Note: Descriptions are shown in the official language in which they were submitted.
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Title of the Invention
SPEED-CHANGINC. TRANSMISSION DEVICE FOR
VEHICLES
Background of the Invention:
Field of the Invention
The present invention relates to a speed-
changing transmission device for vehicles and, more
particularly, to an improvement in a speed-changing
transmission device for vehicles, of the type having
a counter shaft adapted to be driven by an input shaft
which in turn is driven by an engine,.a transmission
shaft for driving a wheel axle or the like, the counter
shaft and the speed-changing shaft being connected to
each other through a forward transmission gear system
and also through a backward transmission gear system,
and clutches disposed in respective transmission paths
and adapted to be selectively used to effect the changing
of the speed.
Description of the Prior Art
In the conventional speed-changing transmission
device for vehicles, when, for example, the pressure of
the oilifor operating the clutch for:changing the speed
is lowered due to the stop of the engine during parking,
the clutch takes the "off" state to disconnect the
driving wheel axle or the like from the engine. In
this state, it is not possible to utilize the engine
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braking effect.whlch is quite useful particularly when
the vehicle is parked on a steel slope. In such a
case, if the parking brake is opera-ted insufficiently,
the vehicle will-naturally start dangerously. It is
also to be pointed out that, in the event of an:
excessive discharge~of the battery, it is not possible
to start the engine by pushing the vehicle manually,
because the driving..wheel axle is disconnected from
the engine.
Summary of the Invention
It is, thereEore, an ohject of the invention
to provide a speed-changing transmission device in
which, even when the clutch for the speed changing
becomes inoperative or to take the lloff" state
during parking, the direct connectio~..is:maintàined
between~the engine and the driving wheel axle or the
like to ensure the engine braking effect during parking.
According to the invention, the above-stated
object is achieved by a speed-changing transmission
device having the following featuresO
Namely, the invention provides a speed-changing
transmission device comprising: a speed-changing gear
for transmitting the torque to the driving wheel axle
or the like and mounted.at the rear side of an.inputs
shaft drivenl.by the engine coaxially with`the input shaft,
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a counter shaft mounted in parallel with the speed-
changing shaft and carrying a counter gear always
meshing with an input gear:on the input shaft,
a forward speed changing-gear system provided on the
speed-changing shaft and:the counter shaft, the
forward speed changing gear system including a
forward speed-changing gear and a forward counter gear
which are meshing with each other and adapted to transmit
the rotation of the counter shaft to the speed-changing
shaft at a speed reduced as compared with the speed of
the input shaft or in the reverse direction to the
rotation of the input shaft, a backward speed-changing
gear system provided on the speed-changing shaft~and:~he
counter shaft, the backward speed--changing gear system
including a backward speed changing gear, a backward
idle gear and a backward counter gear, a clutch disposed
between the input shaft and the speed-changing shaft
and clutches disposed in the transmission paths provided
by respective speed-changing gear systems between the
input shaft and the speed-changing shaft, the.. clutches
being usabla selectively, a one-way clutch for forward
driving disposed between the input shaft and the
speed-changing shaft, and a one-way clutch for backward
driving disposed between the speed-changing shaft and
the backward speed-changing gear system or between the
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counter shaft and the backward speed-changing gear system.
Brief Descript-ion of the Drawings
The invention is illustrated by way of example in
the accompanying drawings wherein:
Fig. 1 is a vertical sectional side elevational view
of the front portion of mission case of a powered agricultural
machine to which a device of a first embodiment of the invention
is applied;
Fig. 2 illustrates the power transmission system
of the embodiment shown in Fig. 1;
Figs. 3A to 3D are illustrations explanatory of the
operation of forward and backward one-way clutches in the
embodiment shown in Fig. l;
More particularly:
Fig. 3A views show state of engine forward driving,
respective views, forward and backward;
Fig. 3B views show state of engine backward driving,
respective views, forward and backward;
Fig. 3C views show state of engine stopping forward
driving: rotates on its own axis, respective views, forward and
backward;
Fig. 3D views show state of engine stopping backward
driving: rotates on its own axis, respective views, forward and
backward;
Fig. 4 illustrates the power transmission system of
a second embodiment of the invention; and
Figs. 5A to 5D are illustrations explanatory of the
operation of forward and backward one-way clutches in the
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embodiment shown in Fig. 4.
More particularly:
Fig. 5A views show state of engine forward driving,respective views, forward and backward;
Fig~ 5B views show state of engine backward driving,
respective views, forward and backward;
Fig. 5C views show state of engine stopping forward
driving: rotates on its own axis, respective views, forward and
backward;
Fig. 5D views show state of engine stopping backward
driving: rotates on its own axis, respective views, forward and
backward;
Description of the Preferred Embodiments:
Hereinafter, preferred embodiments of the invention
applied to a powered agricultural machine will be described
with reference to the accompanying drawings.
As will be seen from Fig. 1 showing a vertical section,
as well as from Fig. 2 showing the power transmission system
schematically, an engine 1 has a
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crank shaft to which connected is an input shaft 3
through a maln clutch 2. A speed-changing shaft 4
is suppo~ted at its front end by a bearing 5 and is
disposed behind the input shaft 3. The rear end o
the speed-changing shaft 4 is supported by a mission .
case 7 through a medium of a bearing 6. A counter
shaft 8 is mounted in parallel with the speed-changing
shaft 4 and supported by bearings 9,10 on the mission
case 7. A counter gear 11 of small diameter for
backward driving and counter gears 12b,12c for forward
driving having different diameters are carried by the
counter shaft 8. ~ speed-changing gear 14 for backward
driving, rotatably mounted on the speed-changing shaft
through a bearing 13 meshes through an idle gear 15 for
backward driving with a counter gear 11 for backward
driving to constitute a backward speed-changing gear
system.
Speed changing gears 18b,18c for forward
driving, rotatably mounted on the speed-changing shaft
4 through bear-ngs 16,17, engage with counter gears 12b,
12c for forward driving, while anuinput gear 3a of a smàll
diameter formed at the rear portion of the input shaft 3
meshes with a counter gear 12a of a large diameter to
constitute a forward speed-changing gear system.
A clutch 20 for hackward driving is connected
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between the backward speed-changing gear 14 and the
speed-changing shaft 4. Also, provided are clutches
21a,21b,21c for forward driving so as to connect
speed-changing gears 18b,18c to the clutch shaft 4.
These clutches are adapted be operated selectively.
A second speed-changing shaft 22 is connected
to the speed-changing shaft 4 through a gear as shown
in Fig. 2. A group 23 of shift gears slidable on~y
in the axial direction along the second speed-changing
shaft 22 is adapted to be brought into engagement
with a group 25 of second counter gears selectively by
means of a mechanical speed-changing device 26. A
drive pinion shaft 28 drivingly connected to the
second speed-changing shaft 22 through a clutch 27 is
adapted to drive left and right rear driving wheels 31,
31 of the vehicle through a rear wheel differential
gear device 29. The rear wheels 31 are provided with
respective brakes. .:::
The construction of the backward clutch 20 and
the forward clutches 21a to 21c will be explained herein-
under with specific reference to the clutch 21a for the
forward driving by way of example. The clutch 21a
has a clutch housing 32 fitted to the speed-changing shaft
4 and accomodating in an oil-tight manner a piston 33
which is biased in the d~sengag~n~ diæection~by means of
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a spring 33. A friction disc 35 fits in the clutch
housiny 32 slidably only in the axial direction, while
a friction disc 36 is fitted to a hub of an input
gear 3a slidably only in the axial direction. A
working oil deliv~red by an oil pump 37 is introduced
into a speed-changing switching valve 39 through a
relay cylinder 38 fitting the rear end of the speed-
changing shaft 4. As the driver manipulates a
speed-changing lever 40, the spool 41 of the switching
valve 39 is slided in the axial direction to distribute
the oil selectively from an oil passage 7a in the mission
case 7 and an oil passage 38a in the relay cylinder 38
via the oil passages a,b... of the clutch housings of
clutches selected by the speed-changing lever 40. For
instanee, assuming here that the pressurized oil is
supplied to the rear side of a piston 34 via the oil
passage a, the piston 34 makes the frictional discs
35,36 engage with eaeh other thereby to eonnect the input
gear 3a to the speed-ehanging shaft 4.
Thus, the power transmission provided by the
mutual engagement between the forward eounter gear 12e
and the forw-rd speed-changing gear 18c, caused by the
engaging operation of the forward clutch 21c, provides
a rotation speed of first forward speed (V1),which is
the lowest of the forward speeds, to the speed-changing
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shaft 4. Slmilarly, a Eorward second speed V2 is
given throuyh the mutual engagement of the forward
counter gear 12b and the forward speed-changing gear 18b
as the forward cluth 21b is brought into "ON" state, and
the highest forward speed V3 is imparted to the speed-
changing shaft 4 as the forward clutch 21a is put into
operation, by a direct connection. Also, as the
backward clutch 20 is put into operation, a backward
first speed R1 is imparted to the speed-changing shaft 4
through the backward counter gear 11, backward idle
gear 15 and the backward speed-changing gear 14.
The unput gear 3a is coupled to the speed-
changing gear 4 through a one-way clutch 42 which can
deliver to the input shaft 3 only the forward driving
power from the speed-changing shaft 4. Namely, as
shown in Fig. 3a, an outer wheel 42a fitted around the
input gear 3a is adapted to rotate counter-clockwise
as viewed from the rear side. This outer wheel 42a
makes a counter-clockwise rotation relati~ely to an
inner wheel 42b fitting the speed-changing shaft 4 which
rotates in the same direction as the input shaft 3 at
the forward first or second speeds Vl,V2 which is
lower than the speed of the input shaft 3. Therefore,
the input gear 3a and the speed-changing shaft 4 rotate
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freely from each other. The outer wheel 42a making
a counter-clockwise rotation relatively to the inner
wheel 42b and the input gear 3a can rotate freely from
each other also when the speed-changing shaft 4 makes
a clockwise rotation as shown in Fig. 3b. However,
when in~the state shown in Fig. 3c in which the inner
wheel 42b makes a counter-clockwise rotation relatively
to the outer wheel 42a, the speed-changing gear 4 and
the input gear 3a rotate as a unit with each other by
the action of the one-way clutch 42.
The backward speed-changing gear 14 is
connected to the speed-changing shaft 4 through a one-
way clutch 43 which can deliver to the backward speed-
changing gear 14 only the backward driving power from
the speed-changing shaft 4. Namely, an outer wheel
43a fits to the speed-changing gear 14 which is adapted
to rotate only in the clockwise direction as viewed
from the rear side as shown in Fig. 3a. This outer
wheel 43a rotates freely from ans inner wheel 43b
which rotates counter-clockwise at the forward first or
second speed Vl,V2. However, in the state shown in
Fig. 3d in which the inner ring 43b makes a clockwise
rotation reatively to the outer wheel 43a as mentioned
later, the speed-changing gear 14 and the speed-changing
shaft 4 rotate as a unit with each other by the action of
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the one-way clutch 43.
In another embodiment shown in Fig. 4, a
backward speed-changing gear 44 is fitted to the speed-
changing shaft 4, while a backward counter gear 45 for
engagement with the backward idle gear 15 is rotatably
carried by the counter shaft 8 through a bearing 46.
The backward counter gear 45 is connected to the cou~ter
shaft 8 through a backward clutch 47 having a clutch
housing fitting the counter shaft 8. Also, a one-
way clutch 48 for backward driving is dis~osed to provide
a connection between the backward clutch 48 and the
counter shaft 8. The one-way clutch 48 is of the
type capable of delivering to the counter shaft 8
only the forward driving power from the backward counter
gear 45.
Namely, when the inner whhel'48a'fit~ing-to'-the
counter shaft 8 rotating clockwise as viewed from the
rear side makes a clockwise rotation relatively to the
outer wheel 48b fitting to the backward counter gear 45
as shown in ~ig. 5a, the inner wheel 48a and the outer
wheel 48b can rotate independently of each other.
However,'in the state shown in, for example, Fig. 5d
in which the outér wheel 48b makes a clockwise rotation
relatively to the inner wheel'48a, the backward counter
gear 45 and the counter shaft 8 rotate'as a unit with
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each other by the action of the one-way clutch 48.
In the powered agricull:ual machine as shown in
the drawings, the torque of the counter gear 12a is
adapted to be transmitted to a power shaft 51 through
a PTO clutch 49 and a PTO gear unit 50.
In the illustrated and described embodlments,
the forward speed changing gear system and the backward
speed-changing gear system are adapted to be operated
by means o~ hydraulically actuated clutches. The
invnetion, however, can be equally applied to the
systems having mechanically actuated clutches.
