JP2841038B2 - Two-cycle engine crank bearing lubrication system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lubricating oil stored in an oil tank, which is introduced into an intake passage above a crankcase via an oil pump, mixed with intake air (air-fuel mixture), and mixed with each sliding portion in an engine. The present invention relates to a crank bearing lubrication system in a two-cycle engine including a lubrication system of a separate lubrication system for supplying lubricating oil to the engine.

[0002]

2. Description of the Related Art In a recent two-stroke engine, the amount of lubricating oil supplied can be adjusted in accordance with the load of the engine. In general, lubrication devices of the type are widely used.

[0003] Lubricating oil mixed in the intake air is sucked into the crankcase together with the intake air, and then compressed in the crank chamber and sent into the cylinder through the scavenging passage. During this time, lubricating oil is supplied to the sliding portion in the crank chamber and in the cylinder. Even in the crankcase, lubricating oil is stored in the transmission chamber where transmission gears and clutch gears are provided, and the gears are soaked in the lubricating oil. In some cases, the lubricating oil is difficult to spread to the crank bearing supporting the shaft.

Therefore, a lubricating device having a structure in which lubrication of a crank bearing is actively performed has been conventionally proposed. For example, Japanese Patent Application Laid-Open No.
There is a lubricating device described in Japanese Patent No. 62218, which is provided on an inner wall surface of a crank chamber facing a crank web.
A lubricating oil groove is provided across the direction of rotation of the crank web toward the crank chamber side, a lubricating oil passage extending from the end of this lubricating oil groove to the crank bearing is provided, and the inner wall surface below the scavenging passage is connected to the crank bearing. It has a structure in which a penetrating lubricating oil passage is provided.

[0005] In addition, in a separate lubrication system lubricating system, there is a method of promoting the lubricating effect by increasing the amount of lubricating oil supplied to the intake passage. The lubrication of a portion that is difficult to lubricate is not promoted very much, and the effect is weak. In addition, excess lubricating oil is burned to emit white smoke or cause oil dripping.

[0006]

However, the crank bearing lubrication device described in the above publication has room for improvement in the following points. That is, the lubricating oil adhering to the wall surface in the crank chamber and the lubricating oil adhering to the scavenging passage are respectively supplied to the crank bearings via the lubricating oil passages by using gravity, so that the lubricating oil passages Compared with the case of the case, the supply amount of the lubricating oil to the crank bearing is increased by the number of the lubricating oil passages, but since both lubricating oil passages are provided in the common space of the crank chamber, Improvement of lubrication effect cannot be expected much. In addition, since the lubricating oil adhering to the crank chamber is dirty or deteriorated, the lubricating effect is inferior to fresh lubricating oil.

[0007] In particular, the back surface of the crank bearing (the side opposite to the side facing the crank chamber) is often a dead end, and the intake air hardly flows, so that the temperature of the crank bearing rises to a high temperature. May shorten the life of the bearing.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and can sufficiently lubricate a crank bearing with fresh lubricating oil without increasing the amount of lubricating oil mixed in the intake air, and suppresses a rise in the temperature of the crank bearing. It is another object of the present invention to provide a two-stroke engine crank bearing lubrication device capable of extending the life of a bearing.

[0009]

To achieve the above object, the present invention provides a two-stroke engine crank bearing lubricating apparatus comprising: a) lubricating oil stored in an oil tank via an oil pump to intake air at an upper portion of a crankcase; In a two-stroke engine provided with a separate lubrication system for supplying lubricating oil to each sliding portion in the engine after being introduced into a passage and mixing with intake air, b) a crank bearing is provided in the middle of the scavenging passage of the crankcase. A first through-hole extending to the back of
One end is opened at a position downstream of the reed valve in the intake passage, along the wall surface of the intake passage, at a position where the atomized lubricating oil in the mixed intake air flows down, and the other end is opened at the back of the crank bearing. A second insertion hole is provided.

[0010] As described in claim 2, d) it is desirable to provide a weir near the opening of the second insertion hole on the side of the intake passage so as to store the lubricating oil wall flow in the intake passage.

