JPH04321842A - Engine with balancer - Google Patents

Abstract

PURPOSE:To shorten the distance between shafts and the lateral width of a crank case by retreating inward the respective lateral peripheral surface portions of a counterweight and a balancer weight from the respective lower peripheral surface portions, and bringing a crankshaft and a balancer shaft close to each other at the retreated portions. CONSTITUTION:A crankshaft 5 and a balancer shaft 6 are inserted in parallel in a shaft insert hole 4 bored in one of front and rear walls of a crank case 1, and these shafts are laid side by side in the crank case 1. In this arrangement, the respective lateral peripheral surface portions 8, 10 of a counterweight 7 and a balancer weight 9 are retreated inwardly from the respective lower peripheral surface portions 12, 13, and the crankshaft 5 and the balancer shaft 6 are brought close to each other only at the retreated portions. A gap 14 is partitioned between the counterweights arranged side by side, and the balancer weight 9 is disposed on the side of the gap 14. Thus, the rotated balancer weight 9 passes through the gap 14.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine with a balancer.

0002

[Prior art] As a conventional technology for an engine with a balancer,
There is one shown in Figure 2. This conventional technology is as follows. A shaft insertion hole is made in either the front and rear walls of the crankcase 101, and the crankcase 101 is inserted into the shaft insertion hole.
Insert the crankshaft 105 and balancer shafts 106 in parallel, and then insert the crankshaft 105 and balancer shaft 1
06 and 106 are installed horizontally in parallel in the crankcase 101, and the horizontal circumferential surface portion 108 of the counterweight 107 of the crankshaft 105 and the balancer shaft 106.
An interference avoidance gap 111 is maintained between the balancer weight 106 and the horizontal peripheral surface portion 110 of the balancer weight 109 at the time of shaft insertion.

According to the above configuration, the counterweight 10
7 and the balancer weight 109 without interfering with each other.
The crankshaft 105 and balancer shaft 106 can be inserted into the crankcase 101 in parallel.

By the way, in this prior art, the circumferential surface of the counterweight 107 and the circumferential surface of the balancer weight 109 are each formed into an arc shape with a constant curvature.

[0005]

[Problems to be Solved by the Invention] The above prior art has the following problems. Since the circumferential surface of the counterweight 107 and the circumferential surface of the balancer weight 109 are each formed into an arc shape with a constant curvature, the horizontal circumferential surface portion 108 of the counterweight 107 has a lower circumferential surface portion 112 that protrudes significantly downward. Just as it is, it sticks out to the side, and
The lateral circumferential surface portion 110 of the balancer weight 109 largely protrudes laterally, just as the lower circumferential surface portion 113 of the balancer weight 109 protrudes significantly downward. For this reason, the distance between the crankshaft 105 and the balancer shafts 106, 106, which are arranged horizontally in parallel to avoid mutual interference, becomes longer, and the width of the crankcase 101 that houses them becomes larger, resulting in a larger engine. become

An object of the present invention is to shorten the distance between the crankshaft and the balancer shaft.

[0007]

[Means for Solving the Problem] As shown in FIG. 1(B), the present invention provides a shaft insertion hole 4 formed in either the front or rear walls of a crankcase 1, and a shaft insertion hole 4 inserted through the shaft insertion hole 4 into the crankcase 1. The crankshaft 5 and balancer shafts 6, 6 are inserted in parallel into the crankcase 1, and the crankshaft 5 and balancer shafts 6, 6 are installed horizontally in parallel within the crankcase 1, as shown in FIG. As shown in (A), there is an interference avoidance gap when the shaft is inserted between the horizontal circumferential surface portion 8 of the counterweight 7 of the crankshaft 5 and the horizontal circumferential surface portion 10 of the balancer weight 9 of the balancer shafts 6, 6. The engine with a balancer that holds 11.11 is characterized by the following configuration.

As shown in FIG. 1(A), the horizontal circumferential surface portion 8 of the counterweight 7 is retracted inwardly from the lower circumferential surface portion 12 thereof, and the horizontal circumferential surface portion 10 of the balancer weight 9 is The crankshaft 5 and the balancer shafts 6, 6 are moved closer to each other by the amount of the retreat by retreating inward from the lower circumferential surface portion 13.

As shown in FIG. 1(B), a balancer weight passing gap 14 is maintained between the parallelly arranged counterweights 7, and the balancer weight 9 is placed on the side of this balancer weight passing gap 14. The positioned and rotating balancer weight 9 passes through the balancer weight passage gap 14.
Configure it to pass through.

0010

[Operation] As shown in Fig. 1(A), the counterweight 7
The horizontal circumferential surface portion 8 of the balancer weight 9 is retracted inwardly from the lower circumferential surface portion 12 thereof, and the horizontal circumferential surface portion 10 of the balancer weight 9 is
is retreated inward from its lower circumferential surface portion 13, and the crankshaft 5 and balancer shafts 6, 6 are brought closer to each other by the amount of the retreat, so that the distance between the crankshaft 5 and balancer shafts 6, 6 is reduced. can be shortened. Therefore, the width of the crankcase 1 that accommodates them becomes smaller, and the engine can be made smaller.

