JPH02301613A - Liquid-cooled engine - Google Patents

Abstract

PURPOSE:To form a coolant jacket without decreasing stiffness of a cylinder block, especially in its top dead center side, by forming the coolant jacket so as to draft a molding pattern from a crankcase side. CONSTITUTION:In an engine 1, a coolant jacket 35 is defined at positions adjoining an upper portion and both sides of a cylinder bore 7 in a cylinder block 1b. The coolant jacket 35 is made as a cavity made with a metal pattern which is draftable along a cylinder axis from an inside of a skirt 1c defining a crankcase, and makes a tight chamber by closing an aperture 36, which is left at the inside of a skirt 1c after drafting the metal pattern, with a horseshoe-shaped cover 37. By this constitution, the coolant jacket 35 can be formed without opening a cylinder head 1a side of the cylinder block 1b. Consequently, stiffness of the cylinder block 1b is improved without increasing its wall thickness.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] <Industrial Application Field> The present invention relates to a liquid-cooled engine in which a coolant jacket in which a coolant circulates is defined around a cylinder.

<Prior art> In engines that use a liquid such as water or oil as a medium for heat exchange around the cylinder, a jacket is formed around the cylinder to allow the coolant to flow through. (Refer to Utility Model Application Publication No. 58-37920, etc.)
. In the case of an engine with a structure in which the cylinder block and cylinder head are formed separately, this coolant jacket is made by cutting out a male mold along the cylinder axis from the joint surface side of the cylinder head in the cylinder block. It is common to be formed.

<Problems to be Solved by the Invention> Incidentally, the cylinder has the highest temperature near the combustion chamber and is subjected to high thermal stress. Therefore, especially in the case of a cylinder pro-tsuku where the coolant jacket has an annular opening at the joint surface with the cylinder head, it is necessary to make the same part thicker in order to ensure rigidity near top dead center. I have to let it go. At the same time, in order to prevent leakage of coolant into the combustion chamber from the joint surface between the cylinder head and the cylinder block, extremely high processing and assembly precision is required, which tends to increase manufacturing costs.

The present invention was made to solve the problems of the prior art, and its main purpose is to form a coolant jacket without reducing the rigidity of the cylinder block, especially on the top dead center side. Our goal is to provide liquid-cooled engines.

According to the present invention, an object of the present invention is to provide a liquid-cooled engine in which a coolant jacket in which coolant circulates is defined around a cylinder. This is achieved by providing a liquid-cooled engine characterized in that the coolant jacket is formed by cutting out a mold from the crank chamber side of the engine.

In particular, the coolant jacket is formed with a mold that is drawn out along the axial direction of the cylinder, and the opening of the coolant jacket facing the crank chamber is closed with a lid member. Alternatively, the cylinder head and cylinder block may be formed by integral casting, or the coolant may be a lubricating oil for lubricating the engine.

<Function> In this way, the cooling liquid jacket can be formed without opening the top dead center side of the cylinder block, so the rigidity of this part can be increased without increasing the thickness, and the cooling liquid jacket can be increased without increasing the thickness of the cylinder block. Leakage into the combustion chamber can be completely prevented. In particular, productivity is further improved by molding the coolant jacket or integrally casting the cylinder head and cylinder block.

Furthermore, if the cooling fluid and lubricating oil are used in common, even if leakage occurs from the Yoshiba cooling fluid jacket, the actual damage will be extremely small.

<Embodiments> Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 and 2 show a vertical crankshaft, oil-cooled, single-cylinder engine constructed according to the present invention. This engine 1 includes a cylinder head portion 1a, a cylinder block portion 1b, and a crankcase skirt portion I.
C and are formed by integral casting.

A crankcase 2 is bolted to the opening of the skirt IC, and a pair of sliding bearings 3a and 3 are formed at the joint between the skirt IC and the crankcase 2.
b supports the crankshaft 4 along the vertical direction. A piston 8, which is fitted into a cylinder bore 7 formed by integrally casting a cylinder liner 6 into the cylinder block part 1b, is attached to a crank pin 5 formed approximately at the center of the crankshaft 4, and a connecting rod 9. are connected via.

A flywheel 10 is fixed to the upper end of the crankshaft 4. The flywheel 10 is formed by integrally joining two divided bodies that can be divided in the axial direction of the crankshaft 4, and a heat dissipation passage 11 is provided on one of the joining surfaces of the two parts.
is formed.

As shown in FIG. 3, the heat dissipation passage 11 includes a circumferential passage 11a defined by partition walls 12 arranged concentrically, and a radial passage 11 formed by appropriately dividing the partition walls 12.
b, it has a labyrinth shape, and an inlet 13 and an outlet 14 are opened on the inner circumference side and the outer circumference side, respectively.

