U.S. patent application number 15/630314 was filed with the patent office on 2018-12-27 for hydraulic diaphragm control.
The applicant listed for this patent is Wanner Engineering, Inc.. Invention is credited to Richard HEMBREE.
Application Number | 20180372083 15/630314 |
Document ID | / |
Family ID | 62873627 |
Filed Date | 2018-12-27 |
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United States Patent
Application |
20180372083 |
Kind Code |
A1 |
HEMBREE; Richard |
December 27, 2018 |
HYDRAULIC DIAPHRAGM CONTROL
Abstract
A diaphragm pump includes a pumping chamber for pumped fluid and
a hydraulic chamber. A diaphragm has a pumping chamber side and a
hydraulic chamber side. The pumping chamber side of the diaphragm
is proximate the pumping chamber and acts on the pumped fluid. The
hydraulic chamber side of the diaphragm is proximate the hydraulic
chamber. A plunger is in fluid communication with the hydraulic
chamber and acts on the hydraulic fluid, which acts on the
diaphragm. A plunger driver imparts reciprocal motion to the
plunger. The pump includes a sensor assembly sensing position and
direction of the plunger and sensing position of the diaphragm. By
sensing the position of the diaphragm, hydraulic fluid flow is
controlled by a control single valve.
Inventors: |
HEMBREE; Richard; (Port
Coquitlam, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Wanner Engineering, Inc. |
Minneapolis |
MN |
US |
|
|
Family ID: |
62873627 |
Appl. No.: |
15/630314 |
Filed: |
June 22, 2017 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F04B 43/0054 20130101;
F04B 2201/0201 20130101; F04B 2201/1208 20130101; F04B 43/0081
20130101; F04B 43/067 20130101 |
International
Class: |
F04B 43/02 20060101
F04B043/02; F04B 43/00 20060101 F04B043/00 |
Claims
1. A diaphragm pump comprising: a pumping chamber; a hydraulic
chamber; a diaphragm having a pumping chamber side and a hydraulic
chamber side, the pumping chamber side being proximate the pumping
chamber and the hydraulic chamber side being proximate the
hydraulic chamber; a plunger in fluid communication with the
hydraulic chamber; a plunger driver imparting reciprocal motion to
the plunger; a sensor assembly sensing position and direction of
the plunger and sensing position of the diaphragm.
2. The diaphragm pump according to claim 1, further comprising a
valve in fluid communication with the hydraulic chamber.
3. The diaphragm pump according to claim 2, wherein the plunger
driver comprises a stepper motor.
4. The diaphragm pump according to claim 3, further comprising a
controller in communication with the sensor assembly, the stepper
motor and the valve, wherein the sensor assembly.
5. The diaphragm pump according to claim 1, wherein the plunger
drive comprises a crankshaft and wherein the sensor assembly
comprises a first crankshaft sensor sensing position of the
crankshaft.
6. The diaphragm pump according to claim 1, wherein the diaphragm
comprises a diaphragm rod extending from the hydraulic chamber side
and wherein the sensor assembly comprises a sensor sensing a
position of the diaphragm rod
7. The diaphragm pump according to claim 1, wherein the diaphragm
comprises a diaphragm rod extending from the hydraulic chamber side
and wherein the sensor assembly comprises a first sensor and a
second sensor spaced apart from the first sensor, the first sensor
and the second sensor sensing a position of the diaphragm rod.
8. The diaphragm pump according to claim 1, wherein the diaphragm
comprises a diaphragm rod extending from the hydraulic chamber side
and wherein the sensor assembly comprises a linear variable
differential transformer (LVDT) sensing a position of the diaphragm
rod.
9. The diaphragm pump according to claim 1, wherein the plunger
drive comprises a crankshaft and wherein the sensor assembly
comprises a first crankshaft sensor sensing position of the
crankshaft and a second crankshaft sensor sensing the position of
the crankshaft.
