JPS6185519A - Two-cycle crosshead engine - Google Patents

Abstract

PURPOSE:To get rid of any loss in engine output as well as to simplify the structure of a rod seal, by installing a bleeding passage which interconnects an empty space between the rod seal and a piston rod plus a connecting part of a connecting rod to a crankcase. CONSTITUTION:A cylinder lower part is hermetically sealed by a rod seal 22 to contact slidingly with a piston rod 18 at the upper part of a connecting part between the piston rod 18 and a connecting rod 17. There are provided with bleeding passages 23a and 23b which interconnect an empty space between the rod seal 22 and the piston rod 18 plus the connecting part of the connecting rod 17 to a crankcase 13a. In time of reciprocation of a crosshead 20, air inside the crankcase 13a runs in and out the inside of the sealed space. Thus, there is no loss in engine output and, what is more, a rod seal structure also becomes simplified.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a two-stroke crosshead engine in which a crosshead is provided between a piston and a connecting rod, and the crosshead receives rear thrust. This invention relates to a two-stroke engine that is particularly used as a gasoline engine for vehicles such as motorcycles.

Conventional technology In internal combustion engines, there are two types of d structures, the trunk piston type and the crosshead type, which transmit the gas pressure received on the top surface of the piston to the crankshaft through the connecting rod.The crosshead type is larger. It is only used in marine 2-stroke low-speed diesel engines equipped with a supercharger, and the trunk piston type is mostly used in medium-high speed 2-stroke gasoline VA engines for motorcycles and the like.

Such conventional trunk piston type two-stroke gasoline engines do not have a supercharging hoe and use the crank chamber as the primary compression chamber, and the air-fuel mixture is first led to the crank chamber from the intake passage, and is then After being compressed by the compressor, it is sent to the combustion chamber where scavenging and air supply are performed.

However, since the relatively large crank chamber is used as the primary compression chamber, the secondary compression ratio cannot be made too high, and the oil mixed in the mixture causes UJ slippage, which may cause white smoke to be produced from the exhaust pipe. , oil off! ■There were disadvantages such as large size.

& A prisoner trying to repair the group mutually adopted a crosshead type for such an engine,
It is conceivable to seal the small part of the cylinder with a rod seal that slides in contact with screws 1 to 1 above the crosshead, and to form a primary compression chamber isolated from the crank chamber between the rod seal and screws 1. However, in this case, if a sealed space is formed below the rod seal by the crosshead and the liner that guides it, the air in this space is compressed as the crosshead moves back and forth, reducing the engine output to a low drive. At the same time, pressure is applied alternately from above and below to the rod seal, so special consideration must be given to the structure and strength of the rod seal.

Therefore, in the present invention, a piston rod connected to a piston is rotatably connected to the other end of the connecting rod whose one end is connected to the crankshaft, and In a two-stroke crosshead engine in which the lower part of the cylinder is sealed by a rod seal that slides into contact with the piston rod above the connection between the rod and the connecting rod, the space between the rod seal and the connection between the screw rod and the connecting rod. A breathing passage is provided that communicates with the crank chamber.

According to the present invention, air enters and exits the space below the rod seal from the crank chamber as appropriate according to the reciprocation of the piston rod,
The compression effect of air as mentioned above is similar to that of cows. Therefore, there is no loss of engine output, and the structure of the rod seal can be made relatively simple, only receiving pressure from above.

Furthermore, by creating the breathing passage described above, the crosshead part has a honeymoon-like structure similar to the pistons and cylinders of an engine, which reliably absorbs the side thrust caused by crank rotation, and the piston rod has a completely It becomes possible to perform a reciprocating motion.

Figures 1 to 4 show one embodiment of the present invention, and Figure 1 is a longitudinal sectional view of the entire engine. Reference numeral 1 designates a cylinder head, in which an intake hole 3 and an exhaust hole 4 are opened in the sliding movement with the piston 2, the intake hole 3 communicates with an intake passage 5, and the intake passage 5 connects to a carburetor 7 via a reed valve 6. I understand. The exhaust hole 4 communicates with the exhaust passage 8. A spark plug 9 is provided in the upper part of the cylinder head 1.

10 is a cylinder head cover, and 11 is a cooling water passage.

The cylinder head 1 is fixed to a crankcase 13 via a lower cylinder 12. A crankshaft 14 is disposed within the crankcase 13, and a large end 17a of a connecting rod 17 is rotatably connected to a crank 15 of the crankshaft 14 via a crank pin 16. The bearing between the crank pin 16 and the large end 17a is forcibly lubricated with oil by an oil pump, similar to a four-stroke engine.

