GB2228061A

GB2228061A - Flywheel assembly

Info

Publication number: GB2228061A
Application number: GB9003126A
Authority: GB
Inventors: Hirotaka Fukushima
Original assignee: Daikin Manufacturing Co Ltd
Current assignee: Exedy Corp
Priority date: 1986-01-30
Filing date: 1990-02-12
Publication date: 1990-08-15
Anticipated expiration: 2007-01-26
Also published as: GB2228062A; GB2228062B; GB9003127D0; GB2228061B; GB9003126D0

Description

FLYWHEEL ASSEMBLY This invention relates to a flywheel assembly which absorbs a vibration of an inputted power.

In Fig. 3 which is a schematic structural diagram of a conventional clutch disc, 10 is an engine input side and 12 Is an output side from which a power is transmitted to a transmission, for example. A firs-stage torsion spring 14a, a second-stage torsion spring 14b and a third- stage torsion spring 14c are interposed between the input side 10 and the output side 12, and specified torsion angle plays 14d & 14e are provided to the second-stage torsion spring lGb and the third-stage torsion spring 14c.

Further, a first-stage hysteresis torque generating mecha nism 16a, a second-stage hysteresis torque generating mech- anism 16b and a third-stage hysteresis torque generating mechanism 16c are interposed therebetween in the same manner, and plays 16d & 16e are provided to the second- stage hysteresis torque generating mechanism 16b and the third-stage hysteresis torque generating mechanism 16c, respect@@ely.

In the above-mentioned conventional embodiment, a torsion characteristic changes from a first-stage torsion characteristic Kdl. and a first-stage hysteresis characteristic Thl which are both generated by the first-stage torsion spring 14a together with the first-stage hysteresis torque generating mechanism 16a, to a third-stage torsion characteristic Kd3 and a third-stage hysteresis characteristic Th3 which are both generated by third-stage torsion spring 14c together with the third-stage hysteresis torcue generating mechanism 16c, with an increase in a torsion angle as shown by Fiq. 4. However, this characteristic has the following disadvantage.

Namely, it is desired to set the first-stage torsion characteristic Kdl - third-stage torsion characteristic Kd2 to small values as a countermeasure against noises such as gear chattering generated from a transmission in its neuttal position and gear chatterings generated from the transmission and a differential gear in their driving position. On the contrary, however it is necessary to set the first-stage torsion characteristIc Kdl - third-stage torsion characteristic Kd3 to large values as a countermeasure against low frequency vibrations.

Accordingly, the torsion characteristic of Fig. 4 is to be set up separately according to. a characteristIc required to each vehicle. Further, since a level of requrement fo~ noise and vibration control of clutch becomes increasingly, higher in recent years, it sometimes required to realize a characteristic which can never be dealt with by the conventional structure, such as the case that the conflicting countermeasures against the noise and the low frequency are required simultaneously as mentioned above Therefore, such technologies have been developed that vibratos from engine are positively absorbed even by the flywheel.

There have been prior arts, for example, that an auxiliary flywheel 26a and a damper 26b are interposed in series between a conventional clutch disc 20 & flywheel 22 and a crank shaft 24 as shown by Fig. 5, and the aux' - iary flywheel 26a is installed in parallel with the flywheel 22 through a torsion spring as shown by Fig. 6 With regard to this kind of flywheel assembly, also the applicant of the present invention has developed and applied a flywheel assembly as shown in Fig. 7 for a patent, which includes a first flywheel 104 fastened to an engine crank shaft 100 and engaged and disengaged by a clutch disc 102, a second flywheel 106 installed concentri- cally with the first flywheel and set to a specifIed mass, a damper mechanism 108 resiliently coupling the both flywheels, and a fiction damping mechanism 112 which transmits an output from the second flywheel 106 to a spline hub 110 of the clutch disc 102 and damps its vibration only when said clutch disc 102 contacts with the first flywheel 104.

(Japanese Patent ApplicatIon No. 60-44298, United States Patent Application No. 836,365, West German Patent Application No. 36 07 398.9, French Patent Application No. 8603211, Korean Patent Application No 86/1451).

Incidentally, it is desired to further improve this prior art of the present applicant.

In the first place, for example, an inertial damper set to a specified mass may be equipped to a propeller shaft in order to damp a torsional vibration of a so-called drive-transmission system from an engine output shaft to a driven wheel of automobile. The applicant of the present invention gets to invent this invention while intending to damp the torsional vibration of the drive transznission system by the use of a flywheel assembly in place of the inertial damper.

