Pumps – Motor driven – Electric or magnetic motor
Reexamination Certificate
2001-05-07
2003-02-11
Freay, Charles G. (Department: 3746)
Pumps
Motor driven
Electric or magnetic motor
C417S417000, C417S490000, C417S570000
Reexamination Certificate
active
06517330
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a reciprocating pump for inducting and discharging fluid by means of a reciprocating member, such as a piston, a plunger, or the like, and, in particular, to a reciprocating pump provided with a malfunction-detector for detecting malfunctions such as an induction failure and a failure to discharge a fluid under pressure to a destination.
A conventional reciprocating pump employed for the lubrication of a small air-cooled, two-stroke cycle gasoline engine (hereinafter referred to simply as an engine), which is suitable for use as a power source for a portable power working machine such as a chain saw, is shown in FIG.
3
. The pump
2
includes a main body
60
having a cylinder portion
65
that is provided with an induction port
66
and a discharge port
67
. The discharge port
67
is opened and closed by a ball valve
75
. One end of a plunger rod
71
is affixed, such as by press-fitting, to a main plunger body
72
of a reciprocating member
70
. The other end of the plunger rod is slidably received in the cylinder portion
65
. A solenoid
80
attached to one end portion (on the right side in the drawing) of the main body
60
drives the reciprocating member
70
. A delivery passageway member
90
is threaded into the other end portion (on the left side in the drawing) of the main body
60
.
The ball valve
75
is normally urged in a direction to close the discharge port
67
by means of a coil spring
74
, which is interposed between the ball valve
75
and the delivery passageway member
90
. 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 retainer sleeve
84
, which is threaded onto the outer circumferential wall of one end of the main body
60
. A cupshaped cover
85
fits over and is affixed to the outer circumferential wall of the retainer sleeve
84
.
The solenoid
80
is energized by current pulses supplied to it at a predetermined cycle from an outside power source (not shown) by electrical conductors (not shown) that pass through a hole
68
in the main body
60
. When the solenoid
80
is switched to 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 a direction to open the induction port
66
. As a result, fluid (lubricating oil for the 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, a rear flange portion
73
of the main plunger body
72
engages and is stopped by the cover
85
.
FIG. 3
shows the state of the pump
2
when the solenoid
80
is OFF.
When the solenoid
80
is switched to ON, 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 a direction to close the induction port
66
, and at the same time, the fluid in the valve chamber
61
is pressurized so as to push the ball valve
75
open (leftward in the drawing). The flange portion
73
of the main plunger body
72
engages a plastic buffer plate
88
adhered to the right end face of the retainer sleeve
84
. As a result, the discharge port
67
is opened, thus permitting the fluid in the valve chamber
61
to flow into the delivery passageway member
90
.
When the pump
2
of
FIG. 3
is installed on an engine, lubricating oil in an oil tank (not shown) is inducted through an oil strainer and an inlet pipe (not shown) into the valve chamber
61
from the induction port
66
. The lubricating oil thus inducted into the valve chamber
61
is then pressurized and is discharged from the pump
2
through the discharging port
67
, the ball valve
75
, a delivery passageway
92
in the delivery passageway member
90
, a check valve
95
disposed at the delivery port of the delivery passageway
92
, and an oil delivery pipe (not shown) coupled with the delivery passageway member
90
, to the destination, i.e., the moving parts of the engine.
Like any pump, the reciprocating pump described above may malfunction. For example, the induction side of the pump may become clogged so that the oil is no longer normally inducted, or air may be inducted with the oil due to a leak in the line leading to the pump from the supply tank. Also, the pipe leading from the discharge side of the pump may become clogged, thereby making it impossible to feed the oil to the destination thereof. In the event of a malfunction of the pump, it is desirable to stop the engine to avoid seizure or to provide an alarm, warning of the malfunction.
It is conventional to attach a pressure sensor to the reciprocating pump so as to detect a fluctuation of pressure at the delivery port. In this case, the aforementioned abnormalities in the operation of the pump can be detected based on an output (detection signal) emitted from the pressure sensor.
More specifically, as shown in
FIG. 3
, a take-off port
97
is provided on the delivery passageway member
90
so as to provide via a rigid pipe
98
, for instance, a quantity of oil present at the delivery port (a delivery pressure) to a pressure sensor
100
, which detects fluctuations of pressure at the delivery port. Suitable pressure sensors
100
include transducer type sensors, which are designed to generate an electric signal after converting the delivery pressure of oil into another kind of physical quantity (such as the magnitude of displacement) by making use of a diaphragm or the like. Transducer-type sensors include those having a strain gage adhered to a diaphragm, those having a coil and a core symmetrically arranged on both sides of a magnetic diaphragm so as to constitute an equilibrium magnetic circuit, and those in which a conductive diaphragm and an electrode are arranged to face each other so as to constitute a pair of capacitors. The foregoing types are available commercially.
In previously used types of pressure sensors, the output of the pressure sensor
100
changes synchronously with the ON/OFF operation (the discharging and inducting operation by the reciprocating member
70
) of the solenoid
80
as shown in FIGS.
4
(A) to
4
(C). When the oil is normally supplied without the aforementioned abnormalities, the output of the pressure sensor
100
becomes wavy, as shown in FIG.
4
(A); when the oil is cut off, the sensing of a change in output from that of the normal operation slightly lags in time behind (due to the entrainment of air) and at the same time, the amplitude of output is slightly reduced, as shown in FIG.
4
(B); and when the clogging of oil occurs on the delivery side of the pump, the output of the pressure sensor
100
is greatly increased, as shown in FIG.
4
(C). Therefore, it becomes possible, through the processing of the output of the pressure sensor
100
, to detect the type of abnormality in the operation of the pump.
The pressure sensors which are generally available commercially, such as those mentioned above, are somewhat expensive for use in detecting abnormalities, such as the cutoff of oil from the pump intake or the clogging of oil on the delivery side, of a reciprocating pump employed for the lubrication of the engine of a portable working machine such as a chain saw. In addition to the relatively high cost, it is also required in the case of the aforementioned pressure sensors to introduce a fluid such as oil directly into the pressure sensor, thereby raising a problem of the space for mounting the aforementioned pressure sensors on the reciprocating pump.
SUMMARY OF THE INVENTION
The present invention has been made in response to the aforementioned needs. In particular, it is an object of the present invention to provide in a reciprocating pump a detector that is capable of reliably detecting abnormalities in the inducting and discharging of fluid,
Enomoto Kiyoshige
Hironaka Yoshiaki
Kondo Tadashige
Baker & Botts LLP
Freay Charles G.
Gray Michael K.
Kioritz & Corporation
LandOfFree
Reciprocating pump does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Reciprocating pump, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Reciprocating pump will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3137410