Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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SPECIFICATION
SPEED CHANGE GEAR MEC~ANISM
FOR AUXILIA~Y E~UIPMENT DRI~7E
This invention relates to a speed change gear mechanism
using an epicyclic gear train and controlling its speed change
motion with an electromagnetic clutch for use in driving
auxiliary automotive e~ùipment at different speeds relative to
engine speed.
Auxiliary machinery on an automotive engine such as, for
example, an alternator, a compressor for the air conditioning
system, a power steering pump and the like normally are driven by
a direct drive transmission means from an end portion of the
engine crankshaft such as through pulleys, and belts. Therefore,
the auxiliary machinery is always driven at a rotational speed
proportional to the running speed of the engine~ However, most
auxiliary.machinery does not require a rotational speed above a
given amount, and therefore in the high-speed operation of the
engine it is desirable that the excessive rotation of the
auxiliary machinery be avoided by a speed change gear to save
fuel consumption Qf the engine, enhance the durability of the
auxiliary machinery, decrease noises, and further to allow a
reduction in the size and weight of the auxiliary machinery.
A speed change gear mechanism of this general type has
already been proposed by the applicant in Japanese Patent
~j ~o6~ ~
A Application No. ~4~/1982, but that the proposed speed change
gear mechanism comprises a system wherein the operation of the
lap spring for causing engagement or disengagement between an
input rotary member and an output rotary member to change the
60724-1561
rotation transfer from the former to -the latter for direct
coupling or speed change is controlled by a mechanical centri-
fugal clutch. Wlth the mechanical centrifugal clutch, the input
rotational speed at the time of engagement or disengagement of
the clutch is a fixed predetermined value, and therefore the
rotational speed for operation of the reduction transmission
cannot be changed according, for example, to the running state
of the engine. Although the mechanical centrifugal clutch is
advantageous in durability as compared with an electromagnetic
clutch, it is inferior to the electromagnetic clutch in response
efficiency at the time of engagement or disengagement.
The present invention provides a speed change mechan-
ism for driving auxiliary equipment from an engine, including a
reduction gear train arranged to be connected or disconnected
by a lap spring, and operating means for causing selective
engagement and disengagement of the lap spring in response to
at least one predetermined parameter of engine operation, where-
in said operating means comprises an electromagnetic clutch and
said electromagnetic clutch is controlled by control means
arranged to selectively supply electrical current thereto for
causing engagement and disengagement of said clutch in response
to said at least one predetermined engine parameter.
Preferably an epicyclic or planetary gear train is
interposed between an input rotary member and an output rotary
member with the lap spring wound around both the rotary members
and the rotation being transferred from the input rotary member
to the output rotary member by a direct-coupled transmission
system through the lap spring at the -time of tightening the
lap spring and also by a changed-speed transmission system
through the epicyclic gear at the time of loosening. The
electromagnetic clutch is controlled so as to operate for
tightening or loosening the lap
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spring at a desired input rotational frequency established
according to any predetermined parameter.
The invention will describe in connection with preerred
embodiments thereof illustrated in the accompa~ying drawings,
wherein:
Fig. l is a sectional elevation view of a first
embodiment of this invention taken on the central axis of the
mechanism.
Fig. 2 is a sectional elevation view similar to Fig. l
showing a second embodiment of the invention.
Figs. 3 through lO are diagrammatic illustrations of
various embodiments of this invention with Figs. 3 and 4
representative of the physical illustrations of the embodiments
of Figs. 1 and 2, respectively, and Flgs. 5 through lO
representative of six additional modified embodiments.
Referring now in detail to Fig. 1 illustrating the first
embodiment of this invention, a speed change gear mechanism,
generally designated T, is fixed on an end portion of a
crankshaft 2 of an engine l with a bolt 4 through a key 3, and a
p/anc ~
1 p~.~a~a~y or epicyclic gear train 30 and an electromagnetic
clutch 40-are provided between an input shaft 5 on the input side
of the speed change gear mechanism T and a pulley case 6 on the
output side.
The epicyclic gear train 30 comprises a ring gear 31
consisting of an internal gear formed on the inside of the outer
perimeter of a flange 5a fixed on the input shaft 5, a plurality
of planet gears 32 (normally three) engaging therewith, a carrier
33 journaling the planet gears 32 rotatably and also rotatable
itself, and a non-rotatable sun gear 3~ located centrally to
engage the planet gear 32.
