Indicating apparatus in centrifugal force type meter

A speedometer of a centrifugal force type member employing weight members which are rotatable with a shaft for transmission to a thrust member. Displacement of the thrust member takes place and carries a pointer to move with respect to a scale.

BACKGROUND OF THE INVENTION 
This invention relates to an indicating apparatus in a centrifugal force 
type meter. More particularly the invention is directed to such a meter 
used as a speedometer or a rotation meter in a bicycle on a small-sized 
motorized two-wheeled vehicle. 
Up to the present, this kind of meter has not practically been used as a 
running speedometer for a bicycle or a motorized two-wheeled vehicle due 
to a number of shortcomings particularly relating to accuracy. 
SUMMARY OF THE INVENTION 
The main object of the present invention is to overcome the defects of the 
prior art. 
Another object of the invention is an indicating apparatus which is free 
from fluctuation of a pointer. 
A further object of the invention is an apparatus simple in construction. 
The principal features of the invention are directed to an indicating 
apparatus in a centrifugal force type meter employing weight members that 
are radially directed to rotate with a driving shaft for transmission to a 
thrust member disposed in the axial direction thereof; pointer means 
disposed in relation to a scale responsive of said thrust member wherein; 
said thrust member being formed as a tubular body having an opening 
portion in the central axial direction thereof; and said pointer means 
being provided with a turning shaft formed into a screw shaft being turned 
by engagement with a narrowed portion of said tubular body at the opening 
portion thereof. 
Also, within the scope of the invention is a driving shaft being provided 
with a weight guiding member for guiding said weight member in a radial 
direction and preventing the vertical movement thereof.

PREFERRED EMBODIMENTS OF THE INVENTION 
FIG. 1 shows an example of a conventional centrifugal force type meter 
typical of the prior art. Such structure employs a driving shaft 101 
inserted through a tube with teeth 103 having a desired number of teeth 
102, a movable frame 104 is fixed to the upper portion of the tube 103. A 
stationary frame 105 is fixed to the upper portion of the driving shaft 
101 interconnects with the aforementioned structural members by means of a 
pair of arms 107 each having a weight 106 mounted thereon, a spring 108 is 
interposed between the two frames and a pinion 109 engages tube 103 and is 
fixedly provided with a pointer 110. 
If the driving shaft 101 is rotated, the stationary frame 105, the arms 
107, the weights 106, the movable frame 104 and the tube 103 turn together 
and a centrifugal force is imparted to the weights 106 for moving the same 
outwardly in the radial direction, and become steady at a position at 
which the spring force and the centrifugal force are balanced. This 
apparatus is so constructed that tube 103 is moved upwardly by the 
centrifugal force of the weights 106 and the pinion 109 is turned and the 
pointer 110 indicates a designated reading. 
This conventional apparatus has such crucial defects that a changeable 
rotation of a wire cable (not shown) causes fluctuation of the pointer 110 
and the weights 106 are subjected to various impact from the vehicle and 
the like and move especially in the vertical upward and downward 
directions, so that fluctuation of the pointer 110 is very large. 
According to the Figures, a driving shaft made of synthetic resin 1 
arranged to be rotated with rotation of a wheel shaft (not shown) being 
transmitted thereto. lThe driving shaft 1 is provided at its desired 
portion with a pair of guide members 2,2 for weights in such a manner that 
those members 2,2 are integral one with another and extend in the radial 
direction so as to be opposite one to another (see FIG. 3). A pair of 
weights 3,3 each having a given weight are formed into an arc at its outer 
periphery portion (see FIG. 5) and are mounted in the pair of the guide 
members 2,2 so as to be slidably movable in the radial direction and 
restrained in movement in the vertical upward and downward direction by 
lower surfaces 4,4 and upper surfaces 5,5 of the guide member 2,2. 
An upper portion 6 of the driving shaft 1 is inserted into an opening 8 of 
a thrust collar 7, and the thrust collar 7 is urged upwards in the axial 
direction by a spring 10 through a sheeting member 9. 
Additionally, an arm collar 11 is mounted rotatably on the other periphery 
of the thrust collar 7 and both sides of the arm collar 11 and the desired 
portions of the weights 3,3 are pivotally interconnected through a pair of 
arms 12,12. Each arm 12 is connected thereto so that both ends may be 
movable about respective pins 13,13. 
Further, the lower surfaces 4,4 of the pair of the foregoing guide members 
2,2 for restraining the vertically upward movement of the weights 3,3, are 
provided at their respective portions near the center thereof with 
recessed escape portions 19,19. Stoppers 20,20 are employed to limit the 
movement of weights 3,3 in the outwardly radial direction. A flange 21 is 
provided on the outer periphery of the thrust collar 7. The thrust collar 
7 is guided and prevented from rotation by a bearing member 15 provided 
integrally with a scale member 14 fixed to a meter casing (not shown). 
