JP2007239521A - Balancer device of internal combustion engine, and method for assembling the balancer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a balancer device improving efficiency of an assembly work of each component when attaching a crank gear to a crankshaft. <P>SOLUTION: The balancer device comprises: a crank gear 4 positioned and fixed to a crankshaft by a key groove: an idler gear 13 meshed with the crank gear; a balancer shaft 8 to which the rotation is transmitted by the idler gear; and positioning holes 22, 23 formed to a lower housing 7 and the balancer shaft 8 to position both of them at a predetermined rotational position of the balancer shaft. The positioning holes are displaced by an angle θ of twist of helical teeth of the crank gear, with a state where the crank gear is assembled with the idler gear at a reference position of the crankshaft. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a balancer device that is provided, for example, in a lower part of a cylinder block of an internal combustion engine and reduces vibration due to the rotation of the engine, and a method of assembling the balancer device.

  As a conventional balancer device for an internal combustion engine, one described in Patent Document 1 below is known.

  Briefly described, this balancer device includes a balancer housing attached to a lower portion of a cylinder block of an internal combustion engine, and is rotatably supported by the balancer housing and coupled to a front end portion of a crankshaft via a keyway. An idler gear that meshes with the crank gear, a balancer shaft that is rotatably supported inside the balancer housing, and that has a balancer weight integrated with the front end of the balancer shaft, and meshes with the idler gear; And a driven gear for transmitting a rotational force to the balancer shaft.

When the crank gear is driven to rotate along with the rotation of the crankshaft, the driven gear that meshes with the crank gear is rotated and transmitted to the balancer shaft. As a result, the balancer weight rotates via the balancer shaft to absorb the rotational vibration of the engine, thereby reducing the generation of vibration and noise.
JP-A-6-129492

  By the way, in the conventional balancer device, the crank gear, the balancer gear, and the like are provided with the respective gears formed in helical teeth in order to reduce the noise and vibration caused by the meshing.

  However, when the gears are helically toothed, the crank is in a state where the positioning pin is inserted into the positioning hole and fixed so that the driven gear of the balancer device meshes with the crank gear in a state where the rotation timing is matched. Even if the gear is inserted into the crankshaft along the key from the axial direction, it is difficult to insert the helical teeth because the teeth are twisted.

  Therefore, as a method of assembling the crank gear to the conventional crankshaft in the helical tooth, the following three procedures are performed.

  First, when the balancer housing is attached to the cylinder block, the positioning pin is inserted into the positioning holes formed in the balancer housing and the balancer shaft, respectively, and free rotation of the idler gear is restricted in advance.

  Subsequently, after installing the balancer housing, the positioning pin is pulled out to allow free rotation of the balancer gear, and in this state, the timing marks of the crank gear and the balancer gear are visually checked in consideration of the twisting of the gear. Perform alignment.

  Thereafter, the crank gear is pushed in the axial direction of the crankshaft while meshing the crank gear with the balancer gear, whereby the balancer gear is rotated by the amount of twisting of the helical teeth to perform alignment.

  Thus, to position and engage the crank gear with the crankshaft, once the positioning pin is removed from the positioning hole, the positioning of the idler gear is released, and the idler gear is rotated by the helical gear torsional angle. Since it is necessary to engage with each other, these assembling operations become complicated and there is a possibility of erroneous assembling.

  As a countermeasure against this, there is a method of assembling the crank gear first, and then assembling the balancer device later, but in this method, there is a risk that a large load acts on each tooth when the gears are assembled and meshed, resulting in gear dents. is there.

  The present invention has been devised in view of the actual situation of each of the conventional balancer devices, and includes a crank gear made of helical teeth positioned and fixed by a key with respect to the crankshaft, and a helical tooth meshing with the crank gear. A balancer gear, a balancer shaft having rotation weight transmitted by the balancer gear and having a balance weight that reduces engine vibration by the rotation, a balancer housing that rotatably accommodates the balancer shaft, the balancer housing, and the balancer shaft Or a positioning hole formed on both of the balancer shaft and the member that rotates in synchronization with the balancer shaft to position the balancer shaft at a predetermined rotational position, and the crank gear and the balancer gear at the reference position of the crankshaft. In the assembled state It is characterized in that twist angle amount corresponding positioning holes of the both helical teeth are displaced in the crank gear.

