Measuring and testing – Liquid level or depth gauge – Float
Reexamination Certificate
2001-07-30
2004-03-30
Williams, Hezron (Department: 2856)
Measuring and testing
Liquid level or depth gauge
Float
C073S29000R
Reexamination Certificate
active
06711950
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a liquid level detecting apparatus, and particularly has a feature in miniaturization of a liquid level detecting apparatus.
BACKGROUND OF THE INVENTION
A conventional liquid level detecting apparatus
71
is disclosed in Japanese Utility Model Laid-Open No. 2029/1993, and as shown in FIG.
13
and
FIG. 14
, a float arm
72
having a tip end at which a not shown float moving according to variation of a liquid level is provided, is rotatably supported in a main body frame
73
. The float arm
72
is rotatably supported in the main body frame
73
through an arm holder
74
.
A contact holding member
75
is fixed to the arm holder
74
, and a sliding contact
76
is protrusively provided at the tip end of the contact holding member
75
. A pair of holding pieces
74
a
are formed at the arm holder
74
in order to position the float arm
72
and the contact holding member
75
held by the arm holder
74
, the opposing surfaces of the holding pieces
74
a
are formed into arc surfaces to conform to the outer shape of the float arm
72
, the float arm
72
is press inserted into the arc surfaces from an upper opening portion of the holding pieces
74
a
while spreading the holding pieces
74
a
, and a structure is realized in which the float arm
72
does not come out toward the upper portion by elastic restoring force of the holding pieces
74
a.
The sliding contact
76
slides on a circuit board
77
provided in the main body frame
73
and made of ceramic at a predetermined contact pressure.
The circuit board
77
is provided, on its surface, with a not-shown band-like resistor and a not-shown comb electrode arranged into a band along the band-like resistor, the sliding contact
76
is made to slide on and come in contact with the comb electrode at the predetermined contact pressure, and a current variation corresponding to the quantity of varying resistance between the sliding contact
76
and the base end of the resistor is outputted, so that the liquid quantity is detected.
In the liquid level detecting apparatus
71
like this, a bearing structure of the float arm
72
is such that a bearing fit portion
78
is formed in the main body frame
73
, a two-stage cylindrical bearing member
79
having different diameters is rotatably fitted in the bearing fit portion
78
, an end portion
82
of the float arm
72
bent into an L shape in a substantially rectangular direction is inserted to pass through a shaft hole
80
provided in the bearing member
79
and a shaft hole
81
provided in the base portion of the arm holder
74
, a push nut as a falling out preventing member
83
is press fitted to a through end portion
82
a
of the end portion
82
protruding from the lower surface of the bearing member
79
, and the float arm
72
is pulled downwardly from the bearing member
79
by the press fitting of the push nut
83
and is clamped.
A receiving surface
85
for receiving a flange engagement portion
84
formed by header working at the outer periphery of the middle of the end portion
82
of the float arm
72
is formed at a hole fringe portion of the shaft hole
81
of the arm holder
74
, and a contact surface
86
is formed at a position where the main body frame
73
is in contact with the bearing member
79
. The arm holder
74
receives the engagement portion
84
of the float arm
72
at the receiving surface
85
, and the float arm
72
, the arm holder
74
, and the contact holding member
75
are fitted to one another so that they do not rattle. Accordingly, when the push nut
83
is fastened, the bearing member
79
is fixed in a state where it is fastened by both the arm holder
74
and the push nut
83
, and a structure is realized in which the float arm
72
and the bearing member
79
are rotated together. An upward force is always applied to the arm holder
74
by a coil spring
87
electrically connected to the contact holding member
75
. A stepped portion
78
a
of the bearing fit portion
78
and a stepped portion
79
a
of the bearing member
79
receive the upward force of the coil spring
87
, and the float arm
72
, together with the bearing member
79
, does not come out toward the upside. Since the bearing member
79
protrudes from the main body frame
73
to come in contact with the arm holder
74
, and the main body frame
73
is separate from the arm holder
74
, the combination of the float arm
72
, the arm holder
74
and the bearing member
79
is rotated relative to the main body frame
73
.
Incidentally, reference numerals
88
and
89
designate terminals, the one terminal
88
is connected to the circuit board
77
, and the other terminal
89
is connected to the contact holding member
75
through the coil spring
87
.
In recent years, the liquid level detecting apparatus
71
installed in a not-shown fuel tank, a fuel pump and the like are installed as a combined unit in the fuel tank. From a problem of fitting caused from the formation of the unit and so on, the liquid level detecting apparatus
71
is also desired to be miniaturized. Then, an object is to provide a liquid level detecting apparatus which can achieve miniaturization.
DISCLOSURE OF THE INVENTION
A liquid level detecting apparatus of the present invention comprises a float arm provided with a float floating on a liquid surface, an arm holder for holding the float arm and provided with shaft portions as rotation supporting points of the float arm, a main body frame provided with two bearing portions for axially supporting the shaft portions of the arm holder, a circuit board fixed to the main body frame, and a contact holding member provided with a sliding contact sliding on the circuit board and fixed to the arm holder, and the arm holder is positioned between the bearing portions and holds the float arm and the contact holding member. By the structure like this, the liquid level detecting apparatus capable of achieving miniaturization can be provided. Besides, the shaft portions are supported by the two portions of the bearing portions, so that it is possible to provided the liquid level detecting apparatus which is small and in which the axes of the shaft portions are hard to shift.
Besides, a liquid level detecting apparatus comprises a float arm provided with a float floating on a liquid surface, an arm holder for holding the float arm and provided with shaft portions as rotation supporting points of the float arm, a main body frame for axially supporting the shaft portions of the arm holder, a circuit board fixed to the main body frame, and a contact holding member provided with a sliding contact sliding on the circuit board and fixed to the arm holder, in which the two separate shaft portions are provided at the arm holder, two bearing portions for axially supporting the two shaft portions are provided at the main body frame, and the arm holder holding the front arm and the contact holding member is provided between the bearing portions. By the structure like this, the liquid level detecting apparatus,capable of achieving miniaturization can be provided. Besides, the shaft portions are supported at two places of the bearing portions, so that it is possible to provided the liquid level detecting apparatus which is small and the axes of the shaft portions are hard to shift.
Besides, a liquid level detecting apparatus comprises a float arm provided with a float floating on a liquid surface, an arm holder for holding the float arm and provided with shaft portions as rotation supporting points of the float arm, a first frame constituting a main body frame and provided with a first bearing portion for axially supporting the shaft portion of the arm holder, a second frame constituting the main body frame and provided with a second bearing portion for axially supporting the shaft portion of the arm holder, a circuit board fixed to the first frame, and a contact holding member including a sliding contact sliding on the circuit board and fixed to the arm holder, the arm holder is held by the first and the second frames, and
Sakamaki Akira
Tanaka Tomoyuki
Yamaura Takayuki
Frank Rodney
Nippon Seiki Co. Ltd.
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