JPH10184331A - Return oil splash preventing structure for four cycle engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent oil directly returned to a cam chamber from an oil control valve for controlling a device from being splashed and being particulated in a four cycle engine with a valve timing variable device. SOLUTION: A four cycle engine has respective cam shafts 8, 9 for driving intake exhaust valves disposed in a cam chamber 10 above a cylinder head 1 and a valve timing variable device for changing phase angle of the cam shafts by hydraulic control by oil control valves 5, 6 mounted to at least one of the respective cam shafts 8, 9 and also the engine is formed such that return oil from the oil control valves 5, 6 are directly returned in the cam chamber 10 from upper side than the respective cam shafts 8 and 9. In this case, an oil shielding plate 36 is disposed at a position lower than a position to which the oil is returned from the oil control valves 5, 6 in the cam chamber 10 and above the respective cam shafts 8 and 9.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a four-stroke engine in which a variable valve timing device is provided for at least one of respective camshafts for driving an intake valve and an exhaust valve. The present invention relates to a structure for preventing oil from returning from an oil control valve for controlling a variable valve timing device through a cam chamber in a four-cycle engine.

[0002]

2. Description of the Related Art A four-stroke engine having a DOHC type valve system, that is, a valve driving camshaft driven through a timing chain or a timing belt by rotation of a crankshaft is provided with a camshaft on the intake side above a cylinder head. And a four-cycle engine provided on the exhaust side, respectively, in order to change the opening / closing timing of at least one of the intake / exhaust valves according to the operating state of the engine, each cam for driving the intake / exhaust valves is provided. For at least one of the shafts, the oil supplied from the oil pump changes the oil pressure of each of the two oil chambers defined in the device via an oil control valve, and the phase of the camshaft is accordingly adjusted. Variable hydraulic valve timing that changes the angle (Varying
Conventionally, a VVT (abbreviated VVT) device is installed at the end of the camshaft.

In a four-stroke engine provided with such a variable valve timing device, an oil control valve for controlling the distribution of oil supplied from an oil pump to respective oil passages communicating with the respective oil chambers of the variable valve timing device. However, normally, the oil is disposed above the position of the camshaft in which the oil passage is formed, and the oil returned from the oil control valve is directly returned to the cam chamber above the cylinder head.

[0004] On the other hand, in a four-cycle engine, a passage is provided from the crank chamber to the air cleaner box through the cam chamber to leak from the combustion chamber side to the crank chamber through the space between the cylinder inner wall and the piston ring. The blow-by gas is recirculated to the air cleaner box through the passage by the pressure change in the crank chamber due to the reciprocating motion of the piston, and is sent again into the combustion chamber to be re-burned (reduction of the blow-by gas).

[0005] Further, the above-mentioned passage for blow-by gas reduction is provided as a first passage, and a second passage for connecting an intake passage downstream of the throttle valve to the crank chamber through an oil separator and an automatic opening / closing valve. When the throttle is fully opened, the automatic opening / closing valve of the second passage is closed, so that the crank chamber is ventilated only from the first passage by the normal blow-by gas reduction. By opening the on-off valve, gas is sucked from the first passage into the crank chamber, gas is discharged from the crank chamber to the intake passage through the second passage, and the crank chamber is ventilated.
(Positive Cese Ventilate) system is also known.

[0006]

In the conventional four-stroke engine in which the oil from the oil control valve of the variable valve timing device is directly returned to the cam chamber as described above, the oil control valve is located above the camshaft. Because the oil returned to the cam chamber from the oil control valve falls into the cam chamber from above each camshaft, the oil collides with each rotating camshaft, and It will be scattered and atomized.

Therefore, when returning the blow-by bus as described above, the oil scattered and atomized in the cam chamber as described above is discharged to the air cleaner box side together with the recirculated blow-by gas, and is burned in the combustion chamber. In the four-cycle engine using the PCV system, the scattered and atomized oil is sucked into the crank chamber together with the gas sucked through the first passage (blow-by gas reduction passage) passing through the cam chamber. Therefore, P
CV performance will be degraded.

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a four-stroke engine provided with a variable valve timing device, in which oil returned from an oil control valve for controlling the device directly into the cam chamber is used. It is an object of the present invention to prevent the particles from scattering and atomizing.