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The pulley case 6 on the output side has a plurality o~
pulleys 6b, on each of which an auxiliary machine driving belt is
wound, formed on a circumference of a bowllike body 6a. The
pulley case boss is journaled on an end portion of the input
shaft 5 in both fluid-tight and rotational relationship through
an oil seal 7 and a bearing 8. The epicyclic gear train 30 is
enclosed within the pulley case 6. A rear cover 6', comprising
an annular back plate 6c and the annular rotor 41 of the
electromagnetic clutch 40 joined together at solidly the outer
perimeter, is clamped on the rearward open surface of the pulley
case 6 on the engine side with one or more bolts 9.
A hollow fixed shaEt 10 is supported on the outer
perimeter of the input shaft 5 through an oil seal ll and a
bearing 12. The fixed shaft 10 is supported and prevented from
rotating by a bracket 15 mounted on the case-la of the engine 1
by means of a bolt 14 throu~h a buffer 13 such as rubber or the
like. The inner perimeter of the back plate 6c is supported on
an outer perimeter of the fixed shaft 10 through an oil seal 16
and a bearing 17. The back plate 6c has an axial flange 6d
extended to the flange 5a side of the input shaft 5 on its outer
perimeter. A conventional form of one-way clutch 18 is fitted
between the inner perimeter of the flange 6d and the planet gear
carrier 33.
A hollow shaft portion 34a of the sun gear 34 is loosely
fitted on the outer perimeter of the input shaft 5 wi~th a
suitable gap left therebetween and its end portion on the engine
side is coupled to an end portion of the fixed shaft 10 opposite
thereto through an Oldham type coupling lg.
The electromagnetic clutch 40 comprises an annular
solenoid coil 42 enclosed in a case 42a, which is fixed on the
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bracket 15, an annular rotor ~1, and an annular armature 43
disposed opposite the solenoid coil 42 and on the other side of
the rotor 41. A circular-arc slit 41b is provided in the -otor
41, and a non-magnetic material 20 such as rubber copper alloy,
aluminum alloy or the like is fitted fluid-tightly in the slit
41b. The armature 43 is mounted on the end portion of a thin
plate-like and tubular lap spring case 23 which in turn is
mounted on the flange 5a of the input shaft 5. The case 23
surrounds a lap spring 21 the function of which is described
hereinafter. The case 23 prevents the lap spring 21 from
springing outward as a result of centrifugal force and holds the
armature 43 at a suitable gap from the rotor 41. Further, the
case 23 has a multitude of through holes 23a disposed
irregularly. The metallic powder mixed in the lubricating oil
for the epicyclic gear train 30 contained in the pulley case 6 is
discharged from the epicyclic gear train 30 by the through holes
23a as a result of the centrifugal force but is prevented from
coming again into the area of the epicyclic gear train 30 by the
wall surface of the case 23 between the through holes 23a.
An input side drum face 5b and an output side drum face
6e are formed on approximately the same circumferential plan at
flange 5a of the input shaft 5 and flange 6a of the back plate
6c, respectively, and the multiplex winding of lap spring 21,
either rectangular or circular in section, is positioned to
extend over and cover both the drum faces 5b, 6e. An input side
end portion 21a of the lap spring 21 is fixedly mounted in an
engaging groove formed on the outer perimeter of the flange 5a of
the input shaft 5, and an output side end portion 21b is fixedly
mounted on the armature 43 of the electromagnetic clutch 40. The
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tightening direction of the lap spring 21 coincides with a
rotating direction of the flange 5a.
A timing belt 26 is wound on the pulley 25 mounted on
the crankshaft 2 of the engine 1. An electrical power supply 45,
such as a battery, is connected to the solenoid coil 42 through a
current carrying switch 44, and the switch 44 is controlled by a
control signal from an electronic controller 46. In case of the
speed change gear mechanism being used to operate the auxiliary
machinery of the engine; the electronic controller 46 outputs ON
signal to energize the solenoid coil 42 when the engine running
speed reaches a predetermined value.
