GB2091178A

GB2091178A - A combined steering and drive system

Info

Publication number: GB2091178A
Application number: GB8101765A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1981-01-21
Filing date: 1981-01-21
Publication date: 1982-07-28

Abstract

A combined steering and drive system for a child's sit-on vehicle comprises at least a segment of a spheroid and preferably substantially a hemisphere, drive means 74, 80, 82, 84 for rotating the segment about a drive axis passing through the geometric centre of the spheroid and peripheral centre of the segment, vehicle speed control means 52, 54, 60, 62 for pivoting that drive axis about a vehicle speed control axis which is horizontal and perpendicular to the drive axis, and steering means for pivoting the drive axis about a vertical steering axis for controlling the direction of advance of the vehicle over the ground. As illustrated, an electric motor 84 drives a hemisphere at a constant rotational speed through belt and pulleys 74, 80, 82. In a modification, Figure 5 (not shown), an electric motor drives a member which frictionally engages the inside wall of the hemisphere at a position which can be varied to vary the rotational speed of the hemispheres. <IMAGE>

Description

SPECIFICATION Improvements in a combined steering and drive system This invention relates to a combined steering and drive system in small motorised or driven vehicles such as trollies or children's toys.

Conventional steering and drive systems in this type of vehicle involve bulky complicated components including gears. However, because of these many components the steering and drive systems are not compact and often they cannot be protected by means of a simple casing. Consequently, this allows easy access to the components by persons and in the case of children this may well lead to injury when fingers or a hand is placed inside any moving component.

The invention has therefore been made with these points in mind and it is an object of the invention to provide a compact, simple and safe combined steering and drive system.

According to the invention there is provided a combined steering and drive system comprising at least a segment of a spheroid, drive means for rotating the segment about a drive axis passing through the geometric centre of the spheroid and peripheral centre of the segment, speed control means for pivoting that drive axis about a speed control axis perpendicular to the drive axis, whereby when the segment rests on the ground and is rotatably driven about the drive axis, the system advances over the ground at a rate corresponding to the radius of the circular locus of the point of contact of the segment with the ground to the drive axis, that radius and the speed of drive being zero when the point of contact corresponds to the peripheral centre of the segment and increasing as the circular locus of the point of contact becomes increasingly spaced from the peripheral centre, and steering means for pivoting the drive axis about a steering axis perpendicular to the speed control axis and in the plane within which the drive axis is moved upon pivoting about the speed control axis for controlling the direction of advance over the ground.

Such a system can be very simple and preferably is completely enclosed so that is it safe for use in children's toy vehicles. is used in the system and not just a segment.

The drive means can rotate the segment at a constant speed and the steering and drive system advances the vehicle at a rate depending upon the radius of the locus of the point of contact because, as that radius increases, the locus is moved further away from the centre of the periphery and so the peripheral length of the locus per revolution becomes larger, and accordingly the vehicle advances further per revolution.

Thus, as that peripheral length increases, the speed of the vehicle increases.

A number of geometric terms are used in the description and explained herein, and for assistance they may be explained as follows: The surface of a section cut off a sphere or spheroid by a plane other than a plane passing through the geometric centre is a small circle, and the solid cut-off by a sphere or spheroid by a plane of a small circle is a segment. Thus, the geometric centre of the sphere is also the geometric centre of the segment of a sphere.

The peripheral centre of the segment is the point on the surface of the segment which is at the greatest perpendicular distance from the plane of the small circle defining the segment.

Preferably, the system uses a hollow hemisphere and not a segment since this gives the fastest speed per revolution. Also, by making the hemisphere hollow, this has the advantage that the drive means can then be totally enclosed inside the hemisphere and a cover, optionally of hemispherical shape, can enclose the open end of the hemisphere. This keeps the system safe for the use by children.

It will be noted that the speed of advance over the ground in the system of the invention is varied by tilting the drive axis and so the drive means can be very simple without the need of a speed changing gear box.

The drive means can include an electric motor either rotating the hemisphere about the drive axis direction or through reduction gears or pullies and belts. Alternatively, a direct frictional engagement drive between the output from the motor and the inside wall of the sphere may be provided and additionally the motor mounted so that the radius of the circular locus of the point of frictional contact between the two about the drive axis can be varied simultaneously with the pivoting of the drive axis about the speed control axis. In this way control of speed is achieved not only by the variation of the point of contact of the outside of the hemisphere with ground but also by the variation of the point of frictional contact between the output from the motor and the inside of the hemisphere. Thus, in this case, the rate of rotation of the hemisphere about the drive axis is also varied.

In order to attach the system to a vehicle, an upright column extends from the vehicle down into the hemisphere. This column can then carry at its lower end a bearing in which the hemisphere can rotate about the drive axis, the hemisphere being attached to the bearing by an axlejournalled in the bearing. In order to vary the speed of advance, this axle is pivoted relative the column and this can be achieved by a link pivoted between the axle and the column and control of pivoting achieved by means of a link movable relative the axis of the column and extending out of the hemisphere with the column.

