JP2003014050A - Fly wheel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress vibration in an axial direction of a crank system, to prevent the generation of tapping noise, and to reduce the generation of vibration noise. SOLUTION: In a fly wheel 1 mounted on a crank shaft protruded from the rear part of an engine, the fly wheel is formed in a spoke shape that a central part 3 and an outer ring part 4 are intercoupled through a plurality of spokes 5, and a front protrusion amount B of the outer ring part 4 based on the spoke 5 is reduced to zero. A fluctuation width in a fly wheel natural frequency range based on unevenness of a spoke longitudinal thickness t can be minimized. It is preferable that, in the fly wheel 1, a whole is cast and a spoke surface forms a cast skin, and a front part 4a of the outer ring part 4 is cut by a machine. It is preferable that the number of the spokes 5 is odd and the number of the spokes may be 7.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an engine flywheel.

[0002]

2. Description of the Related Art An engine flywheel is mounted on a crankshaft of an engine and functions as an inertia mass for reducing fluctuations in the rotation of the engine. Heretofore, a mere disc-shaped flywheel, that is, a plane type has been generally used as this type of flywheel.

[0003]

However, the present inventors have found that the V6 engine has a plane type flywheel and an AT.
A torque converter (torque converter) was assembled, and an actual machine test was performed by idling. As a result, a problem that a so-called conquer sound was generated occurred.

That is, as shown in FIG. 12, when the engine is operated, the crankshaft 51 and the flywheel 5 are
2, flex plate 53 and torque converter 54
The crank system 55 consisting of rotates, and bending vibration B and axial vibration L caused thereby are generated. At this time, the crank arm 56 and the like vibrate in the axial direction (thrust direction) and collide with the bearing portion 58 on the cylinder block side that supports the crank journal 57. Every time this collision occurs, a noise is heard and becomes an unpleasant noise.

More specifically, as shown in FIG. 13, a bearing metal 59 and a thrust metal 60 are integrally fixed to a bearing portion 58 on the cylinder block side. The crank journal 57 is rotatably supported by the bearing metal 59, and the crank arm 56 is supported by the thrust metal 60 in the thrust direction. There is a slight gap between the crank arm 56 and the thrust metal 60, and the crank arm 56 vibrates within the gap due to the axial vibration of the crank system, and strikes the thrust metal 60 to generate a consonant sound. .

In order to prevent this consonant sound, it is necessary to suppress the bending vibration B and suppress the axial vibration L caused thereby. Therefore, we made the flywheel into a spoke shape,
The idea was to reduce the weight of the flywheel.

However, there are various types of spoke shapes, and not only the spoke shape does not provide the maximum effect, but conversely, it may cause deterioration of the sound of consonants.

Therefore, the present invention was devised in view of the above problems, and its purpose is to suppress axial vibration of the crank system,
The purpose is to reduce noise and vibration noise.

[0009]

According to the present invention, in a flywheel mounted on a crankshaft projecting to the rear of an engine, a center portion and an outer ring portion are formed into a spoke shape in which a plurality of spokes are connected, and The amount of front protrusion of the outer ring portion is set to zero.

It is preferable that the entire flywheel is cast so that the spoke surface is a casting surface and the front surface of the outer ring portion is machined.

The number of the spokes is preferably odd, and the number may be seven.

Further, according to the present invention, the spoke surface is attached to a crankshaft projecting to the rear of the engine, and the center portion and the outer ring portion are connected by a plurality of spokes. In the flywheel that is left as it is, the front part of the outer ring part is projected forward with respect to the front part of the spoke, and is machine cut.
By changing the cutting amount of the outer ring front surface and changing the protrusion amount of the outer ring front with respect to the spoke front, the fluctuation range of the flywheel natural frequency range with respect to the variation in the spoke front-back thickness is changed. .

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, before describing a preferred embodiment of the present invention, a background of development of a flywheel according to this embodiment will be described.

The flywheel according to this embodiment is V6.
Developed to be combined with diesel engine and AT torque converters. The spoke shape is used to reduce the weight. Here, if the number of spokes is an even number, the deformation mode is such that the half-position bends symmetrically, and the deformation (vibration) on one side promotes the deformation (vibration) on the other side. Therefore, the number of spokes is set to an odd number, and independent deformation is allowed for each spoke to disperse the modes. This point will be described later.

