JP7518056B2 - Automotive engine flywheel - Google Patents

Description

The present invention relates to a flywheel for an automobile engine.

In a reciprocating engine, a flywheel is fixed to the crankshaft to impart inertial force to the crankshaft and maintain smooth rotation. In a typical automobile engine, a ring gear is attached to the outer periphery of the flywheel, and the drive gear of the starter motor is meshed with the ring gear.

On the other hand, in hybrid vehicles that use both an engine and an electric motor for running power, a starter motor is not required because starting is performed by the electric motor (or motor generator), but a flywheel is necessary for smooth rotation of the crankshaft. Therefore, as disclosed in Patent Document 1, for example, hybrid vehicle engines use flywheels that do not have a ring gear on their outer periphery.

JP 2009-79645 A

Now, when the flywheel is installed on the engine assembly line, it is done with the engine's crankshaft in a vertical position, and the worker holds the flywheel in his hand, sets it on the engine, and then uses a power screwdriver to screw the bolt into the crankshaft.

In addition, when a ring gear is provided on the flywheel, the worker lifts the flywheel by placing both hands on the ring gear, but because the ring gear is thin and there is a certain amount of clearance between the ring gear and the engine body (cylinder block), the worker can safely set the flywheel on the engine body without getting his hands pinched. The ring gear also provides a good grip for the human hand, so it is less likely that the hand will slip and the lifted flywheel will be dropped . This, combined with the fact that the installation of the flywheel can be done safely and quickly.

In addition, the crank pulley that drives the accessories is fixed with bolts to the end face of the crankshaft opposite the flywheel, so when fixing or removing the crank pulley, it is necessary to stop the crankshaft from rotating. However, if a ring gear is provided on the flywheel, the crankshaft is stopped from rotating by sandwiching some kind of member between the ring gear of the flywheel and the drive gear of the starter motor. The same is true when attaching the flywheel to the crankshaft during engine assembly.

In this way, flywheels with ring gears have been used for purposes other than their original function. On the other hand, flywheels for hybrid vehicle engines do not have ring gears, so on the engine assembly line, they are lifted by placing hands on the smooth outer surface and set on the engine body (crankshaft). However, there are concerns that the smooth outer surface provides poor grip and makes it easy for hands to slip and drop the flywheel, and that the gap between the flywheel and engine body is small, making it easy for hands to get caught between the engine body and the flywheel.

In addition, when fixing the flywheel to the crankshaft or fixing the crank pulley to the crankshaft with bolts, a special jig must be used to stop the flywheel from rotating, which can make installing and removing the flywheel and crank pulley time-consuming.

The present invention has been made against this background, and aims to enable a flywheel that does not have a ring gear to have the same auxiliary function as a ring gear with a simple structure.

The present invention relates to a one-piece flywheel disposed along one end surface of an engine body and fixed to one end of a crankshaft, the flywheel comprising:
" The outer periphery is a thick-walled portion having an outward protruding portion protruding on the opposite side to the engine body, and does not have a ring gear on the outer periphery.
"The thick-walled portion has engagement grooves at a plurality of circumferentially spaced locations, into which a rotation-preventing member can be inserted and removed from the outside of the outer circumferential surface, the engagement grooves being open only to the outer circumferential surface or open both to the outer circumferential surface and in a direction facing the engine body, and the engagement grooves are closed by a dam portion that forms part of the thick-walled portion on the side opposite to the engine body."
The structure is as follows.

The present invention also includes the configuration of claim 2. The invention of claim 2 is as follows in claim 1:
"The radial depth dimension of each of the engagement grooves is set to be equal to or greater than half the radial width dimension of the outward protrusion of the thick-walled portion."
The structure is as follows.
The flywheel's basic purpose is to impart inertial force to the crankshaft, but in the present invention, the flywheel also serves as a damper to prevent twisting or bending of the crankshaft.

In the present invention, when attaching a flywheel to the crankshaft during the engine assembly process, it can be lifted using a hoisting tool with a hook that fits into the engagement groove. In other words, during the flywheel attachment process, the crankshaft of the engine is in a vertical position, so the flywheel can also be moved with its rotation axis in a vertical position, and since the dam is located above the engagement groove in this state, the flywheel can be easily transported by inserting the hook of the hoisting tool into the engagement groove.

In this case, the hoisting tool can be a handheld type, or it can be a type that is placed on a line and suspended from the top rail so that it can move freely. Alternatively, it can be a type that is suspended from an arm that is arranged so that it can rotate horizontally. In any case, by using the hoisting tool, the flywheel can be set safely and quickly on the engine body.

