U.S. patent number 3,631,833 [Application Number 04/833,548] was granted by the patent office on 1972-01-04 for marine propulsion power-assist steering mechanism.
This patent grant is currently assigned to Outboard Marine Corporation. Invention is credited to William J. Shimanckas.
United States Patent |
3,631,833 |
Shimanckas |
January 4, 1972 |
**Please see images for:
( Certificate of Correction ) ** |
MARINE PROPULSION POWER-ASSIST STEERING MECHANISM
Abstract
Disclosed herein is a marine propulsion unit steering mechanism
which includes a double-acting hydraulic piston and cylinder
assembly having a piston rod supporting a piston, a cylinder
mounted for movement on the piston rod and piston. One of the
piston rod and the cylinder is connected to a steering arm provided
on the marine propulsion unit and the other of the piston rod and
cylinder is connected to the transom of a boat. Also included is a
hydraulic fluid control with a spool valve connected through the
piston rod to a remote actuator to control the flow of a continuous
supply of hydraulic fluid to and from the assembly.
Inventors: |
Shimanckas; William J.
(Waukegan, IL) |
Assignee: |
Outboard Marine Corporation
(Waukegan, IL)
|
Family
ID: |
25264723 |
Appl.
No.: |
04/833,548 |
Filed: |
June 16, 1969 |
Current U.S.
Class: |
440/55; 440/61R;
91/216A; 440/62; 440/61B |
Current CPC
Class: |
B63H
25/30 (20130101) |
Current International
Class: |
B63H
25/06 (20060101); B63H 25/30 (20060101); B63h
021/26 () |
Field of
Search: |
;115/18 ;114/150 ;92/110
;91/216A |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Farrell; Andrew H.
Claims
What is claimed is:
1. A marine propulsion device including a marine propulsion unit
mounted for pivotal steering movement in opposite directions
rearwardly of a boat, an actuator operable from a point in the boat
remote from said propulsion unit to pivot the propulsion unit in
opposite directions, and means operatively connected to said unit
and to said actuator for hydraulically increasing the force causing
propulsion unit steering movements in opposite directions and for
locking said propulsion unit against steering movements originating
in said propulsion unit, said means including a piston, a tubular
piston rod fixedly secured to the boat and to said piston, a
cylinder mounted for movement axially of said piston rod, means for
closing the ends of said cylinder to form pressure chambers on each
side of said piston, a valve housing fixedly secured to said
cylinder and having an inlet port and an outlet port, a spool valve
mounted for movement between first, second and third positions in
said valve housing, means for connecting said spool valve to said
actuator, means including a first passage in said spool valve
providing a connection between said inlet port and said outlet port
and preventing communication with said chambers when said spool
valve is in the first position, means including a second passage in
said spool valve providing, when said spool valve is in the second
position, a connection between said inlet port and one of said
chambers in said cylinder and providing, when said spool valve is
in the third position, a connection between said one chamber and
said outlet port, and means including a third passage providing,
when said spool valve is in the second position, a connection
between the other of said chambers and said outlet port, and
providing, when said spool valve is in the third position, a
connection between said inlet port and said other chamber.
2. A marine propulsion device in accordance with claim 1, including
means for biasing said spool valve to the first position.
3. A marine propulsion device in accordance with 1, including means
for constantly supplying pressure fluid to said inlet port, said
means including a pump communicating with a sump, a supply conduit
between said inlet port and said pump, a return conduit between
said outlet port and said sump, and means for bypassing fluid from
said return conduit to said supply conduit.
4. A marine propulsion device in accordance with claim 3, wherein
said bypass means includes a pressure relief valve.
5. A steering arrangement comprising a propulsion unit mounted
relative to a boat for pivotal movement about a horizontal axis to
afford steering movement of said propulsion unit, a steering
control actuator operable from a remote point in the boat, a
piston, a tubular piston rod fixedly secured to the boat and to
said piston, a cylinder fixed to said propulsion unit and mounted
for movement axially of said piston rod, means for closing the ends
of said cylinder to form pressure chambers on each side of said
piston, a valve housing fixedly secured to said cylinder and having
an inlet port and an outlet port, a spool valve mounted for
movement between first, second and third positions in said valve
housing, means for connecting said spool valve to said actuator,
means including a first passage in said spool valve providing a
connection between said inlet port and said outlet port when said
spool valve is in the first position, means including a second
passage in said spool valve providing, when said spool valve is in
the second position, a connection between said inlet port and one
of said chambers in said cylinder and providing, when said spool
valve is in the third position, a connection between said one
chamber and said outlet port, and means including a third passage
providing, when said spool valve is in the second position, a
connection between the other of said chambers and said outlet port,
and providing, when said spool valve is in the third position, a
connection between said inlet port and said other chamber, and a
continuously available source of hydraulic fluid operatively
connected to said inlet port.
