JPH0138170B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention is an improvement of a decompression device for a horizontal internal combustion engine.
In particular, the proximal ends of the decompression shaft and decompression lever are housed in a recess formed in the valve arm chamber cover, and are arranged so that they do not protrude toward the engine control side, with the aim of improving operability and downsizing the engine. The present invention relates to the decompression device. Among internal combustion engines such as diesel engines,
In particular, horizontal internal combustion engines, which are designed to be compact and lightweight and are constructed with a minimum number of parts, are widely used as engines for small agricultural machinery such as power tillers, but this type of horizontal internal combustion engine is generally equipped with a starter motor. Since the engine is started only by hand using the start handle, the engine is equipped with a decompression device that temporarily opens the intake valve or exhaust valve to release the air in the cylinder at the time of starting. Efforts are made to make starting easier. FIG. 1 shows an example of a horizontal internal combustion engine equipped with the conventional decompression device, in which 1 is a cylinder block, 2 is a fuel tank, 3 is a condenser, 4 is a cylinder head, and 5 is one part of the cylinder head 4. An air cleaner 7 is attached to the upper end of the intake pipe 6 connected to the side, and an exhaust muffler 7 is attached to the tip of the exhaust pipe 8 connected to the other side of the cylinder head 4. A fuel valve 10 is inserted which faces downward and sprays fuel oil, which is fed under pressure from a fuel pump 9, into the cylinder. Further, a valve arm chamber cover 11 is mounted on the front side of the cylinder head 4, and a decompression shaft 13 is inserted into the upper wall of the valve arm chamber cover 11 in a direction perpendicular to the valve arm axis 12, that is, in a vertical direction. and a decompression lever 14 connected to the upper end of the decompression shaft 13.
When the decompression shaft 13 is rotated, a cam portion formed on the inner end side of the decompression shaft 13 engages with an arm portion of the exhaust valve arm 16 within the valve arm chamber 15, thereby pushing down the exhaust valve. However, in the horizontal internal combustion engine equipped with the decompression device of the conventional structure, the decompression lever 14
is located between the intake pipe 6 and the exhaust pipe 8, and
Since the head of the fuel valve 10 is covered above, when the start handle 17 is fitted onto the start shaft 18 and rotated with one hand, and at the same time the decompression lever 14 is operated with the other hand, the decompression lever 14 is There was a problem that the distance between the lever 14 and the grip part of the start handle 17 became wide, making the starting operation difficult. In addition, in order to reduce the distance between the decompression lever 14 and the starting shaft 18, the decompression shaft 13 is
A decompression device that is horizontally penetrated from the outer surface of the engine control side of the valve arm chamber cover 11 in parallel with the valve arm shaft 12 is disclosed in, for example, Japanese Utility Model Application Publication No. 163416/1983 and Japanese Utility Model Application No. 55/1983.
In both of these proposals, the decompression shaft 13 protrudes laterally from the outer surface of the valve arm chamber cover 11 on the engine operation side, and the decompression shaft 13 is The decompression lever 14 connected to the protruding end is connected to the intake pipe 6
As a result, the width of the machine must be increased, which creates another problem in that it impedes the miniaturization of the engine. The present invention focuses on the problem of operability of the decompression lever that such conventional horizontal internal combustion engines had and the problem of increasing the size of the engine due to changes in the arrangement of the decompression lever. It is housed in a recess formed in the arm chamber lid,
This is an attempt to solve each of the above-mentioned problems, and its characteristics are that a recess is formed in the valve arm chamber lid by recessing a part of the valve arm chamber lid toward the valve arm chamber, A decompression shaft is rotatably inserted into a shaft insertion hole drilled from the concave wall surface of the recessed portion across the valve arm chamber in parallel with the valve arm axis, and the cam portion formed at the inner end of the decompression shaft is inserted into the valve arm chamber. The decompression lever has a structure in which the outer end of the shaft is positioned opposite to the arm and within the recess, and the proximal end of the decompression lever is connected to the outer end of the decompression shaft within the recess. Embodiments of the present invention will be described below with reference to the accompanying drawings. Figures 2 to 4 show an example of a horizontal internal combustion engine to which the present invention is applied, in which Figure 2 is a front view of the valve arm chamber cover portion, and Figure 3 is a cross-section taken along the line - in Figure 2. FIG. 4 is a sectional view taken along the line -- in FIG. 2. In each of these figures, reference numeral 21 denotes a valve arm chamber cover mounted on the front side of the cylinder head 4 of the horizontal internal combustion engine as shown in FIG.
is fixed to the cylinder head 4 by bolts (not shown) inserted through mounting holes 22 provided at three locations around the periphery. The valve arm chamber cover 21 has a valve arm shaft mount 25 fixed to the cylinder head 4 with bolts 24 in the valve arm chamber 23 inside thereof, a valve arm shaft 26 supported by the valve arm shaft mount 25, A valve train including an exhaust valve arm 27 and an intake valve arm 28 which are swingably supported by the valve arm shaft 26 is housed. The exhaust valve arm 27 and the intake valve arm 28 are tilted about the valve arm shaft 26 by the horizontal reciprocation of the push rod 29, and the intake/exhaust valves 30 and 28 are respectively engaged with the tips of the arm portions 27a and 28a. 31 is the valve spring 32,3
3 to open and close each valve hole at a predetermined timing. The valve arm chamber cover 21 has a part of the ceiling wall 21a and an engine control side continuous thereto in a part facing the arm part 28a of the intake valve arm 28.

