JP4963583B2 - engine - Google Patents

Description

  The present invention relates to an engine, and more particularly to an engine equipped with a breather device that can improve the efficiency of an OHC (overhead camshaft) type engine.

In an OHC (overhead camshaft) type engine, a cam chamber is formed by an upper surface of a cylinder head block and a lower surface of a cylinder head cover covering the cylinder head block. Engine oil is supplied into the cam chamber to lubricate the parts that slide with the camshaft. The engine oil supplied into the cam chamber is used for lubrication and then discharged from the cam chamber to the crank chamber through a drain path (for example, Patent Document 1).
JP 2005-83310 A

  However, in the conventional configuration as described above, for example, when the engine oil staying in the cam chamber increases as the engine speed increases, the rotational resistance of the camshaft (viscous friction resistance, stirring resistance, etc.) Therefore, mechanical loss occurs and engine efficiency is reduced.

  The present invention has been made in view of such circumstances, and an object thereof is to provide an engine that can prevent engine oil from staying in a cam chamber and improve engine efficiency.

An engine according to the present invention is an engine configured to discharge engine oil supplied to a cam chamber formed between a cylinder head cover and a cylinder head block from the cam chamber to a crank chamber through a drain path. The breather tube that leads one end to the crank chamber, the other end communicates to the cam chamber, guides the gas in the crank chamber to the cam chamber, and the breather tube are formed separately, and has one end connected to the crank chamber A blow-by tube with the other end communicating with the intake passage of the engine, the supply amount of the engine oil increases as the engine speed increases, and the internal pressure of the crank chamber is It is characterized by increasing as the engine speed increases.

  According to this configuration, for example, when the engine oil staying in the cam chamber increases as the engine speed increases, the pressure in the crank chamber also increases, so that the cam chamber can be pressurized through the breather tube. As a result, the discharge of engine oil from the cam chamber through the drain path is promoted, and the stay of engine oil in the cam chamber can be prevented. Therefore, occurrence of mechanical loss is suppressed, and engine efficiency (particularly engine output) can be improved.

  Further, part of the blow-by gas that is a pressurizing source in the crank chamber is supplied to the intake system of the engine through the blow-by tube, so that no excessive pressure is applied to the cam chamber.

  The blow-by tube can have a larger flow cross-sectional area than the breather tube. According to such a configuration, only a pressure sufficient to pressurize the cam chamber as described above can be applied to the cam chamber.

  At least one of the breather tube and the blow-by tube can communicate with the crank chamber through a breather chamber formed above the crank chamber.

  Thus, according to the above invention, it is possible to provide an engine that can prevent engine oil from staying in the cam chamber and improve engine efficiency.

  Hereinafter, an engine according to the present invention will be specifically described with reference to the accompanying drawings.

  The engine 10 according to the embodiment of the present invention shown in the side sectional view of FIG. 1 is a DOHC (double overhead camshaft) type engine, but any other suitable OHC (overhead camshaft) type engine, It may be a side valve type engine.

  The engine 10 has a substantially sealed crank chamber 100A, and engine oil 300 is accommodated in the crank chamber 100A. For example, an oil pump 40 driven by the crankshaft 12 of the engine 10 is connected to the lower portion of the crank chamber 100A.

  The oil pump 40 pumps the engine oil 300 through the oil supply path 42, and in the cam chamber 100B formed in a hermetically sealed manner between the upper surface of the cylinder head block 14 and the lower surface of the cylinder head cover 16 covered thereon. Supply.

  The oil supply path 42 is shown schematically in FIG. 1 and can be of any suitable configuration.

  The engine oil 300 supplied into the cam chamber 100B lubricates the parts that slide with the camshaft 18 provided in the cam chamber 100B, and then is discharged from the drain path 44 that opens to the lower portion of the cam chamber 100B. . In the present embodiment, the drain path 44 is formed through the cylinder head block 20 and returns the engine oil 300 to the crank chamber 100A. However, the drain path 44 is an independent pipe outside the cylinder head block 20. There may be.

  In the present embodiment, a breather chamber 100C is formed in the upper part of the crank chamber 100A, and blow-by gas in the crank chamber 100A is sent into the breather chamber 100C through the opening 22. The blow-by gas is separated into gas and liquid in the breather chamber 100C, and the liquid oil accumulated in the bottom of the breather chamber 100C is returned to the crank chamber 100A through the oil return passage 23 immersed in the engine oil in the crank chamber 100A. The breather chamber 100C is integrally formed inside the crank chamber wall 24 forming the crank chamber 100A, but is configured as a space isolated from the crank chamber 100A.

  In the present embodiment, one end of the breather tube 302 is connected to the upper surface of the breather chamber 100C, and the other end of the breather tube 302 is connected to the upper surface of the cylinder head cover 16, thereby the breather chamber 100C and the cam. It communicates with the room 100B.

