JPS6214328Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a scuffing prevention device for a two-stroke engine.

Generally, in a two-stroke engine, engine lubrication is based on a mixed lubrication system. For example, there is a type of engine that has an oil supply path in the inlet passage (intake pipe), but in this type, oil (lubricating oil) is supplied from the oil supply passage in the inlet passage and mixed with fuel. , is supplied into the cylinder. However, when oil and fuel are mixed in the inlet passage in this way, when the engine is cold, especially when the choke valve is activated, the oil/fuel ratio becomes small, causing the piston and cylinder to mix with the fuel (gasoline). Since the oil content is removed by washing, the lubricating performance of the oil deteriorates, resulting in inconveniences. Furthermore, when the engine is cold, the piston has a small heat capacity and therefore expands quickly, but the cylinder has a large heat capacity and therefore does not expand, resulting in a small cylinder clearance. As a result, scuffing may occur on the inner wall of the cylinder (particularly on the inlet side), resulting in scratches on the cylinder.

By the way, as a related technology of this type, ``by operating a switching valve using the negative pressure in the rear intake pipe of the throttle valve and a diaphragm device, lubricating oil can be transferred during high-speed rotation or high-load operation. Japanese Patent Publication No. 47-4524 has already proposed a separate oil supply system for an internal combustion engine in which oil is delivered to the inner surface of the cylinder and into the intake pipe in front of the throttle valve during low-speed rotation or low-load operation. However, in this case, when warming up under idling conditions, oil (lubricating oil) is supplied into the intake pipe under low speed rotation conditions, so the starter device of the carburetor (e.g. When the valve (choke valve) is turned on, the proportion of fuel becomes excessive, and there is a risk of insufficient oil on the inner wall of the cylinder (the sliding surface between the cylinder and piston), resulting in scuffing.

The present invention was developed in view of the above-mentioned circumstances, and its purpose is to reduce the lubrication performance of oil during warm-up when the engine is cold or idling (especially when the engine valve is activated). Further, it is an object of the present invention to provide a scuffing prevention device that can prevent scuffing from occurring and can prevent scuffing without increasing the amount of oil.

The present invention is characterized by forming an oil supply passage opening into the inner wall of the cylinder and the inlet passage, and also includes a temperature sensing means for sensing the temperature of the cylinder, and an oil supply switching means operated by the temperature sensing means. By the functions of the temperature sensing means and the oil supply switching means, when the temperature of the cylinder is low, oil is directly supplied to the inner wall of the cylinder, and when the temperature of the cylinder is high, the oil is supplied to the inlet passage. The reason is that it is configured to supply

Hereinafter, one embodiment of the present invention will be described with reference to the accompanying drawings.

The drawing shows a two-stroke engine equipped with a scuffing prevention device according to the present invention, in which 1 is a cylinder having a cylindrical inner wall 1a, 2 is a piston slidably disposed within the inner wall 1a of the cylinder 1, and 3 is a cylinder having a cylindrical inner wall 1a. An inlet passage formed in the cylinder 1, 4 an exhaust gas passage formed in the cylinder 1, 5
6 is an oil supply passage formed in the cylinder 1 so as to open to the inner wall 1a of the cylinder 1, and 6 is an oil supply passage formed in the cylinder 1 so as to open to the inlet passage 3.
7 is a heat pipe arranged to sense the temperature of the cylinder 1, 8 is an oil supply path switch, and 9 is an oil pump. The oil supply path 5 and the heat pipe 7 are located at a portion of the inner wall 1a where scuffing is most likely to occur, that is, at the opening 3 of the inlet passage 3.
It is located near a.

On the other hand, the oil supply path switching device 8 includes a fluid cylinder 10 consisting of a pair of cylindrical members 10a and 10b, and a diaphragm 11 is sandwiched between the pair of cylindrical members 10a and 10b. Wax 12 is contained in one cylindrical member 10a, and working fluid 13 is contained in the other cylindrical member 10b. Furthermore, the heat pipe 7 is connected to one of the cylindrical members 10a, so that the temperature of the cylinder 1 is transmitted via the heat pipe 7 to the wax 12 within the cylindrical member 10a.