The speed control can be achieved by a lever of the like manually movable by the user. In order to achieve steering of the system, the column can itself be rotated about its upright axis by, for example, a steering wheel and if the column is free to rotate throughout the whole 360" then the system can drive the vehicle in all possible directions including reversing and so no separate reversing of the drive means is necessary.

Preferably, the combined steering and drive system is also provided with sensing means at the peripheral centre of the segment such that when the point of contact coincides with the peripheral centre of the segment, the sensing means stops the drive means since in that position the hemisphere is merely rotating without any advance over the ground.

This simplifies the control of the vehicle because there is no need for an on-off switch control for the drive means.

The drive system is particularly convenient for use in children's toy vehicles of the type when the vehicle body is designed to allow a child to sit and ride on the body whilst controlling the speed and direction of the vehicle by the combined system of the invention. Normally, a single such system will be provided together with idly-mounted rear wheels.

The invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure l is a diagram showing the various mathematical terms used in the description of the invention; Figure2 is a side view of a vehicle including the steering and drive system of the invention; Figure 3 is a sectional view along line A-A in Figure 2; Figure 4 is a diagram similarto Figure 3 but in an alternative position; and Figures 5and 6are sectional views simiiarto Figures 3 and 4 but showing a modified embodiment of the invention.

The vehicle 18 shown in Figures 2 to 4 has a body 20 on which a child or lightweight goods may be placed. The body 20 is shown with a rear support 22 in which an axle 24 is journalled. At either end of this axle are two wheels 26 and 28. This part of the vehicle may in fact be any shape, configuration or design.

At the front of the body is a steering and drive system 30 according to the invention. Upstanding from the system 30 is a column 32 which is freely rotatable in a hole 34 found in the body 20 to allow 360" rotation of the steering and drive system relative the body 20.

The column 32 has a central bore 35 running through it and a circular steering wheel 36 fixed to the top. Below the column 32 a lever support 38 projects downwardly ending in perpendicular foot 40. This foot 40 contains a pin 42 which is at the geometric centre of a hemisphere 44 on which the front of the vehicle rests and travels. Attached to the hemisphere 44 is an axle 48 which is rotatably joined in a centre support 50 which is itself pivotable about the pin 42 on the foot 40.

Slidable within the bore 35 is a rod 52 and pivoted at the top end of the rod 52 by a pin 60 is a crank 54.

The long arm 56 of this crank acts as a speed control lever and the end of the short arm 58 is pivotally slidable relative a slot 64 formed in an upright support 65 standing up from the steering wheel 36 by means of a pin 62.

Thus, when the lever arm 56 is moved in the direction of the arrow 57 (Figure 2), the rod 52 is moved up or down the slot 35. Because the rod 52 is attached by a link 66 to the centre support 50, this causes the latter to pivot together with the hemisphere 44 about the pin 42.

Mounted on the central support 50 is an electric motor 84. The output shaft of this has a small pulley 82 which drives a pulley 74 fixed on the axle 48 by means of a band 80. Thus, the hemisphere is revolved about the axle 48.

The operation of the drive system 30 according to the invention is perhaps best described with reference additionally to the diagram of Figure 1. In that Figure, a sphere 2 is shown in dotted lines with a segment 4 of the sphere in bold type. The geometric centre 6 of sphere is also the geometric centre of the segment 4. The segment has a periphery 8 and the centre 10 of this periphery is shown. The line 16 is that which joins the geometric centre 6 and the peripheral centre 10 and this line corresponds to the axis or axle 48 about which the hemisphere 44 is rotated by the motor 84.

The periphery of the segment 4 makes contact with the ground 12 at a point 14 and the locus of that point as the hemisphere rotates about the line 16 or axle 48 corresponds to the line 90.

Assuming that the hemisphere 44 is in the orientation shown in Figures 1 and 4, the drive system will advance over the ground 12 per revolution about the line 16 or axle 48 a distance corresponding to the periphery of one revolution of the locus 90 and the length of that periphery corresponds to the radius of the point 14 from the line 16.

When the hemisphere 44 is moved to the orientation shown in Figure 3 by operation of the lever 54 then the point of contact becomes the point 14a and the locus is then represented by the line 90a. Since the motor 84 continues to revolve the hemisphere at the same rate of revolution, the vehicle is now moved more quickly over the ground 12 because the peripheral length of the locus 90a for one revolution is now much longer than for the locus 90.

Equally, if the hemisphere is oriented so that the peripheral centre 10 becomes the point of contact with the ground 12, then the hemisphere will merely continue to rotate without advancing anywhere over the ground since now the radius of the locus becomes effectively zero.

The system 30 will of course give an infinite variation in speed between the extremes discussed above.

To steer the direction at which the drive system 30 advances the vehicle over the ground, the column 32 and so the hemisphere 44 can all be rotated about an upright axis 94 by rotating the column 32 relative the body 20 by means of the steering wheel 36.

