Pumps – With signal – indicator – or inspection means
Reexamination Certificate
2002-05-09
2004-06-01
Yu, Justine R. (Department: 3746)
Pumps
With signal, indicator, or inspection means
C417S018000, C417S415000, C417S417000, C417S559000, C073S721000, C073S727000
Reexamination Certificate
active
06742994
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field of the Invention
The present invention relates to a reciprocating pump for sucking and discharging a fluid by means of a reciprocating member such as a piston, a plunger, etc., and in particular to a reciprocating pump provided with malfunction-detecting means for detecting malfunctions or abnormalities, such as sucking failure, and failure to discharge a fluid under pressure up to a destination.
2. The Related Art
An ordinary reciprocating pump to be employed for the lubrication of a small air-cooled two-stroke gasoline engine (hereinafter, referred to as an internal combustion engine) which is adapted to be employed as a power source for a portable power working machine, such as a chain saw, is constructed as shown in
FIG. 11
, for instance. This conventional reciprocating pump shown in
FIG. 11
will be briefly explained as follows. The reciprocating pump
2
basically comprises a main body
60
in which a cylinder portion
65
, provided with awl sucking port
66
and an discharging port
67
to be opened or closed by a ball valve
75
, is fittingly received, a reciprocating member
70
, comprising a plunger rod
71
slidably fitted in the cylinder portion
65
and a main plunger body
72
into which a rear end portion of the plunger rod
71
is press-inserted and fixed thereto, a solenoid
80
attached to one end portion (on the right side in the drawing) of the main body
60
so as to drive the reciprocating member
70
, and a delivery passageway member
90
screw-engaged with the other end portion (on the left side in the drawing) of the main body
60
.
The ball valve
75
is normally urged in the direction to close the discharging port
67
by means of a coil spring
74
which is interposed between the ball valve
75
and the delivery passageway member
90
. On the other hand, the reciprocating member
70
is normally urged toward the right side of the drawing by means of a coil spring
78
which is interposed between the cylinder portion
65
and the main plunger body
72
.
The solenoid
80
is secured between the main body
60
and a securing tube body
84
which is screw-engaged with the outer circumferential wall of one end of the main body
60
. The outer circumferential wall of the securing tube body
84
is encased by a stopper cover
85
having a bottomed cylindrical configuration.
The solenoid
80
is designed to be switched ON (electrical magnetization)/OFF by way of a driving pulse to be fed thereto at a predetermined cycle from an outside power source (controlling device) (not shown). When the solenoid
80
is switched OFF from ON, the reciprocating member
70
is caused to move rightward in the drawing due to the urging force of the coil spring
78
, thereby moving the plunger rod
71
in the direction to open the sucking port
66
. As a result, a fluid (a lubricating oil for the internal combustion engine) is permitted to flow into a valve chamber
61
which is formed between the plunger rod
71
and the ball valve
75
, and, at the same time, the rear flange portion
73
of the main plunger body
72
is contacted with the stopper cover
85
(the state indicated by a solid line in the drawing).
When the solenoid
80
is switched ON in this state, the reciprocating member
70
is caused to move leftward in the drawing due to the generation of magnetic force, thereby moving the plunger rod
71
in the direction to close the sucking port
66
, and, at the same time, the fluid in the valve chamber
61
is pressed so as to push the ball valve
75
leftward in the drawing. As a result, the flange portion
73
of the main plunger body
72
contacts a plastic buffer plate
88
adhered to the right end face of the securing tube body
84
.
As a result, the discharging port
67
is opened, thus permitting the fluid in the valve chamber
61
to flow toward the delivery passageway member
90
.
Therefore, it is possible, through the ON/OFF operation of the solenoid
80
, to enable the lubricating oil in an oil tank (not shown) to be introduced, through an oil strainer and an inlet pipe, etc. (not shown), into the valve chamber
61
from the sucking port
66
. The lubricating oil thus introduced into the valve chamber
61
is then permitted to flow therefrom in a pressurized manner so as to be delivered, through the discharging port
67
, the ball valve
75
, a delivery passageway
92
extending through the delivery passageway member
90
, a check valve
95
disposed at the delivery port of the delivery passageway
92
, and an discharge pipe (not shown) coupled with the delivery passageway member
90
, to the destination, i.e. the sliding portions of the internal combustion engine, etc.
The reference number
68
in
FIG. 11
represents a space for introducing the power cables (not shown) for feeding a driving pulse to the solenoid
80
.
If any operational abnormality occurs in the reciprocating pump described above, e.g. the sucking side of the pump is clogged, i.e. the oil (fluid) can no longer be normally sucked due to the exhaustion of oil (due to the sucking of air), or a clogging of the pipe at the discharge port is generated to thereby make it impossible to feed the oil to the destination thereof it is desirable to take any appropriate countermeasure, such as to stop the internal combustion engine to prevent seizure, or to give an alarm.
Therefore, it is conventionally considered to attach a pressure sensor to the reciprocating pump so as to detect a fluctuation of pressure at the discharge port. In this case, the aforementioned abnormality can be detected based on an output (detection signal) emitted from the pressure sensor.
More specifically, as shown in
FIG. 11
for instance, a take of port
97
is installed to the delivery passageway member
90
so as to introduce, via a rigid pipe
98
for instance, a portion the oil existing at the discharge port (a delivery pressure) into a pressure sensor
100
to thereby detect a fluctuation of pressure at the discharge port.
For this purpose, a pressure sensor
100
of intermediate conversion type, which is designed to pick up all electric signal after converting the discharge pressure of oil into another kind of physical quantity (such as the magnitude of displacement) by making use of a diaphragm, etc., is generally employed. For example, a sensor wherein a strain gage is adhered onto a diaphragm, a sensor wherein a coil and a core are symmetrically arranged on both sides of a magnetic diaphragm so as to constitute an equilibrium magnetic circuit, and a sensor wherein a conductive diaphragm and an electrode are arranged to face each other so as to constitute a pair of capacitors are available in the market.
In this case, the output of the pressure sensor
100
changes synchronously with the ON/OFF operation (the discharging and sucking operation by the reciprocating member
70
) of the solenoid
80
as shown in FIGS.
12
(A) to
12
(C). Namely, when the oil is normally supplied without any aforementioned abnormalities, the output of the pressure sensor
100
becomes wavy as shown in FIG.
12
(A). When the oil is exhausted, e.g., clogging of the sucking side of the pump, the timing of discharging a change in output from that of the normal operation lags slightly behind (due to the entrainment of air) and at the same time, the amplitude of the output is slightly reduced as shown in FIG.
12
(B). When the clogging of oil is caused to occur on the discharge side, the output of the pressure sensor
100
is extremely increased (becomes very high) as shown in FIG.
12
(C). Therefore, it becomes possible, through the processing of the output (detected signals) of the pressure sensor
100
, to detect the type of abnormality that has occurred.
The pressure sensors that are generally available in the market as mentioned above however are somewhat expensive if they are to be employed as detecting means for detecting abnormalities, such as the exhaustion of oil or the clogging of oil on the discharge side, of a reciprocating pump to be employed for the lubrication of an internal com
Enomoto Kiyoshige
Hironaka Yoshiaki
Kondo Tadashige
Baker & Botts LLP
Kioritz & Corporation
Sayoc Emmanuel
Yu Justine R.
LandOfFree
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