As shown in FIG. 1(B), a balancer weight passage gap 14 is formed between the parallelly arranged counterweights 7, 7.
is held, and the balancer weight 9 is positioned on the side of this balancer weight passing gap 14, so that the rotating balancer weight 9 passes through the balancer weight passing gap 14, so that the crankshaft 5 and the balancer shaft 6. Although the balancer weight 9 and the counterweight 7 are brought close to each other, the balancer weight 9 and the counterweight 7 do not interfere with each other during rotation.

0012

Effects of the Invention: The horizontal circumferential surface portion of the counterweight is retreated inwardly from its lower circumferential surface portion, and the horizontal circumferential surface portion of the balancer weight is retreated inwardly from its lower circumferential surface portion; Since the crankshaft and the balancer shaft are moved closer to each other by the amount of the distance between the crankshaft and the balancer shaft, the distance between the crankshaft and the balancer shaft can be shortened. Therefore, the width of the crankcase that accommodates them becomes smaller, allowing the engine to be made smaller.

[0013]

[Embodiment] An embodiment of the present invention will be explained based on the drawings. FIG. 1 is a diagram illustrating an engine with a balancer according to an embodiment of the present invention, and FIG. 1(A) is a vertical cross-sectional front view of the lower part of the engine at a crank angle of 0°. Figure 1 (B) is shown in Figure 1 (
This is a sectional view taken along line B-B of A) with a crank angle of 90°.

In FIG. 1, reference numeral 15 indicates an in-line two-cylinder engine. As shown in FIG. 1A, this engine 15 has a crankcase 1 integrally formed below a cylinder block 16, and an oil pan 17 assembled below the crankcase 1. Also, Figure 1(B)
As shown in the figure, a crankshaft 5 and two balancer shafts 6, 6 are installed in a horizontally parallel manner in a crankcase 1.

The crankshaft 5 has the following structure. As shown in FIG. 1(B), two pairs of crank arms 18 and 1
Both crank pins 19 and 8 are installed between the tips of the crank pins 19 and 8.
The angle of 19 is 360°. Two pairs of counterweights 7 are provided on opposite sides of the two pairs of crank arms 18. The adjacent counterweights 7, 7 on the center side are integrated. A crank gear 20 and a crank pulley 21 are fitted to the front end of the crankshaft 1. A flywheel 22 is attached to the rear end of the crankshaft 5. A dynamo 23 is arranged inside the flywheel 22.

Each balancer shaft 6 has two balancer weights 9 attached thereto, and a balancer gear 24 is fitted to the front end of each balancer shaft 6, respectively. Each balancer gear 24 meshes with the crank gear 20. The gear ratios of the crank gear 20 and balancer gear 24 are made equal. As shown in FIG. 1A, the crankshaft 5 rotates clockwise, and each balancer shaft 6 rotates counterclockwise at the same speed as the crankshaft 5.

The crankshaft 5 and each balancer shaft 6 are assembled to the crankcase 1 as follows. Figure 1 (
As shown in B), the front journal portion 26 of the crankshaft 5 is inserted through the front wall central bearing hole 25 at the center of the front wall 2 of the crankcase 1, and is supported by the front journal portion 26. Each front journal part 28 of each balancer shaft 6 is inserted into the front wall left and right bearing parts 27, 27 on the left and right positions of the front wall 2 of the crankcase 1,
This is supported by a bearing and is prevented from coming off with a retaining nut 29.

Further, a shaft insertion hole 4 is formed in the rear wall of the crankcase 1, and this hole is covered with a removable bearing cover 30. A bearing case 31 is attached to the inner side of the center portion of the bearing cover 30, and the rear journal portion 32 of the crankshaft 5 is inserted through the bearing case 31 to receive the bearing case. Bearing lid left and right bearing parts 33, 33 are located inside the bearing lid 30 left and right positions.
is attached to the rear journal portion 3 of each balancer shaft 6.
4 is inserted and this is supported as a bearing. In addition, Figure 1 (A
), interference avoidance gaps 11 are maintained between the horizontal circumferential surface portion 8 of the counterweight 7 and the horizontal circumferential surface portion 10 of each balancer weight 9 to avoid interference during shaft insertion.

The crankshaft 5 and each balancer shaft 6 are assembled to the crankcase 1 in the following manner. Figure 1
As shown in (B), each balancer shaft 6 is inserted into the crankcase 1 through the shaft insertion hole 4 of the rear wall 3 of the crankcase 1, and the front journal portion 28 of each balancer shaft 6 is inserted into the front wall left and right bearing holes 27. The balancer gear 24 is fitted to the front end of the front journal part 28 protruding from the front journal part 28, and the retaining nut 29 is screwed into the front end part of the front journal part 28. At this time, each balancer shaft 6 is connected to the balancer weight 9 shown in FIG.
The situation is A).