  According to the present invention, for example, in a state where the positioning pin is inserted into the positioning hole, the balancer gear is rotated by the helical tooth twist angle with respect to the actual assembly timing to the crank gear. In this state, after a part of the crank gear is engaged (toothed) with the balancer gear, the positioning jig is removed from each positioning hole. Thereafter, when the crank gear is pushed into the balancer gear from the axial direction, the balancer gear automatically rotates, and proper positioning between the teeth can be performed. Therefore, the operation of assembling the crank gear to the crankshaft is facilitated, and the assembling cost can be reduced.

  Embodiments of a balancer device for an internal combustion engine and an assembling method according to the present invention will be described below with reference to the drawings.

  That is, as shown in FIGS. 1 to 6, a ladder frame 3 made of an aluminum alloy material having a bearing that supports the crankshaft 2 is fixed to the lower surface of the cylinder block 1 of the engine. A balancer device 5 that is rotationally driven by a crank gear 4 provided at a front end portion of the crankshaft 2 is provided at a lower portion of the crankshaft 2.

  An unillustrated oil pan arranged to cover the balancer device 5 from below is fixed to the lower portion of the ladder frame 3.

  The balancer device 5 is supported between the upper housing 6 and the lower housing 7 which are fastened together with a plurality of bolts (not shown) on the lower surface of the ladder frame 3 and the housings 6 and 7 in the longitudinal direction of the engine. A drive shaft 8 and a driven shaft 9 which are balancer shafts arranged in parallel, and helical gears 10 and 11 which are fixed to the respective rear end portions of the shafts 8 and 9 and meshed with each other. ing.

  A first gear 12 is fixed to the front end of the drive shaft 8, and rotational driving force is transmitted from the crank gear 4 to the first gear 12 via an idler gear 13 that is a balancer gear. The driven shaft 9 is rotated via both helical gears 10 and 11.

  Further, as shown in FIG. 4, the drive shaft 8 has three bearings in which large-diameter journal portions 8 a to 8 c formed at three locations in the axial direction are provided between the upper housing 6 and the lower housing 7. 14a, 14b and 14c are rotatably supported.

  Furthermore, lubricating oil is introduced into each of the bearings 14a to 14c through an oil passage 15 formed in each of the housings 6 and 7 and groove grooves 16a to 16c formed on the inner peripheral surface of the bearings 14a to 14c. It has become so. A counterweight 17 is integrally provided between the second and third journal portions 8b and 8c.

  Further, the drive shaft 8 is supported while the helical gear 10 is supported in the axial direction by the thrust receiving portions 18 a and 18 b formed in the front and rear positions of the lower housing 7 in the axial direction. The driven shaft 9 is also rotatably supported by a bearing having the same structure as the drive shaft 8. Both shafts 8 and 9 are set to rotate twice per rotation of the crankshaft 2.

  The crank gear 4 has a disk shape, and an insertion hole 4a through which the front end portion of the crankshaft 2 is inserted is formed in the center. A crankshaft is formed at the upper end of the inner peripheral surface of the insertion hole 4a. A key groove 4b corresponding to a key groove (not shown) is formed, and a wedge-shaped key member, for example, is press-fitted into the key grooves so that the crank gear 4 is coupled to the crankshaft 2. It has become. Further, the crank gear 4 is integrally formed with a plurality of helical teeth 19 having a predetermined angle on the outer periphery and a twist angle in the axial direction.

  Further, as shown in FIGS. 6A and 6B, each helical tooth 19 has a chamfered portion 19a for facilitating meshing with the sub gear 13c on the outer end side of the idler gear 13 (described later) at the end on the crankshaft 2 side. Are formed respectively.

  The first gear 12 is coupled to a front end portion of the drive shaft 8 through a fixing hole 12a penetratingly formed in the center, and helical teeth 12b meshing with the idler gear 13 are integrally formed on the outer periphery.