  One end of the blow-by tube 304 is connected to the upper surface of the breather chamber 100C, and the other end of the blow-by tube 304 is connected to an air cleaner 26 that is a part of the intake path of the engine 10, thereby It communicates with the intake path.

  In the present embodiment, the oil flow cross-sectional area of the blow-by tube 304 is designed to be larger than the oil flow cross-sectional area of the breather tube 302 (generally, the inner diameter is also large).

  With the above configuration, most of the blow-by gas in the breather chamber 100C is supplied into the air cleaner 26 through the large-diameter blow-by tube 304, but a part of the blow-by gas is supplied into the cam chamber 100B through the small-diameter breather tube 302. It comes to be supplied.

  For example, when the rotational speed of the engine 10 increases, the discharge amount of the oil pump 40 that is interlocked with the rotation of the crankshaft 12 increases, and the amount of engine oil 300 that is supplied to the cam chamber 100B per unit time also increases.

  At this time, typically, as the engine speed increases, the pressure in the crank chamber 100A also increases. At the same time, the internal pressure of the breather chamber 100C communicating with the crank chamber 100A also rises, and if the internal pressure of the breather chamber 100C becomes larger than the internal pressure of the cam chamber 100B, the result is that pressure by blow-by gas is applied to the cam chamber 100B. The engine oil 300 in 100B can be expelled through the drain path 44.

  Since a larger diameter blow-by tube 304 is connected to the breather chamber 100C, excessive pressure is not applied to the cam chamber 100B, and the rest is discharged into the air cleaner 26, and outside air is passed through the fuel supply device 28 and the like. It is mixed and used for combustion of the engine 10.

  In the present embodiment, the cylinder head of engine 10 tilts to one side, and crank chamber 100A extends to the other side. The intake system is arranged on the same side as the crank chamber 100A extends. Therefore, the breather chamber 100C arranged at the highest position of the crank chamber 100A is connected to the cam chamber 100B and the air cleaner in the crank chamber 100A. Located relatively close to 26. In such an arrangement, the breather tube 302 and the blow-by tube 304 can be arranged almost linearly when applied to a two-wheeled vehicle, which is advantageous for handling each tube.

  Further, in the present embodiment, the configuration in which both the breather tube 302 and the blow-by tube 304 are connected to the breather chamber 100C is shown, but basically the breather chamber 100C and the crank chamber 100A have the same internal pressure. The breather tube 302 and the blow-by tube 304 can be configured to communicate with any chamber. Furthermore, it is not necessary for both the breather tube 302 and the blow-by tube 304 to communicate with the same chamber. For example, it is possible to configure one to communicate with the breather chamber 100C and the other with the crank chamber 100A.

  FIG. 2 is a graph showing test results of the breather device according to the present embodiment, in which the horizontal axis represents the engine speed and the vertical axis represents the engine output. In the graph, the broken line indicates the case where the breather tube is connected as in the present embodiment, and the solid line indicates the case where the breather tube is not connected as in the conventional case.

  According to the test results, it can be seen that the breather apparatus according to the present embodiment has improved engine output in a relatively high engine speed range.

  Although the present disclosure includes specific embodiments, since various modifications are possible, the specific embodiments cannot be considered in a limited sense. The subject matter of this disclosure includes all novel and non-obvious combinations and sub-combinations of the various elements, features, functions and / or properties disclosed herein. The claims particularly point out certain combinations and subcombinations regarded as new and non-obvious. Other combinations and sub-combinations of features, functions, elements, and / or properties may be claimed through amendments of the current claim or through the presentation of new claims in this or related applications. Such claims, whether broader, narrower, equivalent or different from the scope of the original claims, are considered to be included within the subject matter of this disclosure.

  As described above, the present invention can be applied to a vehicle (such as a motorcycle) that is required to provide an engine that can prevent engine oil from staying in the cam chamber and improve engine efficiency.

1 is a side sectional view of an engine showing a configuration of an engine according to an embodiment of the present invention. It is a graph which shows the test result of the engine concerning embodiment shown in FIG.

Explanation of symbols

10 engine
14 Cylinder head block
16 Cylinder head cover
18 Camshaft
26 Air cleaner
42 Oil supply path
44 Drain path
302 breather tube
304 blow-by tube
100A crankcase
100B Cam room
100C breather room
300 engine oil

Claims (2)

An engine configured to discharge engine oil supplied to a cam chamber formed between the cylinder head cover and a cylinder head block from the cam chamber to a crank chamber through a drain path,
A breather tube having one end communicating with the crank chamber, the other end communicating with the cam chamber, and guiding the gas in the crank chamber to the cam chamber ;
The breather tube is formed separately, and includes a blow-by tube having one end communicating with the crank chamber and the other end communicating with the intake passage of the engine.
The supply amount of the engine oil increases as the engine speed increases,
The engine characterized in that the internal pressure of the crank chamber increases as the rotational speed of the engine increases.   The engine according to claim 1, wherein the blow-by tube has a larger flow cross-sectional area than the breather tube.

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