JPH0710041Y2 - Vertical crankshaft engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] <Industrial field of application> The present invention relates to an OHC type vertical crankshaft engine.

<Prior Art> As a transmission device for synchronously driving a crank shaft and a cam shaft in an internal combustion engine, a timing belt device having a relatively low operating noise tends to be frequently used. It is considered to be effective in promoting noise reduction when it is used in an engine, such as an engine for an external machine, in which it is difficult to take sufficient soundproofing measures.

By the way, particularly in the case of a vertical crankshaft type general-purpose engine in which a cooling fan is provided above the cylinder and the crankshaft is arranged vertically, in order to reduce the height dimension and enhance the ventilation around the cylinder head, The belt / pulley mechanism is preferably located below the cylinder.

<Problems to be Solved by the Invention> On the other hand, considering the mountability of the timing belt to the timing pulley, a gap is required for the timing belt to escape from the end face in the axial direction of the timing pulley.

However, the fact that such a gap must be defined leads to an increase in the axial dimension of the engine, and reduces the effect of providing the belt / pulley mechanism below the cylinder, which promotes the downsizing of the engine. Above all, it is not preferable.

On the other hand, it cannot be overlooked that sludge may adhere to the lower cam journal portion when the lubricating oil that has lubricated the valve mechanism flows down.

An object of the present invention is to provide an improved vertical crankshaft engine that avoids such inconvenience.

[Structure of the Invention] <Means for Solving the Problems> According to the present invention, such a purpose is to interlock and connect a vertically arranged crankshaft and a camshaft arranged on the cylinder head side. Therefore, there is provided a vertical crankshaft engine having a transmission device including a timing pulley provided on the camshaft and the crankshaft, and a timing belt horizontally laid on the timing pulley, and a housing chamber of the transmission device is provided. The timing is provided in a portion of the outer wall of the accommodating chamber, which is defined below the cylinder, and substantially opposes the axial end surface of the timing pulley on the camshaft side, at least between the timing pulley and the axial end surface of the timing pulley. (EN) Provided is a vertical crankshaft engine, characterized in that an axially outwardly recessed portion that allows a belt to enter therein is formed. More is achieved.

<Operation> With this configuration, it is possible to form a space required for mounting the timing belt without causing an increase in the axial dimension of the engine by only partially recessing the inner surface of the outer wall of the transmission device housing chamber. it can. In addition, since the lubricating oil that lubricates the valve mechanism flows down into this recess, sludge and the like are settled in the recess, and the possibility of entering the journal of the cam shaft is alleviated.

<Embodiment> Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows a vertical crankshaft type, forced air cooling type, single cylinder engine constructed according to the present invention. A crank case 3 is integrally abutted and coupled to an opening on the right side of a cylinder block 2 that constitutes the engine body 1, and a pair of ball bearings provided at a joint portion between the cylinder block 2 and the crank case 3. The crankshaft 5 is supported by 4a and 4b along the vertical direction. The crank pin 6 formed at the substantially central portion of the crank shaft 5 has
A piston 8 slidably fitted in a cylinder bore 7 provided in the cylinder block 2 is connected via a connecting rod 9.

A balancer shaft 10 is pivotally supported at the joint between the cylinder block 2 and the crankcase 3 in parallel with the crankshaft 5. The balancer shaft 10 is for canceling the primary vibration force generated by the eccentricity of the crank pin 6, and is connected to the crank shaft 5 through the gear means 11 to be connected to the crank shaft 5. It is driven to rotate at the same speed and in the opposite direction.

A head cover 12 is integrally abuttingly connected to the opening on the left side of the cylinder block 2. A pair of upper and lower journals 13a and 13b is formed at the joint between the cylinder block 2 and the head cover 12. The journals 13a and 13b form a camshaft 14 extending parallel to the crankshaft 5. It is supported by its both ends. This camshaft
14 is a cam pulley 15 integrally formed on the lower end side
And a crank pulley 16 fixed to the crankshaft 5 via a timing belt 17 wound around the crankshaft 5.
It is driven at a rotation speed of 1/2.

An intake valve 19 and an exhaust valve 20 which are elastically urged in a valve closing direction by valve springs 18a and 18b are provided on the left side of the cylinder block 2. Both of these valves 19
The 20 are arranged side by side at an appropriate interval in a plane parallel to the crankshaft 5 and via the direct lifters 22a and 22b to the pair of cams 21a and 21b formed on the camshaft 14. They are engaged with each other, and are opened / closed at appropriate timing according to the rotation of the crankshaft 5.

A flywheel 23 is fixed to the upper end of the crankshaft 5. A blade 24 acting as a cooling fan is integrally formed on the outer peripheral portion of the axial end surface of the flywheel 23. Further, a permanent magnet 25 is fixed to a part of the outer periphery of the permanent magnet 25 so that a required ignition spark is generated at a predetermined timing in cooperation with the ignition device 26 fixed to the cylinder block side. . Further, a recoil starter 27 is connected to the shaft end of the crankshaft 5.

A lubricating oil tank 28 is arranged on the right side of the crankcase 3. This lubricating oil tank 28 is made of a semi-transparent synthetic resin material, and its bottom walls 29a and 29b are formed in two stages, and the shallow bottom part
The boss portion 30 projecting downward on the 29a is the crankcase 3
It is liquid-tightly fitted in the through hole 31 formed in. This boss
Continuing with 30, the protrusion 32 extends along the inner surface of one side wall of the lubricating oil tank 28 until it reaches the upper wall.
A passage 34, which opens toward the lower wall of the crankcase 3 and opens to the upper space of the lubricating oil tank 28 via the reed valve 33, is provided inside the 32. The passage 34 allows the lubricating oil to flow only from the bottom of the crankcase 3 to the upper portion of the lubricating oil tank 28.