  The idler gear 13 includes a main gear 13a disposed at the center in the axial direction, two sub gears 13b and 13c disposed so as to be relatively rotatable on both sides of the main gear 13a, a main gear 13a, and both the sub gears 13b. , 13c, and two sets of springs (not shown) that urge the sub-gears 13b, 13c to rotate relative to the main gear 13a in the circumferential direction. The idler gear 13 is rotatably supported by the upper housing 6 by idler bolts 20 inserted through a cylindrical portion integrally formed on the inner peripheral side of the main gear 13a.

  The main gear 13a is formed in a substantially cylindrical shape, and helical teeth 21a that mesh with the helical teeth 19 of the crank gear 4 are formed on the outer periphery. On the other hand, both the sub-gears 13b and 13c are formed in a substantially thin disk shape, and the same number of helical teeth 21b and 21c as the helical teeth 21a of the main gear 13a are integrally formed on the outer periphery. . The helical teeth 21a, 21b, 21c of the main gear 13a and the sub gears 13b, 13c are set at the same position.

  A part of the one side sub-gear 13b and the main gear 13a mesh with the first gear 12, and a part of the other side sub-gear 13c and the main gear 13a similarly mesh with the crank gear 4.

  As shown in FIGS. 4 and 5, the rotational direction of the idler gear 13 and the crank gear 4 is previously determined via the first gear 12 in the lower radial direction of the lower housing 7 and the inner radial direction of the drive shaft 8. 1 and 2nd positioning holes 22 and 23 are formed, respectively. Further, a positioning pin 24 for temporary fixing, which is a positioning jig, is inserted into the positioning holes 22 and 23 from below the lower housing 7.

  That is, the first positioning hole 22 of the lower housing 7 is formed so as to penetrate the bottom wall from above and below, and the inner diameter thereof is set to be larger than the outer diameter of the positioning pin 24, so An annular gap C is formed. On the other hand, the second positioning hole 23 on the drive shaft 8 side is drilled to almost half of the diameter length of the drive shaft 8, and the inner diameter thereof is smaller than the outer diameter of the small-diameter tip 24 a of the positioning pin 24. Is set to be slightly smaller, and is large enough to lock the tip 24a by press-fitting.

  Further, the first and second positioning holes 22 and 23 coincide with each other at positions where the idler gear 13 is rotated in advance counterclockwise by a predetermined angle from the position shown in FIG. 3, the idler gear 13 that meshes with the helical teeth 19 of the crank gear 2 rotates by the twist angle of the helical teeth 21 a to 21 c (θ angle in FIG. 3). The positioning centers of the positioning holes 22 and 23 are set so as to coincide with each other.

  Further, as shown in FIG. 3, the crank gear 4 and the idler gear 13 are engaged with each other at the reference position of the crankshaft 2 on the outer peripheral side of the front end surface of the crank gear 4 and the outer peripheral side of the front end surface of the idler gear 13. Are formed with timing marks 25, 25, and 26, respectively.

  Here, the reference position of the crankshaft 2 refers to a case where each piston in each cylinder of the internal combustion engine is at the top dead center position or the bottom dead center position.

  Similarly, on the outer peripheral side of the front end surface of the idler gear 13 and the outer peripheral side of the front end surface of the first gear 12, the timing marks 27 for positioning the idler gear 13 and the first gear 12 at the reference position of the crankshaft 2 as described above, 28 are formed.

  Hereinafter, an assembling procedure of the balancer device 4 having the above-described configuration will be described with reference to FIGS.

  First, as shown in FIGS. 7A and 7B, the idler gear 13 and the first 12 are previously positioned by the positioning pin 24. That is, as shown in the figure, the positioning holes 22 and 23 are aligned at a position where the idler gear 13 is rotated counterclockwise by the angle θ as shown in the figure. The portion 24a is press-fitted into the positioning hole 23 and held. Thereby, the first gear 12 and the balancer shaft 8 are temporarily fixed.

  Thereafter, the balancer device 5 is bolted to the lower surface of the ladder frame 3 via the upper housing 6, and the entire balancer device is attached to the cylinder block 1.

