Steering device for use in a toy car

A steering device for use in a toy car includes an output member having a pair of deformable arms and coupled to a servo, and an input member having side surfaces to be in contact with the free ends of the arms. When the great amount of reaction force from the wheel is applied through the input member to the arm of the output member, this force will be absorbed by the arm due to its elastic deformation so that the damage of the servo is nothing.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a steering device adapted for use in a toy 
car, such as radio controlled cars. 
2. Description of the Prior Art 
A radio controlled toy car comprises a transmitter which is to be operated 
by a modeler through a steering stick and a forward-reverse stick, a 
receiver which receives signals of radio waves from the transmitter, and 
servos which are operated by signals from the receiver, but translated 
into mechanical movements. These mechanical movements are put out from a 
servo horn to the model unit to be controlled. The model car having these 
elements can be controlled at will by manipulating a stick of the 
transmitter quickly or slowly, to full range of throw or half way, the 
movement of the servo horn is hooked up to be transmitted to, for 
instance, front wheel/steering of the car. 
An example of a steering device for use in a toy car according to a prior 
art is shown in FIG. 3. The device includes cylindrical members 2, 3 
having a pair of arms and disposed on the chassis 1. Both the cylindrical 
members 2, 3 are fixed to the chassis 1 by means of a screw 4. When the 
cylindrical members 2, 3 are to be fixed to the chassis 1, a spring 6 is 
interposed between the head 5 of the screw 4 and the upper surface of the 
cylindrical member 2 and the biasing force of the spring 6 is applied to 
the surfaces of both cylindrical members 2, 3 which are in abutment 
against each other. Said surfaces in abutment of the cylindrical members 
2, 3 are tapered surfaces cut away in two opposite directions so that when 
the tapered surfaces of both the cylindrical members 2, 3 are mated 
completely together, both the cylindrical members will provide a rod 
having no clearance at the joint portions of their outer circumferential 
surfaces. 
One of the cylindrical member 2 will be coupled to output shaft 8 of the 
servo 7, and the other cylindrical member 3 will be coupled to a link (not 
shown) to be connected to wheels. 
According to the embodiment as shown according to the prior art, when the 
servo 7, having received a signal from the transmitter, causes the output 
shaft 8 to be rotated, the cylindrical member 2 will also be rotated 
through an angle corresponding to the rotation of said output shaft. 
However, since the spring 6 forcibly pushes the cylindrical member 2 
against the cylindrical member 3, the cylindrical member 3 is caused to 
rotate together with the cylindrical member 2 to provide a necessary 
steering angle to a wheel. 
If a wheel hits a rock or drops in a crack on a road so that the steering 
of said wheel is uncontrollable; and when the output shaft 8 of the servo 
7 is rotated under such a condition, the cylindrical member 2 alone at the 
side of the servo 7 will be rotated against the biasing force of the 
spring 6. Because the cylindrical member 3 can not be rotated, the tapered 
surfaces will slip against each other, and accordingly, the servo 7 can 
not create a reaction force more than a predetermined value. 
As is clearly seen from FIG. 3, according to the prior art, the sliding 
resistance between the cylindrical member 2 and 3 is adjusted by biasing 
the spring 6 against the top surface of one of the cylindrical members. 
Since the biasing force of spring 6 is variable due to inherent variation 
in the manufacture thereof, or the biasing force may be varied depending 
on how much the screw 4 is tightened, it is difficult to keep constant the 
sliding resistance between the cylindrical members 2, 3 for every product. 
Furthermore, the requirement of a spring 6 itself causes a increase in the 
number of parts and makes the management of the parts more complicated. 
The present invention has therefore as an object subject to solve or 
eliminate the problems of the prior art as above explained. 
In order to solve the problems as above mentioned, there is provided a 
steering device for use in a toy car including an output member having 
integrally formed therewith a cylindrical part adapted to be coupled to 
the output shaft of a servo, and a pair of arms so formed as to surround 
the cylindrical part, and an input member having a bore placed on the 
cylindrical part, and a portion connected to the link for a wheel, 
characterized in that the side edge portions of the input member will be 
in abutment with the free ends of the arm of said output member. 