Next, FIG. 7 shows the result of the preliminary examination conducted before actually manufacturing the flywheel. This graph shows the relationship between natural frequency (frequency) and evaluation. The evaluation means the result of sensory evaluation, and the larger the value out of 10 is, the better the evaluation is. For the time being, 7 points were set as the acceptance reference point. This graph is created based on the analysis results.

◯ is the natural frequency data of the flywheel alone, and Δ and □ are the natural frequency data in the actual operating state of the crank system. Especially △ is the rear end bending of the crankshaft system, □
Is the natural frequency of the coupled bending and torsion of the crankshaft. A circle on the one-dot chain line a is the natural frequency of the first-order mode, and a circle on the two-dot chain line b is the natural frequency of the fifth-order mode. That is, as the vibration mode increases from the first order to the fifth order, the natural frequency of the flywheel simple substance changes from the one-dot chain line a to the two-dot chain line b.

The rightmost circle (subscript p1) is the conventional plane type data, which has a high natural frequency and a low evaluation. The circle mark (subscript p2) at the bottom left is a thin type with a light weight, though it is a plain type. The natural frequency has decreased and the evaluation has increased, but it is not yet sufficient. The second circle (suffix 7s1) from the left has a light weight with 7 spokes, and its natural frequency was slightly higher than that of the thin plane type, and the evaluation was further improved. The uppermost circle (suffix 7s2) is the further improved 7-spoke shape, and the natural frequency was further increased, and the evaluation was improved. The ◯ (suffix 6s) at the lower right is a spoke shape with 6 spokes, and the natural frequency was higher than that of the 7-spoke type, and the evaluation was greatly deteriorated.

As a result of investigating the causes of the different evaluations of the various flywheels, it was found that the flywheel has a large relationship with the natural frequency during actual operation of the crank system. That is,
The range or width of natural frequencies from the 1st to the 5th order of the flywheel falls within the natural frequency area c of the rear end bending of the crankshaft system and the natural frequency area d of the coupling of bending and torsion of the crankshaft. I found that the evaluation was good when I was not caught. Expressing this numerically, it is sufficient that the natural frequencies of the first to fifth orders of the flywheel fall within the optimum frequency range 480 to 650 Hz indicated by the outline arrow e.
In this way, the natural frequencies of the two do not match with each other, resonance and coupled vibration of the crank system are prevented, and a consonant noise during vehicle mounting is prevented.

As shown in the graph, the thin plane type p2 and the initial type 7-spoke type 7s1 are caught in the area c where the primary is lower, and the 6-spoke type 6s is the area where the 5th is higher. It is caught in d and neither can be said to be a good result. On the other hand, the improved 7-spoke type 7s2 is in the optimum frequency range of 480 to 650 Hz in the first to fifth orders, which is a good result.

From the above examination results, the development as a 7-spoke type was advanced, and the flywheel of this embodiment was manufactured.

FIG. 1 shows a flywheel of this embodiment, and FIG. 2 shows an enlarged lower half of FIG. Here, it is shown in the form of a flywheel assembly in which a ring gear 2 is attached to the outer periphery of the flywheel 1. The flywheel 1 is a one-piece cast product and is machined in places. The dotted pattern in FIGS. 1 and 2 and the fine jagged pattern in FIG. 2 represent the casting surface that has not been machined. This flywheel is attached to the crankshaft protruding from the rear end of the engine,
Ft is before the engine side and Rr is after. The engine is a V6 diesel engine.

As shown in FIG. 3, the crankshaft is projected from the rear end portion of the engine E, and the flange 20 is attached to the outer peripheral portion of the crankshaft. Flange 2
The flywheel assembly and the flex plate 15 are sequentially fixed to the rear surface portion of 0 by a plurality of bolts 22 via a washer 21 from the front. Further, a torque converter (not shown) is attached to the rear of these so as to be relatively movable in the axial direction.

Returning to FIGS. 1 and 2, the flywheel 1
Includes a central boss portion 3 formed in the central portion thereof, an outer ring portion 4 located at the outermost radial direction, and a plurality of (seven) spokes 5 connecting the central boss portion 3 and the outer ring portion 4 to each other. Prepared mainly for. The central boss portion 3 serves as a mounting portion to the crankshaft, and has a stepped central hole 6 for inserting the crankshaft, and a plurality of (8) bolt holes for inserting the fastening bolts 22. 7 at equal intervals in the circumferential direction.

The outer ring portion 4 has a plurality of (6
Individual) torque converter mounting tool holes 8 are provided, and the torque converter mounting tool holes 8 allow the bolts for mounting the torque converter to be inserted into the flex plate 15. Outer ring part 4
The entire front surface portion 4a of the above is finished to a flat surface by mechanical cutting, and is projected forward by a dimension B with respect to the front surface portion of the spoke 5. In the rear surface portion 4b of the outer ring portion 4, only a portion 4c on the outer side in the radial direction is finished into a flat surface by mechanical cutting, and the portion 4c is projected rearward from other portions,
The other portion is a casting surface flush with the rear surface of the spoke 5. A press-fitting surface 9 for press-fitting the ring gear 2 and a back plate 10 for axially positioning the ring gear 2 are formed on the outermost peripheral portion of the outer ring portion 4. The press-fitting surface 9 and the front surface of the back plate 10, that is, the contact surface, are smoothed by mechanical cutting. A rotation balance adjusting hole 11 is drilled from the front surface portion 4a to a predetermined depth at one location in the outer ring portion 4 in the circumferential direction.

The number of spokes 5 is an odd number, seven in this embodiment. These spokes 5 extend radially outward from the central boss portion 3, are arranged at equal angular intervals in the circumferential direction, and have a rectangular cross section in the circumferential direction. An adapter mounting hole 12 having an internal thread is provided in the longitudinal middle portion of each spoke 5. It is used to install adapters when performing performance tests on a single engine on a production line. Since the adapter is mounted from the rear, the periphery of the rear end of the adapter mounting hole 12 is slightly raised,
A mounting seat 13 is formed by mechanical cutting.

Here, the rear surface portion 3b of the central boss portion 3 has a larger diameter than the front surface portion 3a, and a circular flex plate contact surface 14 is formed on the entire rear surface portion 3b. The flex plate contact surface 14 is a flex plate 15 (see FIG. 3).
(See) contacting or seating, and is naturally finished by machine cutting. The front surface 3a is also machined to a flat surface by the flange 20 (see FIG. 3) on the crankshaft side. The flex plate 15 is interposed between the flywheel 1 and the torque converter T / C, and
When the shaft vibrates in the axial direction, direct collision with the flywheel 1 is prevented and the shock is absorbed. The outer periphery of the flex plate contact surface 14 is a rounded surface having a dimension r, along which the flex plate 15 is curved and
By restoring, a predetermined spring effect and damping effect can be obtained. Further, the rounded surface prevents the flex plate 15 from being bent tightly and prevents the flex plate 15 from being cracked or damaged. The outer diameter of the flex plate contact surface 14 is D.

Surface 1 per such flex plate
In order to form No. 4, a paddle-like plate 16 is provided at the root portion between all the spokes 5. The plate portion 16 is continuous with the spokes 5 on both sides and the outer peripheral portion of the central boss portion 3, and the rear surface 16 a forms a part of the flex plate contact surface 14. The central boss portion 3 has a front-rear thickness that is about half that of the central boss portion 3 and is positioned in the latter half of the central boss portion 3. Seen from the spokes 5, the plate portion 16 exists only after the center of the spokes 5 in the front-rear direction, and does not exist over the entire front-rear thickness t of the spokes 5.

A characteristic of the flywheel 1 is that the vibration modes can be ideally divided or dispersed because the number of the spokes 5 is an odd number. That is, FIG. 8 shows a deformation mode in each order of the flywheel 1. normal is the state of no deformation, and Mode1, Mode2 ... Are the states of deformation of the primary mode, the secondary mode ... The attached value is the natural frequency of each order mode. As shown in this figure, the natural frequency of the first to fifth modes is 507.3 to 6
At 28.2Hz, it falls within the optimum frequency range of 480 to 650Hz.

