JPH0325457Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to an engine balancer device in which a balancer drive gear is fixed to the end of a balancer shaft by a plurality of tightening bolts.

(Prior Art) A conventional balancer device fixes a balancer drive gear to a balancer shaft by arranging a plurality of tightening bolts at equal intervals in the rotation direction. According to such a bolt arrangement structure, in order to increase the inertial mass, it is necessary to increase the weight of the weight part itself of the balancer shaft, which increases the overall weight of the balancer device.

(Purpose of the invention) The purpose of the invention is to increase the unbalance of the balancer shaft without directly increasing the weight of the weight part by devising the arrangement structure of the bolts for tightening the balancer drive gear. It is.

(Means for Achieving the Object) In order to achieve the above object, the present invention provides an engine balancer device in which the balancer drive gear is fixed to the end of the balancer shaft with a plurality of tightening bolts. A tightening bolt is arranged only on the weight side of the balancer shaft, and a lightening hole is formed in a portion of the balancer drive gear on the opposite side to the weight side.

(Example) In FIG. 1 showing a longitudinal cross-sectional view of an engine equipped with a balancer device according to the present invention, a crankcase 1 is divided into two halves with a mating surface A as a boundary, and is integrally connected by bolts 2. A crankshaft 5 is rotatably supported by the crankcase 1 via a bearing 3. A balancer chamber 6 is formed in the front part of the crankcase 1, and a single primary balancer shaft 8 having a weight portion 8a at the left and right ends is housed in the balancer chamber 6. The weight portion 8a is formed in a mirror-symmetrical phase with respect to the phase of the crank pin 36 of the crankshaft 5. A disc-shaped balancer chamber housing 17 is fitted into the left end portion of the balancer chamber 6 with a plug, and is fixed to the crankcase 1 using the bolts 2 mentioned above. The left end of the balancer shaft 8 is supported by the balancer chamber housing 17 via a needle bearing 18, and the right end of the balancer shaft 8 is supported by the crankcase 1 together with a balancer drive gear 20 via a bearing 21. A clutch cover 10 is fixed to the right end face of the crankcase 1 by bolts 11, a pump casing 15 of a water pump 12 is fixed to the end face of the clutch cover 10, and a pump drive shaft 16 of the water pump 12 is connected to a balancer shaft. It is arranged on the same axis as 8.

The balancer drive gear 20 is formed separately from the balancer shaft 8, is removably fixed to the right end surface of the balancer shaft 8 together with an auxiliary weight 22 by a plurality of tightening bolts 23, and meshes with the crank gear 24 of the crankshaft 5. It's on. That is, the balancer shaft 8 is configured to rotate in the opposite direction to the crankshaft 5 via the balancer drive gear 20 and the crank gear 24. Balancer shaft 8 and balancer drive gear 20
is positioned in the rotational direction by a positioning pin 19.

The balancer drive gear 20 is integrally provided with a cylindrical shaft portion 20a that extends slightly to the left, and the outer peripheral surface of the cylindrical shaft portion 20a is supported by the crankcase 1 via a bearing 21. On the other hand, a flange portion 8b having the same outer diameter as the cylindrical shaft portion 20a is integrally formed on the right end portion of the balancer shaft 8, and the outer peripheral surface of the flange portion 8b is supported by the crankcase 1 via a bearing 21. There is. That is, the bearing 21 supports the balancer drive gear 20 on the right half of its inner peripheral surface, and supports the balancer shaft 8 on the left half.
The right end flange portion 8b is supported. Further, the right end edge of the right weight portion 8a of the balancer shaft 8 is connected to the bearing 2.
balancer drive gear 2.
The stepped portion 20b of the bearing 21 is in contact with the right edge of the inner ring of the bearing 21. Further, the left end edge of the outer ring of the bearing 21 is positioned by contacting the stepped portion 25 of the crankcase 1, and the right end edge of the outer ring of the bearing 21 is positioned by the locking plate 25.
(Watushia) is locked. Locking plate 2
6 is removably fixed to the crankcase 1 with bolts (not shown).

The balancer drive gear 20 has internal spline teeth 2.
7 is formed, and the outer peripheral spline teeth 28 at the tip of the pump drive shaft 16 are spline-fitted to the inner peripheral spline teeth 27. The pump drive shaft 16 is rotatably supported by the clutch cover 10 via a bearing 30, and a pump vane 31 is fixed to an end of the pump drive shaft 16 inside the pump casing 15. 32 is a water inlet, 33 is a water discharge part, 3
4 is a seal, and 35 is a drain plug. Also 3
6 is a crank pin.

