air through the holes.

Description

The present invention relates to improved eddy current rotary machines, in which torque transmission between a driving part and a driven part is carried out by eddy-currents as in the case of an eddy-current-type coupling or an eddy-current-type brake device.

In the conventional machines as described above, for example in the conventional eddy-current-type coupling, an exciting winding is provided on an iron yoke member supported by the machine frame, a magnetic drum supported by a driving shaft and an inductor supported by a driven shaft are arranged between legs of said yoke member with a suitable air gap therebetween, and a magnetic path is formed through the above-mentioned members, whereby torque transmission between the driving and driven parts is attained by utilizing the eddy-currents generated between said magnetic drum and inductor.

According to the construction as described above, when the torque to be transmitted is very large or slip is large, a large loss energy is generated by the eddy-currents at the torque transmitting surface of the magnetic drum, but the magnetic drum is surrounded by the yoke member and the air gap surrounding said drum is relatively narrow, so that removal of heat from the magnetic drum, e.g., by ventilation, is very poor. To overcome this, enlargement of the machine body or provision of a water cooling device for passing cooling water through the magnetic drum becomes necessary, thus necessitating an expensive and complicated structure of the machine.

Therefore, an essential object of the present invention is to provide improved eddy-current rotary machines in which radiation or dissipation of the loss heat generated by the eddy-currents can be effectively attained without causing enlargement, expensiveness and complication of the machine.

According to the present invention, the above-mentioned object has been effectively attained by the machine comprising in combination: a first structure having at least two concentric eddy-current drums of magnetic material supported with a radial gap therebetween by nonmagnetic means interposed between the drums intermediate the ends thereof, the first structure being rotatably mounted for rotation about an axis concentric with the drums; a plurality of inductor members disposed in a circular array concentric with the axis and forming an inductor disposed in the gap between the drums on one side of the nonmagnetic means, the inductor constituting a second structure and being rotatably mounted for rotation about an axis coaxially with the first structure; a yoke member disposed in the gap between the drums on the other side of the nonmagnetic means from the inductor; exciting means for generating a magnetic flux passing through and linking the inductor, the yoke member, and both of the drums; and driving means coupled to one of the structures for causing it to rotate relative to the other structure for producing eddy-currents in both of the drums to transmit a torque from the driven structure to the other structure.

The foregoing essential object and other objects as well as detailed features of the invention will become more apparent and more readily understandable from the following description when read in conjunction with the accompanying drawings, in which the same or equivalent members are designated by the same reference characters and numerals.

In the drawings:

FIG. 1 is a side view, in section of one part, of a first example of the invention;

FIG. 2 is a vertically sectioned front view along line (II-II) in FIG. 1;

FIG. 3 is a perspective view of one part of the magnetic drum in the example of FIG. 1;

FIG. 4 is a vertically sectioned side view of only the upper half portion of a second example of the invention;

FIG. 5 is a side view, in vertical section, of only the upper half portion of a third example of the invention;

FIG. 6 is a side view, partially sectioned, of a fourth example of the invention;

FIG. 7 is a side view, partially sectioned, of a fifth example of the invention; and

FIG. 8 is a sectional view along line VIII-VIII in FIG. 7.

DETAILED DESCRIPTION OF THE INVENTION

The invention will be described in detail in connection with various examples thereof.

Referring to FIGS. 1, 2 and 3, the machine comprises a machine frame 1; a driving shaft 2 supported by the frame 1 through a bearing 3 and connected to the shaft of a driving motor (not shown); a driven shaft 4 supported by the frame 1 through a bearing 5; a magnetic structural body 6 supported by the driving shaft 2 by means of a hub 24, this body consisting of inner and outer eddy-current generating drums A and B which are separated through a suitable distance, but connected to each other at their central portions by means of nonmagnetic members 23; and an inductor 7 supported by the driven shaft 4 through a supporting plate 25, this inductor comprising a plurality of inductor pieces 27 which are magnetically separated from one another by means of nonmagnetic pieces 26 disposed between the plate 25 and inductor pieces 27 and arranged in a circumferential array.

The inductor pieces 27 are inserted into a space formed between the opposing inner and outer magnetic drums A and B from one side of the drums, and an iron yoke 8 is inserted into the space from other side of the drums, said yoke being fixed to the machine frame 1 and being provided with an exciting winding 9. The magnetic drums A and B are provided with ventilating holes 10 and 11, respectively. The ventilating hole 11 is provided with cooling fins 12 acting as centrifugal fans due to rotation thereof. Of course, both ventilating holes 10 and 11 may be provided with the fins 12 and these fins may be attached on the inside or outside of the ventilating hole or holes. The supporting plate 25 is provided with a ventilating hole 13, and the machine frame 1 is provided with a suction inlet 14, air exhausting holes 15 and an air guide plate 16.

