JP3140652B2 - Structure of elbow pipe for cooling water inlet in internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a cooling water inlet elbow for guiding cooling water cooled by a radiator to a cooling water jacket in an internal combustion engine in a water-cooled internal combustion engine.

[0002]

2. Description of the Related Art In a recent internal combustion engine, for example, as described in Japanese Utility Model Application Laid-Open No. 1-131131, a valve case containing a thermostat valve is integrally formed on a side surface of a cylinder block of the internal combustion engine. A cooling water return pipe from a lower tank in a radiator is connected to a cooling water inlet pipe that also serves as a lid and is mounted on the valve case.

[0003] On the other hand, in the case of a cab-over type vehicle, FIG.
As shown in FIG. 2, a slant type internal combustion engine 1 in which the axis 2 of the cylinder bore is inclined at an appropriate angle θ with respect to a horizontal plane 4 when viewed from the direction of the crankshaft 3 is mounted. By the way, with respect to this slant type internal combustion engine 1, the above-mentioned "The valve case incorporating the thermostat valve is integrally formed on the side surface of the cylinder block in the internal combustion engine."
When applying that, as shown in FIGS.
Cylinder block 5 in the slant type internal combustion engine 1
A valve case 6 having a thermostat valve 7 built therein is integrally formed on the upper surface of the cooling water inlet pipe 8 which also serves as a lid attached to the valve case 6 and is disposed in front of the slant type internal combustion engine 1. Tank 1 in radiator 9
It is usual to connect the cooling water return pipe 11 from zero.

In this case, the cooling water inlet pipe 8 serving also as a lid for the valve case 6 is formed as an elbow pipe which is bent at an acute angle of 90 degrees or less, as shown in the figure, so that the portion at the relevant portion is formed. The height of the cooling water return pipe 11 and the inner diameter of the passage are controlled by the elbow pipe 8 for the cooling water inlet.
It is configured to expand from a relatively small inside diameter on the side to a relatively large inside diameter on the valve case 6 side.

[0005] For this reason, the conventional elbow pipe for cooling water inlet is shown in FIGS. 11 and 12 in order to manufacture the elbow pipe by injection molding of a synthetic resin or die casting of a light alloy. There is an elbow pipe 8 'configured as shown, and an elbow pipe 8 "configured as shown in Fig. 13 and Fig. 14. That is, the former elbow pipe 8' is connected to the cooling water return pipe 11. A horizontal pipe section 8a 'having a circular cross section, a vertical pipe section 8b' having a circular cross section extending integrally downward from the horizontal pipe section 8a ', and diverging downward integrally from a lower end of the vertical pipe section 8b'. And a tapered tube portion 8c 'that expands in a shape like a circle.
The flange 8d 'for joining to the valve case 6 is integrally formed on the outer periphery of the lower end of the pipe, and the inner diameter d2' of the vertical pipe 8b 'is made substantially equal to the inner diameter d1' of the horizontal pipe 8a '. On the other hand, the inner diameter d3 'of the lower end of the tapered tube portion 8c' is configured to match the inner diameter of the valve case 6.

The latter elbow pipe 8 "has a circular cross section 8a" to which the cooling water return pipe 11 is connected.
And a vertical section 8b "having a circular cross section extending integrally downward from the horizontal section 8a" and a vertical section 8b ".
And a tapered pipe portion 8c "that expands downwardly and integrally from the lower end of the tapered pipe portion 8c". A flange portion 8d "for joining to the valve case 6 is provided on the outer periphery of the lower end of the tapered pipe portion 8c".
The inner diameter d2 "of the vertical pipe portion 8b" is made larger than the inner diameter d1 "of the horizontal pipe portion 8a", while the inner diameter d3 "of the lower end of the tapered pipe portion 8c" is formed as follows. It is configured to match the inner diameter of the valve case 6.

The two elbow tubes 8 ', 8 "
Are shown in the figure, as indicated by the two-dot chain line,
a ', 8a ", a pair of left and right molds A', B 'for forming the outer sides of the vertical pipe portions 8b', 8b", the tapered pipe portions 8c ', 8c "and the flange portions 8d', 8d". A ", B"
And core dies C ', C "for forming the inside of the horizontal tube portions 8a', 8a", and forming the inside of the vertical tube portions 8b ', 8b "and the tapered tube portions 8c', 8c". By using the core dies D 'and D "for the production, the injection molding of a synthetic resin or the die casting of a light alloy can be performed.

[0008]

However, in the former elbow tube 8 ', the inner diameter d1' of the horizontal tube portion 8a 'and the inner diameter d2' of the vertical tube portion 8b 'are substantially the same. Since the pipe having a narrow inner diameter is bent at an acute angle with a smaller radius at the same inner diameter, the cooling water rapidly changes its direction while maintaining a high flow velocity. From the inside diameter d2 'to the large inside diameter d in the tapered tube portion 8c'.
There is a problem that the pressure loss in the elbow tube 8 'is large because the flow resistance in this portion is large due to the large enlargement ratio of the passage cross-sectional area due to the large enlargement of the passage cross-sectional area.