For example, in the third mode, the way of deformation differs between the s1 spoke and the s2 spoke. In this way, it is the division of the vibration modes that the deformation is made different for each spoke or at different circumferential positions so that the vibration is made independent for each spoke. On the other hand, even-numbered spokes are deformed so that they are bent symmetrically from the half position, and the deformation of one also invites the deformation of the other, which promotes mutual vibration. As a result, the amplitude of the flywheel as a whole is increased, and the axial vibration of the crankshaft is increased. As shown in FIG. 9, the conventional plane type has a bowl-shaped deformation symmetrical with respect to the center of the flywheel, which is getting worse. In this sense, a flywheel with an odd number of spokes is desirable.

Although the number of spokes is seven in the present embodiment, the number of spokes is not limited to this.

Next, a method of mounting the flywheel 1 will be described. In FIG. 4, the lower stage shows the flywheel 1 attached to the V6 engine E, and is a view of the engine E as viewed from the rear. The upper row shows each cylinder # 1, # 2 ... #
6 shows the position of the crank pin 6 and the engine rotation direction.
FIG. 5 is a schematic diagram when the engine is viewed from above, and the arrangement of the cylinders # 1, # 2 ... # 6 is shown. The bank angle 2θ of the engine is 66 °.

When attaching the flywheel 1,
In the early stages of development, once the device was installed, tested, and then removed and tested again, the good results deteriorated. Then, as a result of investigating the cause, it was found that there is an optimum phase for attaching the flywheel 1.
This is also related to the occurrence of crank system vibration in synchronization with the combustion (explosion) cycle of the engine. As a result of trial and error, it was found that the attachment as shown in Fig. 4 was optimal.

That is, when the pistons of the # 5 and # 6 cylinders of the engine E are at the top dead center TDC of the expansion (combustion) stroke start timing, the opposite side of the # 5 and # 6 cylinders with the crank center C as the boundary. One of the spokes 5 is located at the position. FIG. 4A shows an example of # 5 cylinder, and FIG. 4B shows an example of # 6 cylinder.

In FIG. 4 (a), the piston of the # 5 cylinder is at the top dead center TDC of the expansion (combustion) stroke start timing. This is understood from the fact that the crankpin CP5 of the # 5 cylinder is on the center line of the right bank in the upper diagram. At this time, as shown in the lower diagram, one spoke 5a is located on the opposite side of the # 5 cylinder with the crank center C as a boundary. The spokes 5a are substantially along the center line of the right bank or the # 5 cylinder, and are substantially along the combustion or explosion stroke direction (indicated by the outlined arrow) of the piston of the # 5 cylinder. The same applies to the # 6 cylinder shown in FIG. 4 (b). In this way, it was confirmed that the above-described mounting method with the left and right two cylinders as a reference is effective in reducing vibration noise and preventing consonant noise.

Since the flywheel of this embodiment has a spoke shape, the response vibration of the flywheel with respect to the input vibration in a certain bending direction varies depending on the mounting phase of the flywheel. By using the above mounting method, the response vibration of the flywheel is optimized for the bending vibration generated in the actual engine, the vibration amplitude of the flywheel can be minimized, and the vibration in the crankshaft direction can be reduced. .

Next, the plate portion 16 will be described. In the flywheel 1 of this embodiment, the flex plate contact surface 14 is formed at the rear part. Since the counterpart flex plate 15 is fixed, the shape and dimensions of the flex plate contact surface 14 (outer diameter D, radius dimension r, etc.)
Can not be changed. On the other hand, the dimensions (length, front-back thickness, width, etc.) of the spokes 5 cannot be changed because the vibration characteristics are mainly determined.

