JPH05280320A - Uniflow 2-cycle engine - Google Patents

Abstract

PURPOSE:To provide a uniflow 2-cycle engine capable of properly recovering lubricating oil by preventing the lubricating oil from being brought in a combustion chamber. CONSTITUTION:In a uniflow system 2-cycle engine 1 having the cylinder wall formed with a scavenging port 9 and the cylinder head provided with an exhaust port 19, the bottom 33 of the downstream end of an intake path 8 communicating to the scavenging port is disposed lower than the lower edge of the scavenging port. An inclined wall 34 is disposed between the bottom of the downstream end and the lower edge of the scavenging port and a communicating path 35 affording communication the bottom of the downstream end and a crank chamber 5 is provided. A normally closed solenoid valve 36 to be controllably opened and closed is interposed in the communicating path.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a uniflow type two-stroke engine.

[0002]

2. Description of the Related Art Conventionally, various types of two-cycle engines have been proposed (for example, JP-A-59-4931).
6, JP-A-59-79040, JP-A-62-113.
820, JP-A-63-248915, JP-A-64-
63617, JP-A-62-135655, etc.).

In such a two-cycle engine,
A uniflow type (single-flow scavenging method) scavenging structure in which a scavenging port is provided on the cylinder wall and an exhaust port is provided on the cylinder head is known. This type of two-cycle engine is generally classified into a small general-purpose engine such as a motorcycle and a large engine such as a ship.

[0004]

However, in the above-mentioned small-sized general-purpose engine, it is intended that the lubricating oil is mixed with the fuel and burned to reduce the so-called LOC (lubricant oil consumption). The problem awareness is relatively low. Also,
In the large marine engine, the lubricating oil scraped up or scraped off by the piston ring or the oil ring flows out of the cylinder through the scavenging port. Although some design efforts have been made to reduce such spillage, recovery of such lubricating oil has not been specifically considered.

However, since the lubricating oil flowing out from the scavenging port flows back into the combustion chamber due to intake air, L is taken into consideration from various regulations, environmental protection, cleanliness of the combustion chamber, and the like.
It is difficult to adopt such a uniflow two-cycle engine in a general vehicle engine that places importance on reduction of OC and recovery of lubricating oil. The present invention has been made in view of such circumstances, and an object of the present invention is to provide a uniflow two-cycle engine that can prevent lubricating oil from being brought into the combustion chamber and can appropriately collect the lubricating oil.

Another object of the present invention is to provide a uniflow type two-cycle engine which can collect lubricating oil without directly contacting intake air.

[0007]

In order to achieve the above object, the present invention provides a uniflow type two-cycle engine in which a scavenging port is formed in a cylinder wall and an exhaust port is provided in a cylinder head. The bottom of the downstream end of the intake passage communicating with the port is arranged below the lower edge of the scavenging port, and an inclined wall is provided between the bottom of the downstream end and the lower edge of the scavenging port, There is provided a uniflow type two-cycle engine characterized in that a communication passage capable of communicating the bottom of the downstream end portion and the crank chamber is provided.

According to the above configuration of the present invention, the oil sump is formed at the downstream end of the intake passage, and the lubricating oil flowing out from the scavenging port stays in the oil sump. Then, the lubricating oil accumulated in the oil sump is returned to the crank chamber via the communication passage. In a preferred embodiment of the present invention, the scavenging port is spaced around the entire circumference of the cylinder wall, and a downstream end portion of the intake passage forms an intake chamber surrounding the cylinder wall, and is located below a lower edge of the scavenging port. The bottom of the downstream end located below is also spaced apart in the circumferential direction of the cylinder wall with respect to the intake introduction part of the intake passage for introducing fresh air into the intake chamber, for example, the intake introduction part. Located on the other side. According to this configuration, the oil sump does not come into contact with the main flow of the intake air, so that the carry-in of the lubricating oil can be prevented more effectively.

The present invention also provides a uniflow two-cycle engine in which a scavenging port is formed in the cylinder wall and an exhaust port is provided in the cylinder head, so as to capture the lubricating oil that is moved along with the movement of the piston. There is provided a uniflow two-cycle engine characterized in that oil capturing means is arranged above and below the scavenging port and adjacent to the upper edge and the lower edge of the scavenging port.