6. A marine propulsion device in accordance with claim 5, including
means for biasing said spool valve to said first position.
7. A marine propulsion device including a propulsion unit mounted
relative to a boat for pivotal movement about an axis to afford
steering movement of said propulsion unit, and hydraulic means for
controlling pivotal movement of said propulsion unit including a
cylinder connected to one of the boat and said propulsion unit, a
piston movable in said cylinder and dividing said cylinder into
opposing pressure chambers, a rod extending through one end of said
cylinder and connecting said piston to the other of the boat and
said propulsion unit, and a valve connected to said pressure
chambers and including a pressure fluid supply port, a pressure
fluid outlet port, and a valve member movable relative to said
supply and outlet ports and between a first position communicating
said supply and outlet ports independently of said chambers and
preventing fluid flow relative to said chambers, whereby to allow
fluid flow from said supply port to said return port and to lock
said propulsion unit against pivotal movement originating in said
propulsion unit, a second position communicating one of said
chambers with said supply port and communicating the other of said
chambers with said outlet port, whereby to pivot said propulsion
unit in one direction in response to the application of pressure
fluid to said pressure fluid supply port, and a third position
communicating said other of said chambers with said supply port and
communicating said one of said chambers with said outlet port,
whereby to pivot said propulsion unit in the other direction in
response to the application of pressure fluid to said pressure
fluid supply port.
8. A marine propulsion device in accordance with claim 7, including
a steering control actuator operable at a location remote from said
propulsion unit and wherein said valve means includes a valve
housing fixed relative to one of said cylinder and said piston rod
and said valve member comprises a spool valve movably mounted in
said housing and connected to said actuator.
9. A marine propulsion device in accordance with claim 7, and
further including a continuously available source of pressure fluid
including a pump communicating with a sump, a supply conduit
between said inlet port and said pump, and a return conduit between
said outlet port and said sump.
10. A marine propulsion device including a propulsion unit mounted
relative to a boat for pivotal movement about an axis to afford
steering movement of said propulsion unit, a steering control
actuator operable at a location remote from said propulsion unit,
hydraulic means for controlling pivotal movement of said propulsion
unit including a cylinder closed at both ends and connected to one
of the boat and said propulsion unit, a piston movable in said
cylinder and dividing cylinder into opposing pressure chambers, a
piston rod extending through one end of said cylinder and
connecting said piston to the other of the boat and said propulsion
unit, said piston rod including a hollow interior, and valve and
conduit means connected to said pressure chambers and including a
valve housing connected to the other end of said cylinder and a
spool valve movably mounted in said housing, said valve and conduit
means being selectively operable for preventing fluid flow relative
to said chambers, whereby to lock said propulsion unit against
pivotal movement originating in said propulsion unit, for
permitting pressurization of one of said chambers and venting of
the other of said chambers, whereby to pivot said propulsion unit
in one direction, and for pressurizing said other of said chambers
and venting said one of said chambers, whereby to pivot said
propulsion unit in the other direction, and a member extending
through said hollow interior of said piston rod and through said
piston and connected between said actuator and said spool valve for
operating said valve and conduit means.
11. A marine propulsion device in accordance with claim 10 wherein
said valve housing includes a pressure fluid inlet port and a
pressure fluid outlet port and further including a continuously
available source of pressure fluid including a pump communicating
with a sump, a supply conduit between said inlet port and said
pump, and a return conduit between said outlet port and said
sump.
12. A marine propulsion device in accordance with claim 10 wherein
said valve housing includes a pressure fluid inlet port, wherein
said spool valve includes an axial bore communicating with said
hollow interior of said piston rod, and wherein said piston rod
includes a port communicating between said hollow interior thereof
and said chamber adjacent said one cylinder end, and wherein said
spool valve is selectively operable to connect and disconnect said
spool valve bore with said pressure fluid inlet.
