JPH027205Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a gear-linked decompression device for an engine, and more particularly to an improvement in the structure around a decompression arm disposed at the rear of a transmission case of an engine.

Motorcycles equipped with a kit-start engine employ a kit-linked decompression device, in which the decompression arm is attached to an operating shaft that engages with a cam to the kit shaft provided at the rear of the engine's transmission case. is fixed, the rear part of the arm faces rearward, a wire is connected to the rear part with a pin, and by pulling the wire, the exhaust valve is pushed down and the pressure inside the combustion chamber is reduced when the engine is suddenly started.

By the way, in the case of motorcycles, the space between the rear part of the engine transmission case and the vehicle body frame is narrow, and auxiliary equipment is arranged behind the transmission case, so it is difficult to use motorcycles that are designed to be particularly compact. In some cases, it is undesirable for the rear part of the decompression arm to protrude significantly rearward from the rear part of the transmission case.

Also, since the wire is simply connected to the decompression arm by a pin, the stroke ratio of the wire varies, and in order to obtain a sufficient stroke, it is necessary to make the decompression arm longer. This was also a factor in causing the rear part of the decompression arm to protrude significantly rearward.

This idea was created in view of the above circumstances.
The purpose of this is to make the area around the decompression arm more compact by preventing the rear part of the decompression arm from protruding significantly rearward from the rear of the engine's transmission case, and to maintain a constant wire stroke ratio. An object of the present invention is to provide an engine torque-linked decompression device which can sufficiently ensure the following conditions and is particularly suitable for motorcycles designed to be downsized.

In order to achieve such an objective, the present invention is a decompression device that is linked to a lock, in which the rear part of the decompression arm, which is fixed to the operating shaft that engages with the lock shaft provided at the rear of the engine's transmission case with a cam, is moved rearward and downward. A wire is pin-coupled to the rear part of the decompression arm, and an arcuate part centered on the operating shaft is provided upward from the rear part of the decompression arm, and the arcuate part is used as a guide part that comes into contact with this as the wire is pulled. The gist is that.

A preferred embodiment of the present invention will be described below in detail with reference to the accompanying drawings.

Fig. 1 is a right side view of the engine with the main parts cut away, Fig. 2 is an exploded sectional view of the lock shaft interlocking mechanism,
FIG. 3 is a plan view of the cylinder head showing the intake and exhaust valve mechanism, and FIG. 4 is an enlarged right side view showing the main parts of the present invention.

The engine 1 includes a cylinder 3 tilted forward at the front upper part of a crankcase 2. A cam chamber 6 is formed between a cylinder head 4 and a head cover 5, and a camshaft 7
is supported with its axis oriented in the left-right direction, and above this, rocker arm shafts 8 and 9 are supported front and rear parallel, and in front of the front rocker arm shaft 8 are two left and right rocker arm shafts.
The main exhaust valve stem 10... is behind the rear rocker arm shaft 9, as well as the two left and right intake valve stems 11... (only the right one is shown in the figure).
A total of four intake and exhaust valves are arranged radially as shown in FIG. Sub-rocker arms 12..., 13... (only the one on the right side is shown in the figure) are engaged with the stems 10..., 11... of such intake and exhaust valves, respectively.
At the top of 3... are the two Rocker arm shafts 8,
Two left and right Rotzker arms 14 each on top of 9,
15 and 16... (the latter on the left cannot be seen in the figure) are in pressure contact with each other.

In the lower part of the cam chamber 6 of the cylinder head 4, there is a cooling air passage 20 as shown in FIG.
is formed through the cylinder head 4 in the front-rear direction, and a recess 21 recessed toward the rear is formed in the center of the front part of the cylinder head 4 as shown in FIG. , the spark plug 22 is installed from this recess 21 .

The cylinder head 4 has stud bolts 25 and 26 inserted into the left and right sides of the cam chamber 6 from above, respectively, as shown in FIG. 27, and further insert the stud bolt 28 into the front central part of the cooling air passage 22 from the recess 23 above it.
By fastening these bolts 25, 26, 27, and 28 to the cylinder 3, it is fixed onto the cylinder 3.