The elbow tube 8 "in the latter case has a bendable portion whose inner diameter increases from d1" to d2 ", so that the cross-sectional area of the passage is enlarged and the flow velocity of the cooling water is reduced. Since the enlargement ratio of the cross-sectional area of the passage in the pipe portion 8c "is small, the flow resistance in the bent portion and the flow resistance in the tapered tube 8c" can be reduced as compared with the former elbow tube 8 '. On the other hand, the inner diameter of the bent portion at the bent portion from the horizontal pipe portion 8a "to the vertical pipe portion 8b" is rapidly increased from d1 "to d2", so that the inner surface of the portion for the horizontal pipe portion 8a "is used. Core mold C "and vertical tube 8
b, a pair of left and right steps 8 toward the downstream side of the flow, as shown in FIG.
e ″ is formed, and it is not unavoidable that cavitation due to eddy currents occurs downstream of the step 8e ″.

The cavitation increases the flow resistance and causes cavitation corrosion on the inner wall surface. Therefore, it is not possible to sufficiently reduce the pressure loss in the elbow tube 8 ", and also to reduce the cavitation. An object of the present invention is to provide a structure of an elbow pipe for a cooling water inlet which solves these problems.

[0011]

In order to achieve this technical object, the present invention provides a horizontal pipe section having a circular cross section to which a cooling water return pipe from a radiator is connected, and a vertical section extending downward from the horizontal pipe section. A vertical pipe portion, and a tapered pipe portion which expands downwardly and divergently from the lower end of the vertical pipe portion, and is provided on the outer periphery of the lower end of the tapered pipe portion with respect to a valve case for a thermostat valve provided in an internal combustion engine. In a cooling water inlet elbow pipe integrally formed with a joining flange portion, a cross section of the vertical pipe portion is defined such that an axial direction of the horizontal pipe portion is a long axis direction, and an axial line of the horizontal pipe portion. An elliptical shape having a direction substantially perpendicular to the short axis direction is defined as an elliptical shape, and the inner diameter in the long axis direction is larger than the inner diameter of the horizontal pipe portion, and the inner diameter in the short axis direction is substantially equal to the inner diameter of the horizontal pipe portion. " It was.

[0012]

[Operation] As described above, the cross section of a vertical pipe is
As an elliptical shape, the inner diameter in the major axis direction is larger than the inner diameter of the horizontal pipe part, and the inner diameter in the short axis direction is substantially equal to the inner diameter of the horizontal pipe part. The cross-sectional area of the passage can be increased at the bent portion from the horizontal pipe portion to the vertical pipe portion, and the expansion rate of the passage cross-sectional area at the tapered pipe portion extending from the vertical pipe portion can be reduced. And the flow resistance in the tapered tube portion can be reduced.

Further, the major axis direction of the elliptical cross section of the vertical pipe is set to the direction of the axis of the horizontal pipe section, and the minor axis direction of the elliptical cross section is set to a direction substantially perpendicular to the axis of the horizontal pipe section. By making the inner diameter in the short axis direction substantially equal to the inner diameter of the horizontal pipe portion, the connecting portion from the horizontal pipe portion to the vertical pipe portion on the inner wall surface of the bent portion becomes a smooth surface without a step. Cavitation can be reliably prevented from occurring in this portion due to a step as in the conventional case.

In addition, the elbow tube of the present invention has the above-mentioned structure, and is manufactured by injection molding of a synthetic resin or die casting of a light alloy, similarly to the above-mentioned conventional elbow tubes. You can do it.

[0015]

Therefore, according to the present invention, the elbow tube is
While being able to be manufactured by injection molding of a synthetic resin or die casting of a light alloy, the pressure loss when cooling water flows through the elbow tube can be significantly reduced, and the durability of the elbow tube can be reduced. This has the effect of reliably reducing the reduction due to cavitation corrosion.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 4 to 8 show a first embodiment. In this figure, reference numeral 8 denotes an elbow pipe according to the present invention, and this elbow pipe 8 is provided with a radiator 9 disposed in front of the slant type internal combustion engine 1. Inner diameter d1 so that the cooling water return pipe 11 from the lower tank 10 at
And a horizontal pipe portion 8a having a circular cross section.
a vertically extending pipe portion 8b extending downwardly from a, and a tapered pipe portion 8c which expands downward from the lower end of the vertically oriented pipe portion 8b to an inner diameter d3, and is integrally provided with the tapered pipe portion 8c. The slant type internal combustion engine 1
8d for joining to the valve case 6 for the thermostat valve 7 provided on the side surface of the cylinder block 5 in FIG.
Are integrally formed.