In the flywheel 1 of this embodiment, the root diameter of the spoke 5, that is, the outer diameter D0 of the central boss portion 3 is smaller than the outer diameter D of the flex plate contact surface 14. In this case, if the plate portion 16 is completely removed by giving priority to the root shape of the spoke 5, the flex plate contact surface 14 does not have a uniform circular shape and becomes a notch shape, and the contact condition of the flex plate 15 is reduced. Deteriorates, and the fatigue strength of the flex plate 15 is reduced. On the other hand, if the plate portion 16 is provided in the entire front and rear width by giving priority to the flex plate contact surface 14, the length of the spoke 5 will be substantially shortened and the vibration characteristics will be affected. That is, since the rigidity is increased, the natural frequency is also increased, and the optimum frequency range of FIG. 7 is not reached. If the thickness t of the spoke 5 is reduced to reduce the rigidity, the burst strength cannot be secured. The burst strength is a strength measure of how many high revolutions the flywheel can withstand without being broken, and is 10,000 rpm in this embodiment.

Therefore, as a compromise, the plate portion 1 as described above is used.
6 is provided. An ideal flex plate contact surface 14 can be secured by the plate portion 16, and since the plate portion 16 is thinner than the front-rear thickness t of the spoke 5, even if it is added to the root portion of the spoke 5, the vibration characteristics are not significantly impaired. It should be noted that the flywheel provided with the plate portion 16 was used for analysis, but favorable results could be obtained.

Since the plate portion does not affect the vibration characteristics of the flywheel and also serves as a reinforcing member for the root portion of the spoke, it is suitable for any spoke-shaped flywheel.

Next, the outer ring portion 4 will be described. The flywheel 1 of this embodiment is basically cast, and the spokes 5 are
The part of is left as it is, and the surface is the surface of the casting.
In this case, it was found that the front-rear thickness t of the spoke 5 has a manufacturing variation of about ± 1 mm, and the variation in the natural frequency range of the first to fifth modes of the flywheel 1 varies due to this variation. As a result of the investigation, the variation in the frequency range with respect to the variation of the front-back thickness of 1 mm was about 40 Hz. If the frequency range fluctuates too much and falls outside the optimum frequency range of FIG. 7, the product cannot be shipped. On the other hand, if the management is strict to distinguish this, the management cost increases, and if the construction method is changed to suppress the dimensional variation, the component cost increases.

Therefore, the theme of reducing the fluctuation width (range) of the natural frequency range with respect to the variation of the front-rear thickness t, in other words, reducing the sensitivity of the natural frequency variation with respect to the variation of the front-rear thickness of the spoke, was tried. The mistake was repeated.

Here, as a result of conducting an analysis by changing various dimensions of the outer ring portion 4, it was found that the protrusion amount B of the front surface portion 4a has a great influence on the variation sensitivity of the natural frequency. That is,
As shown in FIG. 6, the protrusion amount B of the front surface portion 4 a and the rear surface portion 4
The width C of the machined portion 4c of b in the radial direction and the width D from the machined surface to the front surface of the back plate 10 were variously analyzed, and analysis was performed. B has little effect on this
It was found that the size greatly affects the variation sensitivity. Therefore, by changing the cutting amount of the front surface portion 4a and changing the B dimension, it is possible to change the fluctuation range of the natural frequency range with respect to the variation in the spoke front-back thickness t.

It was also found that the B dimension should be as small as possible in order to reduce the fluctuation range. For example, if the front and rear thickness t of the spokes 5 vary by ± 1 mm,
When B dimension = 2.0 mm, flywheel 1 primary to 5
The natural frequency range of the next mode is 470 to 643 Hz and the fluctuation range is
In contrast to 173 Hz, when B dimension = 0 mm, the natural frequency range of the first to fifth modes of flywheel 1 is 475.8.
The fluctuation range is 153.9Hz at ~ 629.7Hz, which is smaller than that when B dimension = 3.6mm. Therefore, it is best to set the B dimension = 0 mm, that is, the protrusion amount B of the front surface portion 4a is zero.

However, this is not the case in this embodiment. As shown in FIGS. 1 and 2, in the present embodiment, B
= 2 mm. If this is set to zero, further improvement can be achieved. By the way, in this embodiment, the dimension D in FIG.
It is 3.6 mm and the C dimension is 6.5 mm.

Next, the results of the actual noise test are shown in FIGS. In this test, the flywheel and the torque converter were actually assembled to the engine, the engine was operated, and the noise was measured. The black pattern in the figure represents the sound pressure level, and the larger the pattern, the higher the sound pressure level.

