JP3206283B2 - Engine lubrication device - 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 device for supplying oil to a lubricating portion such as between a cylinder bore and a piston of an engine.

[0002]

2. Description of the Related Art In a lubrication system of an engine, particularly a two-stroke engine, oil stored in an oil tank is pressurized by an oil pump, mixed with an air-fuel mixture flowing through an intake passage, and supplied to a lubricating portion such as between a cylinder and a piston. A separate lubrication system is adopted. FIG. 3 and FIG. 4 are lubricating system diagrams showing a conventional example of such a lubricating device of the separated lubrication system.

A lubricating device 100 shown in FIG.
The oil pump 104 is connected in the middle of a lubrication path 103 extending from the oil tank 101 and connected to the two-stroke engine 102, and a solenoid valve 105 is connected downstream of the oil pump 104. Have been. Opening and closing of the solenoid valve 105 is performed by
Control means 106 for controlling the cycle engine 102 in accordance with the operating condition is provided. The solenoid valve 105 is of a two-port two-position type.

Generally, the oil pump 104 is directly driven by the two-stroke engine 102 and operates when the two-stroke engine 102 is started. The control means 106
Opens and closes the solenoid valve 105 finely. For example, as the operating load of the two-cycle engine 102 increases, the solenoid valve 105
Is controlled so as to prolong the valve opening time.

When the solenoid valve 105 is opened, oil pressurized by the oil pump 104 is supplied into the intake passage of the two-stroke engine 102, and the supply of oil is stopped when the solenoid valve 105 is closed. Therefore, the oil supply amount increases in proportion to the valve opening time of the solenoid valve 105.

On the other hand, a lubricating device 110 shown in FIG. 4 is described in Japanese Patent Application Laid-Open No. 2-191807, in which an oil pump 104 connected in the middle of a lubricating path 103 supplies oil in an oil tank 101 for two cycles. The point of supply to the engine 102 is the same as that of the lubricating device 100 shown in FIG. 3, except that the electromagnetic valve 111 connected downstream of the oil pump 104 is of a three-port two-position type. A difference is that a return path 112 extending from the lubrication path 103 and connected to the oil pump 104 on the upstream side is provided.

The electromagnetic valve 111 is finely opened and closed by the control means 106 similarly to the lubricating device 100. When the electromagnetic valve 111 is opened, the oil pressurized by the oil pump 104 enters the intake passage of the two-cycle engine 102. Supplied. When the solenoid valve 111 is closed, the pressurized oil flows through the return path 112 to the pump 104.
Returned upstream.

Since the amount of oil required by the two-cycle engine 102 is very small, a constant displacement plunger pump with high oil discharge accuracy is generally used as the oil pump 104 of the lubricating devices 100 and 110. ing.

[0009]

However, in the case of the lubricating device 100 shown in FIG. 3, if a constant displacement plunger pump is used as the oil pump 104, the oil discharged from the oil pump 104 when the solenoid valve 105 is closed is used. Loses the place to go, and the lubrication path 10
The pressure in 3 may rise abnormally. For this reason,
There is a concern that oil leaks may occur from the connection parts of the hoses that constitute the lubrication path 103, and in the worst case, the hoses may come off or burst.

On the other hand, in the case of the lubricating device 110 shown in FIG.
Is returned to the upstream side of the oil pump 104 via the return path 112. Therefore, even if a constant displacement plunger pump is used, the pressure does not abnormally increase on the downstream side of the oil pump 104. There is no risk of leakage.

However, in the case of the lubricating device 110, since an oil path from three directions is connected to the solenoid valve 111, an expensive three-port two-position type is required for the solenoid valve 111, which greatly reduces the cost of the device. It will be up. For this reason, it is a lubricating device that is difficult to apply to a small and inexpensive vehicle such as a motorcycle.

