Transmitter for monitoring the condition of a tire

Details Transmitter for monitoring the condition of a tire Transmitter for monitoring the condition of a tire

2002-05-29

2004-03-23

Oen, William (Department: 2855)

Measuring and testing

Tire, tread or roadway

Tire inflation testing installation

Reexamination Certificate

active

06708558

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to transmitters of tire condition monitoring apparatuses, and, more particularly, to transmitters attached to wheels, to which tires are connected, for transmitting data indicating the condition of the tires, such as air pressure, to a receiver installed in a vehicle.
A wireless tire condition monitoring apparatus has been proposed to enable a driver to monitor the condition of a tire of a vehicle in a passenger compartment.
With reference to
FIG. 4
, the tire condition monitoring apparatus includes a transmitter
50
for transmitting data indicating the air pressure of the tire to a receiver (not illustrated), which is installed in the vehicle. The transmitter
50
has a square box-like casing
51
and a valve stem
52
, which is formed integrally with the casing
51
. The casing
51
accommodates an electronic board
53
and a battery
54
. A communication hole (not illustrated) is formed in the casing
51
.
The electronic board
53
is substantially square. Two bosses
55
,
56
, which are integrally formed with the casing
51
, fix the electronic board
53
. The bosses
55
,
56
are located at diagonal positions in the electronic board
53
. The electronic board
53
is provided with circuit elements
57
, such as a pressure detecting element and various signal processing elements. A battery
54
is connected to the electronic board
53
for supplying power to the circuit elements
57
.
With reference to
FIG. 5
, the casing
51
of the transmitter
50
is fitted into a valve hole
63
of a wheel
62
such that the casing
51
is located in the interior of a tire
61
. A valve stem
52
introduces air to the interior of the tire
61
through a communication hole. The valve stem
52
also functions as an antenna that transmits the data indicating the air pressure of the tire
61
.
The casing
51
is formed of resin to reduce the weight of the transmitter
50
. When the vehicle is moving, centrifugal force acts on the transmitter
50
, which is attached to the wheel
62
. The centrifugal force is generated in relation to the outer diameter of the wheel
62
, the outer diameter of the tire
61
, and the traveling speed of the vehicle. For example, the centrifugal force is approximately 1,500 G when the vehicle traveling speed is 300 km/h. The centrifugal force deforms the casing
51
such that the positions of the bosses
55
,
56
relative to each other are changed. This generates force, which acts on the electronic board
53
. The electronic board
53
is also affected by the centrifugal force, which is caused by the movement of the vehicle. The electronic board
53
is thus deformed by these forces. This applies excessive force to the circuit elements
57
, thus damaging the circuit elements
57
.
The valve hole
63
of the wheel
62
is formed such that the valve hole
63
is inclined with respect to the rotational axis of the wheel
62
at a predetermined angular range (17.5 to 20.0 degrees). Also, the position of the valve hole
63
may be varied among products. Thus, the inclination angle of the valve stem
52
with respect to the casing
51
needs to be selected such that the casing
51
does not contact a drop center portion
62
a
of the wheel
62
when the transmitter
50
is attached to the wheel
62
.
If the inclination angle of the valve hole
63
with respect to the rotational axis of the wheel
62
is relatively large, the casing
51
is spaced from the drop center portion
62
a
of the wheel
62
at a relatively large interval when the transmitter
50
is attached to the wheel
62
. Thus, if a bead portion
61
a
of the tire
61
contacts the casing
51
when the tire
61
is being attached or detached from the wheel
62
, force acts on the casing
51
to urge the casing
51
toward the drop center portion
62
a
of the wheel
62
. With reference to FIGS.
6
(
a
) and
6
(
b
), the force deforms the casing
51
, as indicated by the broken lines. This deforms the electronic board
53
and thus damages the circuit elements
57
.
SUMMARY OF THE INVENTION
Accordingly, it is an objective of the present invention to provide a transmitter of a tire condition monitoring apparatus that prevents a circuit element from being damaged.
To achieve the foregoing and other objectives and in accordance with the purpose of the present invention, the invention provides a transmitter of an apparatus for monitoring the condition of a tire of a vehicle. The transmitter includes an installed portion, a casing, and an arm. An element for detecting the condition of the tire is installed in the installed portion. The casing accommodates the installed portion. The installed portion is connected to the casing by the arm. The arm tolerates reactive force acting on the casing and protects the installed portion from that reactive force.
Other aspects and advantages of the invention will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.


REFERENCES:
patent: 5731516 (1998-03-01), Handfield et al.
patent: 5844131 (1998-12-01), Gabelmann et al.
patent: 6357833 (2002-03-01), Bajer

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