Furthermore, heat radiation fins 15 are integrally formed on the outer end surface of the flywheel 10 in the axial direction, and are designed to cool the cooling liquid flowing through the heat radiation passage 11 having a labyrinth shape. Further, a permanent magnet 16 is fixed to a part of its outer periphery, and works in conjunction with an ignition device (not shown) fixed to the cylinder block side to generate the required ignition spark at a predetermined timing. is being used.

As shown in FIG. 4, a balancer shaft 1 is provided at the joint between the skirt portion 1c and the crankcase 2 in parallel with the crankshaft 4.
7 is supported. The balancer shaft 17 is connected to the crankshaft 4 through a gear means 18, and is driven to rotate at the same speed and in the opposite direction to the crankshaft 4, and
This cancels out the primary excitation force caused by the eccentricity of the part.

Furthermore, a displacement pump 19 of a known type is attached to one end of the balancer shaft 17 (lower end in FIG. 4), and lubricating oil is sucked from a lubricating oil tank 20 disposed on the right side of the crankcase 2. can be pumped to various parts as will be described later.

A head cover 21 is bolted to the opening of the cylinder head portion 1a. A pair of sliding bearings 22a and 22b are formed at the joint between the cylinder head portion 1a and the head cover 21.
A camshaft 23 extending parallel to the crankshaft 4 is supported by both ends thereof by a and 22b. This camshaft 23 has a cam pulley 24 integrally formed on its lower end side, and a crank pulley 25 fixed to the crankshaft 4.
The crankshaft 4 is driven at a rotational speed of 172 degrees via a timing belt 26 wound between the crankshaft 4 and the timing belt 26 wound between the crankshaft 4 and the timing belt 26 wound between the crankshaft 4 and the timing belt 26 wound therebetween. Further, this timing belt 26 is built into a belt chamber 27 that is configured to be adjacent to the lower part of the cylinder bore 7 in the cylinder block portion 1b so as to communicate the inside of the crankcase 2 and the inside of the head cover 21 with each other. There is.

The cylinder head portion 1a is provided with an intake valve 29 and an exhaust valve 3o, which are normally biased in the valve-closing direction by valve springs 28a and 28b, respectively. These two valves 29 and 3o are arranged in parallel at appropriate intervals in a plane parallel to the crankshaft 4, and the direct lifters 31a and 3o are connected to a pair of cams 23a and fist 23b formed on the camshaft 23. 31b, and are driven to open and close at appropriate timings according to the rotation of the crankshaft 4.

Further, an intake boat 32 is opened on one side (lower side in FIG. 2) of the cylinder head portion 1a, and an exhaust port 33 is opened on the other side (upper side in FIG. 2). A carburetor is directly connected to the opening of the intake boat 32,
A muffler is directly connected to the opening of the exhaust port 33.

As shown in FIG. 5, a cooling liquid jacket 35 is formed in a portion of the cylinder block portion 1b adjacent to the upper side and both sides of the cylinder bore 7. As shown in FIG. The coolant jacket 35 is composed of a cavity formed with a mold that can be punched out from the inside of the skirt IC defining the crank chamber along the cylinder axis to the right in FIG. The opening 36 on the inner surface of the skirt IC is closed with a cover plate 37 having a generally horseshoe shape, thereby creating a sealed space. Further, a small hole 38 communicating with the crank chamber is provided in a portion of the cover plate 37 corresponding to the lowest bottom of the coolant jacket 35 (FIG. 4).

Next, the lubricating oil passage will be explained with reference mainly to FIGS. 1 and 4. The lubricating oil passage is connected to the lower crank bearing 3b.
A first connection path 53 that communicates between the outer peripheral portion of the crank journal and the discharge port of the pump 19 is formed by sealing the portion adjacent to the oil seal 52- with an oil seal 52-; A passage 54 in the crankshaft provided
and a first connecting hole 55 bored in the crankshaft 4 to communicate between the crankshaft internal passage 54 and the first connecting path 53.
and a second connecting hole bored in the fitting portion of the crankshaft 4 with the flywheel 10 to communicate between the upper end side of the crankshaft internal passage 54 and the coolant inlet 13 of the flywheel 10 described above. 56, and a second hole bored from the coolant outlet 14 to the crankshaft fitting hole 57 of the flywheel 10.
The connecting passage 58 and the upper crank bearing 3 are connected from the portion adjacent to the upper crank bearing 3a into the coolant jacket 35.
The third connecting passage 59 installed inside the boss part of the cylinder head part 1a extends from the cylinder head b of the coolant jacket 36 to the upper cam bearing 22a.
It consists of a fourth connecting path 60 installed inside.