  Next, as shown in FIGS. 8A, 8B, and 8C, the crankshaft 2 is positioned so that the key groove of the crank gear 4 is aligned with the reference position of the crankshaft 2, that is, the key member press-fitted into the crankshaft 2. The helical teeth 19 of the crank gear 4 are temporarily meshed with the helical teeth 21c of the idler gear 13 through the chamfered portion 19a. At this time, since the gap C is formed between the positioning pin 24 and the first positioning hole 23, the idler gear 13 is allowed to rotate slightly in the forward / reverse rotation direction (backlash). The crank gear 4 can be easily meshed with the idler gear 13. Further, the presence of the chamfered portions 19a makes it possible to easily engage the crank gear 4 with the idler gear 13 only partially.

  Thereafter, as shown in FIGS. 9A and 9B, in this state, the positioning pin 24 is pulled downward and removed from the positioning holes 22 and 23.

  Subsequently, as shown in FIGS. 10A and 10B, when the crank gear 4 is further pushed into the crankshaft 2, the idler gear 13 automatically rotates clockwise by the twist angle (θ) of each helical tooth 21a to 21c. Thus, a smooth meshing state with the helical teeth 19 of the crank gear 4 is obtained, and the timing marks 25, 25, and 26 are matched to perform proper positioning.

  As described above, according to the present embodiment, after the positioning pin 24 is pulled out as in the prior art, the idler gear 13 is rotated by visual inspection of the timing marks of the crank gear 4 and the idler gear 13 taking into account the helical tooth twist. Rather than aligning, the idler gear 13 is first positioned by the positioning pin 24 in a state in which the helical gears 19 and 21a to 21c are rotated by the twist angle θ, and the helical gear 19 of the crank gear 4 is In this state, the positioning pin 24 is pulled out from the positioning holes 22 and 23 and the crank gear 4 is pushed into the idler gear 13 from the axial direction. Proper positioning of the intervals 19, 21a to 21c is performed.

  Therefore, the assembly work of the crank gear 4 with respect to the crankshaft 2 is facilitated, and the assembly cost can be reduced.

  Further, in this embodiment, the oil in the lower housing 7 can be dropped into the oil pan from the positioning hole 22 at the lower part of the lower housing 7, so that the rotational resistance due to the oil of the drive shaft 8 is sufficiently reduced. Is possible.

  The present invention is not limited to the configuration of the embodiment described above. For example, the positioning jig is not limited to the positioning pin 24.

  The positioning pin may be press-fitted or fitted into the lower housing. Further, the balancer gear can be a first gear instead of an idler gear.

The technical ideas other than the invention described in the claims, as grasped from the embodiment, will be described below.
(1) The balancer device for an internal combustion engine according to claim 1, wherein a positioning jig can be inserted into the positioning hole.
(2) The balancer housing includes an upper housing and a lower housing, and the positioning hole is formed in a lower portion of the lower housing and in the balancer shaft. Balancer device for internal combustion engine.

In this invention, the oil in the lower housing can be dropped into the oil pan from the positioning hole at the lower part of the lower housing, so that the rotational resistance due to the oil of the balancer shaft can be sufficiently reduced.
(3) The internal combustion engine according to (1), wherein a gap is formed between the positioning jig and the positioning hole so that the balancer gear can rotate within one pitch of the helical teeth of the balancer gear. Balancer equipment.

The balancer gear can be rotated by a predetermined angle corresponding to the gap even in the positioned state by the gap between the positioning jig and the positioning hole. For this reason, when positioning the crank gear to the key press-fitted into the crankshaft, even if the balancer gear is positioned, it is possible to obtain a slight meshing state with the crank gear. This facilitates the work of assembling the crank gear to the balancer gear.
(4) The balancer device for an internal combustion engine according to any one of (1) to (3), wherein a chamfered portion is formed at least on the outer end side of the balancer gear and / or on the end side in the insertion direction of the crank gear.

