JPS6228286B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a lubricating device suitable for a two-stroke engine, and more particularly to a device for lubricating a crank pin portion primarily.

Generally, lubrication systems for two-stroke engines include mixed lubrication and separate oil supply lubrication. Although mixed lubrication systems have the advantage of being simple and inexpensive, they cannot supply an appropriate amount of lubricating oil over each load and rotational speed range, and are specifically designed to prevent seizure at high speeds. Since it is necessary to ensure sufficient lubricating oil in the high load range, the amount of lubricating oil in the low speed and low load range becomes excessive, resulting in white smoke in the exhaust gas,
Problems such as smoldering ignition plugs and dirty exhaust parts (mufflers, etc.) occur. Separate oil supply systems can solve the above problems, but on the other hand, they require an oil pump and an oil pump drive device (gear or belt, etc.), making them very expensive and increasing the size and weight of the engine. There are drawbacks.

As a technique for solving the problems with the above-mentioned separate oil supply system, for example, Japanese Utility Model Application Publication No. 57-51108 proposes incorporating a lubricating oil pump (plunger pump) into the crank arm.

In this structure, a plunger is built into the crank arm, and a cam portion for driving the plunger is formed on the connecting rod.

However, according to the above structure, the cam portion of the connecting rod engages with the plunger only when the crank arm portion overlaps the connecting rod in the axial direction (in a direction parallel to the crankshaft), so the plunger is not driven. The timing is limited to when the piston is located near the bottom dead center. Therefore, the plunger is driven intermittently and instantaneously. For this reason, the plunger pump cannot be made effective, and more specifically, it cannot always supply just the right amount of lubricating oil to the bearing.

Furthermore, since the plunger collides with the cam portion of the connecting rod every time the crankshaft rotates, there is also the problem that both are likely to be worn out or damaged.

Furthermore, it is necessary to provide a stopper to the plunger to prevent the plunger from falling out of the hole in the crank arm into the crank chamber when the plunger is not engaged with the cam, making the structure complicated.

In order to solve the above problem, the present invention incorporates a plunger pump into the crank pin, and drives the plunger of the plunger pump by a cam plate attached to the large end of the connecting rod. Specifically, it is structured as follows.

That is, in the present invention, an open end surface is formed at one end of the crank pin portion, and a hole opened in the end surface is parallel to the center line of the crank pin portion and offset in the radial direction of the crank pin portion with respect to the center line. a plunger is slidably fitted into the hole, a spring is built into the hole to bias the plunger in a direction to protrude from the hole, and a pump is provided between the bottom of the hole and the opposite end surface of the plunger. A chamber is formed, the pump chamber is connected to a lubricating oil source via a suction oil passage, a discharge oil passage of the pump chamber is opened on the outer peripheral surface of the crank pin portion, and a cam plate facing the end face is connected to a connecting rod. A cam portion is provided on the open end side of the cam plate in a continuous ring shape around the center line, and the end of the plunger protruding from the hole is fixed to the large end of the cam plate so as not to rotate relatively. It is characterized by being brought into contact with the part.

According to the above configuration, as the large end of the connecting rod rotates relative to the crank pin about its center line, the cam plate also rotates about the center line relative to the crank pin. and rotate. As a result, the cam portion of the cam plate moves in the direction of rotation of the crank pin portion relative to the plunger while continuously coming into contact with the plunger.

Due to this movement and the repulsive force of the spring, the plunger continuously reciprocates, and the suction of lubricating oil from the lubricating oil source to the pump chamber and the supply of lubricating oil from the pump chamber to the bearing section are performed alternately and continuously. . Further, the speed of this suction/discharge operation corresponds to the relative movement speed of the cam portion to the plunger, that is, the rotation speed of the crankshaft. Therefore, the required amount of lubricating oil corresponding to the engine speed is almost continuously supplied to the bearing portion.

Next, embodiments will be described with reference to the drawings.

