CA2042966A1 - Low pressure indicating device for a pneumatic tire - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
An apparatus adapted to be directly connected to the valve stem of an automobile tire to indicate a low pressure condition, comprises a bulb, cell device and compression spring switch assembly uniquely responsive to a low pressure condition in the tire for operating the switch assembly thereby connecting an electrical circuit to energize the bulb. The apparatus also includes a diaphragm and a special method of varying the over all volume of the diaphragm. The apparatus can be adjusted in advance to light the bulb when a selected pressure is detected a low pressure than the predetermined pressure.

Description

~2~66 :""
LOW PRESSURE INDICATING DEVICE FOR A PNEUMATIC TIRE ::
,~ .

The invention relates to a low pressure indicating device for a pneumatic tire, more particularly to a low pressure indicating device capable of being secured to each individual inflating valve of a pneumatic tire in which a light of the device is energized in the ~ ;
presence of a low pressure detection or when the pressure of the pneumatic tire is deflated to a ~ :
pressure below a predetermined proper pressure. ;:- .
' ~ ' :. .
With the increasing costs of tires, it has become highly desirous from an economic point of view to insure that tire pressure does not fall below a certain valve.
It is com~on knowledge in the f ield that lower than normal air pressure in the tire is the maior cause of blowouts, uneven wearing and general deterioration of tires. Commercial truck and bus operators are particularly concerned with obtaining optimum use from tires since the replacement of tires represent a major expense in the operation of trucking or busing businesses.
It is also well known that operating tires at lower than normal pressure reduces the efficiency of the particular unit, hence increasing the cost for ., . . . . ' . ! .. , .. . ~

--2~ 2 9 ~ 6 transporting any given vehicle. In view of high cost for replacing tiresl it will be most profitable to the maximum usable life from tires in rolling business.
The prior art has recognized the need for automatic low pressure indicating systems. Unfortunately, these devices have been complicated, unduly expensive and occasionally too sophisticated for the user to operate.
For example, U.S Pat. No. 3,533,063 issued to G~Eo Garcia on Oct. 6 1970, describes the use of a radio transmitter receiving signals from each of the four tires. In the event of a detected low pressure condition, the radio transmitter generates a signal which is received by a radio receiver located in the cab of the vehicle. In U.S. Pat. No. 2, 229,192 issued to L. Schultz on Jan~ 21, 1941, there is disclosed a mechanical indicating device located in the cab portion of the vehicle having indicators directly related to the pressure of the individual four tires.

These prior art devices have not been accepted by the commercial market because of the inherent complexity and special valve arrangements needed to sense the low pressure in the individual tire. The individual display devices in the cab of the vehicle have also necessitated additional wiring, in some cases radio receivers and transmitters and other complicated and sophisticated apparatuses that are generally disliked by the vehicle operators and users.

;' '; ~ ' ' . .. . : ,, ,,.,; .,; :. '' :

A feature of the present invention is to provide a completely portable device that is attached to the valve stem of an individual tire.
Another object of the present invention is to provide a signal device including a light producing unit which is energized when when the attached tire is deflated to a pressure lower than it should normally have.
Still another object is to provide a signal device with a simple construction for actuating the light producing unit upon detecting a lower pressure in the attached tire than the properly required pressure.
One feature of the present invention is to provide a device which can be used as a cap for the inflating ; ~ valve of a tire as well as a signal device to signal when the pressure in the tire is seriously deflated or falls below the required pressure.
Accordingly, the low pressure indicating device of the present invention includes a cap-like casing having a transparent closed end and an open end, a hollow adapter having a first open end threadably connected to the open end of the cap-like casing, a sécond end to be connected to an inflating valve of a pneumatic tire, and an enclosing wall connecting the first and second end. A transverse partition with a passage is provided in the enclosed wall adjacent to the second end of the . .

.

,. , , , , :, . ..

__ ~ 6 adapter. A light unit is provided in the cap-like casing. The light unit includes a battery, a bulb, and -a leaf spring and electrically connected to one another in series. A compression spring sleeved around a push rod provides a closed electrical path for energizing the bulb in the normal position, and an open electrical path for extinguishing the bulb in the compressed positionO A diaphragm is hermetically disposed over the transverse partition be~ween the first and second .
ends of the adapter to define a chamber in-~etween the diaphragm and the transverse partition. An adjusting screw member varies the height of the chamber between the diaphragm and the tra~sverse partition OtheL features and advanta~es of the present invention will become more apparent in the following detailed description, including drawings, all of which shows a non-limiting form of the invention, and of which:

Figure 1 shows an exploded view of a low pressure indicating device of the present invention.