13. A marine propulsion device in accordance with claim 12 wherein
said spool valve has a radial bore communicating with said axial
bore and communicable with said pressure fluid inlet port depending
upon the location of said spool valve in said housing.
Description
BACKGROUND OF THE INVENTION
Steering mechanisms for marine propulsion units generally are
mechanically connected to the steering arm of the marine propulsion
unit to impart mechanical steering forces to the marine propulsion
unit. These mechanisms can include a friction lock or positive lock
to restrain steering movements which originate in the propulsion
unit.
SUMMARY OF THE INVENTION
The marine propulsion steering mechanism of this invention provides
a power assist for steering forces originating from a remote
actuator as well as a power assist for restraining steering forces
originating from the propulsion unit. This is accomplished by
connecting a double acting hydraulic piston and cylinder assembly
between the steering arm of a marine propulsion unit and a steering
cable connected to a remote actuator. The specific arrangement
includes a fixedly mounted piston and a cylinder mounted for
movement relative to the piston. Hydraulic fluid is continuously
supplied to the assembly to assure immediate availability of
hydraulic force to either assist or restrain the steering forces. A
control valve is provided in the assembly to control the flow of
hydraulic fluid to the cylinder and is operatively connected
through the piston to a remote actuator. The assembly is pivotally
connected to the boat and to the marine propulsion unit to
accommodate steering and to allow for vertical pivotal movement of
the marine propulsion unit to clear obstacles in the water and for
repair.
Other objects and advantages will become apparent from the
following description when read in connection with the accompanying
drawing in which:
FIG. 1 is a top view of a marine propulsion unit mounted on the
transom of a boat.
FIG. 2 is a section view of the steering mechanism with the
hydraulic fluid system shown diagrammatically.
FIG. 3 is a view of a portion of the steering mechanism showing the
neutral position of the control valve.
FIG. 4 is a section view of a portion of the steering mechanism
showing the position of the spool valve in the valve housing for
moving the cylinder to the right.
FIG. 5 is taken on line 5--5 of FIG. 3 showing the inlet port and
the outlet port in the valve housing.
DESCRIPTION OF THE INVENTION
The steering mechanism 10 of this invention is shown in FIG. 1
pivotally connected to a steering arm 12 for a marine propulsion
unit 14 and to a steering actuator 16 operable from a remote point
in a boat. The marine propulsion unit 14 is mounted rearwardly of a
transom 18 on a boat on a swivel bracket for steering movement
about a vertical axis. The swivel bracket is connected to a clamp
bracket for pivotal swinging movement about a horizontal axis. The
steering actuator 16 can be of various forms and in the disclosed
construction is of a push-pull or Bowden wire type having a cable
sheath 20 having a threaded end 21 secured to the transom 18 by
means of a bracket assembly 22. The actuator 16 also includes a
steering cable 24 mounted for movement within the sheath 20 to
provide steering movements for the propulsion unit 14. The bracket
assembly 22 includes a retainer 23 fixedly secured to the transom
18 and a ball-type swivel connector 25 supported for pivotal
movement by the retainer 23 and having a threaded bore 27 to
threadedly receive the threaded end 21 of the sheath 20. Although
the propulsion unit 14 is shown as part of an outboard motor, the
steering mechanism 10 is also adaptable for use with a propulsion
unit of a stern drive unit.
In accordance with the invention, means are provided for supplying
a hydraulic power assist steering force to the propulsion unit 14
to increase the steering forces originating in the steering cable
24 and for supplying a hydraulic power assist steering force to the
propulsion unit 14 to restrain or counter the steering forces
originating in the propulsion unit 14. In this regard hydraulic
means are operatively connected to the propulsion unit 14 and to
the remote actuator through the steering cable 24. Such means
comprises the steering mechanism 10 which includes a hydraulic
piston and cylinder assembly 26 connected at one end to the
steering arm 12 and at the other end to the steering cable 24.