The present invention has been made to solve such a problem. Even when a constant displacement plunger pump is used as an oil pump, an abnormal pressure in a lubrication path due to opening and closing of a solenoid valve is provided. An object of the present invention is to provide an engine lubricating device that can use an inexpensive two-port two-position type solenoid valve that does not rise and that can reliably prevent excessive supply of oil to the engine. And

[0013]

To achieve the above object, an engine lubricating apparatus according to the present invention comprises an oil tank for storing oil and a lubrication path extending from the oil tank and connected to an oil supply section of the engine. An oil pump connected in the middle of the lubrication path to supply oil to the oil supply unit of the engine; a return path branched from the oil pump downstream of the lubrication path and connected to the oil pump upstream side; An electromagnetic valve for opening and closing the path, and control means for controlling opening of the electromagnetic valve in accordance with the operating condition of the engine, wherein a return path branching section in the lubrication path and an oil supply section of the engine are provided. A first check valve that allows only the flow of oil from the oil pump to the engine is provided between On the flow side, a second check valve that allows only the flow of oil from the solenoid valve to the upstream side of the oil pump is provided, and the opening pressure of the first check valve is set higher than the opening pressure of the second check valve. It is characterized by.

[0014]

According to the engine lubricating device having the above configuration,
When the solenoid valve is closed, the return path is closed, and the oil pressurized by the oil pump is supplied to the oil supply unit of the engine via the lubrication path. When the solenoid valve opens, the return path is opened, and the pressure in this return path is lower than the pressure in the oil supply section of the engine. It is returned to the lubrication path upstream of the pump.

Therefore, even when a constant displacement plunger pump suitable as an oil pump is used, there is no abnormal pressure rise in the lubrication path due to the opening and closing of the solenoid valve, and concerns such as oil leakage can be avoided. Further, since the solenoid valve only interrupts one oil path (return path), an inexpensive two-port two-position type solenoid valve can be used.

Further, the opening pressure of the first check valve provided in the lubrication path is made larger than the opening pressure of the second check valve provided in the return path. Only the second check valve having a low valve opening pressure is opened, and the oil flows through the return path and is returned to the upstream side of the oil pump. At this time, even if the oil flows to the engine side, the oil is blocked by the closed first check valve, and the excessive supply of the oil to the engine is reliably prevented.

[0017]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a longitudinal sectional view showing an example of an engine to which a lubricating device according to the present invention is applied. This engine 1
For example, a two-cycle single-cylinder engine for a motorcycle, in which a cylinder block 3 and a cylinder head 4 are fixed to a crankcase 2 in order.

A cylinder bore 5 is formed in the cylinder block 3, and a combustion chamber 6 is formed in the cylinder head 4 so as to match the cylinder bore 5, and a spark plug 7 is screwed into the center of the combustion chamber.

A piston 8 is slidably inserted into the cylinder bore 5, while a crankshaft 9 is rotatably supported in the crankcase 2, and a piston pin 11 provided on the piston 8 and Crankshaft 9
Are connected by a connecting rod 13.

The crankcase 2 has a reed valve device 1
A carburetor 16 is connected to the reed valve device 14 via an inlet pipe 15. On the other hand, a scavenging port 17 and an exhaust port 18 are formed in the cylinder block 3, and the exhaust port 18 has an exhaust muffler 19.
Is connected.

The mixture of air and fuel generated by the carburetor 16 is fed into the crankcase 2 through an inlet pipe 15 and a reed valve device 14 by a negative pressure generated in the crankcase 2 when the piston 8 rises. And is primarily compressed as the piston 8 descends.

The air-fuel mixture primarily compressed in the crankcase 2 is scavenged through the scavenging port 17 into the cylinder bore 5, is secondarily compressed by the ascending piston 8, is ignited by the ignition plug 7, and is ignited by the ignition plug 7. It burns in 6 and the combustion gas pushes down the piston 8. The combustion gas is exhausted from the exhaust port 18 as exhaust gas.