In addition, since the crankshaft can be held non-rotatable by utilizing the engagement groove, it is easy to attach and detach the flywheel to and from the crankshaft, and also to attach and detach the crank pulley to and from the crankshaft. Generally, one end face of the engine body has a part (or member) that protrudes outward beyond the flywheel, and by abutting the anti-rotation member inserted into the engagement groove against this protruding part, the flywheel can be held non-rotatable. The anti-rotation member does not need to be a dedicated part, and a bar material or the like can be used.

As described above, a suitable means for increasing the inertial force while making the flywheel as light as possible is to form the outer periphery thick , as in the present invention . However, thickening the outer periphery makes it possible to increase the width of the outer periphery, which has the advantage that the engagement groove can be set to a size that allows the suspension device and anti-rotation member to be securely inserted and removed.

2A and 2B are diagrams showing a flywheel according to an embodiment, in which (A) is a front view seen from the engine body side, (B) is a cross-sectional view taken along line B-B of (A) and a cross-sectional view taken along line IB-IB of FIG. 2A, and (C) is a cross-sectional view taken along line C-C of (A). 1A is a rear view seen from the opposite side to the engine body, FIG. 1B is a cross-sectional view taken along line B-B of FIG. 1A, and FIG. 1C and FIG. 1A is a cross-sectional view of the flywheel in a lifted state, and FIG. 1B is a cross-sectional view of the flywheel in a stopped state.

Next, an embodiment of the present invention embodied in a flywheel 1 for a hybrid vehicle will be described with reference to the drawings. In the following, the terms "front and rear" are used to specify directions, but the front and rear directions refer to the direction of the crankshaft axis, with the side where the timing chain and crank pulley are located being referred to as the front, and the side where the transmission is located being referred to as the rear.

(1) Description of Structure As shown in Figure 1, the flywheel 1 is disk-shaped and is disposed on the rear surface (one end surface) of the engine body (mainly the cylinder block and oil pan) 2. In the center of the flywheel 1, there is a central hole 4 into which the rear end (one end) of the crankshaft 3 is fitted. Around the central hole 4, there are a number of mounting holes 6 for fixing the flywheel 1 to a flange 5 provided on the rear end of the crankshaft 3 with bolts (not shown).

The flywheel 1 has a thin-walled section 7 in the center including the area where the central hole 4 is formed, and a thick-walled section 8 with a rearward protruding portion at the outer periphery. Between the two, there is an unequal thickness section 9 that is continuous with the thin-walled section 7 and increases in thickness toward the outside, and an equal-thickness intermediate section 10 located between the unequal thickness section 9 and the thick-walled section 8 and whose rear surface steps down from the thick-walled section 8.

The unequal thickness portion 9 has an inclined front surface 9a and an inclined rear surface 9b, and the inner and outer diameters of the inclined rear surface 9b are smaller than the inner and outer diameters of the inclined front surface 9a. Therefore, the unequal thickness portion 9 has a front flat surface 9c that is flush with the thin-walled portion 7, and a rear flat surface 9d that is flush with the rear surface of the intermediate portion 10. In this embodiment, the mass is shifted toward the outer periphery, so that the necessary inertial force can be secured while keeping the weight as small as possible.

Engagement grooves 11 that open radially outward and forward are formed in three locations equally spaced apart in the circumferential direction in the thick-walled portion 8 of the flywheel 1. The engagement grooves 11 are formed in a trapezoidal shape that spreads outward when viewed from the front, but it is also possible to form them with equal widths when viewed from the front. The flywheel 1 is a one-piece die-cast product , and the engagement grooves 11 are formed with a slight draft.

The engagement groove 11 does not open to the rear. Therefore, the engagement groove 11 is blocked from behind by the dam portion 12 that constitutes part of the rear surface of the thick portion 8. The dimensions of the engagement groove 11 are, for example, sufficient for the maximum groove width to be about 20 to 25 mm and the depth to be about 10 to 15 mm.

As shown in FIG. 2, a shallow auxiliary groove 13 is formed in the rear surface of the flywheel 1, extending across the thick portion 8 and the intermediate portion 10 to the outer periphery of the unequal thickness portion 9. The auxiliary groove 13 is for positioning the rotating member (e.g., the torque converter and CVT input shaft flange that constitute the transmission) that is fixed to the rear surface of the flywheel 1, and the rotating member is fixed with bolts (not shown) in a number of tapped holes 14 formed in the flywheel 1.

The engagement groove 11 described above is also open to the front, but it is also possible to form the engagement groove 11 in a form that opens only to the outer circumferential direction as shown in Fig. 2(C) as a first variant , or to form the engagement groove 11 in a form of a tapped hole that opens only to the outer circumferential surface as shown in Fig. 2(D) as a second variant. In either case, the radial (radial) depth dimension E1 of the engagement groove 11 is equal to or greater than half the radial width dimension E2 of the thick-walled portion 8.