The piston and cylinder assembly 26 includes a piston 28 and a
cylinder 30 mounted for movement axially of the piston 28. One end
of the piston 28 and cylinder 30 is attached to the boat and the
other is attached to the propulsion unit. The piston 28 is provided
with a central aperture 29 having a threaded portion 40 and is
sealed with respect to the cylinder 30 by means of an O-ring 32
provided in an annular groove 34. The piston 28 is retained in a
relatively fixed position (i.e., ignoring some pivotal movement
relative to the boat transom) by means of a tubular piston rod 36
pivotally secured to the transom 18 of the boat by means of the
bracket assembly 22. The piston rod 36 is threaded at one end for
connection to the threaded bore 27 in the swivel connector 25 and
at the other end for connection to the threaded portion 40 of the
aperture 29 in the piston 28. For purposes to be mentioned later, a
number of ports 42 are provided in the piston rod 36 adjacent to
the piston 28.
Means are provided for closing the ends of the cylinder 30 in the
form of an end wall 44 at one end of the cylinder to form a
pressure chamber 46 on one side of the piston 28 and a plate 48 at
the other end of the cylinder to form a pressure chamber 50 on the
other side of the piston 28. The end wall 44 includes a central
aperture 52, a port 54 and a threaded annular flange 56. The plate
48 is retained on the cylinder 30 by means of a snap ring 60 and
includes an aperture 58 through which the tubular piston rod 36
extends. The plate 48 is sealed to the cylinder 30 and to the
piston rod 36 by means of O-rings 62 and 64 positioned to sealingly
engage the inner surface of the cylinder 30 and the outer surface
of the piston rod 36, respectively.
The hydraulic means also includes a continuously available source
of hydraulic fluid connected to the assembly 26. The hydraulic
fluid is supplied to the assembly by means of a pump 66 which can
be driven directly off of the marine propulsion unit 14 to supply
hydraulic fluid whenever the unit is operating or by an independent
power source such as an electric motor. The pump 66 is connected to
the assembly 26 by a supply conduit 68 and to a reservoir or sump
70 by a conduit 72. Hydraulic fluid from the assembly 26 is
returned to the reservoir or sump 70 through a return conduit
74.
The flow of hydraulic fluid to the pressure chambers 46 and 50 in
the cylinder 30 is controlled by means of a control valve 76
mounted on the end wall 44 of the cylinder 30 and operatively
connected to the remote actuator by the cable 24. The control valve
76 includes a valve housing 78 secured to the cylinder 30 and is
provided with a central cavity 82 threaded at 84 for connection to
the threaded flange 56 provided on the end wall 44 and is sealed to
the cylinder by means of an O-ring 85. The control valve also
includes a spool valve 80 mounted for movement axially within the
cavity 82 between a centered no-force position to second and third
positions on opposite sides of the centered position as explained
later in greater detail.
Hydraulic fluid is admitted to the central cavity 82 in the valve
housing 78 through an inlet port 86 connected to the supply conduit
68 and is discharged from the cavity 82 through an outlet port 88
connected to the return conduit 74. The central cavity 82 is
coaxial with the aperture 52 in the end wall 44 and is connected to
the port 54 by means of a first axially extending bore 90 and a
port 90'. The central cavity 82 is also connected to the outlet
port 88 by means of a second axially extending bore 92 connected to
the cavity 82 by internal annular grooves 94 and 96 located
adjacent the ends of the central cavity 82.
In order to allow the steering mechanism 10 to move freely with
respect to the steering arm 12, means are provided for pivotally
connecting the valve housing 78 to the steering arm 12. Such means
includes a flange or ear 85 which extends from the valve housing 78
and has an aperture 87. This means also includes a bifurcated lever
arm 89 pivotally connected to the steering arm 12 and having
apertures 91. The lever arm 89 is positioned to straddle the flange
85 and a pivot pin 93 is inserted through the apertures 91 and the
aperture 87.
The flow of hydraulic fluid through the inlet port 86 and the
outlet port 88 in the valve housing 78 to the cylinder 30 is
controlled by means of the spool valve 80 which is connected to the
actuator for movement from the first or no-force position to the
second and third positions in the central cavity 82. The spool
valve 80 is provided with an axially extending bore 98 having an
internally threaded section 99, a first passage or annular groove
104 having a discharge port 106 in end wall 108, a second axially
elongated passage or annular groove 110, and a third passage or
annular groove 100 connected to the bore 98 by a port 102.