[0009]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a cam chamber above a cylinder head for driving intake and exhaust valves. A camshaft is installed, and at least one of the camshafts is equipped with a variable valve timing device that changes the phase angle of the camshaft by hydraulic control by an oil control valve, and return oil from the oil control valve is provided. In a four-stroke engine configured to return directly into the cam chamber from above each camshaft, an oil shielding plate is provided above each camshaft below the position where oil is returned from the oil control valve in the cam chamber. It is characterized by being provided.

Further, in the structure for preventing return oil scattering of a four-stroke engine according to the first aspect of the present invention, as described in the second aspect, the oil control valve is connected to the upper surface of the front end portion of the cylinder head and to the upper portion. A groove with an open lower side is formed integrally with the cam cap to which it is attached so as to cross each camshaft in proximity to the oil control valve and return oil from the oil control valve. An oil drain hole is communicated with the groove, and an oil shielding plate is attached to a lower open surface of the groove to form a passage for guiding return oil from the oil control valve. Is what you do.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a return oil scattering prevention structure for a four-stroke engine according to the present invention will be described below with reference to the drawings.

FIGS. 1 and 2 show a four-stroke engine according to an embodiment of the present invention, in which a belt cover for covering a front side of an engine is removed around a portion where a variable valve timing device (VVT) is installed. FIG. 1 shows a state viewed from the front, and FIG. 2 shows a state viewed from the side.

In the four-stroke engine of this embodiment, one cam cap 2 common to both the intake and exhaust camshafts is connected to the upper surface of the front end portion of the cylinder head 1. Valve timing variable devices 3 and 4 that change the phase angle of the cam shaft by hydraulic pressure with respect to each of the intake-side and exhaust-side valve drive cam shafts (not shown) rotatably supported by the cam cap 2.
Are provided, and oil control valves 5, 6 corresponding to the respective valve timing variable devices 3, 4 are attached to the cam cap 2, respectively.

FIG. 3 shows a cross section along the axial direction of one camshaft in such a four-stroke engine. Above the cylinder head 1, the cylinder head 1 including the rear part of the cam cap 2 is shown. A head cover 7 is provided so as to cover the entire upper part. Each cam shaft 8 is formed by the cylinder head 1, the cam cap 2, and the head cover 7.
A cam chamber 10 for accommodating (9) is defined, and a variable valve timing device 3 (4) is provided at a front end portion of a cam shaft 8 (9) protruding outward from the cam chamber 10. I have.

1 and 2, the variable valve timing device 3 (4) is removed from the front upper end of the cam cap 2 on the front side of the engine where the variable valve timing devices 3 and 4 are disposed. Further, a belt cover 11 is provided so as to cover a timing belt (not shown) and the like which is wound around the device 3 (4).

The camshaft 8 side of the valve drive camshaft (the same applies to the other camshaft 9) will be described. The lower part of the bearing, which is recessed in the lower semicircular shape on the upper surface of the cylinder head 1, will be described. A cam portion 8b for opening and closing the valve 12 is rotatably held by the journal portion 8a by the upper portion of the bearing recessed in an upper semicircular shape on the lower surface of the cam cap 2. The camshaft 8 has a front end protruding forward from the front end surfaces of the cylinder head 1 and the cam cap 2, and the variable valve timing device 3 is mounted on the front end of the camshaft 8.

The variable valve timing device 3 has a cylindrical oil housing 13 rotatably mounted on a front end portion of a cam shaft 8 protruding from the front of the engine. Timing pulley 14 for hanging the timing belt from the shaft
Are formed integrally, and by changing the pressure in each of the oil chambers 13a and 13b defined inside the oil housing 13, the oil housing 13 and the camshaft 8 are relatively rotated, whereby the oil A structure conventionally known as a helical gear type (or vane type) hydraulic valve timing variable device that changes the phase angle of the cam shaft 8 with respect to the timing pulley 14 formed integrally with the housing 13. is there.

In this embodiment, a timing belt (not shown) and a timing pulley 14 (15) are used to link the rotation of the crankshaft with the variable valve timing device 3 (4). The crankshaft and the variable valve timing device may be linked by using a chain and a sprocket.

