JP2000186562A - Engine structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide engine structure formed in a compact manner. SOLUTION: In an engine 5 to transmit rotation of a primary output shaft 17 to a final output shaft 19 through a gear, a primary shaft 17 is arranged on the division surface 18 of a dividable crank case 13. The primary output shaft 17 is arranged in parallel to the surface 18 of the dividable crank case 13 in a position spaced away from the division surface 18 of the crank case 13 and at least the gear 20, mounted on the primary shaft 17, of gears 20 and 21 to intercouple the two shafts 17 and 19 is removably arranged.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine structure, and more particularly to an engine structure suitable for a small boat such as a personal watercraft.

[0002]

2. Description of the Related Art When an engine speed is increased / decreased and transmitted to an output shaft, a crankshaft (primary output shaft) and a drive shaft (final output shaft) are connected via gears (drive gear and driven gear) having different numbers of teeth. In general, the connection is made by using At this time, each gear is often formed integrally with each shaft.

[0003] The positional relationship between the two shafts is that, when the axial direction of the drive shaft is parallel to the axial direction of the crankshaft, the center of both shafts is arranged on the split surface of the crankcase. It is common in terms of gender.

[0004]

However, when the gear (drive gear) on the crankshaft side is formed integrally with the crankshaft, the drive gear must be larger than the crank web due to processing restrictions. To reduce the rotation of the crankshaft and transmit it to the drive shaft, the gear on the drive shaft side (driven gear) must be larger than the drive gear, which increases the size of the engine and wastes space in the crankcase. Will be In particular, when both shafts are arranged on the split surface of the crankcase, the lateral width of the engine becomes long.

Although it is technically possible to make the drive gear smaller than the crank web, it is necessary to make a large clearance for the machining cutter on both sides of the drive gear.
As a result, problems such as an increase in the overall length of the crankshaft and an increase in the runout of the gear portion occur.

As a method of reducing the width of the engine, there is a method of arranging the center of the drive shaft below, for example, the split surface of the crankcase. In this case, the bearing that supports the drive shaft must be held by a separate holder, but since the drive shaft is subjected to a thrust force in the axial direction, the holder has a holding part for holding the bearing and a holder for holding the holder. This is not preferable because the thickness of the holding portion increases and the size of the holder increases.

Furthermore, if a gear is formed integrally with the shaft, it is almost impossible to change the gear ratio unless the entire shaft is replaced, so that it lacks versatility.

The present invention has been made in view of the above circumstances, and has as its object to provide a compact engine structure.

Another object of the present invention is to provide an engine structure which makes effective use of space in a crankcase.

[0010]

According to an aspect of the present invention, there is provided an engine structure for transmitting rotation of a primary output shaft to a final output shaft via a gear, as set forth in claim 1. In the engine, the primary output shaft is arranged on a split surface of the splittable crankcase, and the final output shaft is arranged at a position away from the split surface of the crankcase in parallel with the primary output shaft. Among the gears connecting the shafts, at least a gear attached to the primary output shaft is detachably provided.

In order to solve the above-mentioned problem, a bearing holding the final output shaft is press-fitted into a bearing mounting hole provided in the crankcase, and an oil is further inserted therein. The bearing is configured to be pressed by the holder into which the seal is press-fitted.

Further, in order to solve the above-mentioned problems,
As described in claim 3, an opening is formed in the crankcase, and a case cover for closing the opening and the holder for the bearing are integrally formed.

Furthermore, in order to solve the above-mentioned problem, as described in claim 4, an engine auxiliary device is connected to a side opposite to an output end of the final output shaft.

[0014]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a left side view showing an example of a personal watercraft equipped with an engine to which the present invention is applied. FIG. 2 is a plan view of the personal watercraft shown in FIG.

As shown in FIGS. 1 and 2, the personal watercraft 1 has a handlebar 2 at the upper center of the hull, and a straddle-type seat 3 is provided behind the handlebar. An engine room 4 is formed in the hull, and houses an engine 5, a heat exchanger 6, a silencer 7, a fuel tank 8, and the like.

From the rear of the engine 5, an impeller shaft 9 extends rearward in parallel with the advancing direction axis 10 of the hull, passes through a jet pump 11 provided at the bottom of the ship, and has an impeller (not shown) at its rear end. Can be Also,
A jet nozzle 12 is provided at the rear of the jet pump 11 and projects to the rearmost portion of the hull.

When the engine 5 operates and the impeller shaft 9
Rotates, water at the bottom of the ship is sucked into the jet pump 11 from the bottom of the ship by the action of the impeller, and the jet nozzle 1
It is injected backward from 2. Then, the small planing boat 1 moves forward by the reaction of this injection. In addition, the jet nozzle 12 is rotated left and right by operating the handlebar 2, so that the traveling direction of the personal watercraft 1 can be arbitrarily changed.

