CA1252648A

CA1252648A - Speed change gear

Info

Publication number: CA1252648A
Application number: CA000476197A
Authority: CA
Inventors: Yasuo Shimizu
Original assignee: Honda Motor Co Ltd
Current assignee: Honda Motor Co Ltd
Priority date: 1984-03-12
Filing date: 1985-03-11
Publication date: 1989-04-18
Also published as: GB8506358D0; DE3508808C2; DE3508808A1; GB2156016A; JPS60192154A; GB2156016B

Abstract

ABSTRACT OF THE DISCLOSURE

A speed change mechanism for automotive engine for operating auxiliary equipment at different speeds relative to the engine speed, an epicyclic gear train is interposed between an input rotary member and an output rotary member, a lap spring is wound around both said rotary members with rotation being trans-ferred from said input rotary member to said output rotary member by either a direct-coupled transmission system through the lap spring upon tightening the lap spring or a changed-speed trans-mission system through said epicyclic gear train by loosening the lap spring. An electromagnetic clutch is operated for tightening or loosening the lap spring in response to a controller sensing a predetermined parameter.

Description

17rJ/l8 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 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 ~S~s;~8 170/181 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.

1~5~ 17~/181 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 ~ 170/181 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 ~5'~ i70/181 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 ~5~ 170/181 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 ~ i7~/18 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 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.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A speed change mechanism for driving auxiliary equip-ment 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, wherein said operating means comprises an electromagnetic clutch and said electromagnetic clutch is con-trolled by control means arranged to selectively supply electri-cal current thereto for causing engagement and disengagement of said clutch in response to said at least one predetermined engine parameter.

2. A mechanism as claimed in claim 1 comprising an epicyclic gear train interposed between an input rotary member and an output rotary member, said lap spring being wound around both said rotary members for rotation to be selectively trans-ferred from said input rotary member to said output rotary member either by direct-coupled transmission through the lap spring when tightened or by a change-speed transmission through said epicyclic gear train when the lap spring is loosened.

3. A mechanism as claimed in claim 2, wherein said elec-tromagnetic clutch comprises a solenoid coil fixed on a static member, a rotor opposite to the solenoid coil, and an armature opposite to the rotor and engaging with one end of said lap spring, said output rotary member including said rotor, and said input rotary member including said armature.

4. A mechanism as claimed in claim 2 or 3, wherein said epicyclic gear train comprises a ring gear rotatable together with said input rotary member, a sun gear fixed on a static member, a planet gear engaging the ring gear and the sun gear, and a carrier holding the planet gear and rotatable together with said output rotary member, said lap spring being arranged to tighten on said ring gear and said carrier concurrently for connecting same in response to the operating state of said electromagnetic clutch.