Note: Descriptions are shown in the official language in which they were submitted.
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PENDULUM PISTON MOTOR
The present invention relates to a hydraulically or pneumatically
actuateable pendulum piston motor or toroid piston motor, whereby is meant a
motor having a piston which is reciprocatable in a circular cylindric (toroid)
chamber and which has a central output shaft, and in which the piston is
arranged to perform a reciprocating work under the action of a hydraulic
pressure medium like oil, water or another liquid, or a pneumatic pressure
medium like air, another gas, steam, combustion gases etc., whereby the
pressure medium is alternatingly introduced into opposite pressure chambers
of the motor, so that the piston exerts a reciprocating pendulum movement.
Pendulum piston motors or ring piston Itoroid type) motors of the said
type are known for instance from DE-O-1.750.601 or GB-P-2.239.053. In the
apparatus of said two patent publication there is obtained a reciprocating
loscillating) movement of the output shaft, which movement is suited for
certain applications. It may, however, be difficult to make use of such
reciprocating movement as a drive means for applications where a constant
driving in one and the same direction is necessary, and therefore, the said
motors are not suited as drive motors for rotary machines, for vehicles and
other apparatus in which there is desired a drive movement with a constant
direction of rotation and a constant of nearly constant drive force.
A further rotary actuator is known from GB-A-2.312.248. Said rotary
actuator is formed with a piston assembly moving in a toroidal pressure
chamber to provide an angular motion of a drive shaft over a flange plate
connected to said drive shaft over a ratchet type clutch. The actuator is
adapted to transform pressure signals into angular motion, and it operates
from pressure signals.
None of the known prior art apparatus is capable of providing a uniform
rotation in one single direction of an output shaft using a reciprocating
pendulum piston motor.
The primary object of the invention therefore has been to solve the
problem of providing a pendulum piston motor of the above mentioned type, in
which the output shaft rotates in one and the same direction and which has
controllable, constant or nearly constant drive force, notwithstanding the
fact
that the piston performs a reciprocating pendulum movement.
A motor of the said type presents several advantages, namely that it
can be made with sma(I dimensions and as a lightweight unit, the drive force
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of the motor can very easily be adapted to the actual needs, it can be driven
with many different types of hydraulic or pneumatic pressure medium, it
provides a very high efficiency in relation to its weight, it provides a
practically
constant drive force over the entire stroke of operation, it can be driven
with a
pressure medium which does not give any exhaust gases at all or any other
unfavourable environmental effects, it can be manufactured to substantially
reduced costs considering the motor effect, than is possible for conventional
OTTO engines, DIESEL engines, WANKEL engines or other types of internal
combustion engines. A further great advantage with the motor in question is
that the motor, for each single operation cycle, develops a work which is far
greater than the work which can be developed per operation cycle by a
conventional internal combustion engine, namely 6-10 times greater that the
work which is developed per operation cycle by a conventional internal
combustion engine or 4-stroke type, or at least 4 times greater that the work
which can be developed by an internal combustion engine of 2-stroke type.
In the accompanying figure 1 there is shown the known principle for an
internal combustion engine having a reciprocatable piston and a rotary crank
shaft comprising an output shaft. It is known that the force from such an
engine is developed according to a type of GAUSS curve, whereby the force is
slowly increasing from 0° for a 2-stroke engine, or from 360°
for a 4-stroke
engine, over a maximum force for the output shaft is obtained at about
90°
and 450°, respectively, whereupon the force is slowly decreasing to a
zero
force at, or very closely following 180° and 540°, respectively.
A pendulum piston motor can be designed so as to give full force during
almost the entire pendulum movement in each of the two opposite directions.
The restriction of the force output is provided by the means for supply of the
hydraulic or pneumatic pressure medium and for inverting the supply direction
thereof, which means can be restricted to 10-20° of a full rotational
turn
thereof. A pendulum motor is diagrammatically illustrated in figure 2.
In figure 3 the power output of a pendulum piston motor is marked with
phantom lines, and the power output of a 4-stroke engine, simiiar to a GAUSS
curve, is marked with the double shadow part at the position between 360
and 540°, that is at two full turns of the engine. In figure 4 there is
correspondingly shown the power output for a pendulum piston motor and for
a 2-stroke internal combustion engine, respectively, at two full turns of the
engine. It is obvious that the average work exterted by a 4-stroke internal
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combustion engine exerts is only about 1 /8 of the work which is exterted by a
pendulum piston motor during the same time of operation, and that the
average work exterted by a 2-stroke internal combustion engine is only about
1 /4 of the work that a pendulum piston motor exerts during a time
corresponding to two turns of the output shaft.
As mentioned above an ordinary pendulum piston motor provides a
reciprocating or oscillating (swingl movement of the output shaft, which
movement can not, without involving special measurements, be utilized as a
drive force in case a drive force having a constant direction of rotation is
desired.
According to the invention the pendulum piston motor therefore is
formed with means for inverting the direction of rotation of the output shaft
either during the clockwise movement or during the counter clockwise
movement of the pendulum piston. This can be done in that the motor is
formed with a planetary gear which inverts the direction of rotation at one of
the movement phases of the pendulum piston. For making it possible to
receive a power output at both directions of rotation the pendulum motor also
comprises two free wheel couplings, a first free wheel coupling for the
"forward" movement and a second free wheel coupling for the "rearward"
movement. The two free wheel couplings are mounted in apposite operation
directions in relation to each other, so as to allow driving and free wheel
running in opposite directions of rotation, whereby the output shaft is driven
with a constant direction of rotation. The planetary gear preferably has a
gear
change of 1:1, but for providing special effects it is also possible to make
use
of any other gear change for the planetary gear, whereby a periodical
fluctuation of the drive movement of the output shaft can be obtained.
The two free wheel couplings foresee a rotary movement of the output
shaft even for a very little movement of the pendulum piston, and depending
on the two counter acting free wheel couplings, including the planetary gear,
there is obtained a stepless reversing of rotary movement of the output shaft.
Depending on the interaction of the two free wheel couplings and the
planetary gear there is automatically obtained a free wheel function of the
output shaft, meaning that there is obtained an idle running whenever an
apparatus which is drivingly connected to the output shaft is running faster
than said drive motor. When the drive shaft of said pendulum piston motor is
still standing said apparatus which is drivingly connected thereto can only
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move corresponding to a clockwise direction of the pendulum piston motor.
Therefore the apparatus of the invention can not involve any braking moment
in the apparatus.
Now the invention is to be described more in detail with reference to
the accompanying drawings. In the drawings figure 1, as mentioned above,
diagramatically shows the operation of an internal combustion engine of 0TT0
type or DIESEL type. Figure 2 diagrammatically shows the operation of a
pendulum piston motor. Figure 3 is a curve showing the work which is exerted
both by a pendulum piston motor according to the invention (phantom line
areal, and by a 4-stroke internal combustion engine (double phantom areal,
and figure 4 correspondingly shows the work exerted by a pendulum piston
motor and by a 2-stroke internal combustion engine. Figure 5 shows a cross
section view through a simple type of pendulum piston motor according to the
invention, as seen in the plane of the output shaft thereof, and figure 6
shows
a cross section view following line VI-VI of figure 5. Figure 7
diagrammatically
shows the operation of a pendulum piston motor according to the invention,
as seen perpendicularly to the output shaft. Figure 8 shows, in the same way
as in figure 5, a combined pendulum piston motor. Figure 9 shows, more in
detail, an example of a control apparatus for alternating the pressure medium
supply to the two piston chambers of the pendulum motor, and figure 10
shows, in detail, the position of the control apparatus after readjustment of
said control apparatus and for introduction of pressure medium in the left
piston chamber as shown in the drawing.
The pendulum piston motor according to the invention, shown in figures
5-7, generally comprises a cylinder housing 1 having a ring shaped (toroidy
cylinder race 2, in which a pendulum piston 3 is arranged to swing
reciprocatingly between the two sides of a piston chamber wall 4 which is
formed with means for supply of pressure medium to the piston chambers 5
and 6 appearing at opposite sides of the pendulum piston 3.