As described above, the variable valve timing device 3 is mounted on the front end portion of the camshaft 8 and the oil control valve 5 is mounted on the cam cap 2 that supports the camshaft 8 according to this embodiment. In the engine,
The oil supplied by the oil pump is distributed and controlled by an oil control valve 5 to apply oil pressure to oil chambers 13a and 13b defined in an oil housing 13 of the variable valve timing device 3, respectively. It is returned directly from the valve 5 to the cam chamber 10.

That is, the oil discharged from the oil pump (not shown) and sent to the cylinder head 1 through the oil passage on the cylinder block side, as shown in FIGS. Oil passage 21 to
23, an oil filter 2 provided on the cam cap 2 side from the mating surface of the cylinder head 1 and the cam cap 2.
4, the oil is supplied from the oil passage 25 of the cam cap 2 to the oil control valves 5 and 6 on the intake side and the exhaust side, respectively.

FIG. 4 shows a state as viewed from the front of the cam cap 2, and FIG. 5 shows a state as viewed from below the cam cap 2. In this embodiment, the oil filter 24 is 4 and 5, since the cam cap 2 is arranged so as to be inserted from the mating surface with the cylinder head 1, the oil filter 24 can be easily attached or replaced. Has become.

From the oil filter 24 to the oil passage 25
The oil supplied to the oil control valves 5 and 6 on the intake side and the exhaust side through the oil control valves 5 and 6 is distributed and controlled by the oil control valves 5 and 6, so that the oil is supplied to each of the cam caps as shown in FIG. 2 and is appropriately distributed to a retard-side oil passage 26 and an advance-side oil passage 27, and is defined inside the oil housing 13 through respective oil passages 28 and 29 formed in the camshaft 8. By applying a hydraulic pressure to each of the oil chambers 13a and 13b and changing the pressure in each of the oil chambers 13a and 13b, the oil housing 13 and the cam shaft 8 are relatively rotated,
The phase angle of the cam shaft 8 with respect to the timing pulley 14 is changed.

The oil returned from the oil control valve 5 by applying oil pressure to each of the oil chambers 13a and 13b of the variable valve timing device 3 is connected to the oil chamber 31 through the mounting hole 31 of the oil control valve 5 and into the cam chamber 10. It is returned directly into the cam chamber 10 through the drain hole 33.

FIG. 6 shows each oil control valve 5,
6 shows the flow of return oil from each of the oil control valves 5 and 6 in the cam chamber 10 by a cross section along the axial direction of the oil control valve 6, and a valve mounting hole 31 for mounting the oil control valves 5 and 6 is provided. In the present embodiment, as shown in FIG. 3, in the present embodiment, the cam caps 2 integrally formed with the cam shafts 8 and 9 cross the respective cam shafts 8 and 9 above the respective cam shafts 8 and 9. A groove 34 having a U-shaped cross section with an open lower side is formed integrally with the cam cap 2 so as to communicate with each of the valve mounting holes 31 and 32 through respective oil drain holes 33.

The lower open surface of the groove 34 has the shape shown in FIG.
As shown in FIG. 6, an oil shielding plate 36 is attached so that at least one longitudinal end of the groove 34 is opened downward as an oil drop port 35, and the groove 34 and the oil shielding plate 36 An oil passage is formed such that the oil returned through each oil drain hole 33 bypasses above the camshafts 8 and 9 without diffusing and drops above the oil return hole 37 of the cylinder head 1. ing.

The fourth embodiment of the present invention having the above structure
According to the cycle engine, the oil returned from the oil control valves 5 and 6 into the cam chamber 10 through the oil drain holes 33 passes through the oil shielding plate 36 without being diffused by the groove 34 and reaches the end thereof. Oil return hole 3 of cylinder head 1 from oil drop port 35
7, the return oil collides with the rotating cam shafts 8 and 9 and scatters in the cam chamber 10 to form fine particles.
7, the oil is returned to the oil pan through the oil return passage on the cylinder block side.

