JPH087050Y2 - Breather mechanism in portable work machine engine - Google Patents

Description

[Detailed description of the device]

[0001]

BACKGROUND OF THE INVENTION The present invention communicates a hole provided in a cam gear supporting shaft provided in a cam chamber with an adjacent crank chamber and utilizes the pressure in the crank chamber by rotating the cam gear.
The present invention relates to a breather mechanism in an engine for a portable working machine, which has a function of a check valve and is intended to lubricate a cam chamber with a breather.

[0002]

2. Description of the Related Art A conventional four-cycle engine is shown in FIGS.
As shown in FIG. 2, when the crank gear 2 fixed to the crank shaft 1 rotates, the cam gear 3 meshing with the crank gear 2 rotates in the opposite direction, and the intake cam 5 connected to the cam gear support shaft 4 and the exhaust gas Forming cam 6, tappet 7,
8, the push rods 9 and 10 are operated to operate the intake valve 13 and the exhaust valve 14 via the rocker arms 11 and 12. One end of the crankshaft 1 transmits power to a power transmission line via a flywheel 15 and a clutch (not shown).
The crankshaft 1 is supported by bearings 18 and 19. The intake valve 13 and the exhaust valve 14 are opened and closed at predetermined times. Here, the crank chamber 40 is lubricated by connecting rod 21
An oil scraping rod 22 provided at one end of the oil scoops up the liquid lubricating oil 60 injected into the crank chamber 40 as the crank shaft rotates. Here, for lubrication of the cam chamber 26 and the valve chamber 27, as shown in FIG. 6, the breather 24 is provided on the head cover 23 fixed to the cylinder head 25, and the liquid lubricating oil 60 is provided.
Is to be lubricated in the process of being discharged as mist from the crank chamber through the cam chamber 26 and the valve chamber 27 to the outside of the engine from the breather 24.

[0003]

[Problems to be solved by the invention] However, the intake cam 5,
Exhaust cam 6, tappets 7, 8, push rods 9, 10
Cam chamber 26 for accommodating one end of the rocker arm 1
It is not easy to lubricate the respective members in the valve chamber 27 that accommodates the other end portions of the intake valves 1, 12, the intake valve 13, the exhaust valve 14, and the push rod. There is a strong demand for effective lubrication of the valve chamber and the cam chamber, because the mist slightly changes depending on the operating condition of the engine and control is not easy. Therefore, the present invention has been made to eliminate the drawbacks of the prior art, and it is an object of the present invention to develop a breather mechanism for a portable working machine engine that can promote lubrication of a cam chamber by utilizing crank chamber pressure. It is intended.

[0004]

That is, according to the present invention, a hole is provided in a cam gear support shaft arranged in a cam chamber continuous with a crank chamber, and the air in the crank chamber is supplied to the cam gear by the hole. It conducts to the sliding portion, and the rotation of the cam gear opens and closes the passage of the air so as to have the function of a check valve. Furthermore, a breather is provided to communicate with the cam chamber to lubricate the inside of the cam chamber. It is intended to achieve the above object by a breather mechanism in an engine for a portable working machine which is designed to promote and open to the atmosphere.

[0005]

