U.S. patent number 3,780,622 [Application Number 05/151,302] was granted by the patent office on 1973-12-25 for hydraulic oscillator and systems actuated thereby.
Invention is credited to Arthur E. Vogel.
United States Patent |
3,780,622 |
Vogel |
December 25, 1973 |
HYDRAULIC OSCILLATOR AND SYSTEMS ACTUATED THEREBY
Abstract
A hydraulic actuator in the form of a fluid actuated
reciprocating motor of extreme simplicity consisting of two movable
elements and hydraulic circuitry. A housing encloses the two
movable elements and the hydraulic circuitry is achieved within the
wall of the housing. The two movable elements consist of a
reciprocable piston in a cylinder and a reciprocable reversing
valve in a chamber. Fluid flow through the system is continuous and
uninterrupted. The reversing valve is moved alternately to its two
different positions and held in such positions, by pressure
differential created by different flow conditions set up at its
opposite ends. These differential flow conditions are set up under
the control of cylinder inlet and outlet ports which are connected
to the valve chamber and are covered and uncovered by the piston
during its reciprocation.
Inventors: |
Vogel; Arthur E. (Columbus,
OH) |
Family
ID: |
22538144 |
Appl.
No.: |
05/151,302 |
Filed: |
June 9, 1971 |
Current U.S.
Class: |
91/296; 91/300;
91/317; 417/403; 417/553 |
Current CPC
Class: |
F04B
53/128 (20130101); F04B 9/10 (20130101); F03C
1/14 (20130101) |
Current International
Class: |
F04B
53/12 (20060101); F04B 9/10 (20060101); F04B
53/10 (20060101); F04B 9/00 (20060101); F03C
1/00 (20060101); F03C 1/14 (20060101); F01l
025/04 () |
Field of
Search: |
;91/290,291,317,316,296,300 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Freeh; William L.
Assistant Examiner: Smith; Leonard
Claims
Having thus described my invention, what is claimed is:
1. A hydraulic oscillator comprising two movable elements only
consisting of a reciprocable piston in a cylinder and a
reciprocable reversing valve in a chamber, means for creating
differential flow conditions at the opposite ends of the valve in
the valve chamber, said means including inlet and outlet ports in
the cylinder which are connected to the valve chamber and are
covered and uncovered by the piston during its reciprocation, said
movable elements disposed in a housing having a main inlet and
outlet with the piston reciprocable in the cylinder formed in said
housing and the valve member reciprocable in the chamber formed in
said housing, said valve member having a single fluid passage
formed intermediate its ends, said valve member fluid passage being
constantly connected to said main inlet, said valve chamber having
opposed ends constantly connected to said main outlet, a passage
between said valve fluid passage and one end of said cylinder and a
passage between one end of said valve chamber and the other end of
said cylinder, said valve member in its extreme end positions
serving to connect alternately the main inlet to one of said
passages and disconnecte the other therefrom, the disconnected
passage being connected to one end of the valve chamber and to said
outlet to create a dynamic pressure differential thereon to hold it
in said extreme position, and a pair of cooperating inlet and
outlet ports in each end of the cylinder alternately exposed and
closed by the piston in its stroke in opposite directions for
creating at the end of each stroke an alternate branch passage from
the main inlet, through the valve member fluid passage and the end
of the cylinder with the exposed ports to the opposite end of the
valve chamber to create a dynamic differential pressure thereon to
cause it to move in a reverse direction.
2. A hydraulic oscillator comprising two movable elements
consisting of a main movable pressure-actuated element and a
movable control valve member located in a main chamber and a valve
chamber respectively; said main movable member disposed in its
chamber for movement therein and dividing the main chamber into
opposed end chambers; said movable valve member disposed in its
chamber and of such form as to divide the valve chamber into a
single intermediate fluid-passage chamber and opposed end
fluid-passage chambers; a main pressure inlet passage always
connected to the intermediate fluid-passage chamber of the valve
member in all its positions of movement; a main outlet passage
always connected to both the opposed end fluid-passage chambers of
the valve chamber; and fluid passages connecting the end chambers
of the main chamber and the end fluid-passages of the valve chamber
under the control of said pressure-actuated element to create
dynamic flow conditions in one of said end fluid-passage chambers
of the valve and static conditions in the other, alternately,
creating a pressure differential in said end fluid-passages
resulting in a reversing movement of the valve member.
3. A hydraulic oscillator according to claim 2 in which the
pressure actuated element is a piston and reciprocates in the main
chamber which is a cylinder; and the valve member is a spool member
which reciprocates in the valve chamber which is cylindrical, the
valve member having a pair of axially spaced lands to provide said
intermediate fluid passage and being of less axial length than the
valve chamber but having axial extensions axially outwardly of the
respective lands so as to produce said end fluid-passages in the
valve chamber.
4. A hydraulic oscillator comprising a housing having a main
pressure inlet and an exhaust outlet, a cylindrical chamber formed
within the housing and having a piston slidably mounted therein,
said chamber having a first pair of axially spaced pressure inlet
ports connected to said main inlet port and being positioned so
that both are closed in an intermediate position of said piston but
are alternately opened as the piston completes its stroke in
opposite directions so as to alternately supply pressure in the
chamber at the opposite faces of the piston, said chamber having a
second pair of axially spaced exhaust ports which are closed in an
intermediate position of said piston but are alternately opened to
opposite ends of said chamber as the piston complestes its stroke
in opposite directions, an inlet port and an outlet port at the
respective end of the chamber being opened simultaneously as the
piston completes its stroke to the opposite end of the chamber,
said chamber having a third pair of ports which always connect with
the respective ends of the chamber and which serve alternately as
inlet and exhaust ports, a reversing valve member mounted for
reciprocation within a valve chamber formed within said housing,
said valve having a single fluid passage formed intermediate its
ends, said main pressure inlet and said first pair of pressure
inlet ports for said cylindrical chamber being always connected to
said fluid passage of the valve, one of said second pair of axially
spaced exhaust ports being constantly connected to one end of said
valve chamber and the exhaust outlet and the other being constantly
connected to the other end of said valve chamber and the exhaust
outlet, said third pair of cylinder end ports being connected to
said valve chamber at axially spaced ports which alternately
respectively communicate with said fluid passage of the valve as it
completes its stroke at one end of the valve chamber and which are
both closed when the valve is in an intermediate position.