In Fig. 1, 1 is a piston, 2 is a cylinder,
3 is a connecting rod. The crankshaft 4 is supported by a cylindrical boss 6 of a crankcase 5 via a bearing 7 in a cantilevered state. Only one end (the left end in FIG. 1) of the crank pin portion 9 is supported by the crank arm portion 10, and the other end is cut off. Crank pin part 9 and crank arm part 10
A plunger pump 11 for lubricating oil is incorporated inside, and the suction port of the pump 11 is connected to the suction oil path 1.
It is connected to an external oil tank 15 via ports 2, 13, etc. as described below. The external suction oil passage 13 has an inlet connected to an oil tank 15, an outlet connected to a hole 16 provided in the boss 6, and is provided with a suction check valve 17 in the middle. The hole 16 is located outside the bearing 7 (on the opposite side from the crank arm portion 10).
It is connected to the annular space 19 between the boss 6 and the crankshaft 4. A space 19 is formed between a pair of annular seals 18 on both sides,
It is connected to the inlet of the suction oil passage 12 inside the shaft 4. The oil passage 12 extends approximately concentrically with the shaft 4, and one end extending in the radial direction of the shaft 4 connects to the annular space 19, and the other end extends within the crank arm portion 10 in the radial direction of the shaft 4. It extends and connects to the plunger pump 11.

In FIG. 2, which is an enlarged partial view, 20 is the large end of the connecting rod 3, and 21 is the large end 20.
A crank pin portion 9 into which the inner cylindrical surface of the crank pin portion 9 is rotatably fitted.
The large end bearing portion (outer peripheral surface) of , O-O is the center line of the bearing portion 21 and the pin portion 9. The plunger pump 11 has a plunger 2 in a hole 25 made parallel to the center line O-O from the pin part 9 to the middle of the arm part 10.
6 and a compression coil spring 27 are fitted, and the center of the hole 25 and plunger 26 is A-A.
is eccentric with respect to the center line OO. pump 1
One pump chamber 29 is formed between the bottom surface 28 of the hole 25 and one end of the plunger 26, and the spring 27 is disposed within the pump chamber 29. The suction oil passage 12 is connected to a pump chamber 29 near the bottom surface 28 of the hole. An inlet of a lubricating oil discharge passage 30 is connected to the pump chamber 29 at a position away from the hole bottom surface 28 . The oil passage 30 extends inside the pin portion 9, has an outlet opening at an intermediate portion in the axial direction (left-right direction in FIG. 2) of the bearing portion 21, and is provided with a discharge check valve 31 in the middle.

The hole 25 is connected to the open end surface 32 of the pin portion 9 (arm portion 1
The other end 33 of the plunger 26 protrudes from the hole 25 and comes into contact with the cam portion 35. The cam portion 35 is centered on the center line O.
It is formed by a protrusion provided on the surface of a circular cam plate 37 perpendicular to -O. As shown in FIG. 3, which is a schematic diagram in the - arrow direction of FIG.
The protruding height h of the cam portion 35 varies smoothly as shown in FIG. 4, which is a partial cross-sectional view of FIG. 3. As shown in FIG.
9 (FIG. 1).

During engine operation, the connecting rod large end 20 rotates relative to the pin portion 9, and the cam plate 37 also rotates relative to the plunger 26 about the center line OO. Therefore, the plunger 26 biased by the spring 27 reciprocates within the hole 25 while contacting the cam portion 35 in response to changes in the cam portion protrusion height h (FIG. 4). As a result, the oil passage 1 is connected to the pump chamber 29 from the oil tank 15 in FIG.
Lubricating oil is sucked in through 3, 12, etc.
Lubricating oil is supplied from the pump chamber 29 to the bearing portion 21 via an oil path 30.

In the above operation, the operating speed of the pump 11 (the reciprocating speed of the plunger 26) is proportional to the relative rotational speed of the cam plate 37, that is, the engine rotational speed, so the amount of lubricating oil supplied to the bearing portion 21 is proportional to the engine rotational speed. Correspondingly, more lubricant is supplied when the engine is in high-speed operating conditions, and less lubricant is supplied when the engine is idling. Note that the lubricating oil after lubricating the bearing portion 21 scatters into the crank chamber from the hole 40 of the large end portion 20 and lubricates the piston 1 and cylinder 2.