According to the crankshaft lubricating device for a two-stroke engine of the present invention having the above-described structure, when the intake air is sucked into the crank chamber through the intake passage during the operation of the engine, the lubrication mixed into the intake air. Part of the oil is formed in the form of mist and adheres to the wall surface of the intake passage, and the attached lubricating oil flows down along the wall surface inclined downward toward the crank chamber due to gravity. Then, part of the wall flow (lubricating oil) flows into the second insertion hole from the entrance (opening) of the second insertion hole extending from the intake passage to the rear surface of the crank bearing. On the other hand, intake air is introduced from the intake passage into the crank chamber and compressed,
When being sucked into the cylinder through the scavenging passage (including the auxiliary scavenging passage), lubricating oil or air is sucked from the crank bearing side to the scavenging passage side through the first insertion hole by the suction (sucking) action. Accordingly, the lubricating oil flowing into the second insertion hole passes through the crank bearing and is sucked out to the scavenging passage through the first insertion hole. During this time, lubricating oil is supplied to the crank bearing to lubricate it. This lubricating oil is a lubricating oil mixed in the intake air and drawn into the crank chamber from the intake passage. Therefore, the lubricating oil is fresh and has excellent lubricating properties, and therefore has a high lubricating effect. In addition, the second facing the intake passage
Since there is a pressure difference between the inlet side of the insertion hole and the outlet side of the first insertion hole facing the scavenging passage (the second insertion hole inlet side> the first insertion hole outlet side), the inlet side of the second insertion hole. The lubricating oil flows positively to the outlet side of the first insertion hole from the first through the crank bearing, so that the crank bearing is sufficiently lubricated. Further, not only the lubricating oil but also the intake air in the intake passage flows from the inlet of the second insertion hole to the outlet of the first insertion hole. Temperature rise is suppressed.

According to the crank bearing lubricating device of the second aspect, the mist droplets of lubricating oil flowing down along the wall surface of the intake passage accumulate in the concave portion defined by the weir, and the lubricating oil is located near the bottom thereof. Since it flows from the opening (entrance) of the two insertion holes, the amount of lubricating oil supplied to the crank bearing increases, and the lubricating action of the crank bearing further improves.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of a two-stroke engine crank bearing lubrication apparatus according to the present invention will be described below with reference to the drawings.

FIG. 1 is a central longitudinal sectional view showing a two-stroke engine provided with the crank bearing lubrication device of the present embodiment, and FIG.
1 is a side view showing a crankcase divided into left and right along a central axis of FIG. 1, and FIG. 3 is a partial sectional view showing the vicinity of an intake port of the engine of FIG.

As shown in FIG. 1, a two-cycle engine 1
In this example, the engine comprises an air-cooled single-cylinder engine, and a large number of cooling fins 2c are provided on the outer periphery of the cylinder 2. A cylinder head 3 is mounted on the upper surface of the cylinder 2, and a spark plug 4 is attached to the center of the cylinder head 3. A cylinder bore 2a is formed vertically through the center of the cylinder 2 and a cylinder liner 2b is fitted to the inner peripheral surface of the bore 2a. A piston 5 is slidably fitted in the cylinder bore 2a in the up-down direction and connected to the upper end of the connecting rod 6 via a piston pin 5a provided laterally to the piston 5, and the lower end of the connecting rod 6 Are connected to the crankshaft 7 via the crankpin 7a.

The mounting surface at the lower end of the cylinder 2 is mounted on a mounting surface around an upper end opening 10a of the crankcase 10 and bolted, and an O-ring 9 inserted into an annular groove 9a is provided between the mounting surfaces. Is interposed. A scavenging passage 8 whose lower end communicates with a scavenging passage 10e in the crankcase 10 is formed on both sides of a lower portion of the peripheral wall of the cylinder 2, and an upper end of the scavenging passage 8 is connected to an outlet-side scavenging port 8a.
And faces the inside of the cylinder bore 2a.

In the crankcase 10, the crankshaft 7 is rotatably disposed via bearings 11L and 11R, and a generator 12 is mounted on one end (left side in the figure). A crank gear 13 is mounted on the other end of the crankshaft 7. Note that the crankcase 10 is a cast product in which cases 10L and 10R (see FIG. 2) divided into right and left parts at the center of the figure are joined and integrated.

An input shaft 14 is supported rotatably via a bearing 14a in parallel with the crankshaft 7, and an output shaft 15 is supported rotatably via a bearing 15a in parallel with the input shaft 14.

A clutch gear 16 is mounted on the right end of the input shaft 14, and the clutch gear 16 meshes with the crank gear 13. A clutch 17 is provided at the right end of the input shaft 14. Also,
The clutch gear 16 includes a kick starter driven gear 1.
8 (also referred to as a kick starting gear) are provided so as to be able to rotate integrally. A sprocket 19 is mounted on the left end of the output shaft 15, and a kick starter idle gear 20 is mounted on the right end. The idle gear 20 meshes with the kick starter driven gear 18.

As is well known, a plurality of transmission gears 29 that can mesh with each other are mounted between the shafts of the input shaft 14 and the output shaft 15.
Further, a kick starter drive gear 22 of a kick starter shaft 21 is mounted on the idle gear 20,
A kick starter lever 21b (partially shown) is attached to the right end. Note that reference numeral 21a in the drawing indicates a spring.