In the machine illustrated in FIGS. 1, 2 and 3 when the driving shaft 2 is rotated, the magnetic structural body 6 supported by the shaft 2 is rotated together with the shaft. On the other hand, when the exciting winding 9 is excited from an electric power source (not shown), a magnetic flux .phi. is established through the magnetic drums A, B and inductor pieces 27 of the inductor 7. Accordingly, if the driving shaft 2 is rotated during excitation of the exciting winding 9, the magnetic flux .phi. is made to fluctuate by relative difference between the rotary speed of the magnetic structural body 6 and that of the inductor 7, whereby an eddy-current is generated in the surfaces of each of the magnetic drums A and B, these surfaces being opposite to the inductor pieces 27, thus causing generation of a torque due to the eddy-current, thereby to rotate the driven shaft 4.

In the above operating condition, cooling air for removing the loss heat generated by the eddy-currents enters into the suction inlet 14 and passes through the ventilating hole 13 of the supporting plate 25. The cooling air passed through the hole 13 is forcibly exhausted outward from the magnetic structural body 6 through the ventilating holes 10 and 11, while cooling the heat generating parts of the magnetic drums A and B, and then is exhausted from the exhaust outlets 15 of the machine frame 1.

FIG. 4 illustrates another example of the present invention, in which the eddy-current generating surface of the magnetic structural body 6 is increased, and the inductor pieces 17 are formed as multilayer pieces. In this example, an auxiliary eddy-current generating drum C is arranged between opposed layers of the inductor pieces and rotated together with the eddy-current generating drums A and B. The same or equivalent members in FIG. 4 are indicated by the same reference numerals as those in FIGS. 1, 2 and 3, and since their functions are substantially equal to those of the example of FIGS. 1, 2 and 3, further explanation of the operation of the example of FIG. 4 is omitted herein.

The example illustrated in FIG. 5 corresponds to a further improvement of the example of FIG. 1. The example of FIG. 5 is substantially equal to that of FIG. 1 except that shielding plates 17 facing inner and outer surfaces of the magnetic drums A and B with narrow air therebetween are provided on the yoke member 8 and supporting plate 25, respectively, and partition plates 18 for shielding the ventilating holes 10 and 11 of the magnetic drums A and B are provided, whereby the inductor pieces 27 and exciting winding 9 are protected from entering of dust thereinto.

For the purposes of effectuating dust protection of the machine, a suitable filter may be provided at the suction inlet 14 of each of the examples as illustrated in FIGS. 1, 4 and 5.

In the illustrated examples, the eddy-current generating members are constructed as cylindrical magnetic drums, but may be formed as circular rings and disposed in opposition to each other in the axial direction, so as to form a magnetic path through the axial air gap, or one of the shafts 2 and 4 may be fixed thereby to use the machine as an eddy-current brake device, or the shafts 2 and 4 may be, respectively, used as the driven shaft and driving shaft.

According to the construction of the present invention, as illustrated in the examples the eddy-current generating drums are arranged at the outside position and extended toward the outside of the iron yoke member, so that contacting of the drums by the ventilating cooling air and accordingly their heat exchange becomes very effective, whereby highly effective dissipation of the loss heat due to the eddy-currents can be attained by the cooling effect of the broad area of the drums. Of course, the above-mentioned cooling effect can be further improved by provision of ventilating holes in the drums. Furthermore, in the present invention, both the inductor and yoke member are arranged in the space formed between opposite drums, so that any thrust force due to magnetic attraction force between various parts cannot be applied to the shafts, thus causing simplification of the bearings. This advantage can cause minimization of the machine structure together with the effective cooling effect, thereby to simplify the construction, manufacturing and inspection of the machine.

The present invention is not limited to the above-mentioned examples and can be modified within the range which is obvious to the persons skilled in the art. For example, as shown in FIG. 6 in which the same or equivalent members as those of the example of FIGS. 1 and 2 are designated by the same reference numerals, there are provided a partition plate 19 supported by the driving shaft 2 so as to separate the outside and inside space of the eddy-current generating structure, cooling fans 20, 21 being provided, respectively, on front and rear surfaces of said partition plate 19, and a ventilating guide plate 22 to protect effectively the machine from overheating due to the eddy-current loss.