Next, I will explain the flow of lubricating oil. The lubricating oil discharged from the pump 19 flows from the first connection path 53 into the crankshaft internal passage 54 via the first connection hole 55 . At this time, lubricating oil is also supplied to the lower crank bearing 3b. Furthermore, the crankshaft internal passage 54 also opens to the crank bin 5.
As a result, lubricating oil is also supplied between the crank bin 5 and the large end of the connecting rod 9.

The lubricating oil that has traveled up the crankshaft internal passage 54 flows into the heat radiation passage 11 through the second connecting hole 56 and is cooled.
From the second connecting passage 58, the air passes through the gap 61 between the crankshaft fitting hole 57 of the flywheel 10 and the portion of the crankshaft 4 adjacent to the outside of the upper crank bearing 3a, and the third connecting passage 59 into the coolant jacket 35. flows into. It cools the surroundings of the cylinder, and flows into the head cover 21 from a passage 63 formed in the portion of the camshaft 23 supported by the upper cam bearing 22a via the fourth connecting passage 60, and lubricates the valve train. . Further, when returning to the crankcase 2 side via the belt chamber 27, the lower portion of the cylinder is cooled.

On the other hand, the coolant also flows down into the crankcase 2 through the small hole 38 of the cover plate 37 and returns into the tank 20. In this way, with the flow rate of the fourth connecting path 60 and the small hole 38,
The flow rate of the lubricating oil as the coolant in the coolant jacket 35 is set appropriately.

In the above embodiment, the coolant jacket 35 is formed using a mold, but it can also be formed using a sand mold. Since there is no need to open the entire surface, the cover plate 37 can be omitted.

[Effects of the Invention] As described above, according to the present invention, since the coolant jacket is formed by cutting from the crankcase side, there is no risk that the rigidity of the cylinder block on the top dead center side will decrease. In particular, if the present invention is applied to an engine having a structure in which a cylinder head and a cylinder block are integrally cast as shown in the above embodiment, the engine can be manufactured with extremely high productivity. Furthermore, since the cylinder block can be made thinner, it is highly effective in reducing manufacturing costs. In addition, by sharing the coolant and lubricating oil, even if there is a defect in the seal of the coolant jacket, the coolant will leak into the crankcase, which will especially prevent operational problems. do not have.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of an engine constructed according to the present invention, and FIG. 2 is a partially cutaway top view. Figure 3 is an end view taken along the line ■-■ in Figure 1;
The figures are an end view taken along the same <: mV-TV line, and FIG. 5 is a cutaway sectional view taken along the same <V-V line. 1...Engine 1a...To cylinder/rod part 1b...Cylinder block part IC...Skirt part 2...Crank case 3a
・3b... Bearing 4... Crankshaft 5... Crank bin 6... Cylinder liner 7... Cylinder bore 8... Piston 9... Connecting rod 1
0... Flywheel 11... Heat radiation passage 11
a... Circumferential passage 11b... Radial passage 12...
・Partition wall 13...Inflow port 14...Outflow port 15
...Radiating fin 16...Permanent magnet 17...Balancer shaft 18...Gear means 19...Pump
20...Tank 21...Head cover 228
・22b...Bearing 23...Camshaft 23a・
23b...Cam 24...Cam pulley 25...
Crank pulley 26...timing belt 27...belt chambers 28a, 28b...valve spring 29...intake valve 30...exhaust valve 31a, 31b...direct lifter 32...intake port 33. ...Exhaust port 35...Cooling liquid jacket 36...Opening 37...Lid plate 38...Small hole 52...Oil seal 5 colors...Logic 1 passage 54...Crankshaft internal passage 55...First connection hole 56...Second connection hole 57...Fitting hole
58...Second connecting road 59...Third connecting road 60
...Fourth connecting path 61...Gap 63...
Applicant: Honda Motor Co., Ltd.
Patent Attorney Yo Oshima - Figure 3 Figure 1￥4 Figure 5

Claims (4)

[Claims] (1) A liquid-cooled engine in which a coolant jacket through which coolant circulates is defined around a cylinder, wherein the coolant jacket is formed by cutting a mold from the crank chamber side of the engine. A liquid-cooled engine characterized by (2) The coolant jacket is formed by a mold that is pulled out along the axial direction of the cylinder, and the coolant jacket has an opening facing the crank chamber side.
The liquid-cooled engine according to claim 1, wherein the engine is closed by a lid member. (3) The liquid-cooled engine according to claim 1 or 2, wherein the cylinder head and cylinder block are integrally cast. (4) The liquid-cooled engine according to any one of claims 1 to 3, wherein the coolant is comprised of lubricating oil for lubricating the engine.