In FIG. 2, which shows a view in the direction of the arrows in FIG. 1, for example, two tightening bolts 23 are provided, and both of them are arranged biased toward the same phase side as the weight portion 8a, and therefore also in the circumferential direction. They are placed at uneven intervals. That is, the bolt 23 is arranged so that the weight of the head of the bolt 23 acts as an auxiliary weight. Further, the auxiliary weight 22 is naturally arranged in the same phase as the weight. Furthermore, two lightening holes 38 are provided on the side opposite to the phase side of the weight portion 8a.
This makes the imbalance of the balancer shaft 8 even more effective. 37 is both bolts 23
It is a common locking washer, and is formed in an arc shape, and both ends are bent after the bolt 23 is tightened. That is, the bent portions 37a at both ends are connected to the bolt 2.
By engaging with the head of 3, the bolt 23 is prevented from rotating.

Note that the positioning pin 19 is shown to be located on the opposite side of the bolt 23 in FIG.
This is shown in the above position for convenience in order to show the pin 19 in the drawing, and in this embodiment, it is placed between the bolts 23 as shown in FIG.

(Function) The weight portion 8a of the balancer shaft 8 is arranged so as to be in a mirror-symmetrical phase with respect to the crank pin 36, so that when the engine is rotating, the crank pin 36 comes to the front position as shown in FIG. When the crank pin 36 is in the rear position, the weight part 8a is in the rear position, and conversely, when the crank pin 36 is in the rear position, the weight part 8a is in the front position as shown by the imaginary line. Furthermore, since the tightening bolt 23 and the auxiliary weight 22 are located in the same phase as the weight portion 8a, they also act as balance weights. Therefore, with respect to the rotation of the crankshaft 5, the inertia mass of the weight portion 8a, the auxiliary weight 22, and the bolt 23 maintains the balance of the entire engine and reduces vibration.

Note that in the illustrated motorcycle engine, only the balancer shaft 8 can be removed for use in racing to improve response.
That is, when removing the balancer shaft 8, remove it from the crankcase 1 together with the pump casing 15 and pump drive shaft 16 shown in FIG.
from the balancer drive gear 20.

Next, the locking plate 26 is removed, and the balancer shaft 8 is rotated so that its weight portion 8a comes forward as shown in the imaginary line, and is pulled out to the right together with the balancer drive gear 20, bearing 21, etc.

Then, the balancer shaft 8, auxiliary weight 22, bolt 23, and positioning pin 19 are removed from the balancer drive gear 20, and only the balancer drive gear 20 is attached to the crankcase 1 via the bearing 21. Thereafter, the clutch cover 10 is attached to the crankcase 1 along with the pump casing 15, pump drive shaft 16, etc., and the pump drive shaft 16 is spline-fitted to the balancer drive gear 20.

Alternative Embodiments Although the illustrated embodiment uses two tightening bolts 23, three, four or more bolts could also be used.

(Effects of the Invention) As explained above, the present invention provides an engine balancer device in which a balancer drive gear is fixed to the end of a balancer shaft with a plurality of tightening bolts.
The above-mentioned tightening bolt that tightens the balancer drive gear is placed only on the weight part side of the balancer shaft, and a lightening hole is formed in the part of the balancer drive gear on the opposite side from the weight part side. (1) Specially Even without increasing the weight of the weight part 8a, the unbalance of the balancer shaft 8 can be increased and the inertial mass can be increased by the arrangement structure of the bolts biased toward the weight part. Specifically, in FIG. 2, the weight increases by the weight of the head of the bolt 23.

Therefore, while being compact and lightweight,
It is possible to provide a balancer device with a large inertial mass, which is practical.

(2) Since the arrangement of the tightening bolts 23 for the balancer drive gear is simply arranged, no special new members are required, and an increase in parts costs can be suppressed.

In short, the present invention allows the tightening bolt 23 of the balancer drive gear 20 itself to be used as an auxiliary weight, thereby reducing the number of parts and assembly man-hours. Together with the formation of the holes 38, unbalance can be easily ensured.

[Brief explanation of drawings]

FIG. 1 is a horizontal cross-sectional view (-cross-sectional view in FIG. 2) of an engine for a two-wheeled motor vehicle to which the present invention is applied, and FIG. 2 is a view taken in the direction of the arrows in FIG. 1. 1... Crank case, 8... Balancer shaft, 8
a... Weight part, 23... Tightening bolt.

Claims (1)

[Scope of utility model registration request] In an engine balancer device in which a balancer drive gear is fixed to the end of a balancer shaft with a plurality of tightening bolts, the tightening bolts that tighten the balancer drive gear are arranged only on the weight part side of the balancer shaft, and the tightening bolts that tighten the balancer drive gear are arranged only on the weight part side of the balancer shaft. A balancer device for an engine, characterized in that a cutout hole is formed in a portion of the balancer drive gear on the opposite side.