U.S. patent number 3,635,605 [Application Number 05/018,177] was granted by the patent office on 1972-01-18 for control means for reversible fluid pressure operated motors.
This patent grant is currently assigned to Broom and Wade Limited. Invention is credited to Raymond John Hall, Derek James Webb.
United States Patent |
3,635,605 |
Hall , et al. |
January 18, 1972 |
CONTROL MEANS FOR REVERSIBLE FLUID PRESSURE OPERATED MOTORS
Abstract
A control means for a reversible fluid pressure operated power
tool comprising an on/off valve to control the flow of fluid to the
motor and a reversing valve for changing the path of the fluid
through the motor. A single manually operable control is provided
for the valves, which control is movable from a first position in
which the motor is inoperative to a second position in which the
motor runs in one direction, and then to a third position in which
the motor runs in the other direction.
Inventors: |
Hall; Raymond John (High
Wycombe, EN), Webb; Derek James (Sonning,
EN) |
Assignee: |
Broom and Wade Limited
(Buckinghamshire, EN)
|
Family
ID: |
10031607 |
Appl.
No.: |
05/018,177 |
Filed: |
March 10, 1970 |
Foreign Application Priority Data
|
|
|
|
|
Mar 17, 1969 [GB] |
|
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13,910/69 |
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Current U.S.
Class: |
417/315; 173/169;
123/387; 418/32 |
Current CPC
Class: |
B23B
45/04 (20130101) |
Current International
Class: |
B23B
45/00 (20060101); B23B 45/04 (20060101); F04b
049/02 (); H01b 011/16 () |
Field of
Search: |
;173/169 ;418/32,243
;417/315 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Freeh; William L.
Claims
We claim:
1. Control means for a reversible fluid pressure operated power
tool having a body portion, manually grippable handle means
projecting from the body portion, a reversible fluid actuated motor
mounted in the body portion, a fluid duct connecting the motor to a
supply of pressurized fluid, control means mounted in the handle
means in the fluid duct for controlling a fluid flow through the
duct, which control means comprise an on/off valve for control of
flow of fluid to the motor, and a reversing valve for controlling
the path of fluid through the motor, and trigger means operable by
a single finger of an operator connected to both valves and movable
linearly by pressure thereon from a first position in which the
on/off valve is in the off condition, through a second position in
which the on/off valve is in the on condition and the reversing
valve is in a first condition, to a third position in which the
on/off valve is in the on condition and the reversing valve is in
the second condition, the trigger means being returned
automatically to the first position when the pressure thereon is
released.
2. Control means as claimed in claim 1 and including a relay valve
movable between two positions in which it directs the fluid to
rotate the motor in its forward and reverse directions respectively
and the reversing valve operates to apply fluid pressure to cause
the relay valve to move between the two positions.
3. Control means as claimed in claim 2 in which the fluid pressure
operates to move the relay valve in one direction between its two
positions and the spring effects movement of the relay valve in the
other direction.