An operation of the gear mechanism of the above
described first embodiment of this invention now will be
described. In an operating condition where the rotational speed
of the crankshaft 2 of the engine 1 is at a predetermined value
or below, the controller 46 closes the current carrying switch 44
to carry a current to the solenoid coil 42 to thereby close the
magnetic circuit connecting the case 42a of the solenoid coil 42,
the rotor 41 and the armature 43, as indicated by the irregular
circle with arrows in the lower portion of Fig. 1 on the electro-
magnetic clutch 40. Thus the armature 43 is attracted to the
solenoid coil 42 to engage with the rotor 41 on the output side
at a predetermined binding force, thereby causing the lap spring
21 to be wound up by the turning force of the input shaft 5 and
to contract the diameter to tighten down onto the input side drum
face 5b and the output side drum face 6e to connect and unify the
drum faces 5b, 6e. Accordingly, the input shaft 5 on the input
side and the pulleys 6b on the output side rotate together to
constitute a one-to-one direct-coupled transmission system. In
this case, each planet gear 32 rotates on its axis and re~Jolves
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in the same direction as the ring gear 31 around the sun gear 34
according to the rotation oE the ring gear 31. This re~oLving
motion causes a reduction in the speed of rotation of the carrier
33. Here, the rotation of the carrier 33 is reduced to less tnan
that of the input shaft S and is slower than the rotation of the
pulley case 6, whereby the difference in rotation is accommodated
by the idling of the one-way clutch 18.
Next, in the operating condition where the rotational
speed of the crankshaft 2 of the engine 1 exceeds a predetermined
value, the controller 46 opens the current carrying switch 44 to
break the current to the solenoid coil 42, thereby terminating
the magnetic force of the solenoid coil 42, and the armature 43
and the rotor 41 are disengaged from each other. Consequently,
the lap spring 21 loosens by reason of its own recoil strength
and centrifugal force to release the binding engagement with the
input side drum face 5b and the output side drum face 6e.
Accordingly, each planet gear 32 rotates on its axis and revolves
in the same direction as the ring gear 31 around the sun gear 3
according to the speed of rotation of the ring gear 31 rotating
together with the input shaft 5. This revolving motion results
in a reduction in the speed of rotation of the carrier 33 and the
rotation of the carrier 33 is transferred to the pulley case 6
through the rear cover 6' as a result of the engagement of the
one-way clutch 18. Thus, a reduction transmission system is
accomplished for reducing the speed of rotation of the ulley
case 6 at the predetermined reduction gear ratio of the epicyclic
gear train 30 relative to the speed of rotation of the crankshaft
2 of the engine 1
In the second embodiment illustrated in ~ig. 2, the
armature 43 of an electromagnetic clutch 40' is formed annularly
in an L shape in section, with the input side end portion 21a
bent radially outward of the lap spring 21 and coupled to an end
portion of an axial flange 43a of the armature 43, and with the
output side end portion 21b bent radially inward of the lap
spring 21 and fixed in an engaging groove formed on ~he carrier
33 functioning as a back plate at the same time. The armature 43
has the radial flange 43b urged toward the flange 5a of the input
shaft 5 by the annular spring 44 interposed between it and the
rotor 41, thereby pressing the input side end portion 21a of the
lap spring 21 onto the flange 5a at all times. The carrier 33 of
the epicyclic gear train 30 is formed as part of or joined to
plate 6c, and hence is rotatable together with the rotor 41. The
one-way clutch 18 is fitted between the sun gear 34 and its shaft
34a and permits the sun gear 34 to rotate relative to the fixed
shaft 10 only in the same direction as the ring gear 31. Other
than the two points above, the construction of this second
embodiment is the same as in the case of first embodiment.
Although not specifically illustrated in Fig. 2,
electrical components corresponding to the current carrying
switch 44, the power supply 45, and the controller 46 in Fig. 1
are also provided in this second embodiment.
In the operation of this embodiment, in an operating
condition where the rotational speed of the engine 1 is at a
predetermined value or below, contrary to the ~irst embodiment,
the controller does not supply current to the solenoid coil 42,
but rather the armature 43 is pressed against the flange 5a of
the input shaft 5 by the spring 44 to engage therewith, the ~ap
spring 21 is thereby tightened by the rotation of the input shaft
5, and therefore the input side drum face 5b and the output side
drum face 6e are joined and unified together to constitute a
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direct-coupled transmission system. As a result, the ring gear
31, the carrier 33"and the rotor 41 rotate together, ~"hereby the
each planet gear 32 and the sun gear 34 would be locked to rotate
together with the ring gear, but the free rotation of the sun
gear 34 is accommodated by idling of the one-way clutch 18
between the sun gear 34 and the shaft 34a.