The present invention constituted by the above means is the cam chamber 2
6, a cam gear support shaft 4 is provided with a hole 81 communicating with the crank chamber, and the hole 81
Is communicated with the outer circumference of the cam gear support shaft 4 through holes 82, 83, 84 communicating therewith, and the cam gear 3 has two inner circumferences with the support shaft 4 and two communicating with the cam chamber 26. Hole 8
2, 83, 84 are provided, and in the vicinity of the bottom dead center of the piston, the holes 81, 82, 83, 84 are formed through the notches 85 of the support shaft 4 as shown in FIGS. Communicate. That is, the crank chamber and the cam chamber communicate with each other. Further, in the vicinity of the top dead center of the piston, the holes 83 and 84 are in the horizontal position in FIG. 2 and the passages do not communicate with each other. Therefore, the rotation of the cam gear 3 causes the hole to function as a check valve that communicates with the cam chamber 26 only when the internal pressure in the crank chamber is high, and the breathing gas is released to the atmosphere through the breather 87 that communicates with the cam chamber. By circulating in the cam chamber 26, lubrication is promoted.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment will be described below with reference to the drawings in order to clarify the gist of the breather mechanism of a portable working machine engine of the present invention. An engine for a portable working machine in which the breather mechanism of the present invention is implemented will be described with reference to FIG. The engine for a portable work machine here is an overhead type, and a cam that meshes with a crank gear 2 fixed to the crankshaft 1 by rotating the crankshaft 1 via a connecting rod 21 by the reciprocating motion of a piston. The gear 3 and the one-piece cam 20 fixed to the gear 3 are both rotatably supported by the cam gear support shaft 4 in the cam chamber 26, and are arranged so as to contact the cam 20. The push rod lifters L and M cause the push rods 9 and 10 to reciprocate up and down by swinging the lifter by the rotation of the cam 20. That is, the cam 20 causes the lifter M to rotate, first pushes up the exhaust side push rod 10 to open the exhaust valve 14 via the rocker arm 12 arranged in the upper valve chamber 27, and When the cam 20 rotates, the lifter L is rotated,
Immediately before the exhaust valve 14 is closed, the intake-side push rod 9 is pushed up, and the intake valve 13 is started to open via the rocker arm 11. Further, the exhaust valve 14 is closed. Further, when the cam 20 rotates, the intake valve 13 also closes so that the operation of the valve is completed. The lifter is constructed by assembling a pair of identical parts facing each other on the axis S,
The contact surfaces with the cams and the contact points with the push rods 9 and 10 are arranged at target positions with respect to the axis S. In this way, the structure is such that one exhaust valve drives both exhaust and intake valves. Further, a breather mechanism B is arranged in the cam chamber 26. That is, the breather mechanism B
Are holes 81 and 82 provided in the cam gear support shaft 4 and notches
85, a hole 83 and 84 provided on the cam teeth wheel, it becomes more breather 87, etc., and a hollow is provided a hole 81 communicating with the crank chamber 40 in the axial direction of the cam gear support shaft 4 The hole 81 communicates with the outer periphery of the cam gear support shaft 4 by the hole 82 and the notch 85, and is provided as shown in FIGS. Further, the cam gear 3 is provided with an inner peripheral portion with the cam gear support shaft 4 and two hole portions 83 and 84 communicating with the cam chamber 26, and in the vicinity of the bottom dead center of the piston shown in FIG. As shown in FIG. 3, the cutout portion 85 of the cam gear support shaft 4 is formed.
The hole portions 81, 82, 83 and the hole portion 84 communicate with each other through. That is, a passage is formed by the hole, and the crank chamber 40 and the cam chamber 26 communicate with each other. Incidentally, in the vicinity of top dead center of the piston, holes 83 and 84 of the cam gear support shaft 4 and the cam gear in the closed-porous, therefore, the passage made by the hole is not communicated. Therefore, due to the rotation of the cam gear, the holes 83 and 84 function as a check valve that communicates with the cam chamber only when the pressure in the crank chamber 40 is high, and the breathing gas is provided at one end of the cylinder to the cam chamber 26. The breather 87, which is in communication with the user, opens the atmosphere. The engine lubrication mechanism with the above structure is
A lubricant is sealed in the valve chamber 27, and a weir 28 is provided in the push rod insertion hole of the valve chamber inside the valve chamber 27 so that the peripheral wall of the insertion hole and the inner wall of the weir 28 are aligned. the 26 push rod insertion hole and provided around the push rod guide 29 to the inner wall of the insertion hole, where, as a lubricant, such as molybdenum containing grease material is used. Further, the lubrication of the crank chamber 40 is performed by scraping up the liquid lubricating oil 60 injected into the crank chamber 40 with the rotation of the oil scraping rod 22 of the connecting rod 21, and the lubricating oil is the cam gear. The cam chamber 26 is lubricated by entering through the hole portion 81 of the support shaft 4 and the like. Further, in the engine for a portable work machine, the operating posture is not constant and is often inclined in various directions. However, when the valve chamber is in the upper part and the cam chamber is in the lower part, it is most common. About 70 degrees, rarely 18
It may be operated with a 0 degree tilt. In that case, there is a functional problem if the lubricant enclosed in the valve chamber leaks to other parts of the engine, but in the structure of this embodiment, the weir 28 prevents the outflow from the valve chamber 27 during normal operation. The push rod guide 29 blocks the outflow from the cam chamber 26. Further, in the case of the tilt operation, the lubricant may enter the push rod cover 30 from the valve chamber 27 over the weir 28. However, in an extreme case where the tilt is 180 degrees, as shown in FIG. On the contrary, the lubricant is returned from the weir 28 to the valve chamber 27, and the push rod guide 2
Since the lubricant is prevented from entering by the valve 9, the lubricants in the valve chamber 27 and the cam chamber 26 do not mix with each other. For example, the breather mechanism B achieves the functions of the check valve and the breather even if the lubricant is inclined as described above. You can.

