JPS6325312Y2 - - Google Patents

Description

[Detailed description of the invention] <Industrial application field> The present invention relates to a fuel tank-mounted vertical overhead valve engine, which reduces the overall height of the engine to make it compact, improves tilting performance, and improves the governor device. To provide an engine that can be processed in common with side valve type engines.

The present invention has a prerequisite structure, for example, as shown in FIGS. 1 and 2, a vertical overhead valve engine E.
This relates to a fuel tank overhead type general-purpose vertical overhead valve engine in which a fuel tank T is arranged on the upper side and a carburetor 1 is arranged on the side, and the carburetor 1 is connected to an intake port 4 of a cylinder head 2 via an intake pipe 5. .

(Background) For general-purpose vertical engines with an overhead fuel tank, side-valve engines were once popular due to the emphasis on manufacturing costs, but recently overhead-valve engines have become popular as part of energy saving efforts and from the perspective of operating costs. There is a tendency to switch to

In this case, the major problem is that the overhead valve type head and head cover raise the overall height and center of gravity of the engine, making it unsuitable for various types of machinery equipped with conventional side valve engines.

Therefore, there was a need to reduce the overall height of the overhead valve engine with the fuel tank mounted overhead to be as small as the overall height of the side valve engine in order to make it compatible with the overhead valve engine without having to change the design of various conventional engine-mounted machines. Ru. For this purpose, it is important, on the one hand, to lower the fuel tank by recessing the bottom of the tank upwards and to cover the head, and, on the other hand, to reduce the total height of the head and head cover.

(Problem that the invention seeks to solve) However, when attempting to lower the fuel tank, the carburetor protruding from the intake port of the cylinder head interferes with the bottom of the fuel tank, which has been lowered to a lower position, causing the fuel tank to drop. There are limits to the reduction of the amount.

Moreover, in this case, since the carburetor and the fuel tank are very close to each other, there is almost no difference in water head, so even if the engine is tilted slightly, the liquid level in the carburetor and the fuel tank tend to be at the same level, and the fuel There is a great possibility that fuel cannot be smoothly supplied from the tank to the carburetor.

(Means for solving the problem) The present invention was proposed to solve the above problem, and was proposed with the aim of keeping the overall height of the engine extremely low and improving the tilting performance of the engine. In order to achieve the purpose, it is constructed as follows (the reference numerals refer to FIGS. 1 to 3).

That is, a recess 7 is formed in the tank bottom wall 6 of the fuel tank so that the head cover 3 is fitted onto the tank, and the recess 7 is fitted over the head cover 3 from above to form the tank bottom wall 6. Head cover 3
The intake pipe 5 is positioned lower than the upper surface 3a, and the intake pipe 5 is formed so that its inlet end 8 is lower than its outlet end 10, and the carburetor 1 connected to the inlet end 8 is connected to the intake pipe 5. It is located lower than the intake port 4 to which the outlet side end 10 connects.

Then, the governor shaft 14 is pivotally supported by passing through the case wall 12 of the crankcase 11 on the side of the carburetor 1,
The inner end 15 of the governor shaft 14 is connected to the crankcase 11.
The governor shaft 14 is interlocked with the centrifugal actuator 16 in the
A lower end 19 of a governor lever 18 is fixed to an outer end 17 of the governor lever 18, and an upper end 20 of the governor lever 18 is interlocked and connected to a throttle lever 21 of the carburetor 1 via a link 22.

(Effects of the Invention) Therefore, to describe the effects of the present invention brought about by the above configuration, the bottom wall of the fuel tank is located lower than the top surface of the head cover, and the carburetor is located lower than the intake port. A sufficient gap can be provided between the bottom wall of the tank and the carburetor, and the placement of the fuel tank is not hindered by the carburetor.

Therefore, the fuel tank can be kept in a low position without interfering with other parts, and the overall height of the engine can be made extremely small compared to conventional overhead valve engines, making the engine compact. .

Furthermore, since there is a sufficient head gap between the bottom wall of the fuel tank and the carburetor, even if the angle of inclination of the engine becomes large, the liquid level in the carburetor can be kept lower than that in the fuel tank. It is possible to secure a suitable water head pressure, to smoothly supply fuel to the carburetor, and to improve the tilting performance of the engine.