Figure 2 i5 a cross sectional view of a low pressure indicating device of the present invention.
Figure 3 illustrates the diaphragm of the low pressure indicating device of the present invention as adjusted to a higher position than the normal position.
Figure 4 illustrates the diaphragm of the low . .

., ~ , ........... . . ........... ....

,, , . . - -, : . , ' . ' , : ~ "

s 2 ~ ~ 2 ~
- . -pressure indicating device of the present invention being adjusted to a lower position than the normal position.
:, ,' .
Referring to Figures 1 and 2, a low pressure indicating device of the present invention is shown to comprise a cap-like casing 60, a hollow adapter 1, a light unit 5, a diaphragm 3 and a resilient means 4.
The hollow adapter 1 has a first open end 11 with two projections 121,122 and a second end to be connected threadably to an inflating valve of a pneumatic tire. An enclosed wall interconnects the first and the second ends. A transverse partition 101 having a central through-hole 104 and a passage 103 is : provided in the enclosed wall adjacent to the second end 10 o the hollow adapter 1. :
A light unit 5 iS provided on a disc member 2 which I -.
~ . .
: in turn is provided in the enclosed wall. The light unit 5 includes a bulb 514, a couple of cells 511, 512, a leaf spring assembly 50 electrically connected .
to one another in series by a known related art~ A :
compression spring 42 is sleeved over a push rod 4. '.
The leaf spring assembly 50 provides a closed electrical path for energizing the bulb 514 in a normal condition, that is to say before the second end 10 of :;
the hollow adapter 1 is threadably connected the inflating valYe o~ a tire to be monitored, and an open :,.
.

.: .:

; j . ~ :, . - . . .. . .. . . .. ... ..

2~2~

electrical path for extinguishing the bulb 514 in a compressed condition, that is after the second end 10 of the hollow adapter 1 is mounted on the inflating valve of the tire to be monitored. In which condition, the compression spring 42 will be compressed by the incoming pressure of the attached tire.
The diaphragm 3 has a flange with an annular groove 31 oriented inward from the periphery of the same. The diaphragm 3 is generally made of elastic material and is provided hermetically on a circular plate 90 which has a central hole. The circular plate 90 engages the annular groove 31 of the diaphragm and later is fixedly attached to the transverse partition 101. The diaphragm 3 and the transverse partition 101 defines a chamber between them.
Since the threaded bolt 80 can be lowered or raised in the tubular member 102, the overall volume of the chamber can be varied accordingly. A push rod 4 with a compression spring 42 around it, is provlded between the disc member 2 and the diaphragm 3 as shown in Figure 2, in a known manner that one end 40 of the push rod 4 is in contact with the leaf spring 50, but the push rod 4 can not push the leaf spring 50l so the push rod 4 can not cause connection, or opening of the electric path while the other end 41 of the push rod 4 is in contact with the diaphragm 3, as illustrated in the picture. Then, the first end 11 of the hollow :; . ., ; : , : :, ;
,. . , , , ,:
.

: ~ : ,: ., , "

--7-- ~2~6~
:'. ' adapter 1 is threadably engaged with the open end of the cap-like casing.
The threaded bolt 80 has a head with a cross dimenslonal area larger than the cross dimensional area of the head 41 of the push rod 4, a concaved upper side 801 and two through-holes 8011. The threaded bolt 80 is threadably sleeved in a tubular member 102. The head 41 of the push rod ~ is in contact with the diaphragm 3 while the periphery of the concave upper L0 side 801 of the threaded bolt 80 abuts the diaphragm 3.
Therefore, when the threaded bolt 80 is slightly raised, the position of the push rod 4 will not change but the overall volume of the chamber will change. In another words~, the diaphragm 3 will become thinner than it is i~s ~r~er p~sition.
~e bottom surface of the circular plate 90 has a .~
plurality of projections extending thereof which hold the cross arms~1022 of the tubular member 102 hold the tubular member 102 in its proper position relative to ., 20- the transverse partition and are kept from rotating.
In order to properly fit on the first end ll of the hollow adapter 1, the disc member 2 is provided with -two recessions 231, 232 into which the projections 121, 122 of the first end 11 of the adapter 1 extend, holding them in a proper arrangement.
To make adjustment more convenient, a groove 803 is provided at the tip of the threaded bolt 80, so that ~;
'.