10. A diaphragm pump sensing and control system, the diaphragm pump
comprising a diaphragm, a hydraulic fluid chamber and a plunger
acting on the hydraulic fluid chamber; the diaphragm pump sensing
system comprising: a first sensor sensing position and direction of
the plunger; and a second sensor sensing position of the diaphragm;
a single valve controlling fluid flow into and out of the hydraulic
fluid chamber.
11. A method for controlling a diaphragm pump, the diaphragm pump
comprising a diaphragm, a fluid chamber containing hydraulic fluid
acting on the diaphragm, a plunger in fluid communication with the
fluid chamber, and a single valve controlling flow into and out of
the fluid chamber, the method comprising: sensing position and
direction of the plunger; sensing position and direction of
movement of the diaphragm;
Description
BACKGROUND OF THE INVENTION
Field of the Invention
[0001] The present invention is directed to a system for
controlling a diaphragm in a diaphragm pump using a solenoid valve
and to a pump including a system using a solenoid valve to control
the diaphragm.
Description of the Prior Art
[0002] Diaphragm pumps are pumps in which the pump fluid is
displaced by a diaphragm. In hydraulically driven pumps, the
diaphragm is deflected by hydraulic fluid pressure forced against
the diaphragm, which acts against the pumped fluid in a
reciprocating motion. Typically, a plunger moves in a reciprocating
manner in a cylinder to act against the hydraulic fluid and force
the fluid against the diaphragm. The hydraulic fluid flow is
controlled by a system of valves. Such control systems for
diaphragm pumps are shown in U.S. Pat. No. 4,665,974 and U.S. Pat.
No. 7,425,120. Such a control system has three main valves for each
cylinder including a spool valve, a check valve that relieves fluid
in an over filled condition, and a check valve utilized for adding
fluid in an under filled condition. For each of the check valves, a
spool valve depending on the diaphragm position is utilized for
actuation. In addition, such diaphragm pumps also typically require
a fourth valve used as an air bleed valve that allows air to exit
the hydraulic chamber such as may occur during priming.
[0003] Although such pumps and such control systems are generally
efficient and reliable, the valves are relatively costly and
require an interrelationship to maintain the proper fluid level and
pressure. Moreover, the pump must be configured with a hydraulic
chamber that allows for correct placement and interrelationship of
the various valves and their associated fluid conduits.
[0004] It can be seen that a new and improved pump and control
system are needed that eliminate one or more of the hydraulic fluid
valves in a diaphragm pump and provide reliable pumping and control
at a reduced cost. In particular, the reduction in the number of
valves and sensors to a single solenoid valve is desirable. The
present invention addresses these problems as well as others
associated with diaphragm pumps and diaphragm position control.
SUMMARY OF THE INVENTION
[0005] The present invention is directed to a diaphragm pump, and
in particular to a diaphragm pump with a control system that
utilizes a single valve to control fluid levels in the hydraulic
chamber. The diaphragm is driven by a plunger connected to a
crankshaft or other drive. The diaphragm includes a non-magnetic
rod connecting to an iron rod that is sensed by one or more
proximity sensors.
[0006] The present invention includes a single solenoid valve
connected to the hydraulic chamber that controls hydraulic fluid
flow into or out of the hydraulic chamber to correct an overfill
condition or underfill condition. In different embodiments, the
plunger may be driven by a crankshaft that may include a proximity
sensor sensing indicator lobes of the crankshaft. In other
embodiments, the plunger may be driven by a lead screw and stepper
motor.
[0007] The iron rod connected to the diaphragm may include a single
sensor working in conjunction with sensors on the lobes of the
crankshaft or may include two proximity sensors to detect the
position of the iron rod and therefore the position of the
diaphragm. In another embodiment, a linear variable differential
transformer accurately detects the position of the iron rod and
therefore the position of the diaphragm. In each embodiment, the
sensors and sensing circuit and/or controller are able to determine
whether the plunger has gone beyond top dead center or bottom dead
center and whether there is an underfilled condition or an
overfilled condition. When this occurs, the single solenoid valve
may be opened or closed to correct the underfilled or overfilled
condition. The use of multiple sensors eliminates the need for more
than one hydraulic fluid control valve.