5. A hydraulic oscillator according to claim 4 including an
additional valve for controlling flow of fluid through the
housing.
6. An oscillator according to claim 4 in which said piston is free
of any passages for hydraulic fluid.
7. A hydraulic oscillator according to claim 4 in which the valve
member is in the form of a spool having a pair of axially spaced
lands with said fluid passage thereof being a single annular
continuous fluid passage formed therebetween, said valve chamber
being of sufficient length to provide chambers at each end of the
spool, said main pressure inlet and said first pair of pressure
inlet ports for said cylindrical chamber being connected to a
common port opening into said valve chamber at an intermediate
position where it will communicate with said annular passage in all
positions of the valve member, said second pair of exhaust ports of
the cylinder being connected to the respective end valve chambers
by ports opening thereinto, each of said ports also being connected
to the main outlet, said third pair of cylinder end ports being
connected to the valve chamber at ports opening into the valve
chamber at intermediate positions corresponding to the axial
spacing of said lands so that they are both closed at an
intermediate position of the valve and alternately communicate with
said annular valve passage and one of the end chambers of the
valve.
8. A hydraulic oscillator according to claim 7 in which the
cylinder and valve chamber are in substantial axial alignment, said
piston in said cylinder having an actuating rod extending from the
housing.
9. A hydraulic oscillator according to claim 7 in which the
cylinder and valve chamber have their axes in parallel
relationship, said piston having actuating rods extending axially
in opposite directions therefrom through opposed walls of the
housing.
Description
The oscillator of this invention is particularly useful in a system
where it is desirable to have a constant source of reciprocating
power. The oscillator can be operated by any suitable source of
hydraulic fluid flow.
Most hydraulic oscillators in the prior art comprising a
reciprocable piston and a reversing valve are operated by four-way
valves. However, hydraulic reversal systems using a four-way
reciprocable valve spool usually require an additional valve, such
as a rotary four-way valve mechanically controlled by the cylinder
movement to ensure a continuing supply of pilot pressure to the
four-way valve spool so that it will not stop in the crossover
position. A four-way valve spool valve used alone to control the
inlet and exhaust of fluid is only permissible with compressible
fluids such as air. This cannot be done with non-compressible
hydraulic fluids such as oil or water, without employing saome
accumulator or pressure relief valve system, to eliminate hydraulic
"water-hammer" or shock, that is inherent with the use of such
four-way valves, because of the fact that all such valves, at
mid-position, are not open to allow unarrested flow.
According to my invention, I employ a hydraulic oscillator which
includes merely two movable elements, mainly the piston to be
reciprocated and a reversing valve which is not a four-way valve
but is a more simple valve. Some of the functions of the usual
four-way valve are performed by the piston cooperating with ports
located at selected positions in the wall of the cylinder and
connected to the valve. These ports are so located and so cooperate
with the valve that there can be a continuous flow of fluid through
the oscillator and the valve will be positively moved from one
reversing position to another and held firmly in such position, by
the creation of differential flow conditions on the opposite ends
of the valve.
As long as the oscillator is subjected to uninterrupted fluid flow
from a suitable source, the oscillator will function to reciprocate
the piston and any movable element connected thereto. This makes
the oscillator especially suitable as a power source for operating
a system having a reciprocable unit which needs a constant source
of power, for example, air compressors on automotive vehicles which
are used to supply air for various air-operated accessories on the
vehicle. I have found the oscillator to be especially useful on an
automotive vehicle which has a hydraulic steering pump that can
supply a constant pressure flow thereto. The air compressor
operated thereby can be used in supplying the air for the air
springs of vehicle levelling systems such as are shown generally in
U.S. Pat. Nos. 3,480,288 and 3,480,293.
The oscillator of my invention will function as long as hydraulic
fluid is supplied to it. A shut-off valve may be provided at the
inlet or the outlet to interrupt flow so as to stop operation of
the oscillator if desired. Such a valve may also be of a nature to
throttle the flow of fluid to thereby vary the speed of operation
of the oscillator.
The best mode contemplated in carrying out this invention is
illustrated in the accompanying drawings in which:
FIG. 1 is an axial sectional view taken through the hydraulic
oscillator showing it in its first phase of operation.
FIG. 2 is a similar view but showing the oscillator in its second
phase of operation.
FIG. 3 is a similar view but showing the oscillator in its third
phase of operation.
FIG. 4 is a similar view but showing the oscillator in its fourth
phase of operation.
FIG. 4A shows a hydraulic oscillator similar to that shown in FIG.
4 but with a different arrangement of the two movable elements.
FIG. 5 is an axial sectional view showing the oscillator of FIGS. 1
to 4 combined with an air compressor which it actuates.
FIG. 5A is a fragmentary axial sectional view showing the piston of
the compressor of FIG. 5 with its valve plate in a different
position.
FIG. 6 is a fragmentary axial sectional view showing an "on-off"
control valve incorporated in the oscillator.
FIG. 7 is a schematic perspective view showing the
oscillator-driven compressor embodied in a vehicle suspension
system.
FIG. 8 is an axial sectional view through an air unloader valve
used in the system.
FIG. 9 is a schematic perspective view showing the
oscillator-driven compressor incorporated in a vehicle suspension
system having a different type of levelling valve.
A general description of the hydraulic oscillator will aid in
understanding the specific description to follow.