The other cylindrical member 10b is fitted onto a base 20, and one end of a rod-shaped valve 14 slidably disposed in the hole 20a of the base 20 slides into the cylindrical member 10b. They are freely fitted and one end surface 14a thereof is joined to the working fluid 13.
Note that this valve 14 is always biased to the right in the figure by the biasing force of a compression spring 15 disposed at the end of the hole 20a.

Further, the valve 14 is formed with a through hole 17 for oil circulation, and the base body 20 is provided with one oil supply passage 16 and a pair of oil discharge passages 18 and 19, respectively. Accordingly, the oil supply path 16 of the base body 20 and the oil discharge path 18 are configured to selectively communicate with each other via the through hole 17 of the valve 14. Note that the oil discharge passage 18 is the oil supply passage 6 of the cylinder 1.
In addition, the oil discharge passage 19 is connected to the oil supply passage 5 of the cylinder 1, respectively.

Next, the operation of the scuffing prevention device constructed as described above will be explained.

First, when the temperature of the cylinder 1 is high, the heat of the cylinder 1 is transferred to the wax 12 via the heat pipe 7.
This wax 12 expands. Accordingly, the diaphragm 11 and the working fluid 13 move to the left in the figure, so the valve 14 is pushed to the left against the biasing force of the compression spring 15. As a result, the oil supply passage 16 and the oil discharge passage 18 are in communication with each other via the through hole 17 of the valve 14 as shown in the drawing, and the oil is transferred from the oil pump 9 to the oil supply passage 16, the through hole 17, and the oil discharge passage 18. The oil flows sequentially through the oil supply passage 6 and is then supplied to the inlet passage 3.

Further, when the temperature of the cylinder 1 is low, the wax 12 contracts, so the valve 14 and the working fluid 13
is moved to the right in the figure by the biasing force of the compression spring 15. Along with this, the oil supply path 16
and the oil discharge passage 18 are blocked from each other, while
The oil supply path 16 and the oil discharge path 19 are in communication with each other. As a result, oil flows from the oil pump 9 through the oil supply passage 16 and the oil discharge passage 19 in sequence, and is supplied from the oil supply passage 5 to the vicinity of the opening 3a of the inlet passage 3.

As mentioned above, when oil and fuel are mixed in the inlet passage 3, the amount of fuel increases when the starter device is on, so the oil/fuel ratio decreases.
The lubricating performance of the oil decreases. In such a case,
By supplying oil directly to locations where scuffing is likely to occur as described above, it becomes difficult for the oil to mix with fuel (gasoline), thereby preventing a decline in the lubricating performance of the oil. In addition, in particular, the oil supply path is switched based on the temperature of cylinder 1, and oil is supplied to the inner wall 1a of cylinder 1 when the temperature is low, so that the engine can be warmed up under idling conditions by operating the check valve. Also, oil is directly supplied to the inner wall 1a, so there is no shortage of oil and smooth warm-up operation is possible.

As described above, the scuffing prevention device according to the present invention prevents scuffing without increasing the amount of oil, so that exhaust smoke does not increase. It also has great effects, such as contributing to noise prevention measures by eliminating scuffing.

[Brief explanation of the drawing]

The drawings are sectional views showing the structure of the scuffing prevention device according to the present invention. 1: Cylinder, 1a: Inner wall, 2: Piston, 3: Inlet passage, 3a: Opening, 4:
...Exhaust gas passage, 5, 6...Oil supply path, 7...Heat pipe as temperature sensing means, 8...Oil supply path switch, 9...Oil pump, 10...Fluid cylinder, 10a, 10b...Cylindrical member, 11...Diaphragm, 12...Wax, 13...Working fluid, 14...Valve, 15...Compression spring, 16...Oil supply path, 17...Through hole, 18, 19...Oil discharge path.

Claims (1)

[Scope of utility model registration request] Oil supply passages opening into the inner wall of the cylinder and the inlet passage are respectively provided, and temperature sensing means for sensing the temperature of the cylinder and oil supply switching means operated by the temperature sensing means are respectively provided. The temperature sensing means and the oil supply switching means are configured to supply oil directly to the inner wall of the cylinder when the temperature of the cylinder is low, and to supply the oil to the inlet passage when the temperature of the cylinder is high. An anti-scuffing device characterized by: