JPH04318258A - Oil-cooled multi-cylinder engine - Google Patents

Abstract

PURPOSE:To improve durability and reliability of a cylinder liner, provided with many oil grooves, by arranging supply oil holes so as to be opened from an internal wall surface, on which force based on a piston lap of the cylinder liner acts, to an external wall surface separated in a circumferential direction. CONSTITUTION:Oil, supplied to an oil supplying oil gallery 30, is allowed to flow in a circumferential groove 36 from supply oil holes 40 via vertical oil grooves 38a in an external wall surface of a cylinder liner 20, and the oil, after cooling the cylinder liner 20, flows down into an oil pan. On the other hand, cooling water flows in a cooling chamber in a cylinder head 14 to cool an exhaust port and an exhaust valve or the like. Here, the supply oil hole 40 is set to a predetermined angle theta relating to a center surface 0-0 containing an axial line of each cylinder and further drilled toward the center of each cylinder. Impact force based on a piston lap is applied to act on an internal wall surface of the cylinder liner 20 in a direction at a right angle relating to the above-mentioned center surface 0-0. In this way, a weak point surface of the cylinder liner is separated from an action surface of the above-mentioned impact force.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oil-cooled multi-cylinder engine in which the cylinder portions of the engine are cooled by oil.

0002

[Prior Art] In a multi-cylinder engine equipped with a cylinder liner such as a diesel engine for a vehicle, a large number of circumferential grooves or spiral grooves are provided on the outer wall surface of the hollow cylindrical liner. Oil-cooled multi-cylinder engines that circulate cooling oil have already been proposed. (For example, see Utility Model Registration Application No. 60967 of 1988) The typical cylinder liner mounting structure of the above-mentioned conventional oil-cooled multi-cylinder engine will be explained with reference to FIGS. 5 and 6.
In the figure, reference numeral 1 indicates a cylinder liner having a hollow cylindrical shape as a whole, and 2 indicates a cylinder bore portion of a crankcase 3 into which the cylinder liner 1 is fitted. The cylinder liner 1 has a flange portion 4 extending radially outward at one end portion on the cylinder head side, and a number of circumferential oil grooves on the outer wall surface in contact with the bore portion 2 of the crankcase. 5 is formed. In the oil groove 5 in the circumferential direction,
It includes both a circular or elliptical annular groove surrounding the outer wall surface of the cylinder liner 1 and a spiral groove carved into the liner outer wall surface with a small helical angle. The oil grooves 5 are communicated with each other by first and second vertical oil grooves 6a and 6b formed on the outer wall surface of the cylinder liner 1 and extending in the cylinder axial direction. And the second vertical oil grooves 6a and 6b are 1 in the circumferential direction, as clearly shown in FIG.
They are arranged at angular intervals of 80 degrees. The first vertical oil groove 6a is formed by a liner oil supply oil gear lary 7 which is drilled near the upper end of the crankcase 3 and extends in the direction of the crank axis, that is, parallel to the center plane 0-0 including the cylinder axis.
The oil supply hole 8 is connected to the oil supply hole 8. The oil supply hole 8 is
For convenience in drilling operations, the first and second vertical oil grooves are normally drilled in a direction perpendicular to the center plane 0-0, and therefore communicate with the oil supply hole 8, as shown in FIG. 6a and 6
b is also arranged in a plane substantially orthogonal to the crank axis 0-0. Further, the outer opening end of the oil supply hole 8 is closed by a plug 9 after drilling.

During operation of the engine, oil is supplied from an oil supply source such as a main oil gear (not shown) to the oil supply oil gear 7, and is supplied from the oil supply hole 8 to the first vertical oil groove 6a of each cylinder liner 1. , flows into a large number of circumferential oil grooves 5 communicating with the vertical oil groove 6a, flows into the left and right sides, goes approximately half way around the outer circumference of the liner, and flows out into the second vertical oil groove 6b, cooling the cylinder liner 1. do. In this configuration, when the piston reaches the vicinity of the vertical dead center, the acting force based on so-called piston slap, which is applied impactively from the inner wall surface of one cylinder liner to the inner wall surface of the other cylinder liner due to a change in acceleration, is 1 and 2nd vertical oil groove 6a
and 6b, there are concerns about the durability and reliability of the cylinder liner 1.

0004

SUMMARY OF THE INVENTION The present invention was proposed in view of the above-mentioned problems in conventional oil-cooled multi-cylinder engines. The purpose of this invention is to improve the durability and reliability of the cylinder liner by making improvements to the arrangement of the oil supply holes.