The hydraulic oscillator of my invention comprises a housing having
a main pressure inlet and an exhaust outlet with a cylindrical
chamber formed within the housing having a movable element in the
form of a piston slidably mounted therein. The cylinder or chamber
has a first pair of axially spaced pressure inlet ports connected
to said main inlet port and being positioned so that both are
closed in an intermediate position of said piston but are
alternately opened as the piston completes its stroke in opposite
directions so as to alternately supply pressure in the chamber at
the opposite faces of the piston. The cylinder has a second pair of
axially spaced exhaust ports which are closed in an intermediate
position of said piston but are alternately opened to opposite ends
of said cylinder as the piston completes its stroke in opposite
directions, one of said inlet ports and one of said outlet ports at
the respective ends of the cylinder being exposed by the piston
simultaneously. A third pair of ports is provided and these ports
are at the respective ends of the cylinder and serve alternately as
inlet and exhaust ports. A second movable element in the form of a
reversing valve is provided and specifically is a spool mounted for
reciprocation within a valve chamber or bore formed within said
housing. This valve has a single fluid passage formed intermediate
its ends. The main pressure inlet and said pair of pressure inlet
ports for said cylinder are always connected to said fluid passage
of the valve by suitable passages. One of said second pair of
axially spaced exhaust ports is constantly connected to one end of
said valve chamber and the exhaust outlet and the other is
constantly connected to the other end of said valve chamber and the
exhaust outlet by suitable passages. The ports of said third pair
which are at the ends of the cylinder are connected by suitable
passages to said valve chamber at axially spaced ports which
alternately respectively communicate with said fluid passage of the
valve as it completes its stroke and one end of the valve chamber
at which are both closed when the valve is in an intermediate
position.
Assuming the valve is at one end of its stroke, pressure fluid is
supplied from the inlet through the valve passage to one of the end
ports of the cylinder into that end of the cylinder and at the same
time fluid is exhausted from the opposite end of the cylinder,
through the end of the valve chamber and out through the outlet. At
the same time, both of the cylinder exhaust ports are closed by the
piston and the opposite end of the valve is therefore not subjected
to any dynamic flow of exhaust fluid as the other end is. This
pressure differential on the opposite ends of the valve created by
dynamic exhaust flow on the one end and static conditions on the
other end, results in firmly keeping the valve in this end position
during this first phase of the operation.
However, when the piston reaches the extent of its movement in the
one direction, one of the pressure inlet ports of the cylinder is
exposed by the piston and at the same time, the corresponding
exhaust port is exposed by the piston. This permits pressure fluid
to flow from the main inlet into the same end of the cylinder
through the alternate branch passage extending from the main inlet
to the said exposed cylinder inlet port. At the same time fluid
exhausts from this end of the cylinder to the opposite end of the
valve and on out to the outlet creating a dynamic flow condition at
that end of the valve. The other pressure inlet port and exhaust
port of the cylinders are closed at this time and there is,
therefore, no dynamic flow on the other end of the valve. This
pressure differential will cause the valve member to move away from
its end position toward the other end of its chamber. This movement
causes the valve to immediately close both ports in its chamber
which connect with the end ports of the cylinder. This prevents
supply of fluid to either end of the cylinder by these ports but
fluid is still being supplied to the one end by the alternate
branch passage including the cylinder inlet port exposed by the
piston.
As the valve completes its reversing movement, it connects the main
inlet through its fluid passage, and the other cylinder end port to
the other end of the cylinder supplying pressure therein to move
the piston in a reverse direction. The valve will be held firmly in
this position by the pressure differential created thereon by the
exhaust of fluid from the other end of the cylinder through the
port at that end which is connected to the other end of the valve
chamber. The end of the valve chamber toward which it moved is not
subjected to dynamic flow since the cylinder exhaust port connected
thereto is closed by the piston. Also, the other exhaust port of
the cylinder is closed by the piston at this time as are the two
pressure inlets of the cylinder.
The valve will stay in this position until the piston completes its
movement in the indicated direction at which time it will again be
moved in a reverse direction. As the piston completes its movement,
the other pressure inlet port and corresponding exhaust port are
exposed by the piston. This sets up a branch alternate passage from
the main inlet, through this cylinder inlet port. The flow of fluid
through the exposed cylinder exhaust port into the other end of the
valve chamber creates dynamic pressure thereon whereas there is
static pressure on the opposite end due to the fact that the
cylinder exhaust port connected thereto is covered. This will
create movement of the valve member in a reverse direction,
immediately closing both of the ports of the valve chamber which
connect to the cylinder end ports. The cycle of operations will be
completed over and over and at no time will fluid flow from the
main inlet to the main outlet be interrupted.
The oscillator will function as long as hydraulic fluid is supplied
to it. A shut-off valve may be provided at the inlet or the outlet
to interrupt flow so as to stop operation of the oscillator. Such a
valve may also be of a nature to throttle the flow of fluid to
thereby vary the speed of operation of the oscillator.
With particular reference to the drawing, I have illustrated in
FIGS. 1 to 4, inclusive, the hydraulic oscillator of my invention.
The following is a detailed description of its structure and
function. It is a fluid actuated reciprocating motor of the most
extreme simplicity - using only the irreducible primaries of two
movable elements and a hydraulic circuitry. It is novel and simple
compared to prior art. It will be noted that the circuitry is
achieved within the wall of the housing that contains the two
movable elements. The housing is number 1 generally in FIGS. 1, 2,
3 and 4. One of the above mentioned elements is the driven element,
or piston generally indicated number 2. The other element is the
flow sensitive reversing valve and is generally indicated number 3.
The housing is provided with an inlet fitting 4, and an outlet
fitting 5, to provide for the admission of fluid to, and the
exhausting of fluid from the motor. The housing is also provided
with end caps 6 and 7. In addition, the housing is also fitted with
a number of press fit ball plugs. These balls merely plug access
holes that were necessary to create intersecting drilled passages.
They are indicated by the number 8. Within the housing there is
another press fit ball, number 9, which is a hydraulic fluid
exhaust flow restrictor.
