GB2157376A

GB2157376A - Magnetically assisted stepless variable ratio transmission

Info

Publication number: GB2157376A
Application number: GB08409093A
Authority: GB
Inventors: Tokuichiro Yoshida
Original assignee: Individual
Current assignee: Individual
Priority date: 1984-04-09
Filing date: 1984-04-09
Publication date: 1985-10-23
Also published as: GB8409093D0

Abstract

A power transmission device comprises an input shaft (2) having a driving wheel (4) axially displaceable along spiral groove (10) on shaft (2), a spring (3) which biases wheel (4) away from the power input end (1) and a driven cone (5) in contact with wheel (4) to provide the variable ratio drive. The wheel and cone have peripheral magnetic portions to increase driving adhesion. A second embodiment (Fig. 5, not shown) provided an input shaft with two spiral grooves, springs and driving wheels on the input side and a respective two cones on the output side. In a further embodiment (Fig. 6, not shown) the driving wheel co-operates with the inner surface of a hollow cone. Both the latter embodiments have peripheral magnetic portions on driving wheel and engaging surface of driven cone. <IMAGE>

Description

SPECIFICATION Magnetically operated power transmission apparatus BACKGROUND OF THE INVENTION FIELD OF THE INVENTION The present invention relates to a magnetically operated or assisted power transmission apparatus and more particularly to improvement of or relative to a power transmission apparatus of the type utilizing magnetic force for making reliable operative connection between a driving pulley and a driven pulley to steplessly transmit rotational power outputted from prime mover to power consuming machine or apparatus.

DESCRIPTION OF THE PRIOR ART A hitherto known stepless power transmission apparatus of the type including a driving pulley and a driven pulley is generally constructed such that the former is designed in the form of a disc and the latter is designed in the form of a truncated cone so that rotational force outputted from prime mover is transmitted to power consuming side by way of frictional contact between both the driving and driven pulleys. Because of the fact that power transmission is achieved merely with the aid of frictional force in the contact area between both the pulleys, the conventional stepless power transmission apparatus has a drawback that some slippage takes place in the contact area, resulting in reduced power transmission efficiency.

SUMMARY OF THE INVENTION Thus, the present invention has been made with the foregoing drawback in mind.

It is an object of the present invention to provide an improved stepless power transmission apparatus of the above-mentioned type which assures that power transmission is achieved without occurence of slippage in the contact area between a disc-shaped driving pulley and a truncated cone-shaped driven pulley.

It is other object of the present invention to provide an improved stepless power transmission apparatus of the above-mentioned type which has high power transmission efficiency.

It is another object of the present invention to provide an improved stepless power transmission apparatus of the above-mentioned type which is simple in structure and therefore can be manufactured at an inexpensive cost.

To accomplish the above objects there is proposed in accordance with the present invention a magnetically operated or assisted power transmission apparatus for steplessly transmitting rotational force outputted from prime mover to power consuming machine or apparatus, comprising a primary shaft operatively connected to the prime mover by way of coupling means and having a spirally extending groove formed over the outer surface thereof, a driving pulley displaceably fitted onto the primary shaft and including engagement means adapted to come in engagement to said spirally extending groove, the driving pulley being constructed by a plurality of radially extending permanent magnets with spacers of non-magnetic material interposed between the adjacent ones, an expansive spring means disposed on the primary shaft so as to allow the driving pulley to be normally urged in the direction away from the power input end of the primary shaft, a truncated cone-shaped driven pulley of which outer conical surface is adapted to come in rolling contact with the outer surface of the driving pEdlrly the driven pulley being made of non-magnetic material and having a number of rod-shaped magnetizable pieces embedded in the outer conical surface so as to make magnetic connection between both the driving and driven pulleys, and a secondary shaft made integral with the driven pulley and extending at a certain inclination angle relative to the primary shaft so as to allow it to be operatively connected to power consuming machine or apparatus at its outermost end by way of an universal joint.

As a modification from the above-described power transmission apparatus a pair of combinations of driving pulleys and truncated coneshaped driven pulleys are arranged in such a manner that the truncated end parts of the driven pulleys are located in the face-to-face relation so that more reliable power transmission is achieved by way of magnetical connection in two contact areas.

Alternatively, an arrangement may be made such that the driving pulley is accomodated in the truncated coneshaped inner space of the driven pulley so that the outer surface of the driving pulley comes in rolling contact with the the inner conical surface of the driven pulley.

Further, the truncated cone-shaped driven pulley is constructed by a plurality of axially extending magnetizable pieces with spacers of non-magnetic material interposed between the adjacent ones.