Next, as shown in FIG. 1(B), the crankshaft 5 with the bearing cover 30 integrally attached through the bearing case 31 is inserted into the crankcase 1 through the shaft insertion hole 4 in the rear wall of the crankcase 1. Insert into. At this time, crankshaft 5
is inserted into the crankcase 1 from the back side of the page toward the front side of the page in the state shown in FIG. 1(A) with the counterweight 7 facing downward. Because of the interference avoidance gaps 11, 11, the horizontal circumferential surface portion 8 of the counterweight 7 and the horizontal circumferential surface portion 10 of the balancer weight 9 do not interfere with each other during this insertion.

Next, as shown in FIG. 1B, the front journal portion 26 of the crankshaft 5 is inserted into the front wall central bearing hole 25, and each balancer shaft 6 is inserted into the bearing 33 at the left and right positions of the bearing cover 30. The rear journal portion 34 is inserted, the bearing cover 30 is attached to the shaft insertion hole 4, and the shaft insertion hole 4 is closed. next,
Front journal portion 2 protruding from front wall central bearing hole 25
Crank gear 20 and crank pulley 21 at the front end of 6.
and fit into place.

In this engine 15, the following measures have been taken to shorten the distance between the crankshaft 5 and each balancer shaft 6. As shown in FIG. 1(A), the lower circumferential surface portion 12 of the counterweight 7 is formed in an arc shape, and both lateral circumferential surface portions 8 are set back inward from the lower circumferential surface portion 12. It has a flat shape. Further, the lower circumferential surface portion 13 of the balancer weight 9 is formed in an arc shape,
Both lateral circumferential surface portions 10 have a flat shape that is set back from the lower circumferential surface portion 13. Then, the crankshaft 5 and each balancer shaft 6 are brought closer to each other by the amount of the retreat.

In this engine 15, in order to prevent the crankshaft 5 and the counterweights 7 and balancer weights 9 of each balancer shaft 6 from interfering with each other during rotation,
The following measures have been taken. As shown in FIG. 1(B), a balancer weight passage gap 14 is maintained between the parallel counterweights 7 and 7, and a balancer weight 9 is placed on the side of this balancer weight passage gap 14. The balancer weight 9 is configured to pass through the balancer weight passage gap 14.

In FIG. 1, reference numeral 35 is a rib formed on the side wall 36 of the crankcase 1. This rib 35 causes the side wall 36 of the crankcase 1 to protrude outward in a U-shape, and holds a balancer weight passage space 37 inside thereof, and the balancer weight 9 is positioned on the side of this balancer weight passage space 37. The rotating balancer weight 9 is configured to pass through a balancer weight passage space 37. Further, reference numeral 38 is a lubricating oil supply pump, and 39 is a governor device.

[Brief explanation of the drawing]

FIG. 1 is a diagram illustrating an engine with a balancer according to an embodiment of the present invention. FIG. 1(A) is a vertical cross-sectional front view of the lower part of the engine at a crank angle of 0°. FIG. 1(B) is a sectional view taken along the line B-B of FIG. 1(A).
It has a crank angle of 90 degrees.

[Fig. 2] Fig. 1 of an engine with a balancer according to the prior art (
A) Equivalent diagram.

[Explanation of symbols]

1...Crankcase, 4...Shaft insertion hole, 5...Crankshaft,
6... Balancer shaft, 7... Counter weight, 8... Lateral circumferential surface portion of 7, 9... Balancer weight, 10... Lateral circumferential surface portion of 9, 11... Interference avoidance gap, 12... Lower circumferential surface portion of 7, 13...
Lower peripheral surface portion of 9, 14... balancer weight passage gap.

Claims (1)

[Claims] Claim 1: A shaft insertion hole (4) is formed in either the front or rear walls of the crankcase (1), and the crankshaft (5) and balancer shaft are inserted into the crankcase (1) through the shaft insertion hole (4). (6) and (6) are inserted in parallel, and the crankshaft (5) and the balancer shaft (6) and (6) are installed horizontally in parallel inside the crankcase (1). death,
There is a shaft between the horizontal circumferential surface portion (8) of the counterweight (7) of the crankshaft (5) and the horizontal circumferential surface portion (10) of the balancer weight (9) of the balancer shaft (6) (6). In an engine with a balancer that maintains interference avoidance gaps (11) and (11) during insertion, the counterweight (
The horizontal circumferential surface portion (8) of 7) is retreated inwardly from its lower circumferential surface portion (12), and the balancer weight (
9) is retracted inwardly from its lower peripheral surface portion (13), and the crankshaft (5) and balancer shafts (6) and (6) are adjusted by the recessed amount. approach,
A balancer weight passage gap (14) is maintained between the parallelly arranged counterweights (7) and (7), and the balancer weight (9) is positioned on the side of the balancer weight passage gap (14); Rotating balancer weight (
9) is configured to pass through the balancer weight passage gap (14).