The hydraulic motor operates as follows: FIG. 1, fluid enters inlet
fitting 4, to passage 21 to chamber between valve spool lands 10,
of said spool 3. Now it will be noted that reversing valve 3, is in
the right hand position and resting against the end cap 6. When the
valve 3 is in the right hand position, passage 21 is open to
passage 11 via spool land cavity 10, and the fluid flow is
continued through passage 12 and port 13 into chamber 14. Fluid
pressure acts against surface 15 and 15A of driven element 2,
driving it and it's output shaft 16 to the left position. It can
now be noted that the output shaft 16 is moving also outside the
motor and can be called upon to perform useful mechanical work of
wide scope. While the driven element 2 is moving from right to
left, hydraulic fluid is being expelled from chamber 17 through
port 18 into passages 19 and 20 and into chamber 22 out through
port-passage 29 through passage 24L past ball restrictor 9 and
finally out through passage 25 of exhaust fitting 5. It will be
noted that during this phase of the motor's operation, the fluid
exhaust flow pressure is greater in chamber 22 than it is in
chamber 23 because of the dynamic flow within chamber 22 and
conversely because of the exhaust circuit conditions in chamber 23
and passage 24R which are static. The resulting pressure
differential between chambers 22 and 23 serve to keep the reversing
valve 3 firmly in its right hand position during the motors first
phase of its operation. This phase continues until the driven
element 2 has reached its complete leftwardly travel and is against
end cap 7, as shown in FIG. 2. At this point, phase 2 begins in the
following manner: Referring further to FIG. 2, it will now be noted
that a port 26, has been opened by the leftward movement of the
driven element, shown generally at 2, and specifically by its
surface 15, said surface being left of port 26. Port 26 is a fluid
pressure source to chamber 14, and is being fed by inlet fitting 4
and passages 21 and 28 through the wall of the housing 1, further
described as intersecting drilled passages disposed radially and
longitudinally within the wall of the housing. Note that access
drillings perpendicular to, and through the wall of the housing,
make not only passages but also holes in the exterior of the wall
that must be plugged. These holes are plugged with press fit ball
plugs 8, as previously partially described. Further referring to
FIG. 2, it will be noted that surface 15 of driven element 2 has
exposed another port 30, which in turn leads through passages 31
and 31R to chamber 23. At this point, it is further explained that
all fluid flow has ceased through port 18, and the fluid in
passages 19 and 20 is now static. Note that during this transition
phase the fluid flow is not interrupted, but is alternately
channeled through branch passage 28, through port 26, into chamber
14, to port-passage 30, through passages 31 and 31R to chamber 23,
through passage 24RR and 24R past ball restrictor 9 through passage
25 and out of the motor through fitting 5. Further, note in FIG. 2
that the dynamic fluid exhaust flow is now through chamber 23, and
that chamber 22 now experiences the static exhaust circuit
condition commonly shared with port-passage 29 and passage 24L.
It should be further noted that the viscous drag of fluid flowing
through chamber 23, port-passage 24RR and passage 24R is further
augmented by the presence of ball restrictor 9, to effect
sufficient pressure differential between chambers 23 and 22 to
insure the complete displacement of reversing spool valve 3, from
its right hand position, through the "dead center" position, to the
completed left hand position, as shown in FIG. 3. With continued
reference to FIG. 2, it is further pointed out that reversing spool
3 is able to move from right to left, because chamber 22 is always
open to port-passage 29, thereby allowing for the discharge of
fluid through passage 24L and out of the motor through passage 25
of exhaust fitting 5. Thus it can be said that reversing spool
valve 3, is urged to move to the left, because of the
aforementioned dynamic pressures in chamber 23, and permitted to
move to the left by the free escape circuits from chamber 22 to the
outlet. Now that reversing spool valve 3 is in the extreme left
position the motor now begins phase three as follows: Fluid flow
continues to enter the motor through fitting 4, passage 21 into and
around cavity 10 of reversing spool valve 3, through port-passage
20, through passage 19, out port 18, into chamber 17. The fluid
pressure acts upon surface 41 and 41A of driven piston element 2,
forcing it to move from left to right. It might be noted that 42A,
42B and 42C are "0" ring seals. Now to continue with the
description of the motor's function with respect to FIG. 3. It will
be noted that the exhausting of fluid from chamber 14 is achieved
via port-passage 13, passages 12 and 11 into chamber 23 and then
out through port-passage 24RR and 24R, past ball restrictor 9, and
out of the motor through passage 25 of exhaust fitting 5. Note that
now the dynamic exhaust conditions continue to exist in chamber 23,
thereby biasing spool valve 3, keeping it firmly in its extreme
left hand position during this phase of the motor's operation.
With continued reference to FIG. 3, this third phase also serves to
pull the work rod 16 back into the housing. It will be further
noted that the pulling motion can also do useful mechanical work
per se. The third phase of the motor's operation ceases when the
driven spool 2 reaches its extreme right hand position, as seen in
FIG. 4. Simultaneously, all fluid discharge from chamber 14 ceases
to flow out of port-passage 13, and passages 12 and 11. Fluid flow
is maintained, however, uninterrupted through the motor, in the
following manner. With continued reference to FIG. 4, as the driven
spool element 2 moved to the extreme right hand position, its left
end surface 41, opened port 45 and port 46. Note that port 45 is an
alternate pressure port similar to port 26 as shown in FIG. 2.
However, this port 45, in FIG. 4, now having been opened, allows
the fluid to continue through the motor via inlet fitting 4,
passages 21 and 28, through this port 45, into chamber 17, then
through port 46 into passage 24LL and 24L, past ball restrictor 9
and out of the motor through passage 25 of exhaust fitting 5. This
dynamic condition has viscous drag through passage 24L and around
ball restrictor 9. The resulting pressure is reflected as a
differential bias to the reversing spool 3. This pressure bias goes
through passage-port 29, into chamber 22, and chamber 23 will now
discharge the fluid contained therein through port-passage 24RR,
passage 24R and out of the motor through passage 25 of exhaust
fitting 5. Because the movement of reversing spool valve 3 from its
left hand position, through dead center position, to the extreme
right hand position, causes the displacement discharge in chamber
23, when reversing spool valve 3 reaches the extreme right hand
position, the fourth phase has been completed, and the reversing
spool valve is again at the position shown in FIG. 1 and the motor
is now back to phase 1 of its operation. As long as fluid is
delivered to inlet fitting 4, and as long as the flow of fluid is
not closed off after leaving exhaust fitting 5, this reciprocating
hydraulic motor will continue to operate indefinitely as herein
described. However, this is not to say that said motor could not be
externally stalled by a resistance to the movement of work rod 16,
if insufficient hydraulic pressure was not available to inlet
fitting 4.
