U.S. patent number 3,841,793 [Application Number 05/399,994] was granted by the patent office on 1974-10-15 for motor-pump system for preventing a vapor lock.
This patent grant is currently assigned to General Motors Corporation. Invention is credited to Daniel C. MacManus.
United States Patent |
3,841,793 |
MacManus |
October 15, 1974 |
MOTOR-PUMP SYSTEM FOR PREVENTING A VAPOR LOCK
Abstract
The impeller of a pump is driven by the armature of a motor for
pumping a liquid. In response to the onset of vapor bubble
formation in the liquid, the impeller load decreases thereby
decreasing the armature current and increasing the impeller speed
to initiate the establishment of a vapor lock condition in the
pump. A relay includes a winding responsive to the decrease in the
armature current at the onset of vapor bubble formation in the
liquid to open a set of contacts for switching a resistor in series
with the motor armature. The resistor decreases the armature
voltage thereby decreasing the impeller speed and increasing the
impeller load to terminate the establishment of a vapor lock
condition in the pump.
Inventors: |
MacManus; Daniel C. (Owosso,
MI) |
Assignee: |
General Motors Corporation
(Detroit, MI)
|
Family
ID: |
23581782 |
Appl.
No.: |
05/399,994 |
Filed: |
September 24, 1973 |
Current U.S.
Class: |
417/45; 388/822;
388/930 |
Current CPC
Class: |
F04D
9/001 (20130101); F04D 15/0066 (20130101); Y10S
388/93 (20130101) |
Current International
Class: |
F04D
15/00 (20060101); F04D 9/00 (20060101); F04b
049/00 () |
Field of
Search: |
;417/42,43,44,45
;318/322,349 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Freeh; William L.
Attorney, Agent or Firm: Jagodzinski; T. G.
Claims
What is claimed is:
1. In combination: a pump including a pump chamber having an inlet
and an outlet and a pump impeller rotatably mounted within the
chamber for drawing liquid into the chamber through the inlet and
for pumping liquid out of the chamber through the outlet when the
impeller is rotatably driven such that the load on the impeller is
directly related to the density of the liquid which is
substantially constant at a maximum level in response to the
absence of vapor bubble formation and which decreases in response
to the onset of vapor bubble formation thereby decreasing the load
on the impeller; a motor including an armature shaft and an
armature winding for rotatably driving the armature shaft such that
the current through the armature winding is directly related to the
load on the armature shaft and such that the speed of the armature
shaft is directly related to the voltage across the armature
winding and is inversely related to the load on the armature shaft,
the armature shaft of the motor coupled with the impeller of the
pump for rotatably driving the impeller such that when the load on
the impeller is substantially constant at a maximum level in
response to the absence of vapor bubble formation in the liquid the
load on the armature shaft is likewise at a maximum level to
maintain the current through the armature winding at a maximum
level and to maintain the speed of the armature shaft at a minimum
level and so that when the load on the impeller decreases in
response to the onset of vapor bubble formation in the liquid the
load on the armature shaft likewise decreases to decrease the
current through the armature winding and to increase the speed of
the armature shaft which in turn increases the speed of the
impeller thereby initiating a regenerative speed increase/load
decrease reaction on the impeller which if left to continue would
lead to the development of a vapor lock condition about the inlet
of the pump chamber so as to prevent the entry of fuel into the
chamber; a resistor connected in series with the armature winding
of the motor for reducing the voltage across the armature winding
when the resistor is not bypassed; means responsive to the current
through the armature winding of the motor for bypassing the
resistor when the current through the armature winding is at a
maximum level in response to the absence of vapor bubble formation
in the liquid to maintain the voltage across the armature winding
at a maximum level and for not bypassing the resistor when the
current through the armature winding decreases due to the onset of
vapor bubble formation in the liquid to increase the speed of the
armature shaft which in turn decreases the speed of the impeller
thereby terminating the regenerative speed increase/load decrease
reaction on the impeller to prevent the development of a vapor lock
condition about the inlet of the pump chamber so as to permit the
entry of fuel into the chamber to increase the load on the impeller
back to the maximum level.