FIG. 3 is a view taken in the direction of the arrow III in FIG. 2, showing the engine 5 viewed from the rear. FIG. 4 is a sectional view taken along line IV-IV in FIG. FIG. 5 is an enlarged view of the lower rear portion of the engine 5, and FIG.
It is sectional drawing which follows the VI line. As shown in FIGS. 3 to 6, the engine 5 is an in-line four-cylinder engine, and a cylinder (not shown) is arranged on the upper surface of a vertically splittable crankcase 13 along a traveling direction axis 10 of the hull. The block 14 is placed.

An intake device 15 is disposed on the left side of the cylinder block 14 with respect to the direction of travel of the hull.
An exhaust device 16 is arranged on the right side as viewed, and the muffler 7 is connected to the exhaust device 16.

A crankshaft 17 as a primary output shaft is arranged in the crankcase 13. The crankshaft 17 is disposed on a split surface 18 of a vertically divided crankcase 13 and extends parallel to the traveling direction axis 10 of the hull.

In the crankcase 13, a drive shaft 19, which is a final output shaft, is disposed at a position apart from the split surface 18 of the crankcase 13, for example, below and parallel to the crankshaft 17. The impeller shaft 9 is connected to an output end of the drive shaft 19, which is a rear end in this embodiment.

At the rear end of the crankshaft 17, for example, a drive gear 20 provided separately from the crankshaft 17 is detachably provided. A driven gear 21 provided separately from the drive shaft 19 is detachably provided at a substantially intermediate portion of the drive shaft 19. The drive gear 20 and the driven gear 21
Are operatively connected to each other, whereby the rotational force of the crankshaft 17 is transmitted to the driven gear 21. In the present embodiment, the driven gear 21 has a larger diameter and a larger number of teeth than the drive gear 20, and
The rotation speed of the motor 7 is reduced and transmitted to the drive shaft 19.

The drive shaft 19 disposed below the split surface 18 of the crankcase 13 is held by bearings 22. The bearing 22 is provided with a bearing mounting hole 23 provided at, for example, a lower portion of the crankcase 13.
Is pressed from the outside, further pressed from outside by the holder 24, and fixed to the crankcase 13 with, for example, bolts 25, and is held at a predetermined position. An oil seal 26 is press-fitted in the holder 24 in advance.
The outer diameter of the holder 24 is formed in the bearing mounting hole 23 of the crankcase 13.

By holding the drive shaft 19 by the bearings 22, a difference is created between the end of the crankshaft 17 and the end of the drive shaft 19, and a space is created in the crankcase 13. Therefore, for example, a starter clutch 27 is disposed in this space, and is attached to the rear end of the crankshaft 17.

The rear part of the crankcase 13 is opened so that the starter clutch 27 can be attached from outside the crankcase 13, and this opening 28 is closed by a case cover 29. The case cover 29 and the holder 24 of the bearing 22 are integrally formed.

Since the engine 5 employs a dry sump lubrication system, an oil tank 30 is provided outside the engine 5, and lubricating oil stored in a lower portion of the crankcase 13 is collected and sent to the oil tank 30. A recovery oil pump 31 and a delivery oil pump 32 for pumping the lubricating oil in the oil tank 30 to each part of the engine 5 are provided as engine accessories.

These oil pumps are of the two-shaft interlocking type, and one of the shafts 33, 34 of the oil pumps 31, 32 is opposite to the output end of the drive shaft 19, that is, Connected to the front end. Further, a water pump 35 for circulating cooling water, which is an engine auxiliary device, is connected to the other shaft 34 end. That is, when the drive shaft 19 rotates, both the oil pumps 31 and 32 are driven, and the water pump 35 is simultaneously driven.

Next, the operation of the present embodiment will be described.

The drive gear 20 is connected to the crankshaft 17
Since the drive gear 20 is detachably provided on the crankshaft 17, there is no restriction on gear processing, and the drive gear 20 having a smaller diameter than the crank web 17a can be provided. Drive gear 20
Is smaller, the driven gear 21 meshing with the drive gear 20 can also be smaller in diameter than the conventional one, and the width of the engine 5 can be reduced. In addition, if the drive shaft 19 is arranged not at the split surface 18 of the crankcase 13 but below the split surface 18, the drive shaft 19 can be arranged closer to the crankshaft 17, and the size of the engine 5 can be further reduced. it can.

Further, the drive gear 20 is provided separately from the crankshaft 17, and the drive gear 20 is detachably provided on the crankshaft 17, so that the gear ratio can be easily changed and the versatility is improved. . Furthermore, if the driven gear 21 is also detachably provided on the drive shaft 19, the combination of gear ratios increases, and the versatility further increases.