In the second place, a facing 116 of the friction damps ing mechanism 112 is connected to a bolt 118 of the second flywheel 106 side in said conventional embodiment, so that it becomes necessary to form a hole 120 on the fIrst flywheel 104 and a working range of the friction damping mech- anism 112 is also limitted to within an area of the hole 120.

Further, in case when a power of a state motor is inputted from a ring gear 122 of the first flywheel 104 at the time of starting the engine, the power is transmitted through the damper mechanism 108 to a crank shaft; so that it is necessary to determine a spring characteristic of the damper mechanism 108 in accordance with a load of te state~ motor to cause a small degree of freedom of design.

Moreover, in the third place, a conec disc spring 114 of the friction damping mechanism 112 is installed on the spline :iuo 110 and a connecting plate 119 which connects the facing 116 to the spline hub 110 is provided, so that a structure of the clutch disc 102 becomes complicated in said conventional embodiment. Furthermore, the facing 116 is also fIxed to the bolt 118 of the second flywheel 106 side, so that the flywheel assembly and the clutch disc 102 are required to be completely disassembled when the worn-out facing 116 is replaced with new one and the replacement work becomes difficult.

A general object of the present invention is to further improve the flywheel assembly in many aspects, in which the flywheel is divided into two blocks and the friction dampIng mechanism absorbing vibration is installed.

A detailed object of the invention is to provide a flywheel assembly which can damp a torsional vibration of a drive-transmission system by utilizing a part of a flywheel mass.

Another detailed object of the invention is to provide a flywheel assembly which effectively absorbs the vibration from engine and at the same time simplifies the structure of the clutch disc, and requires only an easy maintenance.

A further detailed object of the inventIon is to provide a flywheel assembly which enlar-es a working range of t & ction damping mechanism and at the same time eases a design of the damper mechanism.

A still further detailed object of the invention is to provide a flywheel assembly which effectively absorbs the vibration from engine and at the same time simplifies the structure of the clutch disc, and requires only an easy maintenance.

With these objects in view the present invention provides a flywheel assembly including a first flywheel fastened to an engine crank shaft and engaged and disengaged by a clutch disc, a second flywheel supported concentrically with the first flywheel, a damper mechanism resiliently connecting the both flywheels, and a friction damping mechanism which transmits an output from the second flywheel to a spline hub of the clutch disc and damps a vibration only when said clutch disc contacts with the first flywheel, the second flywheel being set to a specified mass which is determined in relation to a drive transmission's inertial mass, characterised by that a spring member of the friction damping mechanism is formed into an approximately annular shape connected to a radially intermediate part of the second flywheel, and approximately annular intermediate plate pressing on the spring member is provided in such a manner as freely engaged with or disengaged from a friction member, and the friction member is connected to the clutch disc through a friction plate.

The flywheel assembly accomplishes the abovementioned objects while connecting the friction damping mechanism to a part of the clutch disc.

Brief Description of the Drawings Fig. 1 is a vertical sectional partial view of a clutch applied with a preferred embodiment of the invention; Fig. 2 is an enlarged view of a part of Fig. 1; Fig. 3 is a structural skelton diagram showing a conventional embodiment; Fig. 4 is a graph showing a torsion characteristic of the conventional embodiment of Fig. 3; Figs. 5 and 6 are structural skelton diagrams showing further prior art embodiments.

Fig. 7 is a vertical sectional view showing further prior art.

A preferred embodiment of the invention is a flywheel assembly including a first flywheel fastened to an engine crank shaft and engaged and disengaged by a clutch disc, a second flywheel supported concentrically with the first flywheel and set to a specified mass, a damper mechanism which connects the both flywheels resiliently, and a friction damping mechanism which transmits an output from the second flywheel to a spline hub of the clutch disc and damps a torsional vibration of the drive-transmission system only when said clutch disc contacts with the first flywheel; characterized by that a spring member of the fiction damping mechanism is formed into an approximately annular shape connected to a radially intermediate part of the first flywheel, an approximately annular intermediate plate pressing on the spring member is provided in suc a manner as freely engaged with or disengaged from the friction member, and the friction member is connected to the clutch disc through a friction plate.

The above-mentioned flywheel assembly of the fouth embodiment functions as follows: The spring member is installed on the second flywheel side and the fiction member is installed on the clutch disc side, so that the friction member is to be replaced together with the clutch disc when the friction member is worn out.