Other objects, features and advantages of the invention will become more clearly apparent from reading of the following description which has been prepared in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings will be briefly described below.

Fig. 1 is a schematic sectional view of a power transmission apparatus in accordance with the first embodiment of the invention.

Fig. 2 is a perspective view of a truncated coneshaped driven pulley with a number of rod-shaped magnetizable pieces embedded in the whole outer conical surface thereof.

Fig. 3 is a perspective view of a driving pulley displaceably mounted on the primary shaft, particularly illustrating how the driving pulley is constructed by a plurality of radially extending permanent magnets.

Fig. 4 is a perspective view of a truncated coneshaped driven pulley which is constructed by a plurality of axially extending magnetizable pieces in the foim of a plate.

Fig. 5 is a schematic sectional view of a power transmission apparatus in accordance with the second embodiment of the invention, and Fig. 6 is a schematic sectional view of a power transmission apparatus in accordance with the third embodiment of the invention.

It should be noted that same or similar components or parts throughout the drawings are identified by the same reference numerals.

DETAILED DESCRIPTION OF THE PRE FERRED EMBODIMENTS Now, the present invention will be described in a greater detail hereunder with reference to the accompanying drawings which schematically illustrate a few preferred embodiments thereof.

Refering first to Figs. 1 to 3, reference numeral 1 designates an output end of an engine (not shown), reference numeral 2 does a primary shaft operatively connected to the output end 1, reference numeral 3 does an expansive coil spring disposed on the primary shaft 2, reference numeral 4 does a driving pulley, reference numeral 5 does a driven pulley designed in the truncated cone-shaped configuration and reference numeral 6 does a secondary shaft. Reference numeral 7 designates a ball bearing for rotatably supporting the primary shaft 2, whereas reference numerals 8 and 9 do ball bearings for rotatably supporting the secondary shaft 6.

As is apparent from Fig. 1, a spirally extending groove 10 is formed over the primary shaft 2 so that the driving pulley 4 is displaceable along the spirally extending groove 10 in the axial direction while it is rotating.

Further, the driving pulley 4 is normally urged in the rightward direction as seen in the drawing under the influence of resilient force of the expansive coil spring 3. The driven pulley 5 designed in the truncated coneshaped configuration is disposed in such a manner that the larger diameter end part that is called low speed side is located at the lefthand end and the smaller diameter end part that is called top speed side is located at the righthand end as seen in the drawing. It should be noted that the lower generating line of the truncated cone-shaped driven pulley 5 is extended in parallel with the center line of rotation of the primary shaft 2 so as to assure that the driving pulley 4 is normally brought in rolling contact with the driven pulley 5.

When the driving pulley 4 assumes the position in the proximity of the larger diameter end part of the driven pulley 5, the latter is caused to rotate at a lower rotational speed.

On the other hand, when it assumes the position in the proximity of the smaller diameter end part of the driven pulley 5, the latter is caused to rotate at a higher rotational speed.

As illustrated in Fig. 2, the driven pulley 5 is made of non-magnetic material and a number of rod-shaped magnetizable pieces 11 are embedded in the whole outer conical surface of the driven pulley 5. Further, as illustrated in Fig. 3, the driving pulley 4 is constructed by a plurality of radially extending permanent magnets 1 2 with spacers of non-magnetic material interposed between the adjacent magnets 1 2. Owing to the arrangement of the rod-shaped magnetizable pieces 11 and the permanent magnets 1 2 made in that way magnetic connection is assured between both the driving and driven pulleys 4 and 5 in addition to frictional connection therebetween whereby rotational force generated by engine is reliably transmitted to power consuming machine or- apparatus.

Next, operation of the magnetically operated or assisted transmission apparatus will be described below.

First, it is assumed that the driving pulley 4 is intially located at the middle position on the primary shaft 2 when engine starts its rotation. If the driving pulley 4 fails to rotate the driven pulley 5 because of dead load of power consuming machine or apparatus at the time of engine starting, it is caused to move to the left as seen in the drawing along the track of the spirally extending groove 10 against resilient force of the coil spring 2 without occurence of rotation as the primary shaft 2 is rotated by engine. It continues to move to the left, that is, toward the low speed side on the driven pulley 5, until the driving pulley 4 is brought in torque balance with the driven pulley 5 which is operatively connected to power consuming machine or apparatus. At this moment the driven pulley starts to be rotated by the driving pulley 4 at a certain reduced rotational speed by way of power transmission assured by magnetic connection between both the driving and driven pulleys 4 and 5 with or without the aid of frictional connection therebetween. Once the driven pulley 5 starts to be rotated, the driving pulley 4 is caused to move to the right as seen in the drawing, that is, toward the top speed side via the intermediate speed area B under the influence of resilent force of the coil spring 3. Thus, the driven pulley 5 is rotated at a gradually increased rotational speed.