[0005]

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a plurality of circumferential oil grooves for circulating cooling oil on an outer wall surface and communicates with the oil grooves to form a cylinder. A cylinder liner provided with a vertical oil groove extending in the axial direction is fitted into the cylinder bore portion of the crankcase, and an oil gear lary for liner lubrication provided extending in the crank axial direction within the crankcase and the cylinder liner are provided. in which the vertical oil groove of the cylinder liner is communicated with the oil supply hole through the oil supply hole, and the oil supply hole is arranged so as to open on an outer wall surface that is circumferentially distant from the inner wall surface on which the force based on the piston slap of the cylinder liner acts. This paper proposes an oil-cooled multi-cylinder engine that is characterized by:

[0006]

[Operation] According to the present invention, the oil supply hole that supplies oil from the liner cooling oil gear to the oil groove in the circumferential direction of the cylinder liner outer wall surface is circular from the liner inner wall surface on which the force based on the piston slap of the cylinder liner acts. Since the cylinder liner is arranged to open on an outer wall surface separated in the circumferential direction, the weak point surface including the vertical oil groove on the outer wall surface of the cylinder liner connected to the oil supply hole opening does not coincide with the surface on which force is applied due to the piston slap. The durability of the cylinder liner is improved.

[0007]

Embodiments Examples of the present invention will be described in detail below with reference to FIGS. 1 to 4. In the figure, reference numeral 10 generally indicates a direct injection multi-cylinder diesel engine for trucks, and 12
1 is a crankcase of the engine, 14 is a cylinder head mounted on the upper end of the crankcase 12, and 16 is a well-known ladder frame or underframe that is mounted on the lower end of the crankcase 12 and has a substantially ladder-like planar shape. , 18 are the cylinder head 14 and the crankcase 12.
A large number of head bolts 20 extend parallel to the cylinder axis and tighten them together through the ladder frame 16 and are fitted into the cylinder bore 22 formed in the crankcase 12 and are hollow as a whole. A cylinder liner having a cylindrical shape, 24 is the same cylinder liner 20
A piston 26 fitted therein has a connecting rod 28 whose one small end is connected to the piston 24.
30 is a crankshaft connected to the other large end of the connecting rod 26, and 30 is a liner oil supply extending in the direction of the crank axis near the upper end of the crankcase 12 and connected to an oil pump (not shown). oil gear for
A main oil gear 32 is formed on a side wall portion of the crankcase 12 adjacent to the lower liner portion and extends in the crank axial direction.

[0008] The cylinder liner 20 is provided with a flange portion 34 extending radially outward at the end thereof on the cylinder head 14 side, and the outer wall surface excluding the flange portion 34 has a In the illustrated embodiment, a large number of circumferential oil grooves 36 are formed at appropriate intervals in the cylinder axis direction. These oil grooves 36 in the circumferential direction have an angular interval of approximately 180 degrees in the circumferential direction on the outer wall surface of the liner, as disclosed in detail in the previously proposed invention or device, for example, in Utility Model Application No. 62-60967. A first vertical oil groove 38a and a second vertical sleeve groove 3 are formed to extend in the cylinder axis direction.
It is divided into one or more appropriate number of passage groups by 8b. As clearly shown in FIG. 2, the liner oil supply oil gear rally 30 and the upper portion of the first vertical oil groove 38a are at an angle θ (as shown in the figure) with respect to the center plane 0-0 including the axes of the plurality of cylinders. The cylinders are connected by oil supply holes 40 for each cylinder, which are bored toward the center of the cylinders at an angle of about 50 degrees. The cooling oil supplied from the liner oil supply oil gear rally 30 to the upper part of the first vertical oil groove 38a through the oil supply hole 40 is divided into left and right sides in the circumferential direction, travels half a turn inside the circumferential groove 36, and passes through the oil supply hole 40 to the upper part of the first vertical oil groove 38a. 2 flows out into the vertical oil groove 38b. If there are two or more passage groups, the cooling oil that has flowed into the second vertical oil groove 38b of the first group then enters the inlet side vertical oil groove of the second group, and in the same way, the cooling oil of the second vertical oil groove 38b of the first group enters the inlet vertical oil groove of the second group. Circumferential groove 3
6 and flow directly into the oil pan from the oil outlet 42 provided in the lower part of the liner outer wall surface, or directly into the oil pan, or
The oil is collected in an oil discharge gear 44 shown by a dotted line and flows down into the oil pan. The oil discharge gear rally 44 is drilled in the side wall of the crankcase 12 so as to extend in the crank axial direction, similarly to the liner oil supply oil gear rally 30 described above.

Further, in this embodiment, as clearly shown in the partially enlarged cross-sectional view of FIG. The upper surface 34b abuts against the lower surface of the cylinder head 14 via a suitable gasket, such as a thin laminate gasket 46. In FIG. 2, reference numeral 48 indicates a bolt hole through which the head bolt 18 is inserted, 50 indicates an outer wall surface of the crankcase 12 in the cylinder bore portion, and 52 indicates a plug attached to the outer drilling end of the oil supply hole 40. be.