Since the friction plate connecting the friction member to the clutch disc is fastened to the clutch disc, the structure of the clutch disc becomes simple.

A clutch according to claim 1 will be described hereunder with reference to Fig. 1.

In Fig. 1, 30 is an engine crank shaft. A first flywheel 32 is fixed to a rear end of the crank shaft 30 by a bolt 31a. A facing 35a of the clutch disc 34 is adapted to contact with an annular surface 33a of the first flywheel 32. A clutch cover 35b is fastened to a rear end face of the first flywheel 32, and a pressure plate 53e is held to the clutch cover 35 through a wire ring 3xc and a diaphragm spring 35d.

The first flywheel 32 is formed into an approximately disc-like shape, and an annular groove 33b is formed at a front outer peripheral part of the first flywheel 32. The second flywheel 36 is installed in the annular groove 33b freely rotatably and con cen.-icnlly with the first flywheel 32.

The second flywheel 36 is formed into an ap-roxi- mately annular shape having a flange 37a at its inner peripheral part, and set to a specified mass adapted to an inertial mass of the drive-transmissicn system such as a transmission (not shown) etc. connected to a rear stage of the clutch.

A torsion spring 38 (damper mechanism) is compressively installed between an outer peripheral part of the second flywheel 36 and an inner peripheral part of the first flywheel 32 to resiliently connect the first flywheel 32 to the second flywheel 36.

A spring constant of the torsion spring 38 is so determined that a resonance point 39a or a character- istic 39 representing a relatIon between a value |#2/#1| and an engine rotatcn N is generated at a rotation region lower than an idle rotation Is supposing that a change in angular velocity or the first flywheel is 81 and a change in velocity of the clutch disc spline hub 35f is #2.

Accordingly, at a normal rotation regicn higher than the idle rotation I, the value |#2/#1| decreases with an increase in the rotation and the change in ancular velocity 62 of the clutch disc spline hub 35f or a rotational fluctuation of the transmission etc.

is practIcally very small.

A friction damping mechanism 240 is interposed between said second flywheel 36 and the spline hub 35f of the clutch disc 34, and the friction damping mechanism 240 is adapted to damp vibrations which are trans misted to the first flywheel 32 when the facing 35a contacts with the pressure surface 33a of the first flywheel 32.

The friction damping mechanism 240 is composed of a bolt 242, a retaining ring 244, a coned disc spr In 246 (spring member), a facing 248 (friction member), a friction plate 250 and an intermediate plate 252 etc. as shown by Fig.2. A threaded part 242a of the bolt 242 is screwed in a flange 37a of the second flywheel 36, and the bolt 242 pierces a hole c of the first flywheel 32. The retaining ring 244 fastened, for example, by a small screw 242b fits onto a rear end face of the bolt 242.The retaining ring 244 is formed into an approximately annular shape ex-ending in the circumferential direction of the first flywheel 32 and second flywheel 36, and notches 244b are formed at plural places of an outer peripheral flange 244a of the retaining rlng 244 with equal distances left therebetween in its circumferential direction. A claw 252a which is provided integrally on an outer peripheral face of said intermedIate plate 252, fits in the notch 244b and the intermediate plate 252 is connected to the retaining ring 244 through the notch 244b and the claw 252a freely slidingly in their axial direction.

The coned disc spring 246 is interposed between the retaining ring 244 and the intermediate plate 252, and the coned disc spring 246 urges the intermediate plate 252 backward i.e. toward the first flywheel 32.

The coned disc spring 246 is also formed into the annular shape extending in the circumferential direc- on of the fIrst flywheel 32 and the second flywheel 36.

The facing 248 is disposed at opposite side to a pressure surface 252b of the intermediate plate 252, and the facing 248 is bonded to an approximately annular disc-like friction plate 250 through a bonding surface 250a. A radially inner peripheral part of the fiction plate 250 is fastened by press-fit onto the spline hub 35f of the clutch disc 34.

The clutch disc 34 and the second flywheel 36 are dis pcsed in parallel at a rear-stage of the first flywheel 32. A torsion spring 35g is equipped in parallel with a hysteresis generating mechanism 35h to the clutch disc 34. The torsion spring 38 and the facing 248 for generating a hysteresis torque are installed in series with the second flywheel 36.