'; " , ':. ~" .''-' ''"; '"., ','''. ' '" ' ';, "..: ''', ."''. ' ' ' '' ;"'~` ., ' ~ , .

2 ~

the threaded bolt 80 can be turned easily by a screw driver, as illustrated in Figures 3 and 4. One thing to be noticed is that when the device of the present invention is mass produced, a special means is provided in the device which w111 stop the bulb from energizing so that the cells can not run out. That special means is removed only when mounting the device to an inflating valve of a pneumatic tire. Another thing to be noticed is that the diaphragm 3 of the device is adjusted in advance such that the bulb is energized only when the predetermined amount of pressure in a pneumatic tire is detected.
The most distinct feature is that the diaphragm 3 ~; of the present device can be adjusted so that the bulb will be lit only at ~he pressure the user selects as minimum optimum. For example, if the diaphragm 3 of the device is adjusted to monitor a predetermined pressure, 32 psi, after fixing the device on the inflating valve of the attached tire, the pressure of the tire enters into the chamber through the passage 103 of the transverse partition 101, pushing the diaphragm 3 upward which in turn pushes the push rod 4 upward so as to interrupt the closed electric path, extinguishing the bulb 514. Or upon reading that there is insufficient pressure in the tire, that is, the pressure being lower than 32 psi, the diaphragm 3 can not over come the compression force of spring 42, thus ,. , ", ,~
: ~. .
~. :

9~ 2 ~

the bulb will be illuminated. Since the device is always mounted on the inflating valve of an individual tire, one does not have to take the trouble to measuring the pressure, but only needs to check the bulb is lit or not, enable him to know if the tire pressure is too low at glance.
With the invention thus explained, it is obvious to those skilled in the art that various modifications and variations can be made without departing from the scope and spirit of the present invention. It is therefore intended that this invention be limited as only in the appended claims.
:
- :' .--:-, .:,.' ~' ':' . , . . .

, , , ~. , , . . :, , , , ;, , ,:

,', ' ,',.' ',- , "' '; ' ' .', ' ' , ' ;'

Claims (2)

1. A low pressure indicating device for a pneumatice tire including a cap-like casing having a transparent closed end and an open end, a hollow adapter having a first open end threadably engaging with said open end of said cap-like casing and a second open end to be connected to an inflating valve of said pneumatic tire, said hollow adapter having an enclosed wall inter-connecting said first and said second end of said adapter, a transverse partition with a central through-hole being formed in said enclosed wall adjacent to said second end of said adapter, a light unit disposed in said cap-like casing, said light unit including a bulb, a cell member, and a leaf spring each electrically connected in series to one another, a diaphragm provided over said transverse partition between said light unit and said transverse partition and hermetically covering said transverse partition, defining a chamber in-between said diaphragm and said transverse partition, a compression spring sleeved over a push rod and disposed between said light unit and said diaphragm, said push rod having a first end abutting said diaphragm and a second end connecting to said leaf spring, said compression spring being compressible and expandable between a first position which provides a closed electrical path, energizing said bulb, and a second position which provides an open electrical path, extinguishing said bulb;
characterized in that said transverse partition further has a passage communicating said chamber with outer environment, a screw assembly including a threaded bolt having a head with a cross dimensional area larger than the cross dimensional area of said first end of said push rod, said head having a concave portion, the periphery of which abuts said diaphragm, said screw assembly being hermetically and adjustably inserted in said central through-hole of said transverse partition.

2. A low pressure indicating device as claimed in Claim 1, characterized in that said screw assembly includes a tubular member having a first end, a second end and a threaded through-hole extending from said first end to said second end, four fingers extending radially and outwardly from said tubular member adjacent to said first end, said tubular member being hermetically inserted in said central through-hole of said transverse partition with said four fingers lying across said transverse partition in said chamber while said second end of said tubular member extends towards said second open end of said hollow adapter, a circular plate with a central hole, a top side and a bottom side being provided over said four fingers of said tubular member with said first end of said tubular member extending through said central hole of said circular plate, said bottom side of said circular plate having four projections extending downward, holding said four fingers in a fixed position, said threaded bolt being engaged in said threaded through-hole of said tubular member.