It should be especially noted that at no time during the
transitions of reversing valve 3, did any cessation of hydraulic
fluid flow occur, with respect to such flow entering or exhausting
from fittings 4 and 5, respectively. Not for even a micro-second,
as would be the case if a four-way spool valve were employed. A
four-way spool valve, controlling both the inleting and exhausting
of fluid is only permissible with compressible fluids such as air.
It is known to the art of hydraulics that this cannot be
successfully done, with the non-compressible fluids such as oil or
water, without employing some accumulator or pressure relief valve
system, to filter out hydraulic "water hammer" to shock, that is
inherent with the use of such four-way valves, because of the fact
that all such valves, at mid-position, are not open to allow
unarrested flow. In contrast, this reciprocating hydraulic motor
has the feature of having "always open" circuitry throughout all
phases of its operation.
Referring to FIG. 4a, a modification of the oscillator is shown in
which the housing IX is of different form to make it possible to
have a movable element or piston 2A with piston rods 16L and 16R
extending from opposite ends thereof through hydraulic seals 24B.
This is desirable for installations having units to be actuated by
each of the piston rods. Because of the oppositely extending piston
rods, it is necessary to dispose the valve 3A with its axis in
parallel realtionship to the axis of the piston 2A rather than in
alignment, as in FIG. 4. All of the equivalent chambers, ports and
passages in this example are designated by the same numerals as in
FIG. 4 with the addition of the subscript character "A". A detailed
description of the operation of this form of the oscillator is not
deemed necessary since it will be identical with that previously
described.
It will be apparent from the above description of both examples of
this hydraulic oscillator or motor that it consists basically of
two movable elements, namely, the main movable pressure-actuated
element, illustrated in these examples as a piston, and the movable
control element or valve, illustrated in these examples as a
spool-type valve, the two elements being located in separate
chambers. The spool-type valve divides the main valve chamber, in
which it axially reciprocates, into an intermediate fluid-passage
chamber and opposed end fluid-passage chambers. The main pressure
inlet for hydraulic pressure is always connected to the main fluid
passage chamber of the valve. Fluid continuously flows from the
main inlet to the main outlet through both end chambers of the
valve, under the control of movement of the piston in such a manner
that dynamic flow conditions are created at one end of the valve
and static conditions are created at the other end of the valve,
alternately, resulting in the reversing movement of the valve.
Thus, the main inlet is always connected to the main outlet and
there is a continuous flow of hydraulic fluid through the
oscillator.
The hydraulic oscillator previously described can be used as a
power unit to perform various functions. One example is shown in
FIGS. 5, 5A and 6 where it is shown connected to an air compressor
so that the reciprocating movement of the driven element will work
the piston of the compressor. As seen in FIG. 5, the end cap 7a is
fitted to main housing 1A and an air compressor end cap 7B is
screwed on main housing A1, at the screw threads generally
indicated at 7T. Note that the air compressor housing 7B, has a
shoulder 7S, which holds end cap 7A firmly in place against main
housing 1A. Further note that end cap 7A is the end of the
hydraulic portion, and further represents the beginning of the air
compressor section. Thus, it should more correctly be referred to
as divider cap 7A. It can be further seen that said divider cap 7A
contains hydraulic seals 42A and 42B, as was the case in FIGS. 1
through 4. Still referring to FIG. 5, note the oscillating shaft 16
connects to an air compressor piston, generally indicated at 50.
The connection or attachment is achieved by a bevel headed allen
cap screw 51, which is screwed firmly into shaft 16 thereby holding
air compressor 50 to shaft 16. It will now be noted that the
oscillating motion of hydraulically driven spool 3 is causing the
likewise oscillating motion of the air compressor piston through
the rod 16. Referring to FIGS. 5 and 5A, it will also be noted that
the bevel of the attachment screw 51 further extends its surface to
retain an air piston inlet valve 52 within air piston 50. However,
it should be pointed out that screw 51 does not hold the inlet
valve plate 52 tightly within air compressor piston 50, but rather,
screw 51 permits limited outward movement of valve plate 52 from
the seating surface 58 of air piston 50 as seen in FIG. 5A. In FIG.
5, valve plate 52 is shown in sealing contact with air piston
surface 58 of piston 50. The sealing is assured by the presence of
"O" rings 53 and 54 shown in FIGS. 5 and 5A. As seen in FIG. 5 and
5A, "O" ring 53 stays affixed to valve plate 52, by virtue of the
fact that it was assembled, stretched over the diameter of inclined
plane surface 59 of valve plate 52. Similarly, "O" ring 54 has been
exapnded into inclined plane surface 60, of valve plate 52. This
"O" ring 54 was selected slightly larger in diameter than the
diameter of inclined plane surface 60 of valve plate 52. This
resulting slight compression of the diameter of the "O" ring 54
maintains it affixed within the valve plate 52. Further, in FIGS. 5
and 5A, another seal 57 is seen in a groove at the outer diameter
of air piston 50 and it is in a sliding engagement with surface 7C
of air compressor housing 7B.
It can now be readily seen how the hydraulic flow of fluid
compresses air, as follows: As described in FIGS. 1 through 4,
hydraulic flow causes shaft 16 to oscillate left and right. Now
then, as seen in FIG. 5, atmospheric pressure enters the air
compressor section as filter 65, through passage 66, through hole
7H and then into chamber 62, as elements 2, 16 and 50 move from
right to left, the air thereby following piston 50. At the same
time, while the air piston moves from right to left, the air in
chamber 61 is being compressed and escapes around spring loaded
exhaust valve 63 and out of the air compressor, through hole 64 of
fitting 68. FIG. 5A shows the air compressor inlet stroke. Shaft 16
and piston 50 are now moving left to right, creating a slight
vacuum in chamber 61. Atmospheric pressure in chamber 62 passes
through radial holes 55 in piston 50 and pushes valve plate 52
open, to allow air to pass around seal 53, through clearance
passage 56, and into chamber 61. After this left to right stroke is
completed, the air will then be compressed in chamber 61, as
previously described. It will be noted that the seating and
unseating of valve plate 52 is accomplished by both the forces of
inertia and air flow at each reversal stroke, and that no inlet
valve biasing spirng is used. Valve plate 52 has sufficient mass
and area to seat and unseat. This feature insures the complete
atmospheric charging of chamber 61, thus each compression stroke
enjoys maximum efficiency.
