JPH0723528Y2 - Engine structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to an engine structure.

(Prior Art) In a diesel engine for a vehicle such as a truck, an intake cam and an exhaust cam for opening and closing an intake valve and an exhaust valve are provided on a side portion of a crankcase, and a tappet and a push rod that cooperate with each cam. Overhead valve type engines that have a valve mechanism are widely used. In this type of engine, oil that normally lubricates sliding surfaces such as rocker arms provided on the cylinder head flows down from the cylinder head into the oil pan through the oil passage provided on the side of the crankcase, and then again. It is pumped up by an oil pump and pumped to various parts of the engine for circulation, but conventionally, the oil passage on the side of the crankcase is in sliding contact between the intake cam and the exhaust cam and the intake and exhaust side tappets. No special measures have been taken regarding the shape and arrangement of the passages for positively lubricating the surface.

(Problems to be solved by the invention) In recent years, there is a tendency that sludge in oil increases and lubrication performance decreases due to EGR etc. widely adopted as part of engine exhaust gas purification measures. Therefore, there is concern that the intake cam and the exhaust cam that drive the intake valve and the exhaust valve, and the intake-side tappet and the exhaust-side tappet that reciprocate by slidingly contacting these cams may wear.

The present invention reduces the wear of the intake cam and the exhaust cam, and the intake side tappet and the exhaust side tappet that are in sliding contact with these cams, by supplying a larger amount of oil to the nose portions of the intake cam and the exhaust cam. It is an object of the present invention to provide an engine structure of this type, which can ensure the durability of the cam and tappet, has a low manufacturing cost, and has a low engine operating noise.

(Means for Solving Problems) The engine device according to the present invention was created to achieve the above object, and controls the intake valve and the exhaust valve of each cylinder on the side of the crankcase. A camshaft having a plurality of sets of intake cams and exhaust cams, and a plurality of sets of intake-side tappets and exhaust-side tappets that follow the intake cams and exhaust cams. In order to allow the intake side tappet and the exhaust side tappet to respectively flow down from the cylinder head toward the oil pan, a leg formed by recessing between a pair of tappet chambers connected at the cylinder side, It consists of a pair of tappet chamber walls on the side far from the cylinder and sides surrounded by the crankcase outer wall, which is spaced apart from the walls, and has an opening at the lower end. A substantially T-shaped oil passage is formed in the crankcase, and the cam nose portions of the intake cam and the exhaust cam are exposed in the side portion of the oil passage.

According to the present invention, the oil passage for flowing the oil from the cylinder head to the oil pan is formed along the outer wall of the tappet chamber for accommodating the intake side and exhaust side tappets, respectively, and both tappets. It is configured as a passage having a substantially T-shaped cross section composed of a leg portion that is recessed between the chambers, and the cam nose portion of the intake cam and the exhaust cam faces this oil passage, so that the oil flowing down in the oil passage is It adheres directly to the cam nose and is supplied in large quantities to the sliding contact surface on the bottom of the tappet. Further, the oil passage having a substantially T-shaped cross section can be formed by casting when the crankcase is cast.

(Embodiment) An embodiment of the present invention will be specifically described below with reference to the accompanying drawings. Reference numeral 10 in the figure generally indicates an overhead valve type diesel engine for a truck, which includes a crankcase 14 in which a plurality of cylinders 12 are arranged in a row and an oil pan 16 attached to the lower end of the crankcase. .
A piston 18 is slidably fitted in the cylinder 12,
The piston is connected to a crankshaft 22 via a connecting rod 20.

A camshaft 24 having an intake cam and an exhaust cam for opening and closing an intake valve and an exhaust valve of each cylinder is housed in one side portion of the crankcase 14, and the camshaft 24 is interlocked with the crankshaft 22. Rotate. The intake cam and the exhaust cam each have a bottomed cylindrical body on the intake side and the exhaust side, respectively.
26 are in sliding contact with each other, and each tappet is slidably fitted in a tappet chamber 28 formed in the crankcase 14. The above tappet chambers 28 provided for each cylinder 12
An oil passage 30 is formed along the outer wall of the cylinder head (not shown) for returning the oil that has lubricated the rocker arm and the like to the oil pan 16, and the outer wall that limits the tappet chamber 28 and the oil passage 30 is a crankcase. 14 is integrally formed during casting.