On the other hand, a bearing 22 for holding the drive shaft 19 is press-fitted from outside into a bearing mounting hole 23 provided in the crankcase 13, and an oil seal 26 is pressed from the outside into the inside by a holder 24 press-fitted in advance. With this configuration, one of the axial thrust forces applied to the drive shaft 19 is received by the crankcase 13 and the other is received by the holder 24.
As a result, the entire thickness of the holder 24 can be reduced as compared with the conventional one, and the holder 24 can be reduced in size and weight by the reduced thickness.

The center position of the oil seal 26 can be easily adjusted by forming the outer diameter of the holder 24 into the bearing mounting hole 23 of the crankcase 13.

Further, the opening 28 of the crankcase 13
Cover 29 and holder 24 of bearing 22 for closing
By forming them integrally, the number of parts can be reduced, and the number of fastening locations, that is, the number of assembly steps can be reduced.

By arranging the starter clutch 27 in the space in the crankcase 13 generated by holding the drive shaft 19 by the bearing 22, the space in the crankcase 13 is effectively used.

Further, by connecting and driving engine accessories such as oil pumps 31 and 32 and a water pump 35 on the side opposite to the output end of the drive shaft 19, an engine accessory drive system is provided. Etc. are simplified, the number of parts is reduced, and the size of the engine 5 can be reduced.

[0037]

As described above, according to the engine structure of the present invention, in the engine that transmits the rotation of the primary output shaft to the final output shaft via the gear, the split surface of the splittable crankcase is The primary output shaft is arranged, and the final output shaft is arranged parallel to the primary output shaft at a position distant from the split surface of the crankcase, and at least the primary output shaft of a gear connecting both shafts is provided. Since the gear to be attached is detachably provided, a gear having a small diameter can be provided, so that the size of the engine can be reduced, the gear ratio can be easily changed, and the space in the crankcase can be effectively used.

Further, since the bearing for holding the final output shaft is press-fitted into a bearing mounting hole provided in the crankcase, and the bearing is pressed by a holder into which an oil seal is press-fitted. The size and weight can be reduced.

Further, an opening is formed in the crankcase, and the case cover for closing the opening and the holder for the bearing are integrally formed, so that the number of parts and the number of assembly steps can be reduced.

Further, since the engine auxiliary device is connected to the end of the final output shaft opposite to the output end, the size and weight of the engine can be reduced.

[Brief description of the drawings]

FIG. 1 is a left side view of a personal watercraft showing an embodiment of an engine structure according to the present invention.

FIG. 2 is a plan view of the planing boat shown in FIG. 1;

FIG. 3 is a view taken in the direction of the arrow III in FIG. 2;

FIG. 4 is a sectional view taken along the line IV-IV in FIG. 3;

FIG. 5 is an enlarged view of a lower rear portion of the engine.

FIG. 6 is a sectional view taken along the line VI-VI in FIG. 5;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Small personal watercraft 5 Engine 13 Crankcase 17 Crankshaft (Primary output shaft) 18 Crankcase split surface 19 Drive shaft (Final output shaft) 20 Drive gear 21 Driven gear 22 Bearing 23 Bearing mounting hole 24 Holder 26 Oil seal 28 Crankcase Openings 29 Case cover 31, 32 Oil pump (engine accessory) 35 Water pump (engine accessory)

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) F02F 7/00 301 F02F 7/00 301F F16H 1/06 F16H 1/06 F term (reference) 3G024 AA44 AA49 BA29 CA01 DA18 EA10 FA00 FA14 GA40 3J009 DA17 EA05 EA21 EA32 EA34 EB20 EC04 EC06 FA10

Claims (4)

[Claims] In an engine for transmitting rotation of a primary output shaft to a final output shaft via a gear, the primary output shaft is disposed on a split surface of a splittable crankcase. The final output shaft 19 is arranged at a position away from the split surface 18 in parallel with the primary output shaft 17, and the gears 20, 2 connecting the two shafts 17, 19 together.
An engine structure, wherein at least the gear 20 attached to the primary output shaft 17 is detachably provided. 2. A bearing 22 for holding the final output shaft 19 is pressed into a bearing mounting hole 23 provided in the crankcase 13, and an oil seal 26 is further inserted therein.
The engine structure according to claim 1, wherein the bearing (22) is pressed by the holder (24) into which the bearing is pressed. 3. An opening 28 is provided in the crankcase 13.
The engine structure according to claim 2, wherein a case cover (29) for closing the opening (28) and the holder (24) of the bearing (22) are integrally formed. 4. The engine structure according to claim 1, wherein an engine auxiliary device is connected to an end of the final output shaft opposite to the output end.