In the present invention, since the chamfered portion is formed, the balancer gear and the crank gear, which are positioned relative to each other, can be temporarily meshed with each other only slightly. This facilitates the assembly work of the crank gear.
(5) The reference position of the crankshaft is a state in which pistons of all cylinders of the engine are located at a top dead center or a bottom dead center. A balancer device for an internal combustion engine.
(6) The balancer for an internal combustion engine according to any one of (1) to (5), wherein timing marks are provided at positions where the crank gear and the balancer gear mesh with each other at a reference position of the crankshaft. apparatus.

It is a bird's-eye view of the balancer device concerning the present invention. It is a top view of the balancer device. It is A arrow directional view of FIG. It is a longitudinal cross-sectional view of the balancer device. It is the BB sectional view taken on the line of FIG. A is a perspective view of a crank gear provided in the present embodiment, and B is an enlarged view of a portion C in FIG. A and B are explanatory views showing an initial process of the assembling procedure of the balancer device. A and B are explanatory diagrams of the next process of the assembling procedure, and C is an enlarged view of a D portion of FIG. A and B are explanatory views showing the next step of the assembling procedure. A and B are explanatory views showing the final process of the assembling procedure.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Cylinder block 2 ... Crankshaft 4 ... Crank gear 5 ... Balancer device 8 ... Drive shaft (balancer shaft)
DESCRIPTION OF SYMBOLS 9 ... Driven shaft 12 ... First gear 13 ... Idler gear 17 ... Balancer weight 19 ... Helical tooth 19a ... Chamfer 21a-21c ... Helical tooth 22, 23 ... Positioning hole 24 ... Positioning pin (positioning jig)
25 ・ 26 ・ 27 ... Timing mark

Claims (3)

A crank gear made of helical teeth positioned and fixed to the crankshaft by a key;
A balancer gear made of helical teeth meshing with the crank gear;
A balancer shaft having a balance weight to which rotation is transmitted by the balancer gear to reduce vibration of the engine by rotating;
A balancer housing that rotatably accommodates the balancer shaft;
A positioning hole that is formed on both the balancer housing and the balancer shaft or a member that rotates in synchronization with the balancer shaft, and that positions the balancer shaft at a predetermined rotational position; and
A balancer device for an internal combustion engine, characterized in that, in a state where the crank gear and the balancer gear are assembled at a reference position of the crankshaft, both the positioning holes are shifted by a helical tooth twist angle in the crank gear. . A crank gear made of helical teeth positioned and fixed to the crankshaft by a key;
A balancer gear made of helical teeth meshing with the crank gear;
A balancer shaft having a balance weight to which rotation is transmitted by the balancer gear to reduce vibration of the engine by rotating;
A balancer housing that rotatably accommodates the balancer shaft;
Provided in both the balancer housing and the balancer shaft or a member that rotates synchronously with the balancer shaft, and the balancer gear engages with the crank gear at the reference position of the crankshaft with respect to the helical gear of the crank gear. A positioning jig insertion portion formed at a position shifted by a twist angle;
A balancer device for an internal combustion engine comprising: A crank gear made of helical teeth positioned and fixed to the crankshaft by a key;
A balancer gear made of helical teeth meshing with the crank gear;
A balancer shaft having a balance weight to which rotation is transmitted by the balancer gear to reduce vibration of the engine by rotating;
A balancer housing that rotatably accommodates the balancer shaft;
Provided in both the balancer housing and the balancer shaft or a member that rotates synchronously with the balancer shaft, and the balancer gear is shifted from the meshing position with the crank gear by a twist angle of helical teeth in the crank gear. A positioning hole in which the two match,
A method of assembling a balancer device for an internal combustion engine comprising:
A step of inserting a positioning jig into the positioning hole and temporarily fixing the balancer shaft to the balancer housing in a rotational direction;
Fixing the balancer housing to the cylinder block;
Positioning the crank gear at a position where a key groove matches the crankshaft positioned at a reference position;
Removing the positioning jig from each positioning hole, and engaging the crank gear and the balancer gear while matching the key groove between the crankshaft and the crank gear while rotating the balancer shaft;
Fixing a crank gear to the crankshaft with the key;
A method of assembling a balancer device for an internal combustion engine comprising:

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