As shown in FIG. 2, the oil passage 30 has a substantially T-shaped cross section in the tappet chamber 28, and a side portion 32 extending substantially parallel to the crankshaft and an intake air passage. Side and exhaust side tappet chambers 28 and a leg portion 34 formed by being recessed. Further, both end portions of the side portion 32 are formed so as to intersect with a rotating body formed by the cam nose portions 36 of the intake cam and the exhaust cam being swept by the rotation of the cam shaft 24, in other words, the cam nose portion 36.
Are formed so as to face the side portion 32 of the oil passage 30.

According to the above configuration, while the engine 10 is in operation, the oil that lubricates the rocker arms on the cylinder head is not allowed to pass through the oil passage.
When flowing down through the oil pan 16 to the oil pan 16, the passage part having a T-shaped cross section flows down at the tappet chamber 28. In particular, the oil flowing down near both ends of the side portion 32 of the oil passage traverses the rotation locus of the cam nose portion 36 of the intake cam and the exhaust cam formed on the cam shaft 24. Since a large amount of oil adheres to and is scattered around, a sufficient amount of oil is supplied to the working surface of the cam and the sliding contact surface of the bottom surface of the tappet 26 which cooperates. Therefore, even under harsh conditions such as the adoption of EGR as an exhaust gas countermeasure or the engine with a supercharger that has a large heat load and the oil quality generally tends to deteriorate, a large amount of oil is added to the intake cam and exhaust cam and to these. Since it is supplied to the sliding surface with the cooperating tappet, there is an advantage that abrasion of each cam and the bottom surface of the tappet can be reduced. Further, as a matter of course, the oil flowing down in the oil passage 30 simultaneously cools the outer wall of the tappet chamber 28, so that the lubrication between the outer peripheral cylindrical surface of the tappet 26 and the inner wall surface of the tappet chamber is improved.
There is also an advantage that the wear of the outer peripheral surface of the can be reduced. Further, since the oil passage having the substantially T-shaped cross section is integrally formed at the same time by casting when the crankcase is cast, there is an advantage that the manufacturing cost is low. Furthermore, since the oil passage forms a closed cross-section structure having a sufficient area, the rigidity of the crankcase is increased, and the operating noise of the engine is reduced.

(Effects of the Invention) As described above, the engine structure according to the present invention has a camshaft having a plurality of sets of intake cams and exhaust cams for controlling the opening and closing of the intake valve and the exhaust valve of each cylinder on the side of the crankcase. And a plurality of sets of intake-side tappet and exhaust-side tappet that are driven by the intake cam and the exhaust cam, in order to cause the oil that lubricates the valve mechanism to flow down from the cylinder head toward the oil pan, A leg formed by recessing between the pair of tappet chambers that respectively accommodate the intake side tappet and the exhaust side tappet and are connected on the cylinder side, and the wall surface of the pair of tappet chambers far from the cylinder and A substantially T-shaped oil passage having an opening at the lower end is formed in the crankcase and is composed of a side portion surrounded by an outer wall of the crankcase that is spaced from the wall surface. Characterized in that the cam nose portion of the intake cam and the exhaust cam is exposed in the side portion of the oil passage,
It is practically useful because it is possible to reduce the wear of the sliding parts of the intake cam and exhaust cam of the overhead valve engine and the tappet that cooperates with them, and improve the durability of the camshaft and tappet.

[Brief description of drawings]

1 is a transverse sectional view showing an embodiment of the present invention, and FIG. 2 is a sectional view taken along the line II-II in FIG. 10 …… Engine, 12 …… Cylinder, 14 …… Crankcase, 16 …… Oil pan, 18 …… Piston, 24 …… Cam shaft, 26 …… Tapet, 28 …… Tapet chamber, 30 …… Oil passage.

Claims (1)

[Scope of utility model registration request] 1. A camshaft having a plurality of sets of intake cams and exhaust cams for controlling the opening and closing of intake valves and exhaust valves of each cylinder on a side portion of a crankcase, and a plurality of sets of camshafts driven by the intake cams and exhaust cams. An intake side tappet and an exhaust side tappet are stored, and the intake side tappet and the exhaust side tappet are accommodated respectively in order to allow the oil lubricated in the valve operating mechanism to flow down from the cylinder head toward the oil pan. Legs formed by recessing between a pair of tappet chambers connected to each other, a wall surface of the pair of tappet chambers on the side remote from the cylinder, and a crankcase arranged at a distance from the wall surface. An oil passage having a substantially T-shaped cross section having an opening at the lower end is formed in the crankcase, and is formed by a side portion surrounded by an outer wall, and the intake air is introduced into the side portion of the oil passage. Engine structure characterized in that to face the cam nose portion of the arm and the exhaust cam