2. In combination: a pump including a pump chamber having an inlet
and an outlet and a pump impeller rotatably mounted within the
chamber for drawing liquid into the chamber through the inlet and
for pumping liquid out of the chamber through the outlet when the
impeller is rotatably driven such that the load on the impeller is
directly related to the density of the liquid which is
substantially constant at a maximum level in response to the
absence of vapor bubble formation and which decreases in response
to the onset of vapor bubble formation thereby decreasing the load
on the impeller; a motor including an armature shaft and an
armature winding for rotatably driving the armature shaft such that
the current through the armature winding is directly related to the
load on the armature shaft and such that the speed of the armature
shaft is directly related to the voltage across the armature
winding and is inversely related to the load on the armature shaft,
the armature shaft of the motor coupled with the impeller of the
pump for rotatably driving the impeller such that when the load on
the impeller is substantially constant at a maximum level in
response to the absence of vapor bubble formation in the liquid the
load on the armature shaft is likewise at a maximum level to
maintain the current through the armature winding at a maximum
level and to maintain the speed of the armature shaft at a minimum
level and so that when the load on the impeller decreases in
response to the onset of vapor bubble formation in the liquid the
load on the armature shaft likewise decreases to decrease the
current through the armature winding and to increase the speed of
the armature shaft which in turn increases the speed of the
impeller thereby initiating a regenerative speed increase/load
decrease reaction on the impeller which if left to continue would
lead to the development of a vapor lock condition about the inlet
of the pump chamber so as to prevent the entry of fuel into the
chamber; a resistor connected in series with the armature winding
of the motor for reducing the voltage across the armature winding
when the resistor is not bypassed; a relay including a pair of
switching contacts connected across the resistor and a current
sensor connected in series with the armature winding of the motor
for closing the contacts so that the resistor is bypassed when the
current through the armature winding is at a maximum level in
response to the absence of vapor bubble formation in the liquid to
maintain the voltage across the armature winding at a maximum level
and for opening the contacts so that the resistor is not bypassed
when the current through the armature winding decreases due to the
onset of vapor bubble formation in the liquid to increase the speed
of the armature shaft which in turn decreases the speed of the
impeller thereby terminating the regenerative speed increase/load
decrease reaction on the impeller to prevent the development of a
vapor lock condition about the inlet of the pump chamber so as to
permit the entry of fuel into the chamber to increase the load on
the impeller back to the maximum level.
Description
DISCLOSURE
This invention relates to a motor-pump system for preventing the
occurrence of a vapor lock condition in the pump.
According to one aspect of the invention, a pump includes a pump
chamber having an inlet and an outlet. A pump impeller is rotatably
mounted within the chamber for drawing liquid into the chamber
through the inlet and for pumping liquid out of the chamber through
the outlet. The load on the pump is directly related to the density
of the liquid. In the absence of vapor bubble formation, the
density of the liquid is substantially constant at a maximum level.
However, at the onset of vapor bubble formation, the density of the
liquid decreases thereby decreasing the load on the impeller. Where
the liquid is a highly volatile petroleum fuel of the type used in
the internal combustion engine of an automotive vehicle, vapor
bubbles are readily formed as the temperature of the fuel
increases.
In another aspect of the invention, a motor includes an armature
shaft and an armature winding for rotatably driving the armature
shaft. The operating characteristics of the motor are such that the
current through the armature winding is directly related to the
load on the armature shaft and the speed of the armature shaft is
directly related to the voltage across the armature winding and is
inversely related to the load on the armature shaft. Preferably,
the motor is of the type having a permanent magnet field.
As contemplated by a further aspect of the invention, the armature
shaft of the motor is coupled with the impeller of the pump for
rotatably driving the impeller. When the load on the impeller is
substantially constant at a maximum level in response to the
absence of vapor bubble formation in the liquid, the load on the
armature shaft is likewise at a maximum level to maintain the
current through the armature winding at a maximum level and to
maintain the speed of the armature shaft at a minimum level.