The specific structure of the breather mechanism and the lubrication mechanism for implementing the breather mechanism are not limited to those in the above-described embodiment, and may be arbitrary. For example, the scope of the present invention and the effects of the invention to be described later are achieved. Needless to say, these changes may be arbitrarily determined, and those changes do not change the gist.

[0008]

As described in detail above, in the breather mechanism in the engine for a portable working machine of the present invention, the hole provided in the cam gear supporting shaft disposed in the cam chamber is provided in the adjacent crank chamber. The function of a check valve that opens and closes a passage formed by the cam gear support shaft and the hole of the cam gear is opened and closed by the rotation of the cam gear that is in communication and is rotatably fitted to the cam gear support shaft, and Since the breather mechanism is provided in the cam chamber, the lubricant in the cam chamber can be circulated by utilizing the pressure in the crank chamber. Furthermore, the valve chamber can be lubricated separately from the crank chamber and the cam chamber,
Appropriate lubrication can be leveled even during the inclined operation of the engine, and the life of the lubricant can be extended. As described above, the present invention exhibits a unique effect that is extremely excellent in practical use.

[Brief description of drawings]

FIG. 1 is a sectional view of an engine in which a breather mechanism of the present invention is implemented.

FIG. 2 is a front view showing an essential part of the breather mechanism of the present invention.

3 is a P-P sectional view of Fig.

4A and 4B are diagrams showing a main part of the structure of the cam mechanism, wherein FIG. 4A is a front view of the cam mechanism, and FIG. 4B is a plan view of FIG.

5 is a cross-sectional view showing the movement of the lubricant when the engine shown in FIG. 1 is tilted.

FIG. 6 is a cross-sectional view of a conventional working machine engine.

7 is a cross-sectional view of a main part of the valve mechanism shown in FIG.

[Explanation of symbols]

 1 crankshaft 2 crank gear 3 cam gear 4 cam gear support shaft 7 tappet 8 tappet 9 intake side pushrod 10 exhaust side pushrod 11 rocker arm 12 rocker arm 13 intake valve 14 exhaust valve 18 bearing 19 bearing 20 cam 21 connecting rod 22 Oil scraper 24 Breather 26 Cam chamber 27 Valve chamber 28 Weir 29 Push rod guide 40 Crank chamber L Push rod lifter M Push rod lifter S shaft 81 Hole portion 82 Hole portion 83 Hole portion 84 Hole portion 85 Cutout portion 87 Breather B breather mechanism

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display area F01M 9/10 FG 13/04 G

Claims (1)

[Scope of utility model registration request] 1. A cam gear support shaft disposed in a cam chamber connected to a crank chamber, wherein a hole is provided in the cam gear supporting shaft, and the air in the crank chamber is conducted to a sliding portion of the cam gear by the hole, The rotation of the gears should be used to open and close the air passage to function as a check valve, and a breather should be provided to communicate with the cam chamber to promote lubrication in the cam chamber and open it to the atmosphere. The breather mechanism in the engine for the portable work machine characterized by the above.