(2) Summary When the flywheel 1 is fixed to the crankshaft 2 during the engine assembly process, the engine body 2 is in a position with the crankshaft 3 vertical, as shown in Figure 3 (A), and the flywheel 1 is lifted using a hoist with three arms 15. The lower ends of the arms 15 are formed with hooks (claws) 15a that fit horizontally into and disengage from the engagement grooves 11, while the upper ends of the arms 15 are journaled by horizontal pins in a holder (not shown), and each arm 15 rotates around its upper end as a fulcrum.

The upper ends of the arms 15 are rotatably connected to a holder to which a locking body, such as a cylindrical one, is attached so as to be movable up and down. When the locking body is lowered, each arm 15 is held immovable, and when the locking body is raised, each arm 15 becomes rotatable (the reverse is also possible). Therefore, the flywheel 1 can move in a stable position, with the dam portion 12 supported from below by the hook portion 15a of the arm 15. Since there is no need to lift the flywheel 1 by hand, there is no problem of fingers getting pinched even if the gap between the flywheel 1 and the engine body 2 is small.

The hoisting tool may be hand-held or may be suspended from a hoisting device arranged on the assembly line. The hoisting device may be an overhead crane or arm type, but in either case, the hoisting tool is movable up and down. By moving it up and down between the table where the flywheel 1 is arranged and the engine body 2, the flywheels 1 can be moved one by one and set on the engine body 2.

As shown in FIG. 3(B), the flywheel 1 can be prevented from rotating by inserting one end of a rod-shaped anti-rotation member 16 into the engagement groove 11 and then abutting the anti-rotation member 16 against the side of a protrusion 17 provided at the rear end of the engine body 2. When fixing the flywheel 1 to the crankshaft 2, a force acts to rotate the flywheel 1, but by using the anti-rotation member 16 to prevent the flywheel 1 from rotating, the installation of the flywheel 1 can be carried out quickly.

In this case, the dam portion 12 is located at the top during the assembly process of the flywheel 1, so the anti-rotation member 16 remains engaged in the engagement groove 11 even if it is not held by a person. Therefore, the worker can quickly tighten the bolts without paying attention to the anti-rotation member 16. This provides excellent workability.

When the crank pulley (not shown) is fixed to the tip surface of the crankshaft 2 with a bolt, the crankshaft 2 can be held non-rotatable by using the anti-rotation member 16. In the process of fastening the crank pulley, the engine body 2 can be placed in a position where the tip of the crankshaft 2 faces upward. In this state, the dam portion 12 of the flywheel 1 is positioned below the engagement groove 11, so the anti-rotation member 16 can be held by the dam portion 12 so that it cannot fall off. Therefore, in this case too, the crank pulley can be fastened quickly without paying attention to the anti-rotation member 16.

When the engagement groove 11 is configured as a tapped hole as shown in FIG. 2(D), a bolt can be used as the anti-rotation member 16, which has the advantage of reliably preventing the anti-rotation member 16 from falling off. In addition, when a long bolt (or a rod with a bolt at the end) is used as the anti-rotation member 16, the worker can hold the anti-rotation member 16 to prevent the flywheel 1 from rotating, so that the flywheel 1 and crank pulley can be easily attached and removed even if the engine body 2 does not have a protrusion 17 that acts as a stopper.

Although the embodiment of the present invention has been described above, the present invention can be embodied in various other ways. For example, the number of engagement grooves is not limited to three, but may be two or four or more. It is also possible to place the engagement grooves in two places 180° apart, and lift the flywheel by placing your fingertips on the dam.

The present invention can be embodied in an engine flywheel. Therefore, it can be used industrially.

REFERENCE SIGNS LIST 1 flywheel 2 engine body 7 thin-walled portion 8 thick-walled portion 9 unequal thickness portion 10 intermediate portion 11 engagement groove 12 dam portion 15 arm constituting hoisting tool 15a hook portion 16 anti-rotation member 17 rearward protrusion of engine body

Claims (2)

A one-piece flywheel disposed along one end surface of the engine body and fixed to one end of the crankshaft,
The outer periphery is a thick-walled portion having an outward protruding portion protruding on the opposite side to the engine body, and does not have a ring gear on the outer periphery.
an engagement groove into which a rotation-preventing member can be inserted and removed from the outside of the outer circumferential surface is formed at a plurality of circumferentially separated positions of the thick-walled portion , the engagement groove being open only to the outer circumferential surface or open both to the outer circumferential surface and in a direction facing the engine body, and the engagement groove is closed by a dam portion constituting a part of the thick-walled portion on the side opposite to the engine body;
Automotive engine flywheel. A radial depth dimension of each of the engagement grooves is set to be equal to or greater than half of a radial width dimension of the outward protrusion of the thick-walled portion.
2. A flywheel for an automobile engine according to claim 1.

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