Therefore, the oil returned from the oil control valves 5 and 6 of the variable valve timing devices 3 and 4 is scattered and atomized in the cam chamber, so that the oil is returned to the air cleaner box side together with the blow-by gas when the blow-by gas is recirculated. It is not discharged and burned in the combustion chamber, nor does the PCV system adopt a four-stroke engine, which is sucked into the crank chamber together with the intake air to deteriorate the PCV performance.

In order to guide the oil returned from the oil control valves 5 and 6 to the oil return holes 37 of the cylinder head 1 without falling onto the respective camshafts 8 and 9, the oil is communicated with the oil drain holes 33. Oil return hole 37
It is also conceivable that the oil passage extending upward is integrally formed with the cam cap 2 itself by casting.
In such a case, in order to secure the effective cross-sectional area of the oil passage, the cam cap 2 itself becomes high, and the mounting position of the oil control valves 5 and 6 becomes high, so that it becomes bulky.

On the other hand, as in this embodiment, the groove 3
In the case where the oil passage is formed by the oil shielding plate 4 and the oil shielding plate 36, the effective cross-sectional area of the oil passage can be secured without changing the height of the cam cap 9 itself by using the thin oil shielding plate 36. Also, the mounting positions of the oil control valves 5 and 6 do not increase.

The embodiment of the return oil scattering prevention structure of the four-stroke engine according to the present invention has been described above.
The present invention is not limited to the above-described embodiment. For example, the present invention is applied to a case where a variable valve timing device is mounted on each of the camshafts on both the intake side and the exhaust side. The present invention can be similarly applied to a four-stroke engine in which the variable valve timing device is mounted on only one of the camshafts on the intake side and the exhaust side.

Further, regarding a specific structure for preventing return oil scattering, for example, the oil shielding plate 36 is formed in a gutter shape so that the cam cap 2 itself does not have the groove 34 and the oil shielding plate 36 has a groove. It is also possible to implement by guiding the oil only by the plate 36.

[0032]

According to the structure for preventing return oil scattering of a four-stroke engine of the present invention as described above, return oil from the oil control valve of the variable valve timing device is scattered in the cam chamber to be atomized. Without returning to the oil pan, it is possible to prevent the fuel from being burned in the combustion chamber together with the blow-by gas and wastefully consumed. It is possible to prevent the deteriorated PCV performance from being caused by sucking the converted oil into the crank chamber.

[Brief description of the drawings]

FIG. 1 is a front view of a four-stroke engine to which an embodiment of a return oil scattering prevention structure according to the present invention is applied, with a belt cover removed from an upper front part thereof.

FIG. 2 is a side view of the upper front part of the engine shown in FIG. 1;

FIG. 3 is a schematic cross-sectional view of an upper portion of the front side of the engine shown in FIG. 1 along an axial direction of one camshaft.

FIG. 4 is a front view showing the cam cap itself of the engine shown in FIG. 1;

FIG. 5 is a bottom view of the cam cap shown in FIG. 4;

FIG. 6 is a schematic cross-sectional view of an upper part on the front side of the engine shown in FIG. 1 along an axial direction of each oil control valve.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cylinder head 2 Cam cap 3 Valve timing variable device 4 Valve timing variable device 5 Oil control valve 6 Oil control valve 8 Cam shaft 9 Cam shaft 10 Cam chamber 33 Oil drain hole 34 Groove portion 36 Oil shielding plate

Claims (2)

[Claims] A cam shaft for driving an intake / exhaust valve is provided in a cam chamber above a cylinder head, and the phase angle of the cam shaft is controlled by at least one of the cam shafts by hydraulic control by an oil control valve. An oil control valve in the cam chamber of a four-stroke engine equipped with a variable valve timing device and configured to return oil from the oil control valve directly into the cam chamber from above each cam shaft. An oil shielding plate is provided above each camshaft below the position where oil is returned from the cylinder.
Cycle engine return oil scattering prevention structure. 2. A cam cap connected to an upper surface of a front end portion of a cylinder head and having an oil control valve mounted on an upper portion thereof, so as to be close to the oil control valve and to cross each cam shaft above the oil control valve. An oil drain hole for returning oil from an oil control valve is communicated with the groove, and an oil shielding plate is attached to the lower open surface of the groove. 2. The structure for preventing return oil scattering of a four-stroke engine according to claim 1, wherein a passage for guiding return oil from an oil control valve is formed.