[0008] These features of novelty and various other advantages that
characterize the invention are pointed out with particularity in
the claims annexed hereto and forming a part hereof. However, for a
better understanding of the invention, its advantages, and the
objects obtained by its use, reference should be made to the
drawings that form a further part hereof, and to the accompanying
descriptive matter, in which there is illustrated and described a
preferred embodiment of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] Referring now to the drawings, wherein like reference
letters and numerals represent corresponding structure throughout
the several views:
[0010] FIG. 1 is a schematic view of a diaphragm pump with a first
embodiment of a sensing system;
[0011] FIG. 2 is a logic and wiring diagram for the diaphragm pump
shown in FIG. 1;
[0012] FIG. 3 is a crankshaft for a 3 cylinder pump such as the
pump shown in FIG. 1 with a sensor and indicator lobes for each
cylinder;
[0013] FIG. 4 is a schematic view of diaphragm pump with a second
embodiment of a sensing system;
[0014] FIG. 5 is a schematic view of a diaphragm pump with a third
embodiment of a sensing system;
[0015] FIG. 6 is a schematic view of a diaphragm pump with a fourth
embodiment of a sensing system;
[0016] FIG. 7 is a schematic view of the diaphragm pump of FIG. 1
with the diaphragm in the bottom dead center (BDC) position;
[0017] FIG. 8 is a schematic view of the diaphragm pump of FIG. 1
with the diaphragm in the top dead center (TDC) position;
[0018] FIG. 9 is a schematic view of the diaphragm pump of FIG. 1
with the solenoid open to add fluid to the under-filled hydraulic
fluid chamber at BDC; and
[0019] FIG. 10 is a schematic view of the diaphragm pump of FIG. 1
with the solenoid open to dump fluid from the over-filled hydraulic
fluid chamber at TDC.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0020] Referring now to the drawings, and in particular FIG. 1,
there is shown a pump, generally designated (100). In particular,
the pump (100) may be a diaphragm pump including a deformable
diaphragm (102). The diaphragm (102) is deformed to act on pumped
fluid in a fluid chamber (104). Flow into and out of the pumped
fluid chamber (104) is controlled by an inlet check valve (106) and
an outlet check valve (108). A hydraulic chamber (110) filled with
hydraulic fluid is on the opposite side of the diaphragm (102). A
plunger (116) reciprocates in a cylinder (114) to act on the
hydraulic fluid, which acts on the diaphragm (102) to force pumped
fluid out as shown in FIG. 10 or to draw pump fluid in as shown in
FIG. 9. The cylinder (116) is driven by a crankshaft (132) through
a connecting linkage (124).
[0021] The pump (100) also includes a tube (112) connected to the
hydraulic chamber (110). The tube (112) is made of a non-metallic
material so as not to be affected by magnetics does not affect
sensors able to sense magnetic materials. The opposite end of the
tube (112) is closed to complete a hydraulic space. The diaphragm
(102) is connected to a non-metallic rod (122). An iron rod (120)
mounts to the non-metallic rod (122) and reciprocates as the
diaphragm (102) is moved outward into the pumping chamber (104) and
retracted back against the hydraulic fluid in the hydraulic fluid
chamber (110).
[0022] In a first embodiment, a proximity sensor (150) is located
proximate the tube (112) so that the sensor (150) can sense the
iron rod (120) inside the tube (112). The rod (122) and the tube
(112) are both made from materials that the sensor (150) will not
detect. It will be appreciated that the sensor (150) may be an
inductive type sensor able to detect the iron rod (120) but not the
connecting rod (122). The sensor (150) is positioned so as to
detect the rod (120) when the diaphragm (102) is at any position
along its normal operating stroke. When the diaphragm (102) travels
beyond top dead center when the hydraulic chamber (110) is in the
over-filled condition, or beyond bottom dead center when the
hydraulic chamber (110) is in the under-filled condition, the
sensor (150) does not detect the iron rod (120). This information
is passed along to a controller (142).