When the thrust collar 7 is moved downward, a turning force is generated in 
thread engaging portion 17 of a pointer shaft 16 arranged to be engaged 
with an inlet narrowed portion 18 of the thrust collar opening portion 8. 
Thereby the pointer 11 is swung to turn, and thus it indicates a vehicle 
speed in accordance with the displacement amount of the thrust collar 7 in 
the vertical direction thereof. 
FIGS. 6 and 7 are views which disclose engagement between the pointer shaft 
16 and the thrust collar opening 8. The pointer shaft 16 is made of sheet 
metal and is formed into a thread engaging portion 17 by being twisted 
into any desired angle. A narrowed portion 18 is formed at the inlet of 
the thrust collar opening 8 whereby the sheet metal with threads can be 
inserted therein. 
In the case where the pointer shaft 16 having the thread engaging portion 
17 is inserted in and is slidably engaged with the thrust collar opening 
8, the thrust collar 7 cannot be turned because the same is prevented from 
rotation by the bearing member 15, but the pointer 22 is free so that the 
same can be turned when the thrust collar 7 is moved vertically downwards. 
If the following is assumed: 
.delta.: Vertical movement amount of the thrust collar, 
.alpha.: Twist angle of the pointer shaft sheet portion, 
.lambda.:Length of the twist portion of the pointer shaft, and : Length 
.theta.: Swing angle of the pointer, 
a relative formula .delta..multidot..alpha.=.lambda..multidot..theta. is 
established, and movement of the thrust collar 7 and the swing angle of 
the pointer 22 are in proportion one to another, and therefore the pointer 
indicates corresponding graduation of speed scale or of a rotation number 
scale. 
FIGS. 8 and 9 show another example of the engagement between the pointer 
shaft 16 and the thrust collar opening 8. The pointer shaft 16 is formed 
into a thread engaging portion 17 by making two thrust grooves 17a,17a in 
opposite sides of the periphery of the pointer shaft of a round rod form. 
A pair of facing projections 18a,18a, are provied in the inlet of the 
corresponding thrust collar opening 8, forming therebetween a narrowed 
portion 18 so that the thread engaging portion 17 comprising the two 
thread grooves can be inserted therein. In this case, it is the same as 
the above example, in that the swing angle of the pointer 22 is in 
proportion to the vertical movement of the thrust collar 7. 
Thus, when the driving shaft 1 begins to rotate, the thrust collar 2 is 
moved downward by the centrifugal forces of the weights, and the pointer 
shaft 16 is turned through the thrust grooves 3,3 engaged with the 
projections 18a,18a. The number of the thrust groove 17a may be enough 
with only one. 
In order to prevent rotation of the thrust collar 7, (see FIG. 2), the 
bearing member 15 engages the thrust collar 7 and is formed integrally 
with scale 14, however, this arrangement causes a defect since in order to 
have an indication of the pointer 22 coincident with a zero position of 
the sacle 14 on completion of the assembled parts of a speedometer, 
corrective steps must be taken. For instance, to previously design a 
speedometer so that the pointer indicates the reading below the zero 
position and thereafter is held at the zero position by a stopper. Another 
approach involves improvement to the accuracy of the relative parts, 
however, it causes additional defects that the pointer reading is liable 
to go beyond the permissible range prescribed, and manufacturing costs 
become comparatively high. 
In order to remove the above defects, according to this invention, the 
bearing member 15 is made, for instance, as shown in FIG. 10 and FIG. 11. 
The bearing member 15 is formed into a cylindrical tubular body and is 
provided at its one end with an opening 24 in which the thrust collar 7 is 
to be mounted, and at its other end with a cover 25 of which the center 
portion is provided with a hole 26 for the pointer shaft. 
Additionally, on the upper and outer periphery of the tube portion 27, a 
pair of projections 28,28 are provided integrally therewith on the 
opposite sides thereof. At a higher level than projections 28,28 and in a 
direction perpendicularly thereto, brims 30,30 each having an indented 
notch 29 are provided for prevention of slip in its outer peripheral 
surface. These brims 30,30 are provided integrally therewith on the 
opposite sides thereof. A rib 31 projecting integrally from the inner 
peripheral surface of the cylindrical tube portion 27 of the bearing 
member 15, is arranged to be engaged with an axially extending groove 34 
made in the outer peripheral surface of the thrust collar 7 so that the 
thrust collar 7 is prevented from rotation thereby. 
A hole 33 is provided having a pair of facing escape portions 32,32 in a 
desired portion of the scale 14 on which graduations for speed or the like 
are described. 
According to this arrangement, on assembly of this invention apparatus into 
a speedometer, a driving portion (not shown) of a speedometer is rotatably 
incorporated with the thrust collar 7 mounted in a speedometer body (not 
shown), and a tip portion of the thrust collar 7 is inserted through the 
scale 14 so as to be exposed from the hole 33 of the scale 14, and the 
scale 14 is fixed to the foregoing body. 