Referring now to FIG. 6, an "on-off" valve is shown and indicated
generally at 70. This valve will stop the oscillator when the air
compressor builds up a selected high pressure and will start it
again when the pressure drops to a selected low pressure. This
on-off valve is not an essential part of the hydraulic oscillating
air compressor, as clearly, it could be employed in a fluid circuit
outside of the wall of the oscillator with exactly the same control
circuit effect. However, as shown in FIG. 6, the on-off control
valve 70 is shown spring loaded by spring 71 to the right hand
position and up against end cap 6. It will be noted that valving
land 70V of this on-off control valve element 70 is shown blocking
hydraulic port 21A from communicating with exhaust port 25 and
outlet fitting 5. This is the "on" position, wherein the oscillator
functions responsive to hydraulic fluid flow as described in detail
with respect to FIGS. 1 through 4.
With continued reference to FIG. 6, the on-off control spool valve
element 70 can be placed in the "off" position by the application
of an external fluid pressure signal, supplied by control line
valve 75. Upon application of said such external pressure signal
from control line 75, valve element 70 would be shifted to compress
spring 71, as such signal would enter chamber 72 by way of passage
73 of fitting 74A. An "O" ring seal, 70S, is shown to confine such
signal pressure to chamber 72 and to the right side of valve
element 70. When the signal pressure in chamber 72 is of a greater
value than the force of spring 71, valve element 70 will be forced
to the left position (not shown). However, it can be immediately
seen that the spool valve land channel section 70C of valve element
70 would be in alignment with passages 21A and 25, thereby
permitting a new short exhaust circuit directly through the motor.
This alternate by-pass circuitry provides for stopping the motor
from oscillating, while still maintaining full hydraulic volume
flow through the unit as follows: Hydraulic fluid enters fitting 4
of FIG. 5, flows through passage 21, around channel 10, of
reversing spool 3, into passage 21A of FIG. 6, around channel
groove 70C of "on-off" control spool element 70, into passage 25,
and out of the motor through fitting 5 of FIG. 6. This condition
maintains the oscillating compressor shut off so long as the off
signal pressure is applied to control line 75. It will be further
understood, however, that the release of control pressure within
line 75 to atmosphere would cause the spring 71 to return the
control valve 70 back to its right hand position, as shown in FIG.
6, at which time outer land 70V of control valve 70 blocks
alternate passage 21A whereby oscillating resumes. The above
mentioned control of pressure signals to line 75 will be further
described in the following control system of the vehicle suspension
of FIGS. 7 and 8 and in still another control system for vehicle
suspension in FIG. 9 wherein no hydraulic shut off is required.
As indicated, the hydraulic oscillator of my invention can drive an
air compressor and this compressor may supply air to the air
springs of a vehicle leveling system. It may receive constant
pressure hydraulic fluid from the power steering hydraulic pump on
the vehicle. A control system for vehicle suspension of this type
is shown in FIG. 7 and operates as follows: The source of power is
the vehicle propelling engine from which a fan belt 80 is drive.
It, in turn, rotates drive pulley 81 of a conventional automotive
power steering hydraulic pump, generally indicated at 82. All such
pumps incorporate a flow control means generally indicated at 83,
and such flow control means 83 causes the pump to discharge at an
almost constant gallonage per minute, regardless of the revolutions
per minute of the driven pulley 81. Such resulting G.P.M fluid
outputs are in the 2 G.P.M. category, as is well known to the
art.
A typical automative power steering system is operated as shown in
FIG. 7 by the fluid pump's output being conducted through pressure
line 84P through fitting 84F, into the control valving 85C of the
steering mechanism. Such control valving 85C is of course directed
by steering wheel 88C. During all normal operations of the steering
mechanism 85C, hydraulic fluid is exhausted from it through fitting
87F and then back to the fluid pump reservoir fitting EXR4.
However, it will be observed that the system as shown in FIG. 7
places oscillator unit 1A, and oil cooler unit 88, in a fluid
series circuit with exhaust fitting 87F and fluid pump reservoir
fitting EXR4 via first exhaust line EX1, oscillator inlet fitting
4, through oscillator 1A, out of oscillator outlet fitting 5,
through exhaust line EX2, through oil cooler 88, through exhaust
line EX3, and back to the fluid pump reservoir, through fitting
EXR4. Therefore, it will be noted that oscillator 1A is supplied
with hydraulic fluid power as stated, in series with a conventional
vehicle power steering system and will oscillate as described in
FIGS. 1 to 6.
As oscillator 1A functions, it will be noted that in FIG. 7, the
air for this vehicle control system enters the system through inlet
filter 65, through intake line 66, into air compressor unit 7B and
out of the compressor unit through compressor fitting 68, in the
manner described in FIGS. 5 and 5A.
Air delivery pressure line 89 conducts the compressed air to high
pressure reservoir R1 through fitting 89F. The amount of air
pressure in R1 can be observed by a pressure gauge PG1 fitted to
the tank R1. A snap action air switch C1 is similarly fitted to the
high pressure reservoir R1, at fitting 90. The control switch C1 is
incorporated into this system, to provide the on-off signals to
control line 75. Such signals in line 75 shut off and turn on the
oscillator, as previously described, by element 70 in FIG. 6. The
internal functions of snap-switch C1 are fully shown in FIG. 8.
However, for now, continued reference is made, with respect to FIG.
7. Snap-switch C1 causes the oscillating compressor to maintain the
air pressure in the high pressure reservoir R1 between 100 and 125
P.S.I. regardless of the intermittent consumptions of the rest of
the system. Two air lines, 91A and 91B, are shown leading from the
high pressure reservoir R1. 91A leads to a conventional air
pressure regulating reducing valve C2, the function of which is to
maintain a pressure in the low pressure reservoir R2 at 15 P. S. I.
