JPS6346257B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a water-cooled internal combustion engine equipped with a water jacket.

Conventionally, in this type of internal combustion engine, a cylinder block is constituted by an inner wall having a cylinder hole and an outer wall surrounding the inner wall and defining a part of the water jacket between the inner wall and the inner wall. It is known that a cylinder head is joined to the upper end, and a head cover is joined to the upper end of the outer wall, the head cover covering the cylinder head and defining the other part of the water jacket therebetween. Since the upper ends of the inner and outer walls are formed on the same plane, machining and assembly of the joint between the inner wall and the cylinder head is difficult due to interference with the outer wall.

The present invention has been proposed in view of the above, and an object of the present invention is to provide an internal combustion engine that can eliminate the above-mentioned conventional drawbacks, is lightweight, and has a good appearance.

To achieve this object, the present invention comprises a cylinder block comprising an inner wall having a cylinder hole and an outer wall surrounding the inner wall and defining a part of the water jacket therebetween. a head cover having an upper end of the outer wall lower than an upper end of the inner wall, a cylinder head joined to the upper end of the inner wall, covering the cylinder head and defining another portion of the water jacket therebetween; is joined to the upper end of the outer wall, the cylinder block is made of a single iron-based material, and the head cover is made of a light alloy.

An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, a V-type two-stroke internal combustion engine E is mounted on a body frame F of a motorcycle.
The crankshaft 1 of this engine E and the output shaft 2 of the transmission driven by it are arranged parallel to the axles of the front and rear wheels Wf, Wr, and the output shaft 2 connects the rear wheels Wr through a chain transmission 3. drive

Engine E has first and second engine blocks that have a bank angle of 90 degrees to each other around crankshaft 1.
The first engine block Ea is arranged substantially horizontally so as to face the front of the vehicle, and the second engine block Eb is disposed substantially vertically so as to face upward.

As shown in Figure 2, each engine block Ea,
Eb consists of a common crankcase 4 that supports the crankshaft 1, and a cylinder block 5 fixed to the common crankcase 4 by bolts (not shown), and the cylinder block 5 has an inner wall forming a cylinder hole 7 into which a piston 6 slides. 8, and engine blocks Ea, Eb surrounding this inner wall 8 and between it.
The outer wall 9 defines a part of the water jacket 10, and the upper end of the outer wall 9 is connected to the inner wall 8.
In the illustrated example, it is lowered to a position close to the intake and exhaust ports of the cylinder block 5. A thread is cut on the outer periphery of the upper end of the inner wall 8 which protrudes outward from the upper end of the outer wall 9, and the cylinder head 12 is screwed onto the inner wall 8 via this thread. Therefore, the above-mentioned thread cutting and screwing of the cylinder 12 can be carried out without being hindered by the outer wall 9 in any way.

In the illustrated example, the cylinder block 5 and the cylinder head 12 are made of a single iron-based material with high wear resistance and heat resistance and a low coefficient of thermal expansion, such as cast iron, and the head cover 15 is made of a light alloy, such as an Al alloy. configured. In this way,
Adoption of the step structure at the upper ends of the inner and outer walls 8, 9 reduces the amount of iron-based materials with high specific gravity, which is effective in obtaining lightweight engine blocks Ea, Eb with less thermal distortion of the cylinder block 5. It is.

The cylinder head 12 cooperates with the piston 6 to define a combustion chamber 13, and an ignition plug 14 with an electrode facing the combustion chamber 13 is screwed onto a boss portion 12a at the center of the cylinder head 12. Also, boss part 1
A mounting hole 16 provided at the center of a head cover 15 that covers the cylinder head 12 is fitted into the cylinder head 2a.
Further, a nut 17 is screwed onto the boss portion 12a to press the head cover 15 to the upper end of the outer wall 9. A head cover 15 defines the other portion of the water jacket 10 between it and the cylinder head 12.

At the bottom of the V-shaped groove 19 sandwiched between the first and second engine blocks Ea, Eb, the blocks Ea,
A water pipe 18 is provided to distribute cooling water to the water jacket 10 of Eb. The water pipe 18 has a tapered shape as shown in FIG. Connecting short pipes 22, 23 connected to the respective water jackets 10 of the second engine blocks Ea and Eb, and the water jacket 1 of the first engine block Ea located on the smaller diameter side than the inlet 20.
A connecting end tube 22 continuous to 0 is integrally formed. The illustrated water pipe 18 is for a three-cylinder engine in which the first engine block Ea has two cylinders and the second engine block Eb has one cylinder, so there are two connection short pipes 22 on the first engine block Ea side. , the connecting end pipe 23 on the second engine block Eb side is one. The water pipe 18 has its mounting protrusion 21 fixed to the outer wall of the crankcase 4 with bolts 24 (see Fig. 4), and a knock pin 25 is attached to the water pipe 18 and the crankcase 4 to define the fixed position. Both halves are fitted into each other.

The connecting short pipes 22 and 23 of the water pipe 18 extend parallel to the axes of the corresponding engine blocks Ea and Eb, respectively, and are tightly fitted into the inlet pipe 26 at the bottom of the corresponding cylinder block 5. The connecting short pipes 22 and 23 have the function of communicating between the water pipe 18 and the water jackets 10 of the first and second engine blocks Ea and Eb, and also have the function of communicating between the crankcase 4 and the first and second engine blocks Ea and Eb.
It also has a positioning function that defines the joining position of engine blocks Ea and Eb with each cylinder block 5.