Furthermore, since the position of the carburetor is set lower than the intake port, even if the float valve closes incorrectly due to forgetting to cut off the fuel or getting caught in dust, the fuel in the carburetor will leak into the combustion chamber. Therefore, it is possible to prevent the water hammer phenomenon from occurring and damaging the cylinder head, or from diluting the lubricating oil by the amount of fuel mixed in and causing poor lubrication.

Further, as described above, since the carburetor is located low with respect to the side wall of the crankcase, the process of machining the governor device on the side wall of the case can be shared with that of machining the side valve type engine.

That is, as mentioned above, overhead valve engines generally have better running costs than side valve engines, so recent general-purpose engines are shifting from side valve engines to overhead valve engines.

Therefore, if the processing equipment for side-valve engines could be applied to overhead-valve engines as is, the processing costs associated with changing engine types could be significantly reduced, but overhead-valve engines and side-valve engines are Since the location of the port is different, the location of the carburetor connected to this intake port is also significantly different.

In addition, due to the need to downsize the engine, it is necessary to keep the governor weight small, and due to the moment generated in this weight, the length of the governor lever must be kept constant (in other words, even though the weight is small, (If the governor lever is lengthened, the rotational moment of the weight will not act as sharply on the governor lever, and the control sensitivity of the governor lever to the carburetor throttle lever will also decrease.)The location of the governor shaft hole in the side wall of the crankcase is also different for both types of engines. Generally, there are differences.

Therefore, the distance between the carburetor and the governor shaft hole differs greatly between side valve type and overhead valve type engines.
However, it has been difficult to standardize the processing of governor devices.

However, in the present invention, as mentioned above, the carburetor is placed low with respect to the side wall of the crankcase even though it is an overhead valve engine, so its position is approximately the same height as the carburetor position of a side valve engine. Therefore, the governor shaft hole can be machined in the same manner as in the side valve type engine. In addition, since the speed regulating lever that swings the governor lever can be installed in the same way as the side valve type, the advantage is that the processing equipment for the entire governor device can be shared in the same way as in the case of side valve type engines. Overall, the processing costs for overhead valve engines can be kept low.

(Example) Hereinafter, an example of the present invention will be described based on the drawings.

Fig. 1 is a left side view of an overhead valve type forced air-cooled engine, Fig. 2 is a plan view thereof, and Fig. 3 is a rear cross-sectional view of the center of the engine. A piston 25, a crankshaft 27, a camshaft 28, a valve train V driven by the camshaft 28, an intake/exhaust valve 30, and other moving members are housed in an outer shell structure such as the headblock 25 and head cover 3.

Further, a cooling device C is disposed at the front of the engine E, and includes a flywheel fan type cooling fan driven by a crankshaft 27, a fan case 31 covering the outer surface of the cooling fan, and the like.

The valve drive camshaft 28 in the crankcase 1 and the rocker arm 32 in the head cover 3 are interlocked and connected via a push rod 33, and the rotation of the valve drive camshaft 28 causes the locker arm 32 of the nut type to swing and take suction. - It presses the exhaust valve 30 so that it can be opened and closed.

Furthermore, a tank stay 33 is attached from the side wall of the crankcase of the engine E, and the tank stay 33 is attached to the side wall of the crankcase of the engine E.
3, fix the fuel tank T on top and mount it on the engine E.

The fuel tank T has a recess 7 in the bottom wall 6 of the tank.
The head cover 3 corresponding to the upper part of the engine E is fitted into this recess 7, and the tank bottom wall 6 is recessed.
is positioned lower than the top surface 3a of the head cover 3.

Further, as shown in FIG. 2, the intake port 4 and the exhaust port 34 are located near the center of the cylinder head 2 facing the front and rear of the head cover 3, and the intake pipe 5 having a curved hanging shape is connected to the intake port 4. The carburetor 1 and the air cleaner 35 are sequentially installed on the outlet side end 10 side, and the exhaust port 34
A muffler 37 is connected to the exhaust pipe 36 through an exhaust pipe 36.

That is, the intake pipe 5 is formed such that its inlet end 8 is lower than its outlet end 10, and the outlet end 10 is connected to the carburetor 1 connected to the inlet end 8. It is located lower than the intake port 4, and is fixed above the cylinder block of the crankcase side wall 12.