The reciprocating motion of the piston 8 in the cylinder bore 5 is converted into the rotational motion of the crankshaft 9 by the connecting rod 13, and the rotation of the crankshaft 9 becomes the output of the engine 1.

The lubricating device according to the present invention is connected to, for example, an inlet pipe 15. FIG. 2 is a lubrication system diagram of a lubrication device 21 showing one embodiment of the present invention.

The lubricating device 21 has an oil tank 22 in which oil is stored.
A lubrication path 23 extending from the oil supply section of the engine 1;
That is, it is connected to the inlet pipe 15. The lubrication path 23 is formed by, for example, a flexible hose.

In the middle of the lubrication path 23, an oil pump 24
Is connected. The oil pump 24 is, for example, a constant displacement plunger pump, which is directly driven by the engine 1 to suck oil stored in the oil tank 22, pressurize the oil, and supply it to the engine 1 side.

The end of the return path 25 branching off from the lubrication path 23 downstream of the oil pump 24 is connected to the lubrication path 23 again upstream of the oil pump 24, and the solenoid valve 26 is connected to the middle of the return path 25. In addition, a control means 27 for finely controlling the opening and closing of the electromagnetic valve 26 according to the operating condition of the engine 1 is provided.

As the control means 27, for example, a microcomputer is used. The control means 27 detects the load of the engine 1 by detecting information such as the throttle opening of the carburetor 16 and the engine speed, and performs control so that the closing time of the solenoid valve 26 becomes longer as the load on the engine 1 increases. . That is, the solenoid valve 26 is opened and closed once, for example, during one revolution of the crankshaft 9 of the engine 1, but is controlled so that the valve closing time becomes longer as the load on the engine 1 increases.

A first check valve 32 is connected between the branch A of the return path 25 in the lubrication path 23 and the oil supply section (inlet pipe 15) of the engine 1 and is located downstream of the solenoid valve 26 in the return path 25. The second check valve 33 is connected to the side.

The first check valve 32 is a check valve that opens when an oil pressure exceeding a certain level is applied.
Only the flow of oil from the engine to the engine 1 is allowed. On the other hand, the second check valve 33 is also a check valve that opens when an oil pressure exceeding a certain level is applied, and allows only the flow of oil from the electromagnetic valve 26 to the upstream side of the oil pump 24.

Here, the opening pressure of the first check valve 32 is set higher than the opening pressure of the second check valve 33, and the pressure applied equally to the first check valve 32 and the second check valve 33 increases. In this case, the second check valve 33 opens first.

When the solenoid valve 26 is closed, the return path 25 is closed, so that the oil pressurized by the oil pump 24 is supplied to the inlet pipe 15 via the lubrication path 23. The oil supplied to the inlet pipe 15 is mixed with the air-fuel mixture, enters the engine 1, and lubricates a sliding portion between the cylinder bore 5 and the piston 8.

When the solenoid valve 26 is opened, the return path 2
5 is opened, and the pressure in the return path 25 is lower than the pressure in the inlet pipe 15, so that the pressurized oil does not flow to the engine 1 side but flows to the return path 25 and flows upstream of the oil pump 24. Side is returned to the lubrication path 23.

Under the control of the control means 27, the time during which the solenoid valve 26 is closed becomes longer as the load on the engine 1 increases, so that an amount of oil corresponding to the engine load is always supplied into the inlet pipe 15, Appropriate lubrication is provided.

According to the lubricating device 21 configured as described above, even if a suitable fixed-volume plunger pump is used as the oil pump 24, an abnormal pressure rise in the lubricating passage 23 due to the opening and closing of the solenoid valve 26. Therefore, concerns such as oil leakage can be avoided. Further, since the solenoid valve 26 only interrupts one oil path (return path 25), an inexpensive two-port two-position type solenoid valve 26 can be used, and the manufacturing cost of the lubricating device 21 is greatly reduced. Become cheap.