[0023] The pump (100) uses a single solenoid valve (140) connected
to the hydraulic chamber (110) to control hydraulic fluid flow. In
a preferred embodiment, the solenoid valve (140) is near the top of
the hydraulic chamber (110) so that air can exit the hydraulic
chamber (110) through the valve (140). The other port from the
valve (140) is connected to a fluid sump by tubing (118). The end
of the tubing (118) should be positioned below the surface of the
fluid so that fluid can either exit or enter the tubing (118).
[0024] In the embodiment shown in FIG. 1, the pump control system
also includes a second set of proximity sensors (154) proximate the
crankshaft (132). The crankshaft (132) includes lobes (134). The
lobes (134) are positioned so that when sensed by sensor (154), the
diaphragm is at either top dead center or bottom dead center. The
lobes (134) are positioned so that as soon as the crank passes top
dead center or bottom dead center, the sensor (154) stops detecting
the lobes (134). An embodiment of the crankshaft (132) is shown in
greater detail in FIG. 3. The crankshaft (132) includes lobes (134)
for each cylinder in a three cylinder pump.
[0025] Referring now to FIG. 2, there is shown a circuit diagram
for the control circuit (144). The control circuit (144) is
connected to the solenoid valve (140) as well as the proximity
sensors (150 and 154). Switches (170 and 172) are energized or
de-energized by the respective sensor (150 or 154) to open or close
the circuit (144) and therefore open or close the valve (140).
Simple and reliable control is therefore obtained with the circuit
(144) requiring only two switches (170 and 172).
[0026] The control circuit (144) connects to the proximity sensors
(150 and 154) and to the solenoid valve (140) and may also connect
to a microcontroller (142). Opening and closing of the solenoid
valve (140) is controlled by the positions detected by the
proximity sensors (150 and 154). It can be appreciated that the
relay energized by the sensor (150) is normally closed so that when
the sensor (150) detects the rod (120) in normal operation, the
circuit (144) is open.
[0027] Referring now to FIG. 4, there is shown a second embodiment
of the pump (100). The pump shown in FIG. 4 is similar to that
shown in FIG. 1 but the pump utilizes a linear variable
differential transformer (LVDT) to detect the iron rod (120). In
the embodiment shown, the LVDT includes three coils (162) that
surround the fiberglass tube (112). Use of the LVDT avoids having
electrical coils immersed in the fluid of the hydraulic chamber
(110). This configuration also avoids feeding wires into the
cycling high pressure of the chamber (110), which may be difficult
and complicated. The LVDT also provides a signal indicating the
position of the diaphragm (102) throughout the stroke and achieves
precise timing for opening of the valve (140).
[0028] Referring now to FIG. 5, there is shown a third embodiment
of a diaphragm pump. In the embodiment of FIG. 5, the plunger (116)
is driven by a linear drive (182) such as a lead screw and a
stepper motor (180) that may be controlled by a controller (142).
As the microcontroller (142) knows the position and direction of
the plunger from inputs from the stepper motor (180), the
microcontroller can therefore infer/determine the proximate
position of the diaphragm. Therefore, only one proximity sensor is
required to indicate an under-fill or an over-fill condition. The
proximity sensor (150) is placed mid stroke of the iron rod (120).
Therefore, when the stroke of the diaphragm (102) exceeds the
normal range in either direction, the sensor (150) signals the
microcontroller (142). In response to the sensed under-fill or
over-fill condition, the microcontroller (142) will open the
solenoid valve (140) at an appropriate time to restore normal
operating conditions.