When the peripheral centre 10 is in contact with the ground and so the drive system does not advance the vehicle over the ground, it is desirable to stop rotation of the hemisphere 44. This can be achieved by means of a sensor 92 projecting from the point 10 which actuates an electrical switch (not shown) to de-activate the motor 84 when the point 10 is in contact with the ground.

Suitable storage batteries to power the motor are provided but for convenience are not shown.

In order to enclose the electrical motor 84 and the drive mechanism to prevent children from touching them and hurting themselves and also to keep these parts free from dust and dirt, a part spherical-shaped cover 96 may be provided as shown in dotted lines in Figure 3, this cover being fixed to the column 32 and so the hemisphere 44 is rotatable relative to it.

The modified system 95 shown in Figures 5 and 6 also includes the hemisphere 44 rotatable about the axle 48 which is in turn rotatably journalled in the central support 50. In this embodiment, however, there is no pulley on the axle 48 and the electric motor 84 does not drive the axle 48 directly. Instead, on the output shaft of the motor is a friction nose 98 which frictionally engages the inside surface of the hemisphere 44. Thus, as the motor rotates, this nose 98 engages the surface of the hemisphere and causes it to rotate about the axle 48. Once the hemisphere rotates about the axle 48, the advance of the system 95 over the ground 12 is the same as for the embodiment 30.

The motor 84 is mounted on a bracket 100 pivoted about the point 42 to the upright column 32. In addition, besides the link 66 attached to the bracket 50 for pivoting the support about the point 42 to adjust the speed of drive, a further link 102 is provided which is attached to the bracket 100. In this way, the point 104 of contact of the frictional drive between the nose 98 and the inside surface of the hemisphere 44 can be varied and so even though the output speed of rotation of the motor remains constant, the rate of rotation of the hemisphere 44 about the axle 48 can now be varied.

In the position shown in Figure 3, the speed of rotation is at its highest and of course at the same time the rate of movement of the vehicle over the ground per revolution is also at its highest. The radius of the locus 106 of the point of contact 104 is half the length of the line 106 shown in Figure 5.

However, when the hemisphere 44 is tilted to the position shown in Figure 6 so that the distance travelled over the ground per revolution is less than in FigureS, the actual rate of revolution of the hemisphere is now less because the locus 106a of the point of contact 1 04a now has a larger radius.

An advantage of the embodiment shown in Figures 5 and 6 therefore is that this gives an enhanced speed variation.

Claims

1. A combined steering and drive system comprising at least a segment of a spheroid, drive means for rotating the segment about a drive axis passing through the geometric centre of the spheroid and peripheral centre of the segment, speed control means for pivoting that drive axis about a speed control axis perpendicular to the drive axis, whereby when the segment rests on the ground and is rotatably driven about the drive axis, the system advances over the ground at a rate corresponding to the radius of the circular locus of the point of contact of the segment with the ground to the drive axis, that radius and the speed of drive being zero when the point of contact corresponds to the peripheral centre of the segment and increasing as the circular locus of the point of contact becomes increasingly spaced from the peripheral centre, and steering means for pivoting the drive axis about a steering axis perpendicular to the speed control axis and in the plane within which the drive axis is moved upon pivoting about the speed control axis for controlling the direction of advance over the ground.

2. A system as claimed in Claim 1 in which the drive means are arranged to rotate the segment at a constant speed.

3. A system as claimed in Claim 2, in which the drive means include an electric motor rotating the segment about the drive axis directly or through a reduction gearing.

4. A system as claimed in Claim 2 in which the drive means include an electric motor whose output is in directfrictional engagement with the inside wall of the segement of the spheroid.

5. A system as claimed in any preceding claim in which the segment is a hollow hemisphere.

6. A system as claimed in Claim 5 in which the drive means are enclosed within the hemisphere and a cover encloses the open end of the hemisphere.

7. A system as claimed in Claim 6 in which the cover is of hemispherical shape.

8. A system as claimed in any preceding claim having an upright column to extend from a vehicle down to the segment of the spheroid, the column carries at its lower end a bearing and the segment of the spheriod being attached to the bearing by an axle journailed in the bearing.

9. A system as claimed in Claim 8 in which the axle is pivoted relative the column by a link pivoted between the axle and the column and control of pivoting is achieved by means of a link movable relative the axis of the column and extending out of the segment with the column.

10. A system as claimed in Claim 8 or Claim 9 in which, to achieve steering of the system, the column is rotatable about its upright axis.

11. A system as claimed in any preceding claim in which sensing means are provided at the peripheral centre of the segment such that when the point of contact with the ground coincides with the peripheral centre of the segment, the sensing means stops the drive means.

12. A system as claimed in Claim 11 in which the sensing means comprises an electrical switch and the drive means includes an electric motor whose energisation is controlled by that switch.

13. A combined steering and drive system substantially as herein described with reference to Figures 2 to 4, or Figures 5 and 6, of the accompanying drawings.

14. A children's toy vehicle having a vehicle body designed to allow a child to sit and ride on the body, a combined steering and drive system as claimed in any preceding claim at the front of the body and idly-mounted rear wheels.