According to the above configuration of the present invention, the lubricating oil which is scraped up or scraped off by the piston ring or the oil ring as the piston moves up and down is captured by the lubricating oil capturing means. Therefore, the lubricating oil does not flow out of the scavenging port and is therefore collected without contacting the intake air. In a preferred embodiment of the present invention, the lubricating oil capturing means has a groove formed in the cylinder wall and a mesh insert housed in the groove to absorb the lubricating oil.

[0011]

Embodiments of the present invention will now be described in detail with reference to the accompanying drawings. FIG. 1 shows a second embodiment of the present invention.
It is a schematic block diagram of a cycle engine. A cylinder bore 2 is formed inside the two-cycle engine 1,
A piston 3 is slidably arranged in the cylinder bore 2. The piston 3 is connected via a connecting rod 4 to a crankshaft 6 in a crank chamber 5 that takes out combustion energy as rotational power.

The upper space defined by the upper portion of the cylinder bore 2 of the engine 1 and the upper surface of the piston 3 constitutes a combustion chamber 7. An intake passage 8 is connected so as to communicate with the combustion chamber 7. The engine 1 has a uniflow type structure, and a plurality of scavenging ports 9 are provided separately on the peripheral wall of the cylinder bore 2 so that the intake air is introduced into the combustion chamber 7 almost uniformly over the entire circumference. Is configured. Note that FIG.
Only two scavenging ports 9, 9 located on opposite sides of the cylinder bore 2 are shown in FIG. An intake chamber 30 communicating with the plurality of scavenging ports 9 is provided so as to substantially surround the cylinder bore 2. The intake chamber 30 includes an intake passage 8
The ends, i.e. the downstream ends, of are connected.

An air cleaner 10 is arranged at the tip of the intake passage 8, that is, at the upstream end, and an air flow meter 11 for detecting the amount of intake air is provided downstream thereof. A supercharger 12 that supercharges intake air is provided downstream of the air flow meter 11. An intercooler 13 that cools the supercharged air is arranged downstream of the supercharger 12, a throttle valve 14 is provided downstream thereof, and a surge tank 15 is provided further downstream to form an intake system. ..

An exhaust passage 18 is provided above the combustion chamber 7.
And the exhaust passage 18 provided in the cylinder head.
An exhaust valve 20 is attached to the opening, that is, the exhaust port 19. The engine 1 of this example is of a cylinder injection type, and an injector 21 for injecting fuel is attached near the exhaust passage 18. Furthermore, in the upper part of the combustion chamber 7,
A spark plug 22 is attached.

To control the engine 1, a controller 23 preferably including a microcomputer is provided. The controller 23 includes an engine rotation signal from the distributor 24, a signal from an intake pressure sensor 25 provided downstream of the throttle valve 14 for detecting the pressure in the intake passage 8, and an accelerator position sensor for detecting the depression amount of the accelerator pedal 26. A signal or the like from 27 is input. The controller 23 performs a predetermined calculation based on these signals, and the throttle valve 1
The throttle opening signal to the actuator 28 of No. 4 and the ignition signal to the ignition plug 22 are output.

FIG. 2 is a vertical sectional view showing the structure of the engine 1. The intake chamber 30 formed around the cylinder bore 2 is formed by an upper wall 31 defining an upper edge, a side wall 32 defining a side edge, and a bottom wall 33 defining a lower edge. The lower surface of the upper wall 31 extends outward substantially horizontally from the upper edge of the scavenging port 9 and projects outward in the radial direction of the cylinder block 16. The side wall 32 extends substantially vertically downward from the outer end of the upper wall 31 and is connected to the outer end of the bottom wall 33, and the bottom wall 33 extends substantially horizontally to the side wall of the cylinder block 16. Bottom wall 3
3 is arranged below the scavenging port 9 in a region opposite to the intake passage 8. In this region, the upper surface of the bottom wall 33 forms a substantially horizontal bottom surface of the intake chamber 30 outside the cylinder block 16, and the bottom surface is obliquely upward toward the inside in the radial direction of the cylinder block 16. It connects with the outer end of the extending swash wall 34. The inner end of the swash wall 34 is connected to the lower edge of the scavenging port 9.

The upper end of the connecting pipe 35 is connected to the bottom wall 33 located on the opposite side of the intake passage 8 and opens at the bottom of the intake chamber 30. The lower end of the connecting pipe 35 is connected to the side wall of the crank chamber 5 and opens into the crank chamber 5. Connection line 3
5, a normally closed electromagnetic solenoid valve 36 is interposed, and the electromagnetic solenoid valve 36 is controlled to open and close by the controller 23. The electromagnetic solenoid valve 36, when opened, connects the intake chamber 30 and the crank chamber 5 to each other via the connecting conduit 35.