The cross section of the vertical pipe portion 8b is defined by the direction of the axis of the horizontal pipe portion 8a being the major axis direction,
An elliptical shape in which the direction substantially perpendicular to the axis of the horizontal pipe portion 8a is the short axis direction, the inner diameter d2a in the long axis direction is larger than the inner diameter d1 of the horizontal pipe portion 8a, and the inner diameter d2b in the short axis direction is smaller. The configuration is made so as to be substantially equal to the inner diameter d1 of the horizontal tube portion 8a.

As described above, the cross section of the vertical pipe 8b is made elliptical, and the inner diameter d2a in the long axis direction is larger than the inner diameter d1 of the horizontal pipe section 8a, and the inner diameter d2b in the short axis direction is set in the horizontal direction. By making the inner diameter d1 substantially equal to the inner diameter d1 of the pipe portion 8b, the cross-sectional area of the passage from the horizontal pipe portion 8a to the vertical pipe portion 8b can be increased at the bent portion from the horizontal pipe portion 8a to the vertical pipe portion 8b. Vertical pipe 8
Since the enlargement rate of the cross-sectional area of the passage in the tapered tube portion 8c extending from the position b can be reduced, the flow bending resistance in the bent portion and the flow resistance in the tapered tube portion 8c can be reduced.

Further, the major axis direction of the elliptical cross section of the vertical pipe 8b is set in the direction of the axis of the horizontal pipe section 8a, and the short axis direction of the elliptical cross section is set in a direction substantially perpendicular to the axis of the horizontal pipe section 8a. On the other hand, by making the inner diameter d2b in the short axis direction substantially equal to the inner diameter d1 of the horizontal pipe portion 8a, the connecting portion from the horizontal pipe portion 8a to the vertical pipe portion 8b on the inner wall surface of the bent portion has a step. Since the surface is smooth without any cavitation, it is possible to reliably prevent the occurrence of cavitation due to a step in this portion as in the conventional case.

In addition, the elbow tube 8 has the above-described structure, so that the horizontal tube portion 8a, the vertical tube portion 8b, and the taper tube portion 8 are formed as shown by a two-dot chain line in FIGS.
c and a pair of left and right molds A and B for forming the outside of the flange portion 8d, a core mold C for forming the inside of the horizontal tube portion 8a, a vertical tube portion 8b and a tapered tube portion 8c. Can be manufactured by injection molding of a synthetic resin or die casting of a light alloy.

In the first embodiment, the axis of the horizontal pipe 8a coincides with the center line of the opening on the lower surface of the flange 8d of the tapered pipe 8c in plan view. As in the second embodiment shown in FIG. 9 and FIG. 10, the axis of the horizontal pipe 8a is appropriately dimensioned by the dimension e with respect to the center line of the opening on the lower surface of the flange 8d of the tapered pipe 8c. The elbow pipe 8 may be configured to be offset so that the elbow pipe 8 is connected to the valve case 6 for the thermostat valve 7.
Can be mounted while avoiding other components such as the intake manifold provided near the.

[Brief description of the drawings]

FIG. 1 is a front view of a slant type internal combustion engine.

FIG. 2 is a right side view of FIG.

FIG. 3 is an enlarged sectional view taken along line III-III of FIG. 2;

FIG. 4 is a vertical sectional front view showing the elbow tube according to the first embodiment of the present invention.

FIG. 5 is a sectional view taken along line VV of FIG. 4;

FIG. 6 is a plan view of FIG. 4;

FIG. 7 is a sectional view taken along line VII-VII of FIG. 4;

8 is a sectional view taken along line VIII-VIII in FIG.

FIG. 9 is a plan view showing an elbow tube according to a second embodiment of the present invention.

FIG. 10 is a sectional view taken along line XX of FIG. 9;

FIG. 11 is a vertical sectional front view showing one conventional elbow tube.

12 is a sectional view taken along the line XII-XII in FIG.

FIG. 13 is a longitudinal sectional front view showing another conventional elbow tube.

14 is a sectional view taken along the line XIV-XIV in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Slant type internal combustion engine 6 Valve case 7 Thermostat valve 8 Elbow pipe 8a Horizontal pipe section 8b Vertical pipe section 8c Tapered pipe section 8d Flange section 9 Radiator 10 Radiator lower tank 11 Cooling water return pipe

Claims (1)

(57) [Claims] 1. A horizontal pipe section having a circular cross section to which a cooling water return pipe from a radiator is connected, a vertical pipe section extending downward from the horizontal pipe section, and a divergent shape extending downward from a lower end of the vertical pipe section. And a cooling water inlet formed integrally with a flange portion for joining to a valve case for a thermostat valve provided in an internal combustion engine on the outer periphery of the lower end of the tapered pipe portion. In the elbow pipe, a cross section of the vertical pipe section is formed into an elliptical shape in which a direction of an