The cylinder housing 1 comprises two house halves 7 and 8 which are
split perpendicularly to the output shaft and which, as known in the art, are
sealed 9 both outwards and inwards in relation to the cylinder race 2 so as to
form two opposite piston chambers 5 and 6 which are sealed in relation to
each other. The pendulum piston 3 is formed as a projecting part having an
inner fly mass 10 with a piston neck 10a which keeps the piston 3 in place in
the cylinder race 2. The fly mass 10 is beared in the centre of the cylinder
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housing by means of bearings i 1, 12 on each side of the housing and under
co-operation of a shaft of rotation 13 and two counter-acting free wheel
couplings 14 and 15, respectively. One 14 of the free wheel couplings
provides a drive transmittance in one direction, marked with arrows 16 and a
5 free wheel function in the opposite direction of rotation, and the other
free
wheel coupling 15 provides a drive transmittance in the opposite direction as
compared with the free wheel coupling 14, marked with the arrows 17. In the
two opposite directions of the free wheel couplings there is, as known per se,
obtained a substantially resistance-free movement of rotation. The right hand
free wheel coupling 15 shown in figure 5 is enclosed in the inner sun wheel
18 of a planetary gear, the outer sun wheel 19 of which is fixed mounted in
an axially projecting collar 20 of the fly mass 10. Said outer sun wheel 19 is
drive connected to the inner sun wheel 18 over three, or more, planetary
wheels 21. For providing an even and uniform movement in both directions of
rotation the planetary gear ought to have a gear change between the planetary
wheels 21 and the inner sun wheel of 1:1. For special use, however, it is
possible to make use or another gear change, so that the piston moves
quicker, or more slowly, in one of the piston movement directions than in the
opposite piston movement direction.
The purpose of the planetary gear is to invert the direction of rotation
during one of the piston movements so that the output shaft 13 is always
driven in the same direction of rotation.
The means for supply of hydraulic or pneumatic pressure medium are
connected to the piston chamber wall 4. Said pressure supply means can be
formed in various ways, but they ought to be arranged and controlled by the
geometry of movement of the pendulum piston, so that the pressure medium
supply is changed between the two piston chambers 5 and 6 at a certain
desired position of the piston 3. For obtaining an optimum work said change
of pressure supply can be made when the piston has reached as far as to the
rear piston chamber wall, or is located very close to said wall. In figure 7
is
indicated that the controlling of the pressure medium supply can be made by
means of a rotatable valve 22 the operation of which can be controlled by the
movement of the piston 3, so that the pressure medium supply is changed
between the two chambers 5 and 6. The operation and controlling of the valve
can be made mechanically, electronically, hydraulically or by any other means
in correspondence to the movements of the piston 3 in the cylinder race 2.
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1n figure 7 is shown that the pressure medium is supplied to piston
chamber 5, and this makes the piston 3 rotate in the clockwise direction. For
draining the hydraulic or pneumatic pressure medium from the non-operative
piston chamber, in figure 7 chamber 6, the apparatus is formed any type of
evacuation means of priorly known type, not shown in the drawings, for
instance a passageway having a non-return valve leading out to the ambient
and provided in the piston chamber wall 4. Such a non-return valve becomes
operative only when the opposite piston chamber is under pressure. In figure 7
there is indicated that the piston chamber 5 providing a clockwise operation
receives pressure medium over a passageway 24 in the piston chamber wall,
whereas the opposite piston chamber 6 is drained of pressure medium.
The pressure supply can be varied as desired and to provide the torque
and the rotational speed which is desired at the output shaft 13. The
apparatus can be formed with a choke valve connected to the pressure
medium supply means for providing a soft starting and a controlled speed and
a controlled torque.
A pendulum piston motor of the above described type can be used for
many different purposes, for instance as a drive motor for a vehicle or a
machine of any type, even without use of a gear box since the force and the
speed at the output shaft 13 can be varied from zero to maximum only by
controlling the pressure of the drive pressure medium. There is also no need
for a sliding clutch for providing a soft starting since this can easily be
accomplished by means of a choke valve which controls the pressure and the
flow of fluid to the cylinder chambers from zero to maximum. A free wheel
running of the vehicle is obtained by the action of the two free wheel
couplings 14 and 15. A rear driving function can be obtained by using a
simple mechanical reverse gear.
In figures 9 and 10 there is shown an apparatus in which the changing
of pressure medium supply between the two pressure chambers 5 and 6 is
made by the piston 3 itself. In this case the pressure change piston is formed
as a rotatable slide 25 which is formed with actuation arms 26 which project
downwards and are provided on opposite sides of the piston chamber wall 4.