Function will be described hereunder. In the clutch engaging state where the facing 35a is pressed on the annular surface 33a of the first flywheel 32 by the pressure plate 35e, a spring force of the diap hragm spring 35d urges the clutch disc 34 to slide on a spline shaft of a transmission (not shown) toward the =rst flywheel 32, and the friction plate 250 presses on the facing 248.In this instance,-.the coned disc spring 246 deforms itself due to a pressing force from the fiction plate 250 and the friction plate 250 and the facing 248 are always pressed together by a constant pressure, so that a friction force generated between the facing 248 and the friction plate 250 is always kept constant.

In the above clutch engaging state, the engine power inputted in the first flywheel 32 is transmitted through two paths: a path through the clutch dsc 34 and a path through the second flywheel 36, the facing 248 and the friction plate 250 to the transmission.

Accordingly, concerning a torque (average torque + fluctuating torque) transmitted from the engine to the transmission, the fluctuating torcue is absorbed by the facing 248 and the second flywheel 36 supported resiliently and floatingly by the torsion spring 38, and only the average torque is transmitted through the clutch disc 34 to the transmission, so that the engine rotational fluctuation and the torque fluctuation can be removed approximately completely.

As compared with a clutch disc 102 illustrated in Fig. 7, the friction plate 250 is only fastened to the spllne hub 35f so that a structure of the clutch disc 34 is very simple.

Moreover, when the entire clutch disc 34 is replaced due to worn-out of the facing 35a & 248 after a long period of use, also the friction plate 250 and the facing 248 are replaced together with the clutch disc 34. Therefore, all consuming parts of the fiction damping mechanism 240 are installed at the clutch disc 34 side so that the fIrst flywheel 32 side and the second flywheel 36 side are not required to be disassembled.

As described above, in the flywheel assembly of the preferred embodiment, the ccned disc spring 246 (spring member) of the friction damping mechanism 240 is formed into the approximately annular shape ccnnected to the radially intermediate part of the first flywheel 32, the approximately annular intermediate plate 252 pressing on the coned disc spring 246 is provided in such the manner as freely engaged with or disengaged from the facing 248 (frIction member), and the facing 248 is connected to the clutch disc 34 through the approximately annular friction plate 250.

Theref ore, it is enough for the clutch disc 34 to fasten the friction plate 50 to the spline hub 35f as compared with the clutch disc 102 of Fig. 7, so that the structure of the clutch disc 34 becomes simple.

Further, when the entire clutch disc 34 is replaced due to worn-out of the facings 35a & 248 after a long period of use, the friction plate 250 and the facing 248 are also replaced together with the clutch disc 34. Therefore, all consuming parts of the friction damping mechanism 240 are installed at the clutch disc 34 side so that the first flywheel 32 side and the second flywheel 36 side are not required to be disassembled and its maintenance becomes easy.

Moreover, a diameter of the coned disc spring 246 becomes larger than that of the coned disc spring 114 of 'Fig. 7,. so that a design of the coned disc spring 246 becomes easy because it is not reaired to generate a large force with a small diameter.

Claims

1. A flywheel assembly including a first flywheel fastened to an engine crank shaft and engaged and disengaged by a clutch disc, a second flywheel supported concentrically with the first flywheel, a damper mechanism resiliently connecting the both flywheels, and a friction damping mechanism which transmits an output from the second flywheel to a spline hub of the clutch disc and damps a vibration only when said clutch disc contacts with the first flywheel, the second flywheel being set to a specified mass which is determined in relation to a drive transmission's inertial mass, characterised by that a spring member of the friction damping mechanism is formed into an approximately annular shape connected to a radially intermediate part of the second flywheel, an approximately annular intermediate plate pressing on the spring member is provided in such a manner as freely engaged with or disengaged from a friction member, and the friction member is connected to the spline hub of the clutch disc through a friction plate.

2. A flywheel assembly as set forth in claim 1 in which the friction damping mechanism is composed of a bolt connected to the second flywheel, an annular retaining ring fixed to the bolt, an intermediate plate held to the retaining ring, a spring member interposed betweeen the intermediate plate and the retaining ring, and a friction member fastened to the friction plate in such a manner as facing on the intermediate plate.

3. A flywheel assembly as claimed in claim 2 in which a claw is projectingly provided at an outer peripheral part of the intermediate plate, the claw being made to fit in a notch opening to an outer peripheral flange of the retaining ring, and the intermediate plate is installed freely slidingly in its axial direction.

4. A flywheel assembly substantially as hereinbefore described with reference to and as illustrated in Figs.

1 and 2 of the accompanying drawings.