The governor shaft 14 is swingably passed through the lower part of the case wall 12 to which the carburetor 1 is fixed, and the tip thereof is bent into a dogleg shape to form a governor fork 38.
Then, the governor fork 38 is interlocked and connected to the centrifugal actuator 16 provided inside the crankcase 11.

Further, the lower end 19 of the governor lever 18 is fixed to the outer end 17 of the governor shaft 14, and the lower end 19 of the governor lever 18 is fixed to the outer end 17 of the governor shaft 14.
The upper end 20 of the carburetor 1 is connected to the throttle lever 21 of the carburetor 1.
are interlocked and connected to each other via a link 22.

A generally doglegged speed control lever 40 is rotatably supported directly on the case side wall 12 located on the right side of the governor lever 18, and one wing portion 41 of the speed control lever 40 is attached to the central portion of the governor lever 18. is connected to the other wing portion 43 via the governor spring 44.
A wire 46 for remote control is led out from there.

The reference numeral 47 is a rotational speed upper limit pin fixed to the side wall 12 of the crankcase, and the reference numeral 48 is a receiving portion of the pin on the regulating lever 40 side.

Further, reference numeral 50 is a rotational speed lower limit pin, and reference numeral 51 is a receiving portion thereof on the speed regulating lever 40 side.

In the governor device constructed in this manner, when the engine speed increases, the flyweight of the centrifugal actuator 16 opens and tilts the governor fork 38 in one direction against the tension of the governor spring 44. The governor lever 18 rotates the throttle lever 21 of the carburetor 1 in the valve-closing direction via the link 22, thereby lowering the engine speed to a predetermined rotation speed.

Therefore, even if the overhead valve engine is processed in the same manner as when the governor lever 18, speed regulating lever 40, etc. are attached to the side valve engine, since the carburetor 1 is placed low, the entire governor mechanism can be maintained in a well-balanced manner in the engine. The governor can be assembled into a 3D controller, and the governor performance can be operated smoothly as described above.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, in which Fig. 1 is a left side view of an overhead valve type forced air-cooled engine, Fig. 2 is a plan view thereof, and Fig. 3 is a central longitudinal rear view thereof. 1... carburetor, 2... cylinder head, 3...
Head cover, 3a...top surface of 3, 4...intake port, 5...intake pipe, 6...bottom wall of tank, 7...
6: recess; 8: inlet end of 5; 10: outlet end of 5; 11: crankcase; 12:
Case wall on one side of 11, 14... governor shaft, 15
... the inner end of 14, 16... the centrifugal actuator, 17...
...Outer end of 14, 18...Governor lever, 19...
...lower end of 18, 20...upper end of 18, 21...
…Throttle lever, 22…link.

Claims (1)

[Scope of utility model registration request] Fuel tank T is located above the vertical overhead valve engine E.
In a fuel tank overhead type general-purpose vertical overhead valve engine in which carburetors 1 are arranged on the sides and the carburetors 1 are connected to the intake port 4 of the cylinder head 2 via an intake pipe 5, the bottom of the fuel tank is A recess 7 is formed in the wall 6 so that the head cover 3 is fitted onto the tank, and the recess 7 is fitted onto the head cover 3 from above so that the tank bottom wall 6 is lower than the top surface 3a of the head cover 3. Position it low, intake pipe 5
is formed such that its inlet end 8 is lower than its outlet end 10, and the carburetor 1 connected to its inlet end 8 is lower than the intake port 4 connected to its outlet end 10. The governor shaft 14 is also positioned low, and the governor shaft 14 is mounted on the case wall 12 of the crankcase 11 on the side of the carburetor 1.
The inner end 15 of the governor shaft 14 is
is interlocked and connected to the centrifugal actuator 16 in the crankcase 11, and the lower end 19 of the governor lever 18 is fixed to the outer end 17 of the governor shaft 14.
The upper end 20 of the carburetor 1 is connected to the throttle lever 21 of the carburetor 1.
A fuel tank overhead-mounted general-purpose vertical overhead valve engine characterized by being interlocked and connected to the engine via a link 22.