As explained above, according to the present invention, the plunger pump 11 and the suction and discharge oil passages 12 and 30 of the pump 11 are provided inside the crankshaft 4, and the crankshaft 4 supports the large end 20 of the connecting rod 3. The outlet of the discharge oil passage 30 is connected to the big end bearing part 21 of the shaft 4, the inlet of the suction oil passage 12 is connected to the lubricating oil source (oil tank 15), and the plunger 26 of the plunger pump 11 is connected to the big end bearing part. Since the connecting rod 3 is provided with a cam plate 37 that is eccentric to the axis O-O of the engine 21 and drives the plunger 26, the amount of lubricating oil supplied can be made approximately proportional to the engine speed. can. Therefore, in high-speed operating conditions, a sufficient amount of lubricating oil to prevent seizure etc. can be supplied to the bearing portion 21, piston 1, cylinder 2, etc., and in idling conditions, the amount of lubricating oil is reduced to the minimum necessary. It can prevent white smoke in the exhaust gas, smoldering of the ignition plug, and dirt on the exhaust section. It also has the advantage of simple structure and low cost. The engine size is almost the same as with mixed lubrication, and is compact. Furthermore, since the large end bearing portion 21 can be lubricated intensively, the life of the engine can be extended.

To explain in more detail, in the present invention, the plunger pump 11 is incorporated into the crank pin portion 9,
The plunger 26 is made to protrude from the open end surface 32 formed on the crank pin part 9, and the plunger 26 is driven by the cam plate 37 attached to the connecting rod large end part 20. It can be constantly engaged and driven.

Therefore, smooth and continuous operation of the plunger pump 11 can be achieved, and the pump 11 can be operated effectively to constantly supply the required amount of lubricating oil to the bearing section 21.

Further, since the plunger 26 and the cam portion 35 do not collide, wear and damage of both can be prevented as much as possible, and durability can be improved.

Furthermore, since the cam plate 37 can prevent the plunger 26 from falling off from the mounting hole 25, there is no need to provide a dedicated stopper for the plunger 26, and the structure can be simplified in this respect as well.

In addition, the present invention is applied to the crank pin portion 9 as shown in FIG.
Both ends 41 and 42 of the pair of crank arm parts 1
In this case, the plunger 26 is protruded from the stepped annular surface 43 between the large diameter end and the small diameter end 42 of the pin portion 9, and the annular cam plate 37 is supported at the small diameter end. It is installed around the end portion 42.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of the embodiment, Fig. 2 is an enlarged partial view of Fig. 1, Fig. 3 is a view taken in the direction of - arrow in Fig.
The figure is a partial cross-sectional view of FIG. 3, and FIG. 5 is a partial cross-sectional view of another embodiment. 3... Connecting rod, 9... Crank pin section, 12... Suction oil path, 15... Oil tank (lubricating oil source), 20... Big end, 21... Bearing section, 25... Hole , 27... Spring, 28... Hole bottom, 29... Pump chamber, 30... Discharge oil path, 32
... end face, 35 ... cam part, 37 ... cam plate, O
-O... Center line of the crank pin.

Claims (1)

[Claims] 1. An open end surface is formed at one end of the crank pin portion, and a hole opened in the end surface is provided at a position parallel to the center line of the crank pin portion and offset in the radial direction of the crank pin portion with respect to the center line, A plunger is slidably fitted into the hole, a spring for biasing the plunger in a direction protruding from the hole is built into the hole, and a pump chamber is formed between the bottom surface of the hole and the end surface of the plunger opposite thereto. , the pump chamber is connected to a lubricating oil source via the suction oil passage, and the discharge oil passage of the pump chamber is opened to the outer peripheral surface of the crank pin portion;
A cam plate facing the end face is fixed to the large end of the connecting rod so as not to be relatively rotatable, and a cam part is provided in a continuous annular shape around the center line on the surface of the cam plate on the open end face side; An engine lubricating device characterized in that an end portion of a plunger protruding from the hole is brought into contact with the cam portion.