[0029] Referring now to FIG. 6, there is shown a fourth embodiment
of a pump. In the embodiment shown in FIG. 6, the pump (100)
utilizes two proximity sensors (150 and 152) to detect the position
of the diaphragm. The sensor (152) acts as an under-fill sensor and
detects the position of an iron rod (120). By using two sensors
(150 and 152) to detect the position of the rod (120), the
controller (142) will be able to determine whether the diaphragm is
beyond the top dead center over-filled condition or beyond the
bottom dead center under-filled position regardless of the position
of the plunger (116). With the two spaced apart proximity sensors
(150 and 152), only the direction of the plunger (160) is needed
rather than the position of the crank (132) relative to top dead
center or bottom dead center.
[0030] It can be appreciated that the operation of the solenoid
valve operates in four main modes. The logic used to open the
solenoid valve (140) is similar in each of the four embodiments.
However, the general operation is described with respect to the
embodiment of FIG. 1 even though applicable to the other
embodiments. In a first mode, the pump is in a normal operating
mode. In a second mode, the pump is in an under-filled operating
mode. In a third mode, the pump is in an over-filled operating
mode, and in a fourth mode, the pump is in a priming condition. The
first mode is shown in FIGS. 7 and 8. In the first operating mode,
the pump (100) has the correct amount of fluid in the hydraulic
chamber (110). The pump (100) is shown with the diaphragm (102) and
the plunger (116) at bottom dead center in FIG. 7. At this
position, the sensor (150) still detects the rod (120) so the
solenoid valve (140) remains closed. With the pump (100) shown with
the diaphragm (102) and the plunger (116) at top dead center in
FIG. 8, the sensor (150) detects the iron rod (120) and the
solenoid valve (140) remains closed.
[0031] As shown in FIG. 9, in the second mode, the plunger (116) is
approaching bottom dead center but the diaphragm (102) has passed
beyond the normal bottom dead center and the proximity sensor (150)
is not sensing the rod (120). The control circuit (144) opens the
solenoid valve (140). As the plunger (116) continues to bottom dead
center, hydraulic fluid is drawn into the hydraulic chamber (110).
The solenoid valve (140) closes once the sensor (154) senses that
the plunger (116) has reached bottom dead center and is beginning
the forward pressure stroke.
[0032] As shown in FIG. 10, in the third operating mode, the
plunger (116) is approaching top dead center but the diaphragm
(102) has gone beyond the normal top dead center position and the
proximity sensor (150) is not sensing the rod (120). A
microcontroller or the control circuit (144) opens the solenoid
valve (140). As the plunger (116) continues to top dead center,
hydraulic fluid is dumped from the hydraulic chamber (110). Once
the plunger (116) is at top dead center, the second set of
proximity sensors (154) senses top dead center from the lobes (134)
and shuts the valve (140) for the suction stroke.
[0033] The fourth mode takes place when the pump (100) is first
assembled and hydraulic oil needs to be primed into the hydraulic
chamber (110). In this scenario, the solenoid valve (140) is held
open for several strokes by the microcontroller regardless of input
from the sensors (150 and 154) to purge air from the hydraulic
chamber (110). After several strokes, the valve (140) is closed and
depending on which mode the pump is in after the solenoid valve
(140) is closed, the oil level in the hydraulic chamber (110) will
be automatically adjusted by the controller to return to
normal.
[0034] It can be appreciated that the present invention achieves
improved control utilizing sensors to detect the true position of
the diaphragm. Control of the fluid levels is accomplished with a
single solenoid valve (140) and eliminates the need for multiple
valves associated with the hydraulic chamber as is required with
the prior art. The present invention achieves greater reliability
and is less expensive and easier to manufacture and maintain.
[0035] It is to be understood, however, that even though numerous
characteristics and advantages of the present invention have been
set forth in the foregoing description, together with details of
the structure and function of the invention, the disclosure is
illustrative only, and changes may be made in detail, especially in
matters of shape, size and arrangement of parts within the
principles of the invention to the full extent indicated by the
broad general meaning of the terms in which the appended claims are
expressed.
* * * * *