However, when the load on the impeller decreases in response to the
onset of vapor bubble formation in the liquid, the load on the
armature shaft likewise decreases to decrease the current through
the armature winding and to increase the speed of the armature
shaft. In response to the increase in the speed of the armature
shaft, the speed of the impeller increases to initiate a
regenerative speed increase/load decrease reaction on the impeller
which, if left to continue, would eventually develop a vapor lock
condition about the inlet of the pump chamber thereby preventing
the entry of fuel into the chamber. Where the pump is supplying
fuel to the internal combustion engine of an automotive vehicle, a
vapor lock condition would disable the vehicle by causing the
engine to stall from a lack of fuel.
In yet another aspect of the invention, a relay includes a current
sensor provided by a control winding which is connected in the
series with the armature winding of the motor. Further, the relay
includes a pair of contacts connected in parallel across a resistor
which is also connected in series with the armature winding of the
motor. When the current through the armature winding is at a
maximum level in response to the absence of vapor bubble formation
in the liquid, the current sensor closes the contacts so as to
bypass the resistor thereby to maintain the voltage across the
armature winding at a maximum level in response to the absence of
vapor bubble formation in the liquid. COnversely, when the current
through the armature winding decreases in response to the onset of
vapor bubble formation in the liquid, the current sensor opens the
contacts so as to not bypass the resistor thereby decreasing the
voltage across the armature winding to decrease the speed of the
armature shaft. In response to the decrease in the speed of the
armature shaft, the speed of the impeller decreases to terminate
the regenerative speed increase/load decrease reaction on the
impeller so as to prevent the development of a vapor lock condition
about the inlet of the pump chamber there-by permitting the entry
of fuel into the chamber to increase the load on the impeller back
to the maximum level.
These and other aspects and advantages of the invention will be
best understood by reference to the following detailed description
of a preferred embodiment when considered in conjunction with the
accompanying drawing.
In the drawing, the sole FIGURE is a schematic diagram of a
motor-pump system incorporating the principles of the invention for
preventing the occurrence of a vapor lock condition in the
pump.
Referring to the drawing, a pump 10 includes a housing which forms
a pump chamber 12 having an inlet 14 and an outlet 16. A pump
impeller 18 is rotatably mounted within the chamber 12 for drawing
liquid into the chamber 12 through the inlet 14 and for pumping
liquid out of the chamber 12 through the outlet 16 when the
impeller 18 is rotatably driven in a clockwise direction. As an
example, the pump 10 may be utilized to supply fuel to the internal
combustion engine of an automotive vehicle. In such event, the
inlet 14 would be immersed within the fuel stored in the fuel tank
of the vehicle while the outlet 16 would be coupled to the vehicle
engine.
The load on the impeller 18 of the pump 10 is directly related to
the density of the liquid passing through the pump 10. In the
absence of vapor bubble formation in the liquid, the density of the
liquid is substantially constant at a maximum level so that the
load on the pump is likewise substantially constant at a maximum
level. However, at the onset of vapor bubble formation within the
liquid, the density of the liquid decreases thereby decreasing the
load on the impeller 18. Where the liquid is a petroleum fuel which
the pump 10 is supplying to the internal combustion engine of an
automotive vehicle, vapor bubbles or pockets are readily formed as
the highly volatile fuel undergoes an increase in temperature.
An electric motor 20 includes an armature shaft 22 and an armature
winding 24 connected between a pair of contact brushes 26 and 28
for rotatably driving the armature shaft 22 in a clockwise
direction when energized from a voltage source 30 through a power
switch 32. Where the pump 10 is installed within an automotive
vehicle, the voltage source 30 may be provided by the vehicle
storage battery and the power switch 32 may be provided by the
vehicle ignition switch. The operating characteristics of the motor
20 are such that the current through the armature winding 24 is
directly related to the load on the armature shaft 22 and the speed
of the armature shaft 22 is directly related to the voltage across
the armature winding 24 and is inversely related to the load on the
armature shaft 22. Preferably, the field of the motor 20 is
provided by a permanent magnet.