[Operator side] It has a recessed part 34 formed by recessing a part of the wall 21b inward, and a boss part 35 formed on the side surface of the recessed part 34 is bored parallel to the valve arm shaft 26. A shaft insertion hole 36 having a central axis in the horizontal direction is provided. In this embodiment, the recessed portion 34 is configured by recessing the upper right quarter portion when viewed from the front to an extent that it does not interfere with the intake valve arm 28, as shown in FIG. In the shaft insertion hole 36 of the valve arm chamber cover 21 having the above configuration, a locking pin 37 inserted across the shaft insertion hole 36 is fitted into an intermediate circumferential groove 38 to prevent axial movement. A regulated decompression shaft 39 is rotatably inserted,
The decompression shaft 39 has a cam portion 40 formed at its inner end, and an engaging protrusion 4 formed on the arm portion 27a of the exhaust valve arm 27 within the valve arm chamber 23.
1, and the outer end 42 is located within the recess 34 without protruding outward from the side surface 21b of the valve arm chamber cover 21. 43 is the outer end 4 of the decompression shaft 39
2, a nut 44 is inserted in the recessed portion 34.
The lever 43 is connected to the decompression shaft 39 at its proximal end by connecting the lever 43 to the decompression shaft 39.
The coil spring 46 is inserted into the protruding portion of the decompression lever 43, has one end fitted into a locking groove 45 formed on the outer surface of the boss portion 35, and has the other end fixed to the base end of the decompression lever 43. When the lever 43 is biased in the direction of the arrow X in FIG. 3 and is in the solid line position of (A), the cam portion 40 of the decompression shaft 39 is not engaged with the protrusion 41 of the exhaust valve arm 27; When the cam portion 4 is rotated to the decompression position (b),
0 engages with the protrusion 41, and is integrally connected to the decompression shaft 39. The decompression device of the present invention has the above-mentioned configuration. Next, its operation will be explained. First, when starting the engine, the decompression lever 43 is held in one hand.

Use your [left hand] to rotate the coil spring 46 in the direction of the arrow Y in Figure 3 to the position indicated by the two-dot chain line against the elasticity of the coil spring 46, and at the same time use your other hand to

Rotate the start handle fitted to the start shaft with your [right hand]. At this time, the cam portion 40 of the decompression shaft 39 that rotates together with the decompression lever 43 engages with the protrusion 41 of the exhaust valve arm 27 and presses the protrusion 41 against the elasticity of the valve spring 33. In order to open the exhaust valve hole by sliding the exhaust valve 31 to the open side via the exhaust valve arm 27, the air forced into the cylinder is
It is released into the atmosphere through the exhaust pipe, reducing the sliding resistance of the piston, making it easier to start by hand. Next, when the engine starts, the decompression lever 43
When the decompression lever 43 is released, the decompression lever 43 automatically rotates in the direction of the arrow X in FIG. and exhaust valve arm 2
7, the exhaust valve arm 27 returns to its normal operating position, opens the exhaust valve 31 at a predetermined timing in conjunction with the bushing rod 29, and the engine enters a normal operating state. In the above embodiment, the cam portion 40 of the decompression shaft 39 is connected to the exhaust valve arm 27 when the engine is started.
Although the exhaust valve 31 is opened by engaging with the protrusion 41 of the cam part 41 to perform a decompression action, it is of course possible to change the arrangement of the recessed part 34 and the decompression shaft 43 and engage the cam part 40 with the intake valve arm 28. It is also possible to open the intake valve 30 side. As described above, in the decompression device of the present invention, a recess is formed in the valve arm chamber cover of a horizontal internal combustion engine by recessing a part of the valve arm chamber cover toward the valve arm chamber, and a decompression device is provided in the recess. The outer end of the shaft and the proximal end of the decompression lever connected to the decompression shaft are accommodated, and the decompression lever is located on the front side of the valve arm chamber lid. Moreover, the distance from the starting shaft is convenient for operation with both hands, and the decompression operation can be performed extremely easily. Moreover, according to the present invention, the outer end of the decompression shaft is located within the recessed part of the valve arm chamber cover, and there is no problem such as protruding toward the engine control side and interfering with the intake pipe, thereby promoting downsizing of the engine. It is extremely effective.

[Brief explanation of drawings]

FIG. 1 is an external view showing an example of a horizontal internal combustion engine equipped with a conventional decompression device, FIG. 2 is a front view of a valve arm chamber cover portion of a horizontal internal combustion engine to which the present invention is applied, and FIG.
The figure is a cross-sectional view taken along the line -- in FIG. 2, and FIG. 4 is a cross-sectional view taken along the line - arrow in FIG. 21... Valve arm chamber cover, 23... Valve arm chamber, 26... Valve arm shaft, 27... Valve arm, 34... Recessed part, 36... Shaft insertion hole, 39... Decompression shaft, 40... Cam part, 42... Shaft outer side End, 43...decompression lever.

Claims (1)

[Claims] 1. A recess is formed in the valve arm chamber cover of a horizontal internal combustion engine by recessing a part of the valve arm chamber cover toward the valve arm chamber, and the valve arm shaft and the valve arm chamber are connected from the recessed wall surface of the recess to the valve arm chamber. A decompression shaft is rotatably inserted into a parallel shaft insertion hole, the cam portion formed at the inner end of the decompression shaft is opposed to the valve arm, and the outer end of the shaft is positioned within the recessed portion. A decompression device for a horizontal internal combustion engine, characterized in that the base end of the decompression lever is connected to the outer end of the decompression shaft within the recess.