The output torque from the servo is transmitted from the arms at the output 
member to the input member and provides a necessary rotary angle to the 
input member. However, when a wheel is in such a condition as not being 
able to rotate, the output torque from the servo will elastically deform 
said arms for the torque to be absorbed by the arms and will not forcibly 
move the wheel. In other words, no reaction force from a wheel more than 
necessary, will be transmitted to the output shaft of a servo. 
Accordingly, the servo will not be damaged; and since excessive torque is 
absorbed by the arms, a spring, as used in the prior art, will not be 
necessary. Furthermore since the elastic force of the arms is determined 
by the configuration and the material of the arms, variation of said 
elastic force from product to product, quite infrequent. 
Other features and advantages of the present invention will be apparent 
from the following description taken in conjunction with the accompanying 
drawings, in which like reference characters designate the same or similar 
parts throughout the figures thereof.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Output member 9 has a base 13 having at the center a cylindrical part 12 
adapted to be coupled to the output shaft 11 of a servo 10. A pair of 
arcuate arms 14 and 15 are provided in a manner to extend from one end of 
the base 13 to surround the cylindrical part 12. The free ends of the 
respective arms 14, 15 are spaced from each other; and pieces 16, 17 
having one end extending toward one another are provided at the upper 
surface of the free ends. The height of the arms 14, 15 is lower than that 
of the cylindrical part 12. The output member 9 is made of plastic 
material, such as polyacetal or polyamide. 
The input member 18, preferably made of the same material as that of the 
output member 9, has a head portion 20 having a bore 19 adapted to be 
placed on the cylindrical part 12, a neck portion 21 narrower than the 
head portion 20 and an attachment portion 22 of a flared configuration. 
The attachment portion 22 is connected to a link (not shown) which serves 
to change the direction of a wheel. The width of the head portion 20 of 
the input member 18 is narrower than the distance between the free ends of 
the arms 14, 15. The thickness of the head portion 20 is so sized that 
when the bore 19 is placed on the cylindrical part 12, the upper surface 
of the head portion 20 is flush with those of the arms 14, 15 or slightly 
lower than the height of the cylindrical part 12. 
In order to combine both members 9 and 18, the head portion 20 is put in 
between the free ends of the arms 14, 15 slightly slanting and the bore 19 
is placed on the cylindrical part 12. When the lower surface of the head 
portion 20 is seated on the upper surface of the base 13, the upper 
surface of the attachment portion 22 is in abutment with the pieces 16, 17 
so that the input member 18 may be prevented from disengagement with the 
arms 14, 15. A screw 23 having a head of larger diameter than that of the 
bore 19 of the head portion 20 of the input member 18 is screwed through 
the cylindrical part into the output shaft 11 of a servo, whereby the 
output member 9 may be secured to the servo 10 and the input member 18 may 
be slidably attached to the output member 9. The width of the attachment 
portion 22 of a flared configuration of the input member 18 is slightly 
wider than the distance between the arms 14, 15 of the output member 9 
when the input member is assembled to the input member 18 so as to avoid 
looseness. 
Rotation of the output shaft 11 causing, will cause rotation of the input 
member 9 secured to the output shaft 11 and one of the arms 14, 15 to push 
the input member 18 and rotate it. 
On the other hand, reaction force from a wheel at a time when steering is 
not possible such as that caused when a wheel hits against a certain 
obstacle, will elastically deform one of the arms 14 or 15 for absorbing 
the force; and this reaction force will not be directly transmitted to the 
servo 10. Accordingly no excessive reaction will not be applied to the 
servo 10, which will not thereby be damaged. 
Both members 9 and 18 may be easily attached to each other by passing the 
head 20 through the space defined between the free ends of the arms 14, 15 
and placing the bore 19 on the cylindrical part to be coupled to the shaft 
of a servo. Pieces 16, 17 prevent the input member 18 from coming off the 
output member 9, so that assembly of both members 9, 18 may be further 
firm. Furthermore, elastic force of the arms 14, 15 may be controlled 
depending on their configuration; and material and variation of elastic 
force from products to product can be reduced. Since this assembly may be 
coupled directly to the shaft of the servo, the entire construction may be 
made very compact. 
As many apparently widely different embodiments of the present invention 
can be made without departing from the spirit and scope thereof, it is to 
be understood that the invention is not limited to the specific 
embodiments thereof except as defined in the appended claims.