In the above configuration, while the engine 10 is operating, the oil is supplied to the oil supplying oil gear gallery 30 by the oil pump (not shown), and the oil is supplied from the oil supply hole 40 to the oil supply holes 40 formed on the outer wall surfaces of the liners 20 of the plurality of cylinders. The oil flows through the first vertical oil groove 38a and inside the circumferential groove 36 as described above, cools the liner, and then flows down into the oil pan. on the other hand,
A cooling water chamber 54 is provided inside the cylinder head 14 (see FIG. 1), and cooling water pumped by a water pump (not shown) flows through the cooling water chamber 54 inside the cylinder head 14 and is exhausted. After cooling the ports, exhaust valves, etc., the water is returned to the water pump via the radiator.

Now, as mentioned above, the oil supply hole 40 is formed toward the center of the cylinder at an angle θ with respect to the center plane 0-0, and on the other hand, the impact force due to the piston slap generally traverses the center line of each cylinder. Since the force acting on the inner wall surface of the cylinder liner in the direction perpendicular to the center plane 0-0, the opening of the oil supply hole 40 facing the outer wall surface of the cylinder liner 20 is sufficiently circumferentially away from the surface on which the force based on the piston slap acts. In other words, the weak point surface of the cylinder liner 20 passing through the first vertical oil groove 38a and the second vertical oil groove 38b communicating with the oil supply hole 40 is far away from the surface on which the force based on the piston slap is applied. As a result, the durability and reliability of the cylinder liner 20 are significantly improved.

In the case of the illustrated embodiment, the flange portion 3 of the cylinder liner 20 is
4 is placed directly on the crankcase upper surface 12a,
As shown in FIG. 5, compared to the normal structure in which the cylinder liner flange part 4 is fitted into the counterbore part 3' provided in the crankcase 3, the crankcase upper surface 12a
and the cylinder liner upper surface of the plurality of cylinders, that is, the flange portion upper surface 34b, the fluctuation in height is significantly reduced,
There are additional benefits that can effectively improve the performance of the cooling oil seal and gas seal. This means that the machining accuracy in the depth direction of the counterbore portion 3' in FIG. This is based on the fact that it is low. Furthermore, in the illustrated embodiment, there is no need to machine a counterbore part for receiving the flange part 34 of the cylinder liner 20 into the crankcase 12, so it is possible to reduce the machining cost commensurate with the counterbore machining cost. It's self-evident.

Furthermore, in the above embodiment, the circumferential groove 36 for circulating the cooling oil is formed on the outer wall surface of the cylinder liner 20.
However, the present invention can of course be applied to a case where a spiral groove is provided on the outer wall surface of the cylinder liner 20. Further, in the present invention, the circulation pattern of the cooling oil is changed in various ways, such as by partially changing the cross-sectional area or changing the arrangement interval of the circumferential groove or the spiral groove according to the heat load on each part of the cylinder liner. Can be widely applied to all engines with oil-cooled liners.

0004

Effects of the Invention As described above, the oil-cooled multi-cylinder engine according to the present invention has a large number of circumferential oil grooves for circulating cooling oil on the outer wall surface, and communicates with the oil grooves. A cylinder liner provided with a vertical oil groove extending in the direction of the cylinder axis is fitted into the cylinder bore of the crankcase, and an oil gear lubricant for liner lubrication provided extending in the direction of the crankshaft is provided in the crankcase, and the above The vertical oil groove of the cylinder liner is communicated with the oil supply hole through the oil supply hole, and the oil supply hole is arranged to open on the outer wall surface that is circumferentially distant from the inner wall surface on which the force based on the piston slap of the cylinder liner acts. This feature is industrially useful because it can improve the durability and reliability of a cylinder liner that has a large number of oil grooves for circulating cooling oil on its outer wall surface.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing one embodiment of the present invention.

FIG. 2 is a plan view of the upper surface of the crankcase of the engine shown in FIG. 1;

FIG. 3 is an enlarged sectional view of the cylinder liner attachment portion of the engine shown in FIG. 1;

FIG. 4 is a partial plan view of the cylinder liner including a cross-sectional view taken along line IV-IV in FIG. 3;

FIG. 5 is an enlarged sectional view of a cylinder liner attachment portion in a conventional oil-cooled engine.

[Figure 6] A plane perpendicular to the cylinder axis of a conventional engine (
6 is a cross-sectional view taken along line VI-VI in FIG. 5. FIG.

[Explanation of symbols]

10 Multi-cylinder engine 12 Crank case 14 Cylinder head 16 Ladder frame 20 Cylinder liner 30 Oil gear for liner oil supply 36
Circumferential oil grooves 38a and 38b Vertical oil groove 40 Oil supply hole

Claims (1)

[Claims] 1. A cylinder liner having a plurality of circumferential oil grooves for circulating cooling oil on an outer wall surface and a vertical oil groove communicating with the oil grooves and extending in the cylinder axial direction, A liner oil supply oil gear fitting fitted into a cylinder bore of a crankcase and extending in the crank axial direction within the crankcase communicates with a vertical oil groove of the cylinder liner through an oil supply hole,
An oil-cooled multi-cylinder engine characterized in that the oil supply hole is arranged so as to open in an outer wall surface that is circumferentially distant from the inner wall surface on which a force based on the piston slap of the cylinder liner acts.