On the inner surface of the other side wall of the lubricating oil tank 28, a second passage opening into the deep bottom portion 29b and communicating with the outside of the upper wall of the lubricating oil tank 28.
35 have been extended. A hose port 36 is fitted in an opening in the upper wall of the second passage, and is connected to a lubricating oil supply passage 37 provided in the cylinder block 2 via a flexible tube 38. A one-way valve 39 that allows only the inflow of the lubricating oil from the lubricating oil tank 28 is interposed at the most upstream end of the lubricating oil supply passage 37.

The lubricating oil supply passage 37 extends along the cylinder axis in the upper wall of the cylinder block 2, and a cam journal portion located on the upper side through an oil reservoir 40 formed in the middle portion thereof.
Similarly to 13a, the crank bearing portion 4a located on the upper side is branched to supply the lubricating oil.

The upper surface of the engine body 1 configured as described above is covered with a cover C that also serves as a fan shroud over substantially the entire surface.

The above OHC engine has gear-like timing pulleys 15 and 16 in order to drive the camshaft 14 synchronously with the crankshaft 5.
A timing belt 17 having internal teeth that mesh with this is used. The belt / pulley type transmission device is built in a belt chamber B formed below the cylinder 7 in the cylinder block 2.

When winding the timing belt 17 around the pulleys 15 and 16, the timing belt 17 is first mounted in advance, and then the crankshaft 5 is mounted between the coupling surfaces of the cylinder block 2 and the crankcase 3. At this time, one loop end of the timing belt 17 is inserted into the belt chamber B and is exposed to the outside from the head cover 12 mounting surface side of the cylinder block 2.

Next, attach one loop end of the timing belt 17 to the cam pulley.
The cam shaft 14 is attached to the journal portions 13a and 13b while being wrapped around 15. By fixing the head cover 12 to the end surface of the cylinder block 2 in this state, the cam shaft 14 is supported by the cylinder head portion of the engine so as to rotate in synchronization with the crank shaft 5.

By the way, when mounting the cam shaft 14 on the end surface of the cylinder block 2, it is necessary to allow the timing belt 17 to escape in the axial direction. In order to provide an escape space for that purpose without increasing the size of the engine, in the present invention,
As also shown in FIG. 2, a recess 41 is formed in the outer wall portion of the cylinder block 2 and the head cover 12 facing the cam pulley 15 in the outer peripheral portion of the journal portion 13b for supporting the cam shaft 14, and It is supposed to form an escape space when the timing belt is attached.

Further, the lubricating oil that has flowed down from the lubricating oil supply passage 37 is stored in the lower portion of the cylinder block 2 including the cylinder head 12 so as to immerse the cam pulley 15 and the timing belt 17, but it is recessed from the opening surface of the lower journal portion 13b. Since 41 is low, impurities such as sludge that have a high specific gravity
It will be accumulated in the bottom, and it is possible to reduce the adverse effects caused by the sludge and the like adhering to the journal portion 13b.

[Effect of the Invention] As described above, according to the present invention, it is possible to promote the miniaturization of the engine without deteriorating the wearability of the timing belt. Moreover, it is possible to make it difficult for the sludge to enter the journal portion of the cam shaft. Therefore, there is a great effect in improving the assembling property of the engine including the maintainability and improving the durability.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of an engine constructed according to the present invention, and FIG. 2 is a partial elevational view showing a head cover removed. DESCRIPTION OF SYMBOLS 1 ... Engine main body, 2 ... Cylinder block 3 ... Crank case, 4a ・ 4b ... Ball bearing 5 ... Crank shaft, 6 ... Crank pin 7 ... Cylinder bore, 8 ... Piston 9 ... Connecting rod, 10 ... Balancer shaft 11 ... Gear means, 12 ... head cover 13a / 13b ... journal part 14 ... cam shaft, 15 ... cam pulley 16 ... crank pulley, 17 ... timing belt 18a / 18b ... valve spring 19 ... intake valve, 20 ... exhaust valve 21a / 21b ... cam 22a / 22b ... direct Lifter 23 ... Flywheel, 24 ... Blade 25 ... Permanent magnet, 26 ... Ignition device 27 ... Recoil starter 28 ... Lubricant tank, 29a / 29b ... Bottom wall 30 ... Boss part, 31 ... Through hole 32 ... Ridge, 33 ... Reed valve 34 ... Passage, 35 ... Second passage 36 ... Hose port, 37 ... Lubricating oil supply passage 38 ... Flexible tube 39 ... One-way valve, 40 ... Oil reservoir 41 ... Recess

Claims (1)

[Scope of utility model registration request] 1. A timing pulley provided on each of the cam shaft and the crank shaft for interlockingly connecting a vertically arranged crank shaft and a cam shaft provided on the cylinder head side, and a horizontal position on the timing pulley. A vertical crankshaft engine having a transmission composed of a timing belt suspended in a direction, the storage chamber of the transmission being defined below the cylinder, and the cam on the outer wall of the storage chamber. An axially outwardly facing concave portion, which is large enough to allow the timing belt to enter, is formed at least in a portion substantially facing the axial end surface of the timing pulley on the shaft side, at least between the timing pulley and the axial end surface of the timing pulley. Vertical crankshaft engine.