FIG. 10 shows the flywheel 1 of this embodiment.
(Fig. (A)) and the conventional plane type (Fig. (B)) are compared. As shown by the line J in the figure (b), a potato-like pattern appears periodically, which is a consonant sound. On the other hand, as shown in FIG. 6A, the flywheel 1 of the present embodiment does not generate a consonant sound. This shows that the flywheel 1 of this embodiment is excellent.

FIG. 11 shows the flywheel 1 of this embodiment.
4 is a comparison between the case where the engine is mounted on the engine E in the optimum phase as shown in FIG. 4 (FIG. 4A) and the case where the engine is mounted with a phase difference (see FIG. 4B). As can be seen from the figure, the black pattern is smaller in the figure (a) than in the figure (b), and the sound pressure level is lowered as a whole. From this, it is understood that the flywheel mounting method of the present embodiment is excellent.

The embodiments of the present invention are not limited to those described above, and various other embodiments are possible. For example, the engine is not limited to V6 diesel and may be of any type (L4, V8, gasoline, etc.). It is possible to change the number of spokes accordingly. For example V8
It's like an engine with 9 spokes. In the above V6 engine, the flywheel mounting phase is determined based on the # 5 and # 6 cylinders, but if it is better to refer to the other cylinders, that may be done.

[0049]

In summary, according to the present invention, the following excellent effects are exhibited.

(1) The optimum spoke shape of the flywheel can be achieved.

(2) The axial vibration of the crank system is suppressed,
It is possible to prevent vibration noise and reduce vibration noise.

[Brief description of drawings]

FIG. 1 shows a flywheel of the present embodiment, (a) is a vertical side view, and (b) is a rear view.

FIG. 2 is an enlarged view showing a lower half of FIG.

FIG. 3 is a side view showing a mounted state of a flywheel.

FIG. 4 is a rear view of the same.

FIG. 5 is a schematic plan view showing an arrangement of cylinders.

FIG. 6 is a schematic side view showing each dimension of the outer ring portion.

FIG. 7 is a result of preliminary examination of each flywheel shape.

FIG. 8 is a perspective view showing each deformation mode of the flywheel of the present embodiment.

FIG. 9 is a perspective view showing a conventional plane type deformation mode.

FIG. 10 is a noise test result comparing the present embodiment with a conventional plane type.

FIG. 11 is a noise test result comparing the mounting method according to the present embodiment and the mounting method with a phase difference.

FIG. 12 is a diagram showing a deformation mode of a crank system.

FIG. 13 is a sectional view of a crankshaft support portion.

[Explanation of symbols]

1 flywheel 3 Center boss 4 Outer ring 4a front part 5,5a spokes 51 crankshaft B Outer protrusion of outer ring E engine Thickness before and after spoke

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Osamu Kimura             Isuzu Motors, 8 Soil Shelf, Fujisawa City, Kanagawa Prefecture             Fujisawa Factory Co., Ltd.

Claims (5)

[Claims] 1. A flywheel attached to a crankshaft projecting from a rear part of an engine, wherein the center part and an outer ring part have a spoke shape in which a plurality of spokes are connected to each other, and a forward projecting amount of the outer ring part with respect to the spoke is set. A flywheel featuring zero. 2. The flywheel according to claim 1, wherein the entire surface is cast so that the spoke surfaces are cast surface and the front surface of the outer ring portion is machined. 3. The number of spokes is odd.
Alternatively, the flywheel according to item 2. 4. The number of spokes is seven.
Flywheel as described. 5. A spoke shape in which a center portion and an outer ring portion are connected to each other by a plurality of spokes, the spoke shape being attached to a crankshaft projecting to the rear of the engine, and the whole being cast, leaving the surface of the spoke as a casting surface. In the flywheel in which the front surface of the outer ring portion is projected forward with respect to the front surface of the spoke and is machined, the cutting amount of the front surface of the outer ring portion is changed, and the projection of the front surface of the outer ring portion with respect to the front surface of the spoke is changed. A method for changing the fluctuation range of the flywheel natural frequency range, which comprises changing the fluctuation range of the flywheel natural frequency range with respect to variations in the spoke front-back thickness by changing the amount.