When the solenoid valve 26 is closed, the oil pressure is applied only to the first check valve 32, so that the first check valve 32 is opened and the oil is
When the solenoid valve 26 is opened, the oil pressure is equally applied to the first check valve 32 and the second check valve 33, so that only the second check valve 33 having a low valve opening pressure is opened. The oil flows through the return path 25 and is returned to the upstream side of the oil pump 24. Therefore, for example, a negative pressure due to intake pulsation is generated in the inlet pipe 15, and this negative pressure tries to suck oil in the lubrication path 23,
Blocked by the valve pressure of the closed first check valve 32,
Excessive supply of oil is reliably prevented.

The oil supply section of the engine 1 is not limited to the inlet pipe 15, but, for example, an injection device for directly injecting oil into a sliding portion between the cylinder bore 5 and the piston 8 is provided. May be connected.

[0038]

As described above, the engine lubrication apparatus according to the present invention comprises an oil tank for storing oil, a lubrication path extending from the oil tank and connected to an oil supply section of the engine, and a lubrication path for the engine. An oil pump that is connected in the middle of the oil pump to supply oil to the oil supply portion of the engine, a return path that branches from the oil pump downstream of the lubrication path and is connected to the oil pump upstream, and that opens and closes the return path. An electromagnetic valve, and control means for controlling the opening of the electromagnetic valve in accordance with the operating condition of the engine. An oil pump is provided between the return path branching section in the lubrication path and the oil supply section of the engine. A first check valve that allows only oil flow from the engine to the engine side, and a solenoid valve downstream of the solenoid valve in the return path. A second check valve that allows only the flow of oil to the upstream side of the oil pump is provided, and the opening pressure of the first check valve is set higher than the opening pressure of the second check valve. .

According to this, even if a constant displacement plunger pump suitable as an oil pump is used, there is no abnormal pressure rise in the lubrication path due to the opening and closing of the solenoid valve, and concerns such as oil leakage can be avoided. Also, since the solenoid valve only interrupts one oil path (return path), an inexpensive two-port two-position solenoid valve can be used, and the manufacturing cost of the lubricating device is greatly reduced.

Further, by setting the valve opening pressure of the first check valve higher than the valve opening pressure of the second check valve, even if oil flows to the engine side when the solenoid valve is opened, the second check valve will Also, since the flow of oil is blocked by the valve pressure of the first check valve having a high valve opening pressure, an excessive supply of oil to the engine can be reliably prevented.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of an engine to which a lubrication device according to the present invention is applied.

FIG. 2 is a lubrication system diagram of a lubrication device showing one embodiment of the present invention.

FIG. 3 is a lubrication system diagram of a lubrication device showing a conventional technique.

FIG. 4 is a lubrication system diagram of a lubrication device showing a conventional technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Engine 15 Inlet pipe which is an oil supply part of engine 21 Lubricator 22 Oil tank 23 Lubrication path 24 Oil pump 25 Return path 26 Solenoid valve 27 Control means 32 First check valve 33 Second check valve A Return path branch in lubrication path Department

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-5-89818 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) F01M 1/16

Claims (1)

(57) [Claims] 1. An oil tank for storing oil, a lubrication path extending from the oil tank and connected to an oil supply section of the engine, and connected to the middle of the lubrication path to supply oil to the oil supply section of the engine. The oil pump, a return path branched from the oil pump downstream side of the lubrication path and connected to the oil pump upstream side, a solenoid valve for opening / closing the return path, and opening of the solenoid valve depending on the operating condition of the engine. A first check valve that allows only oil flow from the oil pump to the engine side between the return path branching section in the lubrication path and the oil supply section of the engine. And a second channel that allows only oil flow from the solenoid valve to the upstream side of the oil pump on the return path downstream of the solenoid valve. An engine lubricating device comprising a check valve, wherein the opening pressure of the first check valve is set higher than the opening pressure of the second check valve.