Means are provided for connecting the spool valve 80 to the
steering cable 24 to transfer steering movements originating from
the remote actuator to the propulsion unit. Such means includes a
tubular member or extension 112 which projects axially through the
aperture 52 in the end wall 44, the aperture 29 in the piston 28,
and the bore of the piston rod 36. O-ring seals 51 and 53 are
provided in the apertures 52 and 29, respectively, to sealingly
engage the tubular extension 112. The tubular extension 112 is
externally threaded at one end for connection to the internally
threaded section 99 in the spool valve 80 and is connected at the
other end to the cable 24 by means of a cable connector 114
positioned for movement axially in the piston rod 36. The cable
connector 114 is sealed within the bore of the piston rod 36 by an
O-ring 116. A fluid flow path is provided between the bore of the
extension 112 and the bore of the piston rod 36 by means of a
number of ports 118 provided adjacent to the connector 114.
A hydraulic power assist steering force from forces originating in
the steering cable 24 is provided to the propulsion unit by moving
the spool valve 80 from the first or no-force position to either
the second position or the third position within the valve housing
78. When the spool valve is in the first position, FIG. 3, means
including the first passage 104 provide a connection between the
inlet port 86 and the outlet port 88 for the continuous flow of
hydraulic fluid through the valve 76. Such means is more
specifically defined by a flow path which includes the inlet port
86, the first passage or groove 104 in the spool valve 80, the port
106 in the end wall 108, the internal annular groove 96 at the end
of the second bore 92 and the outlet port 88. The cylinder 30 will
not move with respect to the piston 28 under hydraulic actuation
whenever the spool valve 80 is in the first position or no-force
position because the fluid in the pressure chambers 46 and 50 is
trapped in the cylinder 30.
The cylinder 30 is moved to the right with respect to the piston 28
by pressurizing the chamber 46 and relieving pressure in the
chamber 50. In this regard, the spool valve 80 is moved axially to
the right or to the second position in the valve housing 78 as
shown in FIG. 4. When the spool valve is in the second position,
means including the second passage 110 provide a connection between
the inlet port 86 and the pressure chamber 46 for flow of hydraulic
fluid to the pressure chamber 46 in the cylinder 30. Such means is
more specifically defined by a flow path which includes the inlet
port 86, the second passage or annual groove 110 in the spool valve
80, the first bore 90 and the port 54 in the end wall 44. Also,
when the spool valve is in the second position, means including the
third passage 100 provide a connection from the other chamber 50 to
the outlet port 88 for the discharge of fluid from the chamber 50.
Such means is more specifically defined by a flow path which
includes the ports 42 in the piston rod 36 affording flow through
the piston rod bore, the ports 118 in the tubular extension 112
affording flow from the bore of the piston rod to the bore of the
tubular extension, the axial bore 98 in the spool valve 80, the
port 102 to the third passage or annular groove 100, the internal
annular groove 96 to the second bore 92 and the outlet port 88.
Hydraulic fluid flowing through the ports 118 in the extension 112
is confined in the space in the bore of the piston rod 36 between
the cable connector 114 and the piston 28 by means of the O-ring
seals 116 and 53, respectively.
The cylinder 30 is moved to the left with respect to the piston 28
by pressurizing the chamber 50 and relieving pressure in the other
chamber 46. In this regard, the spool valve 80 is moved to the left
or to the third position in the valve housing 78 as shown in FIG.
2. When the spool valve is in the third position, means including
the third passage 100 provide a connection between the inlet port
86 and the pressure chamber 50 for the flow of hydraulic fluid to
the pressure chamber 50 in the cylinder. Such means is more
specifically defined by a flow path which includes the inlet port
86, the third passage or annular groove 100, the port 102 to the
axial bore 98, the bore of the tubular extension 112, the ports 118
to the bore of the piston rod 36 and the ports 42 to the chamber
50. Also, when the spool valve 80 is in the third position, means
including the second passage 110 provide a connection between the
pressure chamber 46 and the outlet port for the discharge of
hydraulic fluid from the other chamber 46. Such means is more
specifically defined by a flow path which includes the port 54 to
the first bore 90, the second passage or annular groove 110, the
internal annular groove 94, the second bore 92 and the outlet port
88.
In order to prevent movement of the cylinder 30 with respect to the
piston 28 when the remote actuator is released by the operator,
means are provided for biasing the spool valve 80 to the first or
no-force position in the cavity 82 of the valve housing. Such means
comprises a pair of springs 81 provided in the cavity 82 on each
side of the spool valve 80.