4. Control means for a reversible fluid pressure operated motor,
which comprises:
a. a two position relay valve comprising a shuttle movable in a
cylinder under fluid pressure differences applied to opposite ends
thereof and against a return spring, said shuttle being arranged in
its two positions to direct fluid pressure into the motor for
rotation thereof in opposite directions respectively;
b. a housing with a bore open at one end and closed at the other
end with an inlet port into the closed end and two ports in the
sidewall of the bore at successive positions intermediate in the
length of the bore from the closed end, said two ports leading
respectively through ducts to the side and one end of said
shuttle;
c. a two-part piston valve member fitting in fluidtight relation
within said bore and having freedom for limited axial sliding
movement therein, said piston valve member comprising a tubular
sleeve and a plunger in fluidtight relation within the sleeve and
having freedom for limited axial sliding movement therein;
d. said plunger having at its end adjacent the closed end of the
bore clearance within the sleeve and an enlarged head which
cooperates with the adjacent end of the sleeve to constitute an
on-off valve by which the said clearance may be put into
communication with or shut off from the closed end of the bore and
said inlet port, the other end of the plunger projecting from the
other end of the sleeve and being accessible at the open end of the
bore for manual endwise pressure thereon;
e. said sleeve having in its wall and leading from said clearance a
port which registers with one of the ports in the sidewall of said
bore in all positions of sliding movement of the sleeve and hence
maintains said clearance in communication with one end of the relay
valve and also having a further port which in one end position of
the sleeve movement registers with the other port in the sidewall
of the bore and puts the other end of said relay valve into
communication with the external atmospheric pressure, the sleeve
when in its other end position opening said other port in the
sidewall to the closed end of the bore and hence to the inlet;
and
f. the plunger and sleeve being arranged for cooperation in the
bore in such manner that fluid pressure applied to the closed end
of the bore urges both the plunger and the sleeve outwardly of the
bore to the limits of their freedom of movement, the enlarged head
closing off the clearance from the inlet, manual pressure on the
accessible end of the plunger to move the plunger within the sleeve
to the limit of its movement therein lifts the enlarged head from
the sleeve and admits fluid pressure from the inlet to both the
side of and one end of the relay valve and further manual pressure
moves both the plunger and the sleeve together to cut off the fluid
pressure from one end of the relay valve and to open that end to
atmospheric pressure.
5. Control means for a reversible fluid pressure operated motor,
which comprises:
a. a two position relay valve comprising a shuttle movable in a
cylinder under fluid pressure differences applied to opposite ends
thereof and against a return spring, said shuttle being arranged in
its two positions to direct fluid pressure into the motor for
rotation thereof in opposite directions respectively;
b. a housing with a bore open at one end and closed at the other
end with an inlet port into the closed end and two ports in the
sidewall of the bore at successive positions intermediate in the
length of the bore from the closed end, said two ports leading
respectively through ducts to the side and one end of said
shuttle;
c. a two-part piston valve member fitting in fluidtight relation
within said bore and having freedom for limited axial sliding
movement therein, said piston valve member comprising a tubular
sleeve and a plunger in fluidtight relation within the sleeve and
having freedom for limited axial sliding movement therein;
d. said plunger having at its end adjacent the closed end of the
bore clearance within the sleeve and an enlarged head which
cooperates with the adjacent end of the sleeve to constitute an
on-off valve by which the said clearance may be put into
communication with or shut off from the closed end of the bore and
said inlet port, the other end of the plunger projecting from the
other end of the sleeve and being accessible at the open end of the
bore for manual endwise pressure thereon;
e. said sleeve having in its wall and leading from said clearance a
port which registers with one of the ports in the sidewall of said
bore in all positions of sliding movement of the sleeve and hence
maintains said clearance in communication with one end of the relay
valve and also having a further port which in one end position of
the sleeve movement registers with the other port in the sidewall
of the bore and puts the other end of the said relay valve into
communication with the external atmospheric pressure, the sleeve
when in its other end position opening said other port in the
sidewall to the closed end of the bore and hence to the inlet;
and
f. the plunger and sleeve being arranged for cooperation in the
bore in such manner that fluid pressure applied to the closed end
of the bore urges both the plunger and the sleeve outwardly of the
bore to the limits of their freedom of movement, the enlarged head
closing off the clearance from the inlet, manual pressure on the
accessible end of the plunger to move the plunger within the sleeve
to the limit of its movement therein lifts the enlarged head from
the sleeve and admits fluid pressure from the inlet to both the
side of and one end of the relay valve and further manual pressure
moves both the plunger and the sleeve together to cut off the fluid
pressure from one end of the relay valve and to open that end to
atmospheric pressure; and in which
g. the relay valve cylinder is closed at one end with a port
connected by a duct to the bore aforesaid for admission and exhaust
of fluid pressure to move the shuttle, is open at the other end to
receive exhaust and scavenge air from the motor with an outlet to
atmosphere, and the cylinder has at different circumferential
positions at the same position lengthwise of the cylinder three
ports of which one is an inlet port connected by a duct aforesaid
to one of the ports in the sidewall of the bore and the other two
are outlet ports connected to two inlets to the motor for forward
and reverse rotation thereof; and
h. the shuttle has ports and internal passageways which in one
position of the shuttle connect the inlet port to one of the outlet
ports, the other outlet port being connected to atmosphere and in
the other position of the shuttle the connections to the outlet
ports are reversed.
