JPH0756215B2 - Vertical crankshaft engine - Google Patents

Description

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

<Prior Art> For example, in a general-purpose engine used in a lawn mower or the like in which the crankshaft is vertically arranged, it is preferable that the general-purpose engine be as light as possible, and a forced cooling fan directly connected to the crankshaft is provided. An air-cooled structure is generally adopted (see, for example, Japanese Utility Model Publication No. 63-32343).

<Problems to be Solved by the Invention> By the way, in the engine having such a configuration, miniaturization is also an important issue. Therefore, it is customary to arrange the parts in close contact with each other, and the cooling efficiency tends to deteriorate. Further, in the case of an engine of the type in which fuel is supplied to the carburetor by gravity, it is difficult to reduce the height of the engine because the fuel tank needs to be placed above the liquid surface of the float chamber of the carburetor. It was

The present invention has been made to remedy such inconveniences, and its main purpose is to provide a vertical crankshaft engine which can promote miniaturization and weight reduction of the engine and can improve cooling efficiency. It is in.

[Structure of the Invention] <Means for Solving the Problems> According to the present invention, such an object is to provide a vertically arranged crankshaft, a cooling fan driven by the crankshaft, and the crankshaft. Is a vertical crankshaft engine that is driven by the engine and has a camshaft disposed on the cylinder head side, the cooling fan is disposed above the cylinder block in the engine, and the cooling fan is disposed on one side of the cylinder block. An exhaust port is arranged on the upper side, an intake port is arranged on the lower side on the other side of the cylinder block, and at least a part of the fuel tank is arranged above the carburetor connected to the intake port so as to overlap. It is achieved by providing a vertical crankshaft engine characterized by being installed.

<Operation> By doing so, the exhaust port side, which is particularly heated, is cooled more strongly. Further, since the exhaust passage can be configured with the shortest distance, heat radiation can be suppressed to the minimum.
In particular, if the intake port is arranged on the lower side and the fuel tank is arranged above the carburetor, the head difference of the fuel can be made large without increasing the overall height of the engine.

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

1 and 2 show 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 which constitutes the engine body 1, and a pair of ball bearings provided at a joint between the cylinder block 2 and the crank case 3 The crankshaft 5 is supported by 4a and 4b along the vertical direction.
A piston 8 slidably fitted in a cylinder bore 7 provided in the cylinder block 2 is connected to a crank pin 6 formed at a substantially central portion of the crank shaft 5 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 bearings 13a and 13b is formed at the joint between the cylinder block 2 and the head cover 12, and the camshaft 14 extending parallel to the crankshaft 5 is formed by these bearings 13a and 13b. It is supported by its both ends. The cam shaft 14 has a large timing pulley 15 integrally formed on the lower end thereof and a small timing pulley 16 fixed to the crank shaft 5, and a timing belt 17 wound between the small timing pulley 17 and the crank shaft 5. of
Driven at 1/2 speed.

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 furan wheel 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 in 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, like the cam bearing portion 13a located on the upper side, through the oil reservoir 40 formed in the middle portion thereof. Lubricating oil is supplied by branching to the crank bearing portion 4a located on the upper side.

As also shown in FIG. 3, an intake port 50 is provided on one side (lower side in FIG. 2) of the cylinder block 2 and an exhaust port 51 is provided on the other side (upper side in FIG. 2). Each is open. That is, the intake port 50 is designed so that the intake air and the exhaust gas cross flow in the direction orthogonal to the axis of the crankshaft 5.
And an exhaust port 51. The intake port 50 and the exhaust port 51 extend in a substantially horizontal direction and substantially parallel to each other, but as described above, the intake valve 19 and the exhaust valve 20 are vertically parallel in a common vertical plane, And exhaust valve 20
Since this is disposed on the upper side, the exhaust port 51 is disposed on the upper side.

On the other hand, the muffler 52 is directly connected to the opening of the exhaust port 51, and the carburetor 53 is directly connected to the opening of the intake port 50. The carburetor 53 is connected to a governor mechanism 54 gear-driven by the crankshaft 5 via a link mechanism (not shown), and the throttle valve opening degree is automatically adjusted so as to maintain a set rotation speed. It is supposed to be controlled.

An air cleaner case 56 containing a filter element 55 made of filter paper is connected to the upstream end of the intake passage of the carburetor 53. The inner space on the downstream side of the filter element 55 in the air cleaner case 56 is a flexible tube.
It communicates with the space above the oil level of the lubricating oil tank 28 via 57. This is because the lubricating oil OL is circulated by the fluctuation of the internal pressure of the crankcase 3 as described above, so that when the piston 8 moves downward and the lubricating oil OL is pushed back into the lubricating oil tank 28, This is a measure to make the space above the surface negative.

Above the carburetor 53, the carburetor 53 and the air cleaner case
A fuel tank 58 formed of a synthetic resin material is arranged so as to partially overlap 56.

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 almost the entire surface. The cover C is formed integrally with the fuel tank 58.

When the flywheel 23 rotates together with the crankshaft 5, the blades 24 provided on the flywheel 23 act as a centrifugal fan, and the cooling air flows downward along the inner surface of the cover C to cool the cylinder block 2. At this time, since the exhaust port 51 side is arranged at a position closer to the cooling fan, the exhaust port 51 side having a relatively high temperature is cooled more strongly. Here, the exhaust port 51 is linearly extended in the horizontal direction, the exhaust passage length is the shortest distance, and the heat radiation area is suppressed to the minimum, so that it is preferable that the other part is affected by the exhaust heat. To be prevented.

On the other hand, since the intake port 50 is arranged on the lower side, the carburetor 53 can also be arranged at a relatively low position. Therefore, the fuel tank 58 can be arranged above the carburetor 53 without increasing the height dimension, and the head difference between the carburetor 53 and the fuel tank 58 can be made larger.

[Effects of the Invention] As described above, according to the present invention, there is a great effect in improving the cooling efficiency and ensuring a sufficient head pressure with respect to the liquid surface of the carburetor without causing an increase in the height dimension of the engine. is there.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of an engine constructed according to the present invention, and FIG. 2 is a top view showing a partly cut away. FIG. 3 is a partial left side view showing the head cover removed. 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 …… Bearing part 14 …… Cam shaft, 15 …… Timing large pulley 16 …… Timing small 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 …… Projection line, 33 …… Reed valve 34 …… Passage, 35 …… Second passage 36… … Hose port, 37 …… Lubricant oil supply path 38 …… Flexible tube 3 9 …… One-way valve, 40 …… Oil reservoir 50 …… Intake port, 51 …… Exhaust port 52 …… Silencer, 53 …… Vaporizer 54 …… Governor mechanism, 55 …… Filter element 56 …… Air cleaner Case 57 …… Flexible tube 58 …… Fuel tank

Claims (1)

[Claims] 1. A vertical crankshaft engine comprising a vertically arranged crankshaft, a cooling fan driven by the crankshaft, and a camshaft driven by the crankshaft and arranged on the cylinder head side. The cooling fan is disposed above the cylinder block in the engine, the exhaust port is disposed above one side of the cylinder block, and the intake port is disposed below the other side of the cylinder block. Is disposed, and at least a part of the fuel tank is disposed above the carburetor connected to the intake port so as to overlap with each other.