The armature shaft 22 of the motor 20 is coupled directly to the
impeller 18 of the pump 10 for rotatably driving the impeller 18
from the armature shaft 22 such that the load on the impeller 18 is
the load on the armature shaft 22. When the load on the impeller 18
is substantially constant at a maximum level in response to the
absence of vapor bubble formation in the liquid, the load on the
armature shaft 22 is likewise at a maximum level. Accordingly, due
to the operating characteristics of the motor 20, the current
through the armature winding 24 is at a maximum level while the
speed of the armature shaft 22 is at a minimum level. Alternately,
when the load on the impeller 18 decreases in response to the onset
of vapor bubble formation in the liquid, the load on the armature
shaft 22 likewise decreases. Again, due to the operating
characteristics of the motor 20, the current through the armature
winding 24 decreases while the speed of the armature shaft 22
increases thereby increasing the speed of the impeller 18.
As the speed of the impeller 18 increases, less liquid and more
vapor is able to enter the pump chamber 12 through the inlet 14
because the vapor is more mobile than the liquid. Consequently, the
load on the impeller 18 further decreases thereby increasing the
speed of the impeller 18 to further decrease the liquid and
increase the vapor entering the pump chamber 12. If allowed to
continue, the eventual consequence of this regenerative speed
increase/load decrease reaction is the development of a back
pressure or vapor lock about the inlet 14 of the pump chamber 12
thereby preventing the entry of fuel into the chamber 12. Where the
pump 10 is supplying fuel to the internal combustion engine of an
automotive vehicle, the development of a vapor lock condition about
the inlet 14 of the pump chamber 12 would disable the vehicle by
causing the engine to stall from a lack of fuel.
In order to prevent the occurrence of a vapor lock condition in the
pump 10, an anti-vapor lock arrangement is provided by a resistor
34 and a relay 36. The resistor 34 is connected in a series circuit
with the armature winding 24 of the motor 20 for reducing the
voltage across the armature winding 24 when the resistor 34 is not
bypassed. Specifically, the voltage across the armature winding 24
is reduced by an amount equal to the voltage across the resistor
34.
The relay 36 includes a current sensor provided by a control
winding 38 and a set of switching contacts provided by a pair of
flexible and magnetizable reeds 40 and 42 which are
electromagnetically coupled with the control winding 38. The
contacts 40 and 42 are normally disposed in an opened position and
are electromagnetically operable to a closed position against an
inherent spring bias tending to return them to the opened position.
In the usual manner, the reeds 40 and 42 are enclosed within an
evacuated envelope 44 to ensure their sensitivity and durability.
The control winding 38 is connected in series with the armature
winding 24 of the motor 20. The switching contacts 40 and 42 are
connected in parallel across the resistor 34.
When the current through the armature winding 24 of the motor 20 is
at a maximum level in response to the absence of vapor bubble
formation in the liquid, the electromagnetic field developed by the
flow of the armature current through the control winding 38 is
sufficient to overcome the spring bias of the switching contacts 40
and 42 which close so that the resistor 34 is bypassed. With the
resistor 34 bypassed, the voltage across the armature winding 24 of
the motor 20 is maintained at a maximum level thereby to maintain
the speed of the armature shaft 22 and the speed of the impeller 18
at a maximum level.
When the current through the armature winding 24 of the motor 20
decreases in response to the initiation of vapor bubble formation
in the liquid, the electromagnetic field developed by the flow of
the armature current through the control winding 38 is insufficient
to overcome the spring bias of the switching contacts which open so
that the resistor 34 is not bypassed. With the resistor 34 not
bypassed, the voltage across the armature winding 24 of the motor
20 is decreased to decrease the speed of the armature shaft 22 and
the speed of the impeller 18. As the speed of the impeller 18
decreases, the regenerative speed increase/load decrease reaction
on the impeller 18 is terminated to prevent the development of a
vapor lock condition about the inlet 14 of the pump chamber 12.
Accordingly, more fuel is permitted to enter the pump chamber 12
thereby increasing the load on the impeller 18 back toward a
maximum level. As the load on the impeller 18 increases to a
maximum level, the current through the armature winding 24 of the
motor 20 likewise increases to a maximum level to reclose the
contacts 40 and 42 through the electromagnetic action of the
winding 38. With the contacts 40 and 42 closed, the resistor 34 is
again bypassed.
It will now be appreciated that the foregoing description of a
preferred embodiment of the invention is made for demonstrative
purposes only and that various alterations and modifications may be
made to the illustrated embodiment without departing from the
spirit and scope of the invention.
* * * * *