In an operating condition of'the embodiment of Fig. 2
where the rotational speed of the engine 1 exceeds a predeter-
mined value, a current is supplied to the solenoid coil 42, the
armature 43 is attracted to and displaced toward the rotor 41
side by the solenoid coil 42 in opposition to the force of the
spring 44 thereby becoming disengaged from the flange 5a of the
input shaft 5 and engaged with the rotor 41 concurrently,
whereby the lap spring 21 is loosened to disconnect the input
side drum face 5b from the output side drum face 6e. Conse-
quently, the planet gear 32 rotates on its axis and also revolves
in the same direction as the ring gear according to the rotation
o the ring gear 31 rotating together with the input shaft 5, and
since the rotating motion makes the sun gear rotate counter to
the ring gear 31 against the fixed side of shaft 34a, the one-way
clutch is engaged, and the carrier 33 and the rotor 41 de-
celerated in rotation speed along with the revolving motion of
the planet gear 32 to rotate at the intrinsic reduction gear
ratio of the epicyclic gear, thus, constituting a reduction
transmlssion system.
Figs. 3 to Fig. 10 represent various embodiments
relating to this invention in block diagram for ease o under-
standing of various modifications and combinations that may be
used to form embodiments of this invention, and for clarity and
170/1i31
comparison like reference characters represent like parts in all
the embodiments.
Fig. 5 represents a third embodiment, wherein the
construction of the epicyclic gear train 30 and the one-wa~
clutch 18 is the same as the first embodiment, however, operation
of the electromagnetic clutch and the lap spring is the same as
the second embodiment.
~ ig. 6 represents a fourth embodiment, wherein the
construction of the epicyclic gear train 30 and the one-way
clutch 18 is the same as the second embodiment, however,
operation of the electromagnetic clutch and the lap spring i5 the
same as the first embodiment.
Fig. 7 represents a fifth embodiment, wherein the ring
gear 31 of the epicyclic gear train 3Q has the fixed side carrier
33 disposed on the output side and the sun gear 34 on the input
side, and the one-way clutch 18 is disposed between the carrier
33 and the output side. The electromagnetic clutch is of the
same construction as the first embodiment.
Fig. 8 represents a sixth embodiment, wherein the ring
gear 31 is on the output side, the carrier 33 is on the fixed
side, the sun gear 34 is on the input side, and the one-way
clutch 18 is disposed between the ring gear 31 and the output
side. The planet gear 32 is comprised of two idle gears engaging
with each other. The electromagnetic clutch is of the same
construction as the first embodiment.
Fig. 9 represents a seventh embodiment, wherein the ring
gear 31 is on the fixed side, the carrier 33 is on the output
side, the sun gear 34 is on the input side, and the one-way
clutch 18 is disposed between the ring gear 31 and the fixed
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i10/1~1
side. The electromagnetic clutch is of the same construction as
the second embodiment.
Fig. lO represents an eighth embodiment, ~herein the
ring gear 31 is on the output side, the carrier 33 is on ~he
fixed side, the sun gear 34 is on the input side, and the one~ ay
clutch 18 is disposed between the carrier 33 and the fixed
side. As in the case of the slxth embodiment, the planet gear 32
is constituted of two idle gears engaging with each other. The
electromagnetic clutch is of the same construction as the second
embodiment.
With respect to the relation between the first embodi-
ment and the third embodiment and also the relation between the
second embodiment and the fourth embodiment, a speed change
operation by controlling the current supplied to the electro-
magnetic clutch can be reversed in the fifth and sixth embodi-
ments for which the electromagnetic clutch 40 in the same
construction as the first embodiment is incorporated and also in
the seventh and eighth embodiments for which the electromagnetic
clutch 40' in the same construction as the second embodiment is
incorporated by having each electromagnetic clutch replaced by
the electromagnetic clutches 40' and 40 in the construction of
the second embodiment and the first embodiment.
As described above, according to this invention,
tightening and loosening operation of the lap spring is affected
on the electromagnetic clutch, therefore a superior reply effi-
ciency at the time of engaging or disengaging the clutch is
obtainable as compared with a conventional mechanical centrifugal
clutch. Further, the electromagnetic clutch is controlled for
tightening or loosening operation of the la~ spring at a selected
input rotational speed established according to a predetermined
i7r
parameter such as engine rotational speed or the like by the
controller. Therefore, a value of the input rotational speed can
be set electrically with ease and no replacement will be required
for the electromagnetic clutch itself or the parts thereof,
unlike a mechanical centrifugal clutch requiring a replacement of
the parts such as flyweight, spring or the like, whereby an
improved matching of the engine and auxiliary machinery is
facilitated. Further, with an electromagnetic clutch for control
of the tightening and loosening of the lap spring, the wrapping
boosting effect of the lap spring may minimize the required
binding force of the clutch, and therefore a small electromotive
force will be satisfactory for the electromagnetic clutch to
work, whereby the solenoid coil of the electromagnetic clutch can
be reduced in size and weight, and only a small current is
required for operation to thereby minimize the energy loss.