The intake chamber 30 includes the intake chamber 30.
An oil level sensor (not shown) for detecting the level of the lubricating oil accumulated at the bottom of the is installed. The detection result of the oil level sensor is input to the controller 23. An oil pan 17 for storing the recirculating lubricating oil is provided below the crank chamber 5. Next, the operation of the engine 1 will be described.

The operation of the engine 1 causes the piston 3 to move up and down, and the lubricating oil on the inner peripheral surface of the cylinder bore causes the piston 3 to move.
It is scraped up or scraped off by the oil ring. Lubricating oil flows out from the scavenging port 9 and the slanted wall 3
Run down along 4. The lubricating oil that has flowed down stays at the bottom of the intake chamber 30, as indicated by reference numeral 39 in FIG.

When a relatively large amount of lubricating oil accumulates at the bottom of the intake chamber 30 and the oil level sensor detects a level of lubricating oil above a predetermined level, the controller 23
Determines the operating state of the engine 1 based on the engine rotation signal from the distributor 24 and the signal from the intake pressure sensor 25. When the controller 23 determines that the engine 1 is stopped or the engine 1 is operating at a low boost pressure (for example, a boost pressure of 10 l / min or less), it excites the solenoid of the electromagnetic solenoid valve 36. Then, the electromagnetic solenoid valve 36 is opened. The intake chamber 30 communicates with the crank chamber 5 through the connecting pipe 35, and the lubricating oil collected at the bottom of the intake chamber 30 flows down into the crank chamber 5 through the connecting pipe 35 to the oil pan 17. Bring to reflux. Controller 23
May open the electromagnetic solenoid valve 36 when the engine 1 is operating at a rotational speed equal to or lower than a predetermined rotational speed, for example, at the time of idling rotation.

As described above, in the engine 1 of this embodiment, the intake chamber 30 is connected to the downstream end of the intake passage 8, and the intake chamber 30 communicates with the plurality of scavenging ports 9. The bottom surface of the intake chamber 30 is positioned below the scavenging port 9 in a region opposite to the intake passage 8 and is continuous with a swash wall 34 that extends obliquely upward toward the inside in the radial direction of the cylinder block 16. The radially inner end of the slanted wall 34 is
Connect to the lower edge of the scavenging port 9. In addition, the intake chamber 3
A connecting conduit 35 that connects the bottom portion of 0 and the crank chamber 5 is provided, and a normally closed electromagnetic solenoid valve 36 that is controlled to open and close is interposed in the connecting conduit 35.

According to the engine 1 thus constructed, the lubricating oil on the inner peripheral surface of the cylinder bore flows out from the scavenging port 9 and collects at the bottom of the intake chamber 30. Therefore,
It is possible to prevent the lubricating oil from being brought into the combustion chamber 7. Thus, it becomes possible to recover the lubricating oil and reduce the LOC. Also, by appropriate control of the electromagnetic solenoid valve 36,
The bottom portion of the intake chamber 30 is provided with the crank chamber 5 only at an appropriate time when the fresh air can be prevented from escaping, for example, when the engine is stopped.
Can communicate with.

Further, since the intake chamber 30 forms an oil sump in the region opposite to the intake passage 8, the lubricating oil flowing out from the scavenging port 9 can be prevented from flowing back into the cylinder bore 2 by the main flow of intake air. 3 and 4
FIG. 7 is a partially enlarged view of a cylinder bore and its surroundings showing another embodiment of the present invention.

A concave peripheral groove 40 surrounding the scavenging port 9 is provided, and an oil recovery passage 41 communicating with the crank chamber 5 is connected to a lower portion of the peripheral groove 40. A mesh insert 42 that absorbs lubricating oil is accommodated in the circumferential groove 40. The lubricating oil scraped up or scraped off by the oil ring or the piston ring 3a as the piston 3 moves up and down is captured by the mesh insert 42 without flowing out from the scavenging port 9, and the circumferential groove 40 and the oil recovery. Return to the oil pan 17 through the passage 41.

FIG. 5 is a partially enlarged view around the cylinder bore showing a modified example of the structure shown in FIGS. 3 and 4. In this example, independent grooves 43 and 44 are arranged above and below the scavenging port 9, and the mesh insert 42 is accommodated in the grooves 43 and 44. An oil recovery passage (not shown) is connected to the grooves 43 and 44 as in the above embodiment, and the oil recovery passage communicates with the crank chamber 5.