The small end 17b of the connecting rod 17 is attached to a piston rod pin 19 at the lower end of a piston rod 18 fixed to the piston 2.
The crosshead 20 is rotatably connected through the crosshead 20. The crosshead 20 is slidably inserted into a cylindrical liner 21 fixed to the lower cylinder 12, and is guided by the liner 21 to perform linear movement.

Therefore, side thrust due to the rotation of the crank 15 does not act on the piston 2.

In addition, since the piston 2 and the piston rond 18 reciprocate integrally, as will be described later, the piston rond 18
is fixed to the piston 2 by screwing.

The lower end of the cylinder hole 1a of the cylinder head 1 is sealed by a rod seal 22, and the cylinder hole 1a is connected to the crank chamber 138 in the crankcase 13. i have been The rod seal 22 is provided on the liner 21 above the crosshead 20, and the piston rond 18 reciprocates through it, but the space between the rod seal 22 and the piston rond 18 is always maintained in a sealed state. be done. A breathing passage 23a that opens into the crank chamber is bored in the wall of the lower cylinder 12 in the axial direction.
2) and passing through the liner 21 to its inner surface, a radial breathing passage 23b
is connected to. Therefore, the rod seal 2 in the liner 21
A normally closed space between the crosshead 2 and the crosshead 20 communicates with the crank chamber 13a through breathing passages 23b and 23a, and when the crosshead 20 reciprocates, air from the crank q 13a enters and exits the closed space.

The space between the piston 2 and the rod seal 22 in the cylinder hole 1a becomes a primary compression chamber. That is, the air-fuel mixture sent from the intake passage 5 through the intake hole 3 is compressed between the rod seals 22 by the downward movement of the piston 2. A delivery port 24 is opened at the bottom of the cylinder hole 1a, and the delivery port 24 communicates with a scavenging port 26 via a scavenging passage 25 provided outside the cylinder hole 1a. The scavenging port 26 is open to the entire combustion area above the cylinder hole 1a, and the air-fuel mixture compressed in the primary compression chamber between the piston 2 and the rod seal 22 is transferred to the scavenging passage 25.
The scavenging air 026 is sent to the combustion chamber portion above the piston 2 through the scavenging air 026, expelling the combustion waste gas from this portion through the exhaust passage 8 and replenishing fresh air.

Next, the structure of the metering section of the engine will be explained with reference to FIGS. 2 to 4. Crosshead 20 of screw rod 18
The upper part has a hollow cylindrical shape with the same diameter up to the upper end, and the piston 2 is fixed to the upper end with a bolt 28 with a spigot washer 27 in between. Bolt 28 is piston rod 1
The piston rod 18 and the piston 2 are screwed together through the bolt hole 30 provided in the center of the head of the piston 2 into the axial screw hole 29 provided in the piston 8, and
It is fixed by tightening it together through. and bolt 28
A non-turn washer 31 is inserted between the head of the piston 2 and the non-turn washer 31, and the non-turn washer 31 is caulked to the bolt 28 and the screw 2 at four locations as shown at 32 in FIG. 28 is prevented from rotating. The piston rod 18 and the spigot washer 27 and the spigot washer 21 and the piston 2 are each positioned by a knock pin 33.

The bolt 28 has an opening in the lower end surface and extends along the axis.
An oil passage 34b is provided which branches in the radial direction at the upper part and opens to the outer circumferential surface, and between the upper surface of the spigot washer 27 and the surface of the piston 2 that comes into contact with it, there are 1) oil passages 34b and 4. A radial communicating passageway 34
c is formed. These oil passages 34c communicate with an annular groove 35 formed between the outer periphery of the spigot washer 27 and the piston 2. 34d
is drilled.

The hollow part of the piston rod 18 forms an oil passage 34a, and the layered oil from the large end of the connecting rod 17 enters the oil passage 34a from below the piston rod 18, as shown by the arrow in FIG. From the passage 34a to the oil passages 34b, 34c, the annular groove 35 and the oil passage 34
It reaches the outer circumferential surface of the piston 2 through d and lubricates between the piston and the cylinder wall. 36 is a piston ring. The oil passage 34b formed in the bolt 28 does not function as a throttle to adjust the oil pressure.