Furthermore, as shown in FIGS. 7 and 8, a driving motor may be enclosed within the machine frame including therein the eddy-current generating structure. The machine of FIGS. 7 and 8 comprises, in a machine frame 1 which is provided with air suction inlets 42, 43 and an air exhaust outlet 36 and which supports a driven shaft 4 through bearings 32, an electric motor comprising a stator 28 having a stator winding 29 and a rotor 30 having an end ring 31; a hollow shaft 35 supporting said rotor 30 therearound and supported by means of bearings 33, 34 on the driven shaft 4 which passes through the hollow space of the shaft 35; a fan plate 37 provided with double fans 38, 39 and supported by the hollow shaft 35; an eddy-current generator consisting of magnetic drums A and B which are connected by a nonmagnetic member 41 so as to form a space therebetween, this eddy-current generator being attached to the driven shaft 4 by means of a hub 44 formed integrally with the inner magnetic drum A and having a ventilating hole 45; inductor pieces 27 inserted into the gap between the drums A and B and supported by the fan 38 by way of a nonmagnetic piece 40; yoke member 46 supported by the machine frame and extended into the gap between the drums A and B; and an exciting winding 47.

In the machine as illustrated in FIGS. 7 and 8, if the stationary winding 29 is excited, the rotor 30 is rotated, whereby the hollow shaft 35 is also rotated thereby to rotate the fans 38 and 39, so that the inductor pieces 27 are rotated while passing through the gap between the drums A and B. In this state, if the exciting winding 47 is excited, a magnetic flux .phi. is established. Accordingly, eddy-currents are generated in the magnetic drums A and B and a torque is produced between the inductor pieces 27 and the magnetic drums, whereby the driven shaft 4 is driven as in the case of the example of FIG. 1.

In this example, cooling air is sucked in through the inlets 42 and 43 and discharged out from the outlet 36 by action of the double fans 38 and 39, whereby the cooling of the eddy-current device and driving motor is effectively attained. As seen from the construction of the example of FIGS. 7 and 8, an extremely miniaturized eddy-current coupling machine can be realized by skillful combination of an electric motor and an eddy-current device.

Claims

1. An eddy-current rotary machine comprising in combination: a first structure having at least two concentric eddy-current drums of magnetic material supported with a radial gap therebetween by nonmagnetic means interposed between said drums intermediate the ends thereof, said first structure being rotatably mounted for rotation about an axis concentric with said drums; a plurality of inductor members disposed in a circular array concentric with said axis and forming an inductor disposed in said gap between said drums on one side of said nonmagnetic means; said inductor constituting a second structure and being rotatably mounted for rotation about an axis coaxially with said first structure; a yoke member disposed in said gap between said drums on the other side of said nonmagnetic means from said inductor; exciting means for generating a magnetic flux passing through and linking said inductor, said yoke member, and both of said drums; and driving means coupled to one of said structures for causing it to rotate relative to the other structure for producing eddy-currents in both of said drums to transmit a torque from

2. An eddy-current rotary machine as claimed in claim 1, in which ventilating holes are provided in the drums for ventilation of the space

3. An eddy-current rotary machine as claimed in claim 2, in which ventilating fins are provided bridging the ventilating holes of the drums.

4. An eddy-current rotary machine as claimed in claim 1, in which the inductor members of the inductor are each divided into several concentric layers, and an additional eddy-current generating drum is mounted on said first structure and disposed between adjacent layers of said divided

5. An eddy-current rotary machine as claimed in claim 2, in which shields are supported adjacent the ends of said drums to provide an air baffle between the drums and the yoke member on one side and between the drums and the inductor on the other side, and the ventilating holes in one of said drums are in registration with corresponding holes of the other of said drums with plates spanning the space between the drums around

6. An eddy-current rotary machine as claimed in claim 1, in which the driving means is coupled to said second structure and is in the form of a shaft, and wherein a partition plate is mounted on said shaft for rotation, fan elements are provided on both sides of said partition plate radially spaced from said shaft, and said inductor members are joined to

7. An eddy-current rotary machine which comprises a driven shaft supported by a machine frame having ventilating holes; an electric motor enclosed in said machine frame and consisting of a stator and a rotator, the rotator being supported by a hollow shaft through which said driven shaft passes; an eddy-current generator consisting of mutually opposed concentric radially spaced apart magnetic drums supported by said driven shaft adjacent one end of said hollow shaft; a plurality of inductor members inserted in the space between said drums and supported by said hollow shaft; an exciting winding supported in the space between said drums by the machine frame; and a double fan type ventilating fan supported by said hollow shaft positioned between said electric motor and said eddy-current generator, whereby said motor and generator portions in the frame are effectively cooled.