By the way, since lubricating oil flows through the bottom of the cam chamber 6 as is known, the oil flows through the insertion hole (not shown) of the stud bolt 27 inserted into the rear central part of the cam chamber 6 and into the cooling air passage 20 below. There is a risk of leakage. For this purpose, a rubber packing 29 is interposed between the head 27a of the stud bolt 27 and the bottom of the cam chamber 6. As shown in FIG. 3, this rubber packing 29 has a notch 29a formed in a part of its outer periphery to follow the shape of the inner wall of the cam chamber 6.
By engaging 9a with the inner wall of the cam chamber 6, the rubber packing 29 can be reliably placed at a predetermined location, thereby making it possible to prevent incorrect assembly. Here, 30 in FIG. 3 is a flat washer interposed between the rubber packing 29 and the bolt head 27a.

On the other hand, on the rear right side of the transmission case 2a, which is integrated with the crankcase 2, a kick shaft 31 for starting the engine is supported with its axis oriented in the left-right direction. It protrudes from the case 2a, and a kick pedal (not shown) is fixed to the right end 31a. This hard shaft 3
1, the starter gear 33 is rotated via the one-way clutch 32 which moves forward to the right in FIG. I'm starting to do that.

When the engine 1 is mounted on a motorcycle, the right side in FIG. 1 faces forward, and the upper side faces forward in FIG. 3.

The rear right side of the transmission case 2a of the above-mentioned kick-start type engine 1,
An operating shaft 40 is supported rearward and upward and parallel to this, and as shown in FIG. 2, the right end 40a of the operating shaft 40 projects from the mission case 2a, and the left end 40b of the operating shaft 40 faces into the mission case 2a. A cam follower 41 is integrally fixed to the shaft, and a return spring 42 is stretched between the cam follower 41 and the bearing boss portion 2b that supports the operating shaft 40. The tip 41a of this cam follower 41 is made to face above the kick shaft 31.

On the other hand, the cam follower tip 41a of the kick shaft 31
A camshaft 35 is spline-fitted onto the shaft of the portion facing the camshaft 35, and the camshaft 35 is biased to the right in FIG. They are attending at a distance from each other.

Then, as shown in FIG. 2, the base 43a of the decompression arm 43 according to the present invention is integrally fixed to the right end 40b of the operating shaft 40, and the rear part 43b of the decompression arm 43 is fixed as shown in detail in FIG. facing the rear and lower part of the operating shaft 40, that is, the operating shaft 40
The rear 4 is located behind and below the axis C of the
3b and initialize it. The cam follower 41 thus integrated via the operating shaft 40
As shown in FIG. 4, the decompression arm 43 constitutes a bell crank that expands downward in side view.

The decompression arm 43 is pressed between two press plates 4.
As shown in FIGS. 4 and 5, a pin hole 46 is provided in the rear part 43b, and an arc-shaped part 47 centered on the axis C of the operating shaft 40 extends upward from this part 43b. Both press plates 44 and 45 are bent outward from the rear portion 43b to the arcuate portion 47 to form an arcuate guide groove 48 having a V-shaped cross section. This arcuate guide groove 48 is located within a plane perpendicular to the axis C of the operating shaft 40, as shown in FIGS. 2 and 4.

FIG. 5 is a side view of the decompression arm 43, and numeral 49 in the figure is a mounting hole for the operating shaft 40 provided in the base 43a, and FIG. 6 is a side view of the decompression arm 43.
FIG.

The pin 50 to which the rear end of the wire 51 is fixed is locked into the pin hole 46 provided in the rear portion 43b of the decompression arm 43 described above.

The wire 51 is sufficiently long and has its front end extending to the front of the right side wall of the head cover 5. The wire 51 is inserted into an outer tube 52, which is connected to the cylinder head cover 5 and the transmission section at the front and rear, respectively. The outer tube 52 is supported at the rear of the case 2a, and boots 53 and 54 are connected to the front and rear ends of the outer tube 52, respectively, and the front and rear ends of the wire 51 extend from the boots 53 and 54, respectively.

The front end of the wire 51 is connected to a decompression lever 56.
A pin 55 is coupled to a tip 56a of the decompression lever 56, and a base 56b of the decompression lever 56 is connected to the head cover 5.
The shaft is integrally fixed to the right end 57a of the operating shaft 57, which is supported on the right side of the cover 5 and protrudes from the cover 5 (see FIG. 3). The operating shaft 57 is supported near the front right side of the head cover 5, and the left end 57b of the operating shaft 57 facing into the cam chamber 6 is provided with a cam portion (not shown) cut out in a part of the outer circumference. The part is a protrusion 1 that protrudes rightward at the tip of the right rocker arm 15 that drives the stem 10 of the right exhaust valve.
5a from above.

In this way, a lock-linked decompression device is constructed.

Next, the operation of the above decompression device will be described.