Now, in the two-stroke engine 1 of this embodiment,
The supply of the lubricating oil to the inside is performed by a separate lubrication method. Although not shown, an oil pump is provided, and the lubricating oil in an oil tank (not shown) is supplied to the intake passage (FIG. 3) by the oil pump. Be guided. Then, it is mixed and guided into the intake air fed into the crank chamber 10A from the intake passage, and the lubricant oil is supplied to each sliding portion together with the intake air (air mixture) in the crank chamber 10A.

In the two-stroke engine 1 of this embodiment, as shown in FIG. 1, the interior of the crankcase 10 is centered on a crank chamber 10A in which a crank web 7b of a crankshaft 7 is rotatably arranged. The generator chamber 10B on one side and the transmission gear chamber 10 on the opposite side
C, and the transmission gear chamber 10C is filled with lubricating oil. The right bearing (crank bearing) 11R of the crankshaft 7 has an oil seal 23 disposed inside (on the side of the crank chamber 10A) and the crank bearing 1R.
1R faces the mission chamber 10C, so that the lubricating oil in the transmission gear chamber 10C is
And lubricate well. However, in the left bearing (crank bearing) 11L, the oil seal 23 is disposed outside (on the generator chamber 10B side), and the back surface of the crank bearing 11L is closed by the oil seal 23. Therefore, the lubricating oil sucked into the crank chamber 10A together with the intake air is unlikely to sufficiently spread to the crank bearing 11L.

Therefore, in this embodiment, the crank bearing lubrication device of the present invention is applied to the left crank bearing 11L.
In other words, as shown in FIG. 2, the first opening 10a of the crankcase 10L on the generator 12 side is
The upper end portion 24a of the insertion hole 24 is opened in a concave shape, and the first insertion hole 24 is formed so that the lower end opening 24b passes through the inner peripheral wall portion and reaches the rear surface of the crank bearing 11L as shown in FIG. . The upper end opening 24a of the first insertion hole 24 faces the middle of a scavenging passage 10e formed near the upper end opening 10a of the crankcase 10L. Then, with the cylinder 2 assembled to the crankcase 10, the position of the scavenging passage 10e is made to coincide with the lower end opening (inlet side) 8b of the scavenging passage 8 of the cylinder 2 as shown in FIG.

The intake passage 1 of the crankcase 10L
A second through-hole 25 is formed from the inner peripheral wall near the intake port 10c to the back of the crank bearing 11L, and a recessed lubricating oil reservoir 26 is formed around the upper end opening 25a of the second through-hole 25 (see FIG. 3). That is, in the two-cycle engine 1 to which the present invention is applied, the intake port 10
c is open at the upper part of the joint line of the crankcase 10 (the joint between the left and right case parts). In this example, as shown in FIG. 3, after the intake passage 10b is slightly inclined downward from the intake port 10c, the intake passage 10b is bent slightly upward in the shape of a "ku" and communicates with the inside of the crank chamber 10A. . In other words, the two-stroke engine 1 has the cylinder 2 side slightly upward so that the intake passage 10b is slightly bent near the intake port 10c, and the straight portion of the intake passage 10b communicating with the crank chamber 10A is slightly upward. It is mounted on motorcycles and the like in an inclined position. In FIG. 2, reference numeral 14c denotes an opening for an input shaft, and 15c denotes an opening for an output shaft.

As shown in FIG. 3, an intake pipe (inlet pipe) 2 is provided at an intake port 10c of the crankcase 10.
A flange 27b around an opening 27a at one end is connected by a bolt 27c, and a carburetor (not shown) is connected to the other end of the intake pipe 27. In the intake passage 10b, a reed valve 28 is mounted from the intake port 10c to the vicinity of the bent portion. The reed valve 28 is provided with a pair of valve bodies 28a which are V-shaped in a closed state.
A flows into A, but in the opposite direction, the valve body 28a closes to prevent escape of intake air. Further, a stopper 28b is attached to the outside of each valve body 28a to limit opening of the valve body 28a. The base end of the valve body 28a is fixed to the inner wall surface of the intake passage 10b by a bolt 28c.

The upper end opening 25a of the second insertion hole 25 is
The tongue-shaped weir 26 is located near the bent portion of the intake passage 10b.
The lubricating oil reservoir 26 is formed by extending upward from the vicinity of the upper end opening 25a along the lower surface of the inner peripheral wall of the intake passage 10b. Particularly, with this configuration, the lubricating oil is mixed into the intake air from the middle of the intake pipe 27, and the mist droplets of the lubricating oil S (FIG. 3) pass through the reed valve 28 and pass through the intake passage 1
After flowing into the inner peripheral wall with the intake air and adhering to the inner peripheral wall surface,
The lubricating oil pool 26 accumulates in a lubricating oil reservoir 26 as a so-called wall flow that flows downward along the wall surface due to gravity. Then, since the lubricating oil flows into the second insertion hole 25 from the upper end opening 25a at the bottom thereof, fresh lubricating oil can be efficiently supplied to the crank bearing 11L for lubrication.