The rod seal 22 has an annular shape as a whole, does not have a rotating body with a U-shaped cross section, and has an annular sealing material 3 inside the reinforcing fitting 31.
It is formed by inserting 8. The sealing material 38 is made of an elastic material such as rubber or resin, and has an inner ring portion 39 and an outer ring portion 4.
0 and a thin and flexible diaphragm part 41 that connects these inner and outer ring parts 39 and 40. The diaphragm portion 41 is provided with slack as shown in FIG. The outer ring portion 40 is fixed to the reinforcing metal fitting 37,
The inner ring portion 39 is slidable in the radial direction when the diaphragm portion 41 is bent, and its inner circumferential surface engages with the outer circumferential surface of the piston rod 18 in a honeymoon manner. Therefore, screw 1-rod 18
Even if the inner ring portion 39 moves laterally, the inner ring portion 39 follows the movement of the piston rod 18 while maintaining the above-mentioned sealed state.

This rod seal 22 is fixed to the liner 21 by upper and lower snap rings 42, and as described above, seals the lower part of the cylinder hole 1a to form a primary compression chamber between it and the piston 2.

Crosshead 2 provided at the lower end of the piston rod 18
0 and the rod seal 22 (as mentioned above, it communicates with the crank chamber 13a through the breathing passages 23b and 23a, so the crosshead 20 has the same basic structure as a normal screw I/N. It is rotatably connected to the small end +7b of the connecting rod 17 via the screw 1 and the rod pin 19.The piston rod pin 19 is positioned by the pin clip 43 as shown in FIG. This piston-shaped crosshead 20 is equipped with an oil ring similar to a normal piston, and is provided with an oil return passage 45 (Fig. 3). (It is also possible to make the piston shape oval.

As described above, in the present invention, a piston rod connected to a piston is rotatably connected to the other end of a connecting rod whose one end is connected to a crankshaft, and the piston rod and connecting rod are connected to each other. In a two-stroke crosshead engine in which the lower part of the cylinder is sealed by a rod seal that slides into contact with the piston rod above the connection part, breathing allows the space between the rod seal and the connection part of the piston rod and the connecting rod to communicate with the crankshaft. Since the passage is provided, the air below the rod seal is not compressed by the reciprocating movement of the piston rod, so there is no loss of engine output, and the rod seal can have a relatively simple structure.

Furthermore, since the crosshead portion has a structure similar to the piston and cylinder of an engine, the side thrust caused by the rotation of the crank can be reliably absorbed by the crosshead portion.

[Brief explanation of drawings]

Fig. 1 is a vertical sectional view showing an embodiment of the present invention, Fig. 2 is a soil surface diagram of a piston in the same embodiment, and Fig. 3 is a vertical cross-sectional view showing an embodiment of the present invention.
FIG. 4 is a longitudinal sectional view taken along the line -■, and is a view of FIG. 3 viewed from the left side. 1... Cylinder head, 2... Piston, 3...
Intake hole, 4...Exhaust hole, 5...Intake passage, 6...
Reed valve, 7...Carburetor, 8...Exhaust passage, 9...Spark plug, 10...Cylinder head cover, 11...Cooling water passage, 12...Lower cylinder, 13...Crank case , 14... Crankshaft, 15... Crank, 16... Crank pin,
11... Connecting rod, 18... Piston rod, 19...
...Piston rod bin, 20...Cross head, 2
1...liner, 22...rod seal, 23...
Breathing passage, 24... Outlet port, 25... Evil passage, 26... Evil outlet, 27... Pilot washer, 28... Bolt, 29... Screw hole, 30... Bolt hole , 31... Non-rotating washer, 32... Caulked portion, 33... Dowel pin, 34... Oil passage,
35...Eleven-shaped groove, 36...Piston ring, 37
... Reinforcement fitting, 38 ... Sealing material 139 ... Pa inner ring part, 40 ... Outer ring part, 41 ... Diaphragm, 42
...Snap ring, 43...Bin clip, 44
...Oil hole, 45...Oil return passage.

Claims (1)

[Claims] At the other end of the connecting rod, one end of which is connected to the crankshaft,
In a two-stroke crosshead engine in which a piston rod connected to a piston is rotatably connected, and a lower part of the cylinder is sealed by a rod seal that slides in contact with the piston rod above the connecting portion between the piston rod and the connecting rod, the rod seal A two-stroke crosshead engine, characterized in that a breathing passage is provided that communicates a space between the connecting portion of the piston rod and the connecting rod with a crank chamber.