JPS60119350A - Engine casing for four cycle engine - Google Patents

Abstract

PURPOSE:To increase the strength of an engine casing for a four cycle engine and as well to aim at making the casing lightweight, by constituting a casing body with a monoblock case which is integrally formed extending from a cylinder head section to a crank case section by way of a crank case section. CONSTITUTION:An engine casing body 1 in a four cycle engine for a motor-cycle is composed of an upper cylinder head section 2, an intermediate cylinder section 3, an intermediate section 3 and a mission section 4a extending rearward below the engine. The casing body 1 is formed of a monoblock casing which is integrally formed of, for example, cast magnecium alloy, extending from the cylinder head section 2 to the crank casing section by way of the cylinder section 3.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an engine case for a four-stroke engine mainly used in two-wheeled motor vehicles.

Conventionally, in this type of engine, the cylinder head part,
Generally, the cylinder part, upper case part, and lower case part of the crankcase are formed separately, and these are fastened together using tightening bolts to form the engine case, and the assembly is easy. It is troublesome and also tends to cause distortion on the mating surfaces of these parts and the surrounding areas, so as a countermeasure, we have developed a tightening section.

It is necessary to add extra material to necessary areas such as around the mating surfaces, which often results in an increase in weight.

In order to eliminate such inconveniences, the first aspect of the present invention aims to provide a lightweight engine case with high strength that eliminates the need for fastening work of each part, and the first aspect of the present invention is to It is characterized by a monoblock case that is integrally formed between the cylinder part and the crankcase part.

The object of the second invention is to improve the ease of assembling the crankshaft in the first invention. an opening for mounting an oil pan is formed at a position facing the crankshaft, and an assembly in which a piston is attached to a crankshaft can be inserted into and removed from the case body through the opening; It is characterized by being pivotally supported by a holder separate from the case body to which it is attached.

Next, the present invention will be explained with reference to the illustrated embodiments.

In the drawings, Fil is a motorcycle 4 which includes an upper cylinder head part +21, an intermediate cylinder part (3), and a crankcase part (4) including a lower, rearwardly extending transmission case part (4a). The case body of the cycle engine is shown, and the case body tll is formed by casting molding of a magnesium alloy, for example, from the cylinder head part (2) to the cylinder part (3) according to the characteristics of the present invention. It shall consist of a monoblock case integrally molded over the crankcase part +41, and the bore (3a) of the cylinder part (3) on the lower surface of the crankcase part (4).
As shown in Figures 4 and 5, install the oil pan (
5) is formed, and the assembly in which the piston (8) is assembled to the crankshaft (7) is inserted into the opening (6).
), and the crankshaft (7) is supported by a holder (9) that is removably attached to the crankcase portion (4).

The holders (9) are provided in a pair on both sides of the crankshaft (7) in the axial direction, and each holder (9) is connected to a split surface passing through the shaft support hole (9a) of the crankshaft (7). The block is assembled into the crankshaft (7) and inserted through the opening (61) into the lower end of the cylinder portion (3) as shown in FIGS. 4 and 5. As shown in FIG.
It was supposed to be installed using Ille.

Explosive load and inertia from the piston (8) act on each holder (9), and in this case, if this is a split type, it will be struck by the split surface, open one opening, and be pivoted. Hole (9a
), but by constructing it with an integral block as shown in "2", such inconveniences can be prevented.Also, by constructing the case body with a monoblock case, the shift cylinder part (3) There is no need for tightening bolts between the holder and the crankcase portion (4), and each holder (9) can be mounted without interference with these bolts.

In the drawing, 02) indicates a cylinder liner, and the liner (1,
21 is inserted into the bore (6a) of the cylinder part (3) from below and screwed into the threaded part (12a) on the outer periphery of the lower part of the cylinder part (3). The inner diameter of the liner was also narrowed so that it could also be used as a liner holder facing the lower end of the liner.