The resulting stable power source within the low pressure reservoir
R2 can operate a host of diaphragm and bellows operated
accessories. In the past, such diaphragms and bellows have been
actuated by atmospheric pressure toward partial and variable
vacuums, produced within the vehicle engine intake manifold. It is
well known to the art that no vacuum is available during
acceleration and also, in places of high altitude, the atmospheric
pressure is less than at sea level. Furthermore, flexible vacuum
tubing is expensive because of its thick wall, and it normally
tends to collapse, especially at turns, and at locations where
higher than ambient temperatures are encountered, such as in the
engine compartment and near exhaust pipes etc. In contrast, when
control diaphragms and bellows are actuated by positive pressures,
above atmospheric pressure, a very inexpensive, thin walled,
plastic tubing can be employed and the positive pressures therein
tend to straighten out the kinks, by rounding the radii. This
resulting control system reliability is further augmented by a
considerable reduction in plumbing expense.
Automatic leveling of the vehicle's suspension system is achieved
from the high pressure power source R1, as shown in FIG. 7, by
piping said power through line 91B to a conventional leveling valve
C3, which is mounted upon the vehicle's sprung weight frame 97 and
suitably connected to be actuated by the relevant movement between
said sprung weight 97 and unsprung weight of vehicle axle 96, by
means of connector links 98 and arm valve lever 99. Further, in
FIG. 7, it will be noted that suspension leveling valve C3 operates
as described in previous U.S. Pat. No. 3,480,293. I. e., if the air
springs 93 and 95 require air, leveling valve C3 supplies it to
them via lines 92 and 94 and if air springs 93 and 95 require a
reduction of pressure (like when the vehicle is unloaded), the
leveling valve C3 will expel to atmosphere through outlet port C4
the required amount of air from air springs 93 and 95 to maintain
the vehicle level.
Snap action control valve C1 is shown in detail in FIG. 8. Its
function is to shut off the oscillating compressor when the desired
predetermined air pressure has been pumped into the high pressure
reservoir R1 of FIG. 7. In FIG. 8, inlet fitting is shown at 90,
the pressure within reservoir R1 is conducted into passage 104 of
lower housing of unloader valve C1 and is sealed by the presence of
"O" ring 103 which is in the inclined plane slot 105 of piston slug
101, and because spring 100 is holding piston slug 101 down against
sealing surface 106 of lower housing C1. The aforementioned seal is
established so long as the air pressure in passage 104 does not
overcome the force in spring 100. It will be noted that adjustment
nut C1A has external threads 107 which are partially screwed into
internal threads 108 of upper housing C1B. This provides for the
adjustment of nut C1A to change the loading or spring 100. Further,
in FIG. 8 it will be noted, piston slug 101 is slightly smaller in
diameter than the internal bore of lower housing C1. The resulting
clearance path 111, along the surface of piston slug 101, provides
a very low volume exhaust path from line 75 to atmosphere, as
follows: As shown in FIG. 8, line 75 is able to exhaust the fitting
74B into port 109 along clearance path 111, around "O" ring seal
102, into spring cavity 110 and then out to atmosphere, through
hole 112 of adjustment nut C1A. This of course causes the
oscillating compressor 1A to run, as previously described in FIG.
6, with specific reference to on-off control spool valve element
70.
With continued reference to FIG. 8, it will be understood that the
pressure in port 104 of lower housing C1 is effectively working
upon the circumference area of the circle lip of "O" ring 103,
resting on seal surface 106.
As the oscillating air compressor builds up pressure in the
reservoir R1 to the desired predetermined maximum, such pressure is
also in passage 104. This rising pressure, being approximately 125
P.S.I., tends to compress spring 100 slightly, as piston slug 101
and its self contained "O" ring seal 103, are forced away from seal
surface 106. The moment leakage occurs between seal 103 and surface
106, compressed air flows along clearance path 111, around upper
"O" ring seal 102, cavity 110, through hole 112 to atmosphere. The
clearance path 111 is fitted so closely in the bore of housing C1
as to allow only a minute leak to atmosphere. Therefore, it is to
be noted that the reservoir pressure is not acting upon the entire
end diameter of piston slug 101. This area being much greater than
the area of the lip diameter of "O" ring seal 103 and the pressure
working against this larger area, causes piston plunger 101 to snap
away from housing surface 106, until alternate "O" ring seal 102
strikes and rests upon alternate sealing surface 113, of upper
housing C1B, thereby cutting off the flow of air to atmosphere. It
will be further noted that "O" ring 102 is clinging to piston slug
101, by virtue of it having been installed in inclined plane
surface 114, in a slightly stretched state, larger than its
manufactured diameter. With continued reference to "O" ring seal
102, its lip diameter is larger than that of "O" ring seal 103. As
previously explained, the lip area of seal 103 responded to the
rising pressure in passage 104 and caused the piston slug 101 to
move in opposition to spring 100, followed by the "snap" movement
of piston slug 101 to alternate seal surface 113, and now the same
reservoir pressure holds the piston slug 101 to the alternate
contact surface 113 by virtue of the larger effective area,
provided by the piston slug 101, by the larger lip diameter of the
"O" ring seal 102. While the piston slug 101 is up against the
alternate seal surface 113, some of the compressed air in the
reservoir can flow to the on-off hydraulic by-pass control element
70 within the wall of the oscillator compressor, shown in FIG. 6,
thereby shutting the compressor OFF and achieved in the following
manner. With continued reference to FIGS. 6, 7 and 8, in FIG. 8,
the piston slug 101 being against alternate seal surface 113, a
space exists between lower "O" ring seal 103 and surface 106 of
lower housing C1, thereby completing a passage circuit, from
reservoir R1, through passage 104, across surface 106, to clearance
passage 111, through passage 109, out fitting 74B, through line 75,
into fitting 74A of FIGS. 7 and 6, through passage 73 and finally
into chamber 72 of FIG. 6. The control pressure now in chamber 72
of FIG. 6 pushes hydraulic by-pass valve element 70 to the left,
causing the oscillating air compressor to cease supplying the
reservoir R1 with compressed air. The larger diameter of "O" ring
seal 102, from the diameter of "O" ring seal 103, furthe provides
for the maintainment of contact between piston slug 101 and
alternate seal surface 113 and against the efforts of spring 100,
until such time as the reservoir pressure falls substantially below
the pressure value that was required to move the piston slug 101
away from the first mentioned seal surface 106. Thus, an on-off
pressure differential does exist. However, when the system
pressures in the reservoir R1 of FIG. 7 and in passage 104 of FIG.