Namely, the torque transmission area is displaced from the low speed side A toward the top speed side C via the intermediate speed side B as the driven pulley 5 continues to be rotated steadily. As is apparent from Fig. 1, rotational force of the secondary shaft 6 is transmitted to power consuming machine or apparatus via an universal joint 1 3.

Next, description will be made as to a magnetically operated or assisted power transmission apparatus in accordance with the second embodiment of the invention as illustrated in Fig. 5.

In this embodiment an opposing pair of combinations of driving pulleys 4, 4' and driven pulleys 5, 5' are arranged in such a manner that the truncated end parts of the driven pulleys 5 and 5' are located in the faceto-face relation. Namely, the lefthand combination of driving pulley 4 and driven pulley 5 is located symmetrical to the righthand combination of driving pulley 4' and driven pulley 5' with respect to a central plane extending through the universal joint at a right angle relative to the plane of the drawing. It should be noted that the primary shaft 2 is formed with two spirally extending grooves 10, one of them being intended for the driving pulley 4 and the other one being intended for the driving pulley 4' with such difference therebetween that the direction of extension of the former is opposite to that of the latter.Rotational force of the primary shaft 2 is transmitted to power concuming machine or apparatus via an universal joint 1 3 in the same manner as the foregoing embodiment.

Operation of the power transmission apparatus in accordance with the second embodiment is quitely same to that of the first embodiment and therefore its repeated description will not be required.

Next, description will be made as to a magnetically operated or assisted power transmission apparatus in accordance with the third embodiment of the invention as illustrated in Fig. 6.

As is apparent from the drawing, a driving pulley 4 is accomodated in a truncated coneshaped driven pulley 5 in such a manner that the outer surface of the driving pulley 4 comes in rolling contact with the inner conical surface of the driven pulley 6 which is rotatably supported by means of two ball bearings 14 and 1 5. The primary shaft 2 is also rotatably supported with the aid of suitable bearing means (not shown) in the parallel relation to the inner conical surface of the driven pulley 5.

Operation of the power transmission apparatus in accordance with this embodiment is also same to that of the above-described embodiments and therefore its description will not be required.

Advantageous features of the invention will be summerized below.

1. Since operative connection between the driving pulley and the driven pulley is made by magnetic force with or without the aid of frictional force therebetween, rotational force outputted from engine can be transmitted to power consuming machine or apparatus reliaably without occurence of slippage on the contact area. Thus, high power transmission efficiency is assured.

2. Shifting of the driving pulley on the primary shaft is automatically carried out without necessity for any type of shifting device or mechanism.

3. When it is mounted on a vehicle such as motorcar or the like, engine braking is effectively transmitted to wheels by way of it.

4. It is simple in structure and can be manufactured at an inexpensive cost.

While the present invention has been described above with respect to three preferred embodiments, it should of cource be understood that it should not be limited only to them but various changes or modifications may be made in a suitable manner without departure from the spirit and scope of the invention. For instance, a number of rodshaped magnetizable pieces 11 on the driven pulley 5 as illustrated in Fig. 1 may be replaced with a plurality of axially extending magnetizable plates 11' with spacers of nonmagnetic material interposed between the adjacent ones as illustrated in Fig. 4 without any loss in operational performance. It should be construed that all changes or modifications made in that way are included within the scope of the invention.

Claims

1. A magnetically operated or assisted power transmission apparatus for steplessly transmitting rotational force outputted from prime mover to power consuming machine or apparatus comprising: a primary shaft operatively connected to the prime mover by way of coupling means, said primary shaft being formed with a spirally extending groove over the outer surface thereof, a driving pulley displaceably fitted onto the primary shaft and including engagement means adapted to come in engagement to said spirally extending groove, said driving pulley being constructed by a plurality of radially extending permanent magnets with spacers of non-magnetic material interposed between the adjacent ones.

an expansive spring means disposed on the primary shaft so as to allow the driving pulley to be normally urged in the direction away from the power input end of the primary shaft, a truncated cone-shaped driven pulley of which outer conical surface is adapted to come in rolling contact with the outer surface of the driving pulley, said driven pulley being made of non-magnetic material and having a number of rod-shaped magnetizable pieces embedded in the outer conical surface thereof so as to make magnetic connection between the driving and driving pulleys, and a secondary shaft made integral with the driven pulley, said secondary shaft extending at a certain inclination angle relative to the primary shaft and being operatively connected to power consuming machine or apparatus at its outermost end by way of an universal joint.