The operation of the speed-changing transmission
device of the invention can be achieved even when the
forward clutch 2la is eliminated.
In the speed-changing transmission device of
the first:embodiment o~-the invention, as;thé orward
clutches 21c,21b are operated selectlvely, the speed-
changing shaft rotates at a forward first or second speed
Vl,V2 which is higher than that of the input shaft 3.
Therefore, the inout gear 3a, rotating counter-clockwise
relatively to the speed-changing shaft 4 as viewed from
the rear side can rotate freely. As to the back-
ward onw-way clutch 43, the backward speed-changing gear
14 rotating clockwise relatively to the speed-changing
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shaft 4 can be rotated freely. Therefore, thetorque
of the input shaft 3 is transmitted through the forward
clutch 21c or 21b to the speed-changing gear 4 to drive
the latter at a reduced speed of forward first or
second speeds Vl,V2 corresponding to the selection of
the clutch.
When the backward clutch 20 is put into
operation, the forward one-way clutch 42 is freed as
is the case of Fig. 3a, as~shown in Fig. 3b, so that the
inner and outer wheels 43b and 43a of the backward
one-way clutch 43 rotate unitarily with each other to
drive the speed-changing shaft 4 at a predetermined
backward speed.
In the event that the vehicle starts to move
naturally when it is parked on a slope, the backward
one-way clutch 43 is freed as shown in Fig. 3c, as
is the case of Fig. 3a, but the inner wheel 42b and the
outer wheel 42a are locked to each other because the
the inner wheel 42b of tbe forward one-way clutch 42
rotates counter-clockwise together with the speed-changing
shaft 4 to realize such a state that the outer wheel 42a
makes a clockwise rotation relatively to the inner wheel
42b. Therefore, the torque of the speed-changing
shaft 4 is transmitted to the engine 1 through the input
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shaft 3 to achieve the engine braking effect thereby
to automatically stop the natural running of the
vehicle.
When the automobile is parked on a slope with
its front side directed toward the higher side of the
slope, the outer wheel 43a of the backward one-way clutch
43 tends to make a counter~clockwise rotation relatively
to the speed-changing shaft 4 as shown in Fig. 3d, so
that the inner wheel 43b and outer wheel 43a are locked
to each other so that the torque of the speed-changing
gear 4 is transmitted throgh the backward speed-changing
gear 14, baclward idle gear 15 and the backward counter
gear 11 to the counter shaft 8 and further to the
engine through the counter gear 12a and the input gear 3a
thereby to effect the engine braXing.
In the second embodiment of the invention shown -
in Fig. 4, the forward one-way clutch 42 operates in the
same manner as the described first embodiment. As to
the backward one-way clutch 48, the outer wheel 48b
fitting the backward counter gear 45 makes a counter-clockwise
rotation relatively to the inner wheel 48a fitting the
counter shaft-8 in the state of forward driving of the
of the vehicle ~Fig. 5a) and in the state in whlch the
vehicle is parked with its engine stopped on a descending
slope (Fig. 5c).~ In this state, the inner wheel 48a
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and the outer wheel 48b are freed. However, these
wheels 48a,48b are made torotate as a unit with each
other as the backward clutch 47 is put into operation.
Furthermore, when the vehicle is parked on an ascending
slope, the outer wheel 48b tends to rotate clockwise
to make a clockwise rotation relatively to the inner
wheel 48a as shown in Fig. 5d.
Thus, the one-way clutch 48 is locked so that
the torque of the speed-changing shaft 4 is transmitted
to the engine 1 through the counter shaft 8 to efect "
the engine braking. In this state. it is also
possible to start the engine by manually pushing the
vehicle forwardly.
Thus, according to the invention, the engine
braking effect is obtained to prevent the vehicle
from automatically running in both of ~orward and back
ward directions when the vehicle is parked on a slope
for a long time, irrespective of a pressure drop in
the hydraulic clutches in the transmission system incor-
porating hydraulic clutches and irrespective of the
"OFF" state of mechanical clutch in the transmission
system incorporating mechanical clutches, so as to:~
assist~the parking brake in parking the vehicle safely.
In addition, the speed-changing transmiss~on
device of the invention permits the-engine to be started
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by a manual pushing of the vehicle in ~he event of an
exhaustion of the battery.
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