Description
The invention relates to control means for reversible fluid
pressure operated motors, and in particular but not exclusively,
motors for power tools used for example to drive screw taps.
It is an object of the invention to provide manual control means
for stopping and starting the motor and for changing the direction
of operation, which is operable by one hand.
The invention provides control means for a reversible fluid
pressure operated motor comprising an on/off control valve for the
flow of fluid to operate the motor, a reversing valve for changing
the path of the fluid through the motor and hence changing the
direction of rotation of the motor and a single manually operable
control for the valves which control is movable from a first
position in which the control valve is in the off condition, to a
second position in which the control valve is in the on condition
and the reversing valve is set for forward rotation and then to a
third position in which the reversing valve is set for reverse
rotation, the control valve remaining in the on condition.
In a preferred form of the invention there are means providing a
step in resistance to movement of the control when the second
position is reached whereby this position is defined to the
operator, the resistance being readily overcome by increased manual
effort. The resistance step may be provided, for example, by the
force necessary to move the reversing valve against fluid pressure
or spring means, or both, acting thereon.
The reversing valve may act indirectly by controlling fluid
pressure applied to a relay valve which, in turn changes the path
of fluid flow through the motor.
By way of example of the invention there will now be described a
specific embodiment of a rotary power tool, reference being made to
the accompanying drawings which show various sections through the
tool. In the drawings:
FIG. 1 shows a section through the motor and control portion of the
tool in the "off" condition, the section being on the line C--C in
FIG. 4,
FIG. 2 is a section showing the motor and control portion of the
tool in the "on" condition for forward rotation, the section being
on the line A--A in FIG. 5,
FIG. 3 is a section showing the motor and control portion in the
"on" condition for reverse rotation, the section being on the line
B--B in FIG. 6,
FIG. 4 is a section on the line R--R in FIG. 3,
FIG. 5 is a section on the line F--F in FIG. 2,
FIG. 6 is a section on the line Y--Y in FIG. 3,
FIG. 7 is a section on the line X--X in FIG. 2, and
FIG. 8 is a section, corresponding to FIG. 1, of the complete tool
which embodies a chuck for a screw tap.
In this example the motor is of the air driven sliding vane type.
When this type of motor is made reversible only about 180.degree.
of the cylinder is used for driving in each direction and it is
necessary to provide for release of the air, herein referred to as
scavenge air, which would otherwise be compressed by the vanes in
the half of the cylinder not for the time being used for driving.
This air is usually released through a port provided for inlet of
air when the half of the cylinder is used for driving.
FIG. 1 illustrates the tool in the "off" position with the feed
airline connected.
The tool comprises a housing 17 having a motor 13 and control means
for the motor mounted therein.
The control means for the motor comprise a two part piston valve 30
mounted in a bore 31 provided in the housing 17. The piston valve
30 comprises a tubular sleeve 5 fitting in fluidtight relation
within the bore 31 for axial sliding movement therein, and a
plunger 32 mounted for axial sliding movement within the sleeve 5.
The sleeve 5 is provided with a cutout portion 33, there being a
pin 34 mounted in the housing 17 and extending into the portion 33
to limit the axial sliding movement of the sleeve 5. Ring-type
seals 35 are provided to ensure the parts of the valve 30 fit
together in fluidtight relationship.
The plunger 32 comprises a shaft 2 slidably mounted within the bore
of the sleeve 5 with clearance for part of its length, and having
an enlarged head 36 engageable with the adjacent end of the sleeve
5 adjacent the closed end of the bore. The shaft 2 is provided with
a manually operable trigger 6 at its other end, outside the housing
17.
The closed end of the bore 31 forms a chamber 1a communicating with
a duct 1 through which live air is supplied to the tool. The
plunger 32 cooperates with the sleeve to form an on/off valve, the
part of the space around the shaft 2 adjacent the head 36 being
placed in or out of communication with the chamber 1a as the head
36 is respectively lifted off or rests on the end of the sleeve 5.