2. A magnetically operated or assisted power transmission apparatus as defined in claim 1, wherein the truncated cone-shaped driven pulley is constructed by a plurality of axially extending magnetizable pieces in the form of a plate with spacers of non-magnetic material interposed between the adjacent ones.

3. A magnetically operated or assisted transmission apparatus for steplessly transmitting rotational force outputted from prime mover to power consumpting machine apparatus comprising; a primary shaft operatively connected to the prime mover by way of coupling means, said primary shaft being formed with two spirally extending grooves over the outer surface thereof, one of them being formed on the one half of the primary shaft and the other one being formed on the other half of the same with such difference that their directions of extension are opposite to one another, two driving pulleys displaceably fitted onto the primary shaft and including engagement means adapted to come in engagement to said spirally extending grooves, one of them being disposed on the one half of the primary shaft and the other one being disposed on the other half of the same, each of said driving pulleys being constructed by a plurality of radially extending permanent magnets with spacers of non-magnetic material interposed between the adjacent ones, two expansive spring means, one of them being disposed on the one half of the primary shaft so as to allow the one driving pulley to be normally urged in the direction away from the power input end of the primary shaft and the other one being disposed on the other half of the primary shaft so as to allow the other driving pulley to be normally urged in the direction away from the other end of the primary shaft remote from the input end, two truncated cone-shaped driven pulleys disposed in such a manner that their truncated end parts are located opposite to one another and their conical outer surfaces come in rolling contact with the outer surfaces of the driving pulleys, said driven pulleys being made of non-magnetic material and having a number of rodshaped magnetizable pieces embedded in the outer conical surface thereof so as to make magnetic connection between the driving pulleys and the driven pulleys, and two secondary shafts made integral with the driven pulleys and operatively connected to one another at their innermost ends by way of an universal joint, said secondary shafts extending at certain inclination angle relative to the primary shaft and one of them being operatively connected to power consuming machine or apparatus at its outermost end by way of an universal joint.

4. A magnetically operated or assisted power transmission apparatus as defined in claim 3, wherein each the truncated coneshaped driven pulleys is constructed by a plurality of axially extending magnetizable pieces in the form of a plate with spacers of non-magnetic material interposed between the adjacent ones.

5. A magnetically operated or assisted power transmission apparatus for steplessly transmitting rotational force outputted from prime mover to power consuming machine of apparatus comprising; a primary shaft operatively connected to the prime mover by way of coupling means, said primary shaft being formed with a spirally extending groove over the outer surface thereof, a driving pulley displaceably fitted onto the primary shaft and including engagement means adapted to come in engagement to said spirally extending groove, said driving pulley being constructed by a plurality of radially extending permanent magnets with spacers of non-magnetic material interposed between the adjacent ones, an expansive spring means disposed on the primary shaft so as to allow the driving pulley to be normally urged in the direction away from the power input end of the primary shaft, a truncated cone-shaped driven pulley of which inner conical surface is adapted to come in rolling contact with the outer surface of driving pulley and having a number of rodshaped magnetizable pieces embedded in the inner conical surface thereof so as to make magnetic connection between the driving pulley and the driven pulley, and a secondary shaft made integral with the driven pulley, said secondary shaft extending at a certain inclination angle relative to the primary shaft and being operatively connected to power consuming machine or apparatus at its outermost end by way of an universal joint.

6. A magnetically operated or assisted power transmission apparatus as defined in claim 5, wherein the truncated coneshaped driven pulley is constructed by a plurality of axially extending magnetizable pieces in the form of a plate with spacers of non-magnetic material interposed between the adjacent ones.

7. A power transmission comprising a member which has a part-conical surface and is mounted for rotation and a wheel engageable with the said surface, the wheel being axially displaceable along a shaft to vary the transmission ration between the pulley and the said member, the wheel and the member each having a multiplicity of peripheral magnetic portions to increase driving adhesion between the wheel and the member.

8. A power transmission according to claim 7 in which the wheel engages an outwardly facing surface of the member.

9. A power transmission according to claim 7 in which the member is hollow and the said surface is an inner surface of the member.

10. A power transmission according to any foregoing claim in which the magnetic portions of the member are rod-shaped.

11. A power transmission according to any foregoing claim in which the wheel's magnetic portions comprise magnetic segments separated by non-magnetic segments.