As is apparent from FIG. 2, the first insertion hole 24 and the second insertion hole 25 are connected via the back surface of the crank bearing 11L, and the intake port 10c of the intake passage 10b is connected.
Around and near the upper end opening 10a of the crankcase 10 (in other words, near the lower end opening (inlet side) 8b of the scavenging passage 8);
(See FIG. 1) are in communication with each other via the rear surface of the crank bearing 11L. For this reason, it is sucked into the crank chamber 10A from the intake passage 10b, compressed and
By the flow of the intake air fed into the cylinder 2 from the lower end opening 8b, suction is generated from the rear surface of the crank bearing 11L toward the upper end opening 24a of the first insertion hole 24 and further to the scavenging passage 8. The lubricating oil stored in the lubricating oil reservoir 26 is moved from the upper end opening 25a to the second
Since it is sent to the insertion hole 25-the rear part of the crank bearing 11L-the upper end opening 24a of the first insertion hole 24, the crank bearing 1
One liter is fully lubricated by the lubricating oil.

At the same time, a part of the intake air in the intake passage 10b passes through the same route (from the upper end opening 25a to the second insertion hole 25-the rear portion of the crank bearing 11L-the upper end opening 24a of the first insertion hole 24). Since it flows into the cylinder 2, the rear portion of the crank bearing 11L is ventilated by intake air (particularly air during intake), and therefore, a rise in temperature of the crank bearing 11L is prevented, and the life of the crank bearing 11L is extended. become. Although the embodiment of the crank bearing lubrication device for a two-stroke engine according to the present invention has been described above, the crank bearing lubrication device according to the present invention can be implemented as follows.

A) When it is necessary to lubricate the right crank bearing 11R in the same manner, for example, when the lubricating effect of the lubricating oil in the transmission chamber 10C cannot be expected, the crankcase on the opposite side across the joint line is also required. Similarly to the above embodiment, a first insertion hole 24 and a second insertion hole 25 communicating with the back of the crank bearing 11R are formed.

B) If it is a two-stroke engine, it can be applied to, for example, an engine for driving a four-wheeled vehicle for running on uneven terrain or a working machine, other than the motorcycle.

[0031]

As is apparent from the above description,
The two-stroke engine crank bearing lubrication device of the present invention has the following excellent effects.

(1) Without increasing the amount of lubricating oil mixed in the intake air, the crank bearing can be sufficiently lubricated with fresh and excellent lubricating oil, and the rise in temperature of the crank bearing can be suppressed. Life is extended.

(2) In the crank bearing lubricating device according to the second aspect, the mist-shaped lubricating oil flowing down along the wall surface of the intake passage accumulates in the concave portion defined by the weir, and the second lubricating oil near the bottom is formed. Since the oil flows from the inlet of the insertion hole, the amount of lubricating oil supplied to the crank bearing increases, and the lubricating effect of the crank bearing is greatly improved.

[Brief description of the drawings]

FIG. 1 is a central longitudinal sectional view showing a two-cycle engine provided with a crank bearing lubrication device according to an embodiment of the present invention.

FIG. 2 is a side view showing one of the crankcases divided into right and left along a central axis line in FIG. 1;

FIG. 3 is a partial sectional view showing the vicinity of an intake port of the engine of FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 2 cycle engine 2 Cylinder 7 Crankshaft 8 Scavenging passage 10 ・ 10L ・ 10R Crankcase 10A Crank chamber 10b Intake passage 10c Intake port 10e Scavenging passage 11L ・ 11R Crank bearing 24 First insertion hole 25 Second insertion hole 26 Lubricating oil reservoir 26a Weir 27 Intake pipe (inlet pipe) 28 Reed valve

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) F01M 3/00 F01M 1/06

Claims (2)

(57) [Claims] 1. A separate lubrication system in which lubricating oil stored in an oil tank is introduced into an intake passage at an upper portion of a crankcase via an oil pump and mixed with intake air to supply lubricating oil to each sliding portion in an engine. In a two-stroke engine equipped with a lubricating device, a first insertion hole is provided from the middle of a scavenging passage of the crankcase to a back surface of a crank bearing, and a wall surface of the intake passage downstream of a reed valve in the intake passage. A second insertion hole having an opening at one end at a position where the atomized lubricating oil in the mixed intake air flows down along the axis and an opening at the other end on the back surface of the crank bearing. Crank bearing lubrication device. 2. The crank bearing lubrication system for a two-stroke engine according to claim 1, wherein a weir is provided in the vicinity of the opening of the second insertion hole on the side of the intake passage so as to store the lubricant oil wall flow in the intake passage.