The space around the part of the shaft 2 adjacent the head 36 is in
communication with a port 10 provided in the housing through a
suitable cutout portion in the sleeve 5.
A relay valve 39 is also mounted in the housing and comprises a
shuttle 7 movable between two positions in a cylinder formed in the
housing. The shuttle 7 is provided with ports 9 and 22 extending
therethrough, one or other of which ports is in communication with
the port 10 through a duct 11 in each of the two positions
respectively. The ports 9 and 22 are so arranged to supply live air
from duct 11 to the motor through further ducts so that the
direction of rotation of the motor is reversed by moving the
shuttle from one position to the other.
A spring 8 is provided between the shuttle 7 and the housing to
bias the shuttle to the right (as seen in FIG. 1).
A further duct 3 communicates between a chamber 4 on the right hand
side of the shuttle 7 and the chamber 1a through a port 43 in the
wall of the bore in the housing. The sleeve 5 is arranged to close
the port 43 from the chamber 1a as the sleeve is moved to the right
(FIGS. 2 and 3), and place the port 43 into communication with the
atmosphere through ducts 19 and 20, 21 provided in the sleeve 5 and
shaft 2 respectively.
The live air enters through port 1 and passes into the chamber 1a
behind the plunger 32. Due to the live air pressure acting on the
head 36, the valve is held closed and no air passes it to the motor
13. The live air continues through port 43, duct 3 and into chamber
4, the resultant air pressure in this chamber causing the shuttle 7
to move forward against the force of the spring 8, thus aligning
ports 27 and 9. (See also FIGS. 2 and 5). In this condition there
is no manual pressure on the control trigger 6 and no motor
rotation.
When a light pressure is applied to the trigger 6, the reversing
valve sleeve 5 remains stationary due to the air pressure acting
upon it, (see FIG. 2), but air flows around the head 36, through
ports 10 and 11, and to piston valve 7 (see FIG. 5). This valve
directs the air through ports 9 and 27 into port 12, which leads
directly to the air motor 13, giving the latter forward
rotation.
Scavenge air passes through ports 14 from the air motor 13 into
chamber 25 (see FIG. 5). From here it passes to piston valve 7, and
is directed forward to emerge through port 28 into expansion
chamber 15 where it mixes with the exhaust air from the air motor
13. From chamber 15, the combined air is directed to exhaust port
16.
When a greater force is applied to trigger 6, the valve sleeve 5 is
depressed flush with housing 17 against the live air pressure
acting upon it. (See FIG. 3). This movement cuts off the live air
supply to chamber 4, and aligns port 18 with port 3, thus bleeding
off the residual air in the chamber 4 through ports 18, 19, 20 and
21 out to atmosphere. Due to both the pressure of spring 8 and the
scavenge air pressure in chamber 15, the piston valve 7 moves
backward, aligning ports 22 and 23. The live air, still being fed
into port 11, is now directed by port 22 into chamber 25. From
here, the air passes along ports 26 to the air motor 13, giving it
reverse rotation.
Scavenge air coming from the air motor 13 now passes through port
12, into piston valve 7, and out through port 24, (see FIG. 6) into
expansion chamber 15. Here it joins the exhaust air from the air
motor 13, and both are directed to exhaust port 16.
When the trigger 6 is released, the live air pressure behind the
head 36 pushes both plunger 32 and sleeve 5 forward.
This closes port 3 from exhaust and opens it to live air, thus
building up pressure in chamber 4. When the necessary pressure is
achieved, the piston valve moves forward into the forward rotation
position, ready for the next operation. The release of the trigger
6 also shuts off the air supply to the motor.
While it is stated that the plunger 32 and the valve sleeve 5 act
against live air pressure to achieve the loadings this is not
essential. They could be loaded against springs or other means.
Other variations in the above described example may be made. For
example the air pressure acting on shuttle 7 could be arranged to
act on the other end and hence the motor would run in a forward
direction with shuttle 7 in the rear position and in a reverse
direction with the shuttle in a forward position.
* * * * *