FIG. 6 is a partially enlarged view around the cylinder bore showing another modified example of the structure shown in FIG. In this example,
No mesh insert 42 is provided in the groove 40. The volume of the groove 40 has at least a volume corresponding to the volume of the space formed in the gap between the scavenging port 9 and the outer peripheral surface of the piston 3, and sufficiently captures the lubricating oil that has been scraped up or scraped off, Pass through the oil recovery passage 41.

According to these embodiments, the lubricating oil is prevented from flowing out from the scavenging port 9, and the lubricating oil is collected without coming into contact with the intake air. Thus, it is possible to prevent the lubricating oil from being brought into the combustion chamber 7 with a relatively simple structure, and to collect the lubricating oil and reduce the LOC.

[0028]

According to the configuration of the present invention described in claims 1 and 2, it is possible to provide a uniflow type two-cycle engine which can prevent the lubricating oil from being brought into the combustion chamber and can appropriately collect the lubricating oil. Becomes According to the configurations of the present invention described in claims 3 and 4, it is possible to provide a uniflow two-cycle engine capable of collecting lubricating oil without directly contacting the intake air.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a two-cycle engine according to an embodiment of the present invention.

FIG. 2 is a vertical cross-sectional view showing the structure of the engine shown in FIG.

FIG. 3 is a partially enlarged view around a cylinder bore showing another embodiment of the present invention.

FIG. 4 is a partially enlarged view around a cylinder bore showing another embodiment of the present invention.

5 is a partially enlarged view around a cylinder bore showing a modified example of the structure shown in FIGS. 3 and 4. FIG.

6 is a partially enlarged view around a cylinder bore showing another modified example of the structure shown in FIG.

[Explanation of symbols]

 1 Engine 2 Cylinder Bore 3 Piston 4 Connecting Rod 5 Crank Chamber 6 Crank Shaft 7 Combustion Chamber 8 Intake Passage 9 Intake Port 10 Air Cleaner 11 Air Flow Meter 12 Supercharger 13 Intercooler 14 Throttle Valve 15 Surge Tank 16 Cylinder Block 17 Oil Pan 18 Exhaust Passage 19 Exhaust port 20 Exhaust valve 21 Injector 22 Spark plug 23 Controller 24 Distributor 25 Intake pressure sensor 26 Accelerator pedal 27 Accelerator position sensor 28 Throttle actuator 30 Intake chamber 31 Top wall 32 Side wall 33 Bottom wall 34 Sloping wall 35 Connection conduit 36 Electromagnetic Solenoid valve 40 Circumferential groove 41 Oil recovery path 42 Reticulated insert 43, 44 groove

Continuation of the front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location // F01M 13/00 H 7443-3G

Claims (4)

[Claims] 1. A uniflow type 2 in which a scavenging port is formed on a cylinder wall and an exhaust port is provided on a cylinder head.
In the cycle engine, the bottom of the downstream end of the intake passage communicating with the scavenging port is arranged below the lower edge of the scavenging port, and is inclined between the bottom of the downstream end and the lower edge of the scavenging port. A uniflow type two-cycle engine, characterized in that a wall is provided and a communication passage is provided which allows the bottom of the downstream end and the crank chamber to communicate with each other. 2. The scavenging port is spaced around the entire circumference of a cylinder wall, and a downstream end portion of the intake passage forms an intake chamber surrounding the cylinder wall, and is located below a lower edge of the scavenging port. The bottom of the downstream end portion is formed by the bottom wall of the intake chamber, and the bottom is spaced in the circumferential direction of the cylinder wall with respect to the intake introduction portion of the intake passage for introducing fresh air into the intake chamber. The uniflow two-cycle engine according to claim 1, wherein the uniflow two-cycle engine is arranged in a position. 3. A uniflow type 2 having a scavenging port formed on a cylinder wall and an exhaust port provided on a cylinder head.
In a cycle engine, lubricating oil trapping means for trapping lubricating oil that moves with the movement of a piston is arranged above and below the scavenging port and adjacent to the upper and lower edges of the scavenging port. A uniflow two-cycle engine characterized by the above. 4. The lubricating oil capturing means has a groove formed in the cylinder wall and a mesh insert housed in the groove for absorbing lubricating oil. Uniflow two-cycle engine.