In the event the pressure of the fluid in the supply conduit
becomes excessive, means are provided for bypassing fluid from the
supply conduit 68 to the return conduit 74 in the form of a bypass
conduit 73. Means are provided in the bypass conduit for
restricting flow until the pressure exceeds a predetermined
maximum. Such means is in the form of a relief valve 71 positioned
in the bypass conduit 73. The relief valve 71 can be set to allow
for the flow of fluid from the supply conduit to the return conduit
when the predetermined pressure is reached.
A hydraulic power-assist restraining or backlash force is supplied
to the propulsion unit to counteract steering forces originating in
the propulsion unit when the remote actuator is held fixed by the
operator by means of the connection of the cylinder 30 to the
steering arm 12 and the connection of the spool valve 80 to the
temporarily stationary steering cable 24. In this regard, any
movement of the cylinder 30 and valve housing 78 with respect to
the spool valve 80 from steering movements originating in the
propulsion unit 14 will result in the establishment of a flow path
from the inlet port 86 to one of the pressure chambers 46 and 50
and from the other of the pressure chambers 46 and 50 to the outlet
port 88.
More specifically, as the cylinder 30 moves to the right, as seen
in FIG. 2, the spool valve 80 will be moved to the third position
in the valve housing 78. A flow path will be established from the
inlet port 86 to the pressure chamber 50 and from the pressure
chamber 46 to the outlet port 88 through the spool valve 80 as
described above. The increase in hydraulic pressure in chamber 50
will cause the cylinder 30 to move to the left contrary to the
steering movement originating in the propulsion unit. If the
cylinder 30 moves to the left, as seen in FIG. 4, the spool valve
80 will be moved to the second position in the valve housing 78. A
flow path will be established from the inlet port 86 to the chamber
46 and from the chamber 50 to the outlet port 88 as described
above. The increase in pressure in chamber 46 will cause the
cylinder to move to the right contrary to the force of the steering
movement originating in the propulsion unit.
The propulsion unit 14 can be steered manually in the event the
pump 66 is turned off or becomes inoperative. In this regard, the
spool valve 80 is manually moved to the right or to the left by the
movement of the cable 24 in response to actuation of the remote
actuator by the operator until the spool valve 80 seats against the
valve housing 78, thereby establishing a mechanical connection
between the valve housing and the remote actuator. More
specifically and referring to FIG. 2, when the spool valve 80 is
moved to the left or third position into engagement with the valve
housing 78, the cylinder 30 will start to move with the spool valve
80 reducing the size of the pressure chamber 46 and increasing the
size of the pressure chamber 50. The fluid in the pressure chamber
46 will be forced out through the port 54 into the axially
extending bore 90, through the annular groove 110 in the spool
valve 80 and the annular groove 94 into the second bore 92 and out
through the outlet port 88 into the return conduit 74 to the sump
70. Fluid in the return conduit 14 is supplied to the supply
conduit 68 by means of a bypass conduit 67 connected between the
return conduit 74 and the supply conduit 68. The flow of fluid
through the supply conduit is restricted by means of a one-way
check valve 69 provided in the conduit 67. Fluid will be drawn from
the supply conduit 68 into the other chamber 50 through the inlet
port 86, the annular groove 104 through the port 102 into the axial
bore 98, through the bore of the tubular extension 112 and the
ports 118 into the bore of the piston rod 36 and through the ports
42 into the chamber 50. Since the chamber 50 is smaller than the
chamber 46 due to the presence of the piston rod 36, any excess
fluid from the chamber 46 will flow directly through the return
conduit 74 to the sump 70.
When the spool valve 80 is moved to the right or second position
into engagement with the valve housing 78, fluid is supplied to the
pressure chamber 50 from the supply conduit 68 through the tubular
extension 112 and piston rod 36. Fluid in the chamber 46 is
discharged through the bore 90, annular groove 110, bore 92 to the
return conduit 74. The fluid in the return conduit 74 will flow
directly through bypass conduit 67 and check valve 69 into supply
conduit 68. Since the fluid from the chamber 50 will not be
sufficient to fill the chamber 46, the fluid from the chamber 50 is
augmented by the addition of fluid from the sump 70.
It is within the contemplation of this invention to include the
bypass conduits 67 and 73 within the valve housing 78 and to mount
the pump 66 directly on the valve housing 78.
Various of the features of the invention are set forth in the
following claims:
* * * * *