The actuation arms 26 are pushed by the piston 3 when reaching the end of
its operative stroke, whereby the slide valve is switched over from clockwise
actuation or counter clockwise actuation of the piston, and vice versa. The
pressure medium is supplied through a central bore 27 and through
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passageways 28, 29 and openings 30 and 31 in the valve slide 25 and from
there through further passageways into one of the piston chambers 5 and 6.
In figure 9 the valve slide 25 is shown in a neutral position, in which
position
there is no supply of pressure medium. In figure 10 is shown that the piston 3
has performed a clockwise stroke, has pushed the arms 26 so that the valve
slide 25 has taken a position in which pressure medium is introduced in the
counter clockwise piston chamber 6 through the passageway 29 and the
opening 31 in the valve slide 25, whereby the piston 3 has started its counter
clockwise stroke.
Since the planetary gear 17-21 inverts the direction of rotation at the
outer sun wheel 19 at one stroke of the motor the output shaft 13 will always
rotate in one and the same direction, and this is made possible by the action
of the two counter directed free wheel couplings 14 and 15.
The described pendulum piston motor can accomplish an operation over
up to 340-350° of the rotational turn, and it is obvious from the
diagrammatic
curves of figures 3 and 4 that full effect is developed already from the
moment that pressure medium is supplied to the pressure chamber 5 for
clockwise rotation, and thereby that full effect is developed between about
5°
and 355°, and that the supply of pressure medium is thereafter changed
to be
introduced into pressure chamber 6, in which full effect is developed from
about 365° to about 715°, as calculated on a complete working
cycle
corresponding to two turns of the crank shaft of an internal combustion
engine of OTTO or DIESEL type. It is also evident that a 4-stroke engine,
during a corresponding time, performs a work the average value of which is
only about 1 /8 of the work of a pendulum piston motor, and that a 2-stroke
engine performs a work corresponding to not more than 1/4 of the work
performed by a pendulum motor.
In connection to the changing the supply of pressure medium between
the pressure chambers 5 and 6 there appears an insignificant interruption of
operation, corresponding to 10-20° of the total work of a full
rotational cycle.
Said insignificant interruption of work is normally equalized by the fly mass
10
of the pendulum piston motor. The fly mass 10 has to be braked to stop
before the pressure fluid in introduced in the opposite pressure chamber and
the motor is operated in the opposite direction.
When the valve switches over the supply of pressure medium from one
pressure chamber to the other the drain outlet of pressure medium in the
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inactive pressure chamber has to be closed before pressure fluid in introduced
in said pressure chamber which is thereby made active, which means that the
pressure fluid which is entrapped in the inactive pressure chamber, in case of
using air as pressure fluid becomes compressed. Depending on said
compressing of the entrapped air the piston is braked to stop softly at the
end
of the stroke. The compressed air can be drained using a pressure controlled
valve which opens at a relatively high pressure, for instance 8 bar, whereby
said compressed air is introduced in a compressed air tank 34 (see figure 7)
and is reused as part of a drive pressure medium at the next drive phase.
It is, however, possible to practically completely eliminate such
interruption of operation and to equalize the operation characteristic of the
motor by interconnecting two, or more, motors in series with each other on
the same output shaft 13, as shown in figure 8. fn such case the two or more
motors are rotated in relation to each other following the drive shaft 13,
that
is so that the piston chamber walls 4 of the to or more motors are distributed
round the drive shaft, for instance 180° using two interconnected
motors,
120° using three interconnected motors, etc. The motors thereby are
operated, in relation to each other, so that the interruption of operation,
corresponding to about 355-5° are offset to each other. In figure 8 is
shown
that the means 32, 33 for supply of pressure medium, including the piston
chamber walls, are rotated 180° in relation to each other with
reference to the
output shaft.
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REFERENCE NUMERALS
1 cylinder housing 21 planetary wheel
2 cylinder race 22 rotatable valve
3 pendulum piston 23 draining means
' 5 4 piston chamber wall 24 passageway
cylinder chamber 25 valve slide
6 cylinder chamber 26 actuation arms
7 half part of cylinder 27 central bore
housing
8 half part of cylinder 28 passageway
housing
9 sealing 29 passageway
10 fly mass 30 bore
10a piston neck 31 bore
11 bearing 32 pressure supply means
12 bearing 33 pressure supply means
13 shaft of rotation 34 pressure chamber
14 free wheel coupling
15 free wheel coupling
16 arrow
17 arrow
18 inner sun wheel
19 outer sun wheel
20 collar