8 does, in fact, fall below the stated differential, as is the
case, because the system of FIG. 7 does consume pressurized air
from R1, via line 91A and 91B, the piston slug 101 will quickly
return to the seal surface 106 of lower housing C1. This occurs at
the time when the reduced air pressure force in passage 104 of FIG.
8 can no longer hold piston slug 101 to upper sealing surface 113
because of the opposing force exerted by spring 100 now being
greater. The moment piston slug 101 does return to the first
sealing surface 106 of lower housing C1, the oscillating resumes
functioning in the manner previously described, thereby
replenishing reservoir R1. It has been discovered that the
desirable range of pressure differential to maintain in reservoir
R1 is 100 to 125 P.S.I. However, a different maximum, minimum and
differential can be quickly established by adjusting the threads
107 of nut C1A deeper, or out of the internal threads 108 of upper
housing C1B, as seen in FIG. 8. Similarly, internal threads 155 of
upper housing C1B engage external threads 116 of lower housing C1,
providing a partial pressure differential adjustment. The primary
differential is established by the design selection of the
different circumferences of the "O" ring seals, 102 and 103, that
are applied to piston slug 101 and the long close clearance passage
111. I have further provided the piston slug 101 of FIG. 8 with a
split step piston ring 118 in piston groove 117. This augments the
retardation of flow along close clearance path 111. This insures a
very reliable snap action when used to control compressors
developing a small rate of pressure rise, as in passage 104.
In FIG. 9, I have illustrated my oscillator driven air compressor
incorporated in a vehicle levelling system of the general type
shown in U.S. Pat. No. 3,480,288 in order to obtain a constant air
supply for that system. This vehicle leveling system is shown in
FIG. 9 as two air inflatable, rear shock absorbers, shown generally
at 229A and 229B. They are mountable between the vehicle chassis
and the left and right rear axle housings. Upper mounting holes are
provided at 200L and 200R, suitable for mounting to the chassis.
Similar mounting holes 201L and 201R are provided at the lower end
for mounting to the left and right rear axle housings. It will be
noted that these shock absorbers are provided with flexible rubber
boots 202L and 202R which comprise chambers that can assist the
vehicle's rear springs in suspending the vehicle level when more
passengers or luggage are added to the vehicles gross weight.
The leveling system functions as follows: The engine propelling the
vehicle rotates pulley 81 via fan belt 80 thereby driving hydraulic
steering pump 82. The flow control means 83 of said pump 82
discharges hydraulic fluid at a constant rate regardless of the
varying engine speed, as previously described. The power steering
control unit 85C receives the hydraulic power from the pump 82 via
line 84P and inlet fitting 84F. The flow continues out of the power
steering unit through fitting 87F through exhaust line EX1, to, and
into, oscillating air compressor 1A via inlet fitting 4. Hydraulic
fluid flow continues out of the oscillating air compressor at
fitting 5 and through exhaust line EX2, through oil cooler 88,
through exhaust line EX3, and then back into the pump reservoir,
through fitting EXR4, thus both the power steering unit 85C and
oscillator 1A are supplied with fluid energy. As the oscillator 1A
runs, the air compressor section 7B functions also and air enters
it at intake 65, via line 66. Compressed air leaves the oscillating
compressor via fitting 68 and line 89A to and through pop-off valve
210, continuing to inflatable shock absorber 229A, via line 89B.
Air continues to flow from shock absorber 229A to shock absorber
229B, via line 89C. Air then flows out of shock absorber 229B, via
line 89D, to and through adjustable snorkle leveling valve shown
generally at 207. The snorkle leveling valve 207 exhausts to
atmosphere via its port 203 when the vehicle is unloaded and the
rubber chamber wall 202R is above and uncovering port 203, as
described more in detail in said patent. The line 89B may be
provided with a relief valve 210 having an exhaust port 212 to
prevent the development of excessive pressure therein in case of
overloading of the vehicle.
It will be apparent from the above description that the oscillator
of my invention provides a simple means, where a source of
hydraulic fluid flow is available, for obtaining a constant
reciprocating movement of a movable element. This element may be a
reciprocable element in any of various units. For example, it may
be, as described above, the piston of an air compressor which is
used to control various air-actuated accessories on a motor
vehicle. Such accessories may include the vehicle levelling systems
described above. Such vehicles usually have a hydraulic steering
pump and this pump can be used as a constant source of liquid flow
to the oscillator. The result will be a constant source of air
pressure for the system as compared to the varying source usually
provided by a manifold-actuated vacuum system which varies widely
with the acceleration of the vehicle.
As indicated, the hydraulic oscillator is a simple hydraulic unit
comprising a housing containing a movable element or piston to be
reciprocated and a slidable spool-type valve to serve as a
reversing valve. All fluid passages of the oscillator preferably
are formed within the wall of the housing as described. The
reversing valve is a simple valve spool with a single passage
formed between a pair of axially spaced lands on the valve. The
simplicity of the valve results mainly from provision of control
ports provided in the wall of the cylinder in which the piston is
disposed for reciprocation. These ports are so connected to the
chamber in which the valve reciprocates and to the main inlet and
outlet of the housing that a differential flow effect is set up at
opposite ends of the valve spool to cause it to move at the proper
instant into a reversing position and to stay in that position
until that instant when it is to move in the opposite direction to
its other reversing position. The piston is moved in one direction
by pressure supplied through a passage from the main inlet through
the valve passage and through a port which is never covered by the
piston. When the piston reaches the extent of its movement in that
direction, it uncovers ports which establish an alternate branch
passage from the main inlet through that end of the cylinder to the
opposite end of the valve spool, creating a pressure differential
thereon which causes it to move into its opposite or reversing
position. This action is repeated over and over as long as fluid
flow is supplied to the oscillator. Because of the design of the
reversing valve and the ports which it controls, and the design of
the piston and the ports it controls, the flow of fluid through the
oscillator is never interrupted.
* * * * *