The rib portion 31 of the bearing member 15 is coincident with the engaging 
groove 34 formed in the outer peripheral surface of the thrust collar 7 
and is inserted therein. The lower surface of the pair of right and left 
brims 30,30 come to abut the upper surface of the scale 14. In the course 
of this operation, the pair of projections 28,28 positioned at a different 
lower level than the pair of brims 30,30 are passed through the escape 
portions 32,32 of the hole 33 and reaches below the scale 14. From this 
condition, when the notch portions 29,29 made in the respective outer 
peripheries of the brims 30,30 are held by fingers and the bearing member 
15 is turned thereby; the scale 14 is interposed and held between the 
brims 30.30 and the projections 28,28. At that time, the thrust collar 7 
is turned together with the bearing member 15 which has been prevented 
from rotation by engagement thereto. 
Next, the pointer shaft 16 is mounted in the thrust collar 7 by being 
passed through the hole 16 of the cover portion 25 of the bearing 26 
portion. In this case, the pointer shaft 16 is inserted in such a manner 
that the pair of screw grooves made therein may be engaged with a pair of 
projections provided on the inlet of the thrust collar opening and at the 
same time it is being rotated during insertion. 
Though the pointer mounted therein indicates approximately a zero position 
of the scale 14, the same can be thereafter adjusted to indicate the zero 
position accurately and easily because the bearing member 15, and 
accordingly, the thrust collar can be moved while the pointer shaft 
integral therewith can be moved by the turning operation of the brims 
30.30. Further, thereafter, the scale 14 and the bearing member 15 are 
finally positioned together by an adhesive agent or any other suitable 
means. 
When the driving shaft 1 is rotated (either rotation of the right and left 
directions is possible) in proportion to a vehicle speed, the weights 3,3, 
the arms 12,12, and the arm collar 11 are rotated together. The weights 
3,3 are given a centrifugal force, so that they move respectively in 
radially outward directions along the pair of guide members 2,2 provided 
integrally with driving shaft 1. Accordingly, the arm collar 11 connected 
through the arms 12,12 is pushed downward and the thrust collar 7 of which 
the flange 21 is pushed downward against the spring 10, and becomes steady 
at a position at which the forces are balanced. 
As the thrust collar 7 is moved downward, a turning force is produced in 
the thread engaging portion 17 of the pointer shaft engaged with inlet 
narrowed portion 18 of the thrust collar opening 8, so that the pointer 22 
is swung to indicate a certain reading in accordance with the displacement 
amount of the vertical direction of the thrust collar 7 in proportion to a 
vehicle speed. 
As the rotation speed of the driving shaft 1 is gradually decreased, the 
centrifugal force given to the weights 3,3, is weakened so that the 
weights 3,3 are moved in the radially inward directions, and the thrust 
collar 7 is moved upward by the force of the spring 10. Accordingly, the 
pointer gradually indicates a smaller reading, but because the weights 3,3 
move slidably along the guide members 2,2, the reading property of the 
pointer tends to become non-linear due to frictional resistance 
therebetween. In order to minimize the above during actual use, the amount 
of the weights 3,3 and the spring constant of the spring 10 are set within 
the range to reduce any problem during practical use. Also the escape 
portions 19,19 are made in the surfaces of the guide members 2,2, so that 
the pointer 22 may be able to be easily returned to the zero position at 
the time of stopping of the vehicle. 
According to the present invention, the pointer 22 of a meter has no direct 
relation to the driving shaft 1 in operation and also is so constructed, 
that the movement of each weight 3 in the vertical upward and downward 
direction is prevented and at the same time, the slidable movement in the 
radial inward and outward directions is permitted by each guide member 2 
provided integrally on the driving shaft 1. The weight 3 follows the guide 
member 2 and always rotates integrally and synchronously with the driving 
shaft 1, so that there is no difference in time of fastness and slowness. 
Therefore, the invention apparatus offers the following advantages: 
(a) Fluctuation of the pointer is difficult to occur due to a proper 
frictional force of slidable movement. 
(b) Since the weight and the driving shaft always rotate synchronously with 
each other, there is no changeable rotation of the driving shaft 
especially at the time of a low speed. 
(c) Since the displacement of the weight in the vertical direction is 
restrained, no fluctuation of the pointer is produced by shock or 
vibration, or the like. 
Further, in accordance with another feature of this invention, the pointer 
shaft bearing member is prepared separately from the scale and is inserted 
into and engaged with the scale at different height level projections made 
on the outer periphery thereof, so that indication of the pointer can be 
coincided with a zero position of the scale simply and accurately. 
Many modifications and variations of the present invention are possible in 
light of the above teachings. It is, therefore, to be understood that 
within the scope of the appended claims, the invention may be practiced 
otherwise than as particularly described.