Note that narrowing the span in this way is also advantageous in increasing the support rigidity of the crankshaft (sword).In addition, in the illustrated case, a water cooling jacket 03 is formed on the cylinder portion (3), and the cylinder head portion ( 2), three intake valves 060 and two exhaust valves 05) are arranged radially to form a water-cooled multi-valve four-stroke engine, as shown in Fig. pump σ6
camshafts a and a+ are driven from the drive shaft (16a) of ) via the force of the timing belt a, and the negative side of the transmission case part (4a), which integrally extends rearward from the crankcase part (4), is opened. When the mission mechanism a is assembled to the mission holder (201) covered on the open surface, the mission case part (4a
).

In the drawing, 021) is a head cover that is removably attached to the cylinder head (2), and (22) is a case body (1).
The side cover (, t23) attached to the -side of ) is the oil pump, (2 is the breather joint, (2ω is the engine part to which the motorcycle body A is attached, (2fi) is the carburetor) show.

As described above, according to the present invention, the case body is constructed of a monoblock case that is integrally molded from the cylinder head to the cylinder and crankcase, which eliminates the need for tightening these parts and improves engine performance. This makes the assembly work easier, eliminates the need for animal meat to reinforce the mating surfaces and tightening parts, and together with the reduction in the number of bolts used, the engine can be made as light as possible, and the case rigidity is also increased. This also eliminates the need for stud bolts that connect the cylinder head and cylinder, increasing flexibility in the design of pulp and boat layouts, which had previously been restricted in order to avoid interference, and allowing for multiple valves and multiple valves. It becomes easier to construct a boat, introduce a device on the valve body, etc., and also has the effect that cooling performance can be expected to be improved.

Furthermore, according to the second invention, an opening for mounting the oil pan is formed on the lower surface of the crankcase portion, facing the bore of the cylinder portion.
A crankshaft and piston assembly is freely inserted into and removed from the case body through the opening, and the crankshaft is pivotally supported by a holder separate from the case body that is detachably attached to the crankcase portion. Although the case body is composed of a monoblock case, the crankshaft can be easily assembled into the case body without compromising maintenance, and the opening for installing the oil pan is connected to the crankshaft insertion/removal port. This is advantageous because it does not cause problems such as a decrease in the rigidity of the case or an increase in the number of parts such as a lid to cover it, unlike when a separate opening for inserting and removing the crankshaft is formed. have an effect.

[Brief explanation of the drawing]

1 and 2 are side views of a four-stroke engine to which the present invention is applied, seen from one side and the other, and FIG.
1-III truncated line cross-sectional view Figure 4 is IV-IV in Figure 6.
5 is a bottom view of the case body, and FIG. 6 is a plan view of the cylinder head. fi+...Case body (2)...Cylinder head (3)...Cylinder part (3a)...Bore (4
)...Crankcase part (5)...Oil nozzle (6)...Opening (7)...Crankshaft (
81...Viston (9)...Holder (9
a)...Written amendment for two persons outside the shaft hole (5th edition March 22, 1980, Mr. Commissioner of the Japan Patent Office, 1, Indication of the case, 1982 Patent Application No. 2254 (1 [1 No. 2, Title of the invention) 4-cycle engine engine case 3, relationship with the case of the person making the amendment Patent applicant 532 Honde Giken Kogyo Co., Ltd. 4, agent

Claims (2)

[Claims] 1. An engine case for a 4-cycle engine, characterized in that the case body of the 4-stroke engine is constituted by a monoblock case that is integrally molded from a cylinder head section to a cylinder section and a crankcase section. 2. In a case body of a 4-cycle engine, which is composed of a monoblock case that is integrally molded from the cylinder head section to the cylinder section and crankcase section,
An opening for attaching an oil pan is formed in the case body at a position facing the bore of the cylinder portion on the lower surface of the crankcase, and an assembly including a piston attached to the crankshaft can be freely inserted into and removed from the case body through the opening. An engine case for a four-cycle engine, characterized in that the crankshaft is pivotally supported in a holder separate from the case body and detachably attached to the crankcase portion. 6. The engine case for a four-cycle engine according to claim 2, wherein the holder is constructed of an integral block having no split surface that passes through the shaft support hole of the crankshaft.