Head cover 1 for both engine blocks Ea and Eb
5, an outlet pipe 27 is formed on the side facing these, and these outlet pipes 27 are connected to the inlet of a radiator 29 mounted on the front surface of the vehicle body frame F via a conduit 28, and the outlet of the radiator 29 is connected to the conduit. 30
The water pump 31 is connected to the suction port of the water pump 31 provided at the bottom of the crankcase 4 through the
The outlet is connected to the inlet 2 of the water pipe 18 via the conduit 32.
Connected to 0.

Therefore, the water cooled by the radiator 29 is sucked in by the water pump 31 and sent under pressure to the water pipe 18, from which it flows to both engine blocks.
Ea and Eb are distributed into the water jackets 10 to cool each cylinder block 5 and cylinder head 12, and then flowed out of the outlet pipe 27 and returned to the radiator 29.

A water flow regulating plate 33 is provided within the water jacket 10. As shown in FIG. 3, this water flow regulating plate 33 has an annular shape that fits the outer circumferential surface of the cylinder head 12 and the inner circumferential surface of the head cover 15. A notch 34 is provided on the opposite side from 27. This water flow regulating plate 33 is fixed to the head cover 15 with a plurality of bolts 35. At the time of fixing, the notch 34 enters and the normal position of the water flow regulating plate 33 is made to make it impossible to attach the head cover 15 of the water flow regulating plate 33 at a position other than the normal position opposite to the outlet pipes 26 and 27. Only in this case, a misassembly prevention protrusion 36 that protrudes into the notch 34 is integrally formed on the inner wall of the head cover 15. That is, when the water flow regulating plate 33 is attempted to be attached to the head cover 15 at a position other than its normal position, the misassembly prevention protrusion 36 is inserted into the notch 3 of the water flow regulating plate 33.
This prevents incorrect assembly by interfering with the side edges that do not have 4.

Therefore, the water flow regulating plate 33
is divided into a lower jacket 10a on the inlet pipe 26 side and an upper jacket 10b on the outlet pipe 27 side, and these two jackets 10a, 10b are communicated via a notch 34 on the opposite side to the inlet and outlet pipes 26, 27. let Therefore, the cooling water sent from the inlet pipe 26 to the lower jacket 10a passes through the notch 34 to the upper jacket 10b, and then flows into the outlet pipe 27.
Therefore, the cooling water flows throughout the water jacket 10 from the inlet pipe 26 to the outlet pipe 27 without shorting, and can effectively cool the cylinder block 5 and cylinder head 12.

In FIG. 1, C is a carburetor and A is its air cleaner.

FIG. 6 shows another embodiment of the invention, in which the cylinder head 12 is fixed to the cylinder block 5 by bolts 37, with a gasket 38 interposed between the cylinder head 12 and the cylinder block 5. The outer periphery is extended like a brim,
This embodiment is the same as the previous embodiment except that the water flow regulating plate 33 is formed by the extension.

As described above, according to the present invention, the upper end of the outer wall of the cylinder block is formed lower than the upper end of the inner wall, and the cylinder head is joined to the upper end of the inner wall that protrudes outward from the upper end of the outer wall. Therefore, the processing and assembly of these joints can be easily performed without being hindered by the outer wall, and productivity can be improved.

In addition, since the cylinder block is made of a single iron-based material and the head cover is made of a light alloy, the head cover is made of light alloy, which makes it particularly lightweight, and the upper end of the outer wall of the cylinder block is made closer to the upper end of the inner wall. The synergistic effect of the lower head cover and the extension of the lightweight head cover toward the cylinder block makes it possible to significantly reduce the weight of the entire engine block while maintaining the cylinder block's heat-resistant strength. The elongation effect of the light alloy head cover also improves the appearance of the engine.

[Brief explanation of drawings]

FIG. 1 is a side view of a motorcycle equipped with an internal combustion engine embodying the present invention, FIG. 2 is an enlarged longitudinal side view of the main parts of the internal combustion engine, and FIGS. 3 and 4 are the - and - lines in FIG. 5 is a plan view of the water pipe of the engine, and FIG. 6 is a longitudinal sectional view of the main parts of the engine showing another embodiment of the present invention. 7... Cylinder hole, 8... Inner wall, 9... Outer wall, 10... Water jacket, 12... Cylinder head, 15... Head cover.

Claims (1)

[Claims] 1 The cylinder block 5 is constituted by an inner wall 8 having a cylinder hole 7 and an outer wall 9 surrounding the inner wall 8 and defining a part of the water jacket 10 therebetween. The upper end is formed lower than the upper end of the inner wall 8, a cylinder head 12 is joined to the upper end of the inner wall 8, and the other part of the water jacket 10 is defined between the cylinder head 12 and the cylinder head 12. An internal combustion engine in which a head cover 15 is joined to the upper end of the outer wall 9, the cylinder block 5 is made of a single iron-based material, and the head cover 15 is made of a light alloy.