First, in order to start the engine, when the kick pedal is depressed and the kick shaft 31 is rotated in the counterclockwise direction in FIG.
5a engages with the tip 41a of the cam follower 41 and pushes up the tip 41a. As a result, the operation axis 4
The rear part 43b of the decompression arm 43, which is integrated with the cam follower 41, moves downward through the cam follower 41, and the rear end of the wire 51 connected to the pin 50 moves downward, and the wire 51 is pulled. Due to the cam portion of the left end 57b of the operating shaft 57 which rotates via the decompression lever 56 due to the tension of the wire 51, the tip of one of the rocker arms 15 having the protrusion 15a that engages with the cam portion is lowered. Move, subrotsu car arm 1
2, the stem 10 of the one exhaust valve on the right side is slightly pushed down, and the pressure inside the combustion chamber 23 shown in FIG. 7 can be reduced as expected at the time of a sudden start.

As described above, in the present invention, the rear part 43b of the decompression arm 43 fixed to the operation shaft 40 supported on the rear part of the mission case 2a is made to face lower rear than the axis C of the operation shaft 40, so that the decompression arm 43 As shown in FIG. 1, the rear portion 43b does not protrude rearward from the rear portion of the mission case 2a, and of course does not protrude even during downward movement.

Further, an arcuate portion 47 is formed upward from the rear portion 43b of the decompression arm 43, and an arcuate guide groove 48 centered on the axis C of the operating shaft 40 is formed in the arcuate portion 47.
, the rear part 43b of the decompression arm 43
As the wire 51 moves downward, the wire 51 is guided in pressure contact with the arc-shaped guide groove 48, so that the tension stroke ratio of the wire 51 can be made constant. 51 can be achieved, and the boot 54 does not swing back and forth as the wire 51 is pulled.

In FIG. 4, the arcuate portion 47 slightly protrudes to the rear of the mission case 2a, but the amount of protrusion is extremely small, and the amount of protrusion decreases as the decompression arm 43 moves downward. , there is no problem in practice.

As is clear from the above description, according to the present invention, in the kit-linked decompression device, the rear part of the decompression arm faces rearward and downward from the axis of the operating shaft supporting the decompression arm, and a wire is connected to the rear part with a pin, Further, an arcuate portion centered on the axis of the operating shaft is provided upward from the rear of the decompression arm, and this arcuate portion is configured as a wire guide, so that the decompression arm does not protrude rearward from the rear of the engine transmission case. It is possible to achieve compactness around the decompression arm by preventing this, and when applied to a motorcycle intended for downsizing, it is particularly advantageous in terms of space, and it also realizes a constant wire stroke ratio. It has excellent practical advantages such as being able to secure a sufficient wire stroke.

[Brief explanation of the drawing]

Fig. 1 is a cutaway right side view showing the main parts of an engine to which the present invention is applied, Fig. 2 is an exploded sectional view of the shaft interlocking mechanism, and Fig. 3 is a plan view of the cylinder head showing the intake and exhaust valve mechanism. Figure 4 is an enlarged right side view showing the main parts of the present invention, Figure 5 is a side view of the decompression arm, Figure 6 is a sectional view taken along the line shown in Figure 5, and Figure 7 is the cylinder, cylinder head, and head cover. FIG. In the drawing, 1 is the engine, 2a is the transmission case, 31 is the kick shaft, 35a is the cam, 40 is the operation shaft, 41 is the cam follower, 43 is the decompression arm, 43b is the rear part, 47 is the arc-shaped part, and 48 is the Guide groove, 50 pin, 51 wire, 56
is a decompression lever, and 57 is an operating shaft.

Claims (1)

[Scope of utility model registration request] A decompression arm fixed to an operating shaft that engages with a cam at the rear of the transmission case of the engine and works in conjunction with the rear part of the decompression arm faces rearward, a wire is connected to the rear part of the decompression arm with a pin, and the wire is pulled. In a decompression device that depressurizes the combustion chamber when the engine starts by pushing down the exhaust valve, the rear part of the decompression arm is placed rearward and downward from the axis of the operating shaft that supports the arm. In addition to connecting the wires with pins, an arcuate portion centered on the axis of the operating shaft is provided upward from the rear of the decompression arm, the arcuate portion is used as a guide portion for the wire, and the guide portion is placed on the axis of the operating shaft. 1. A decompression device for an engine that is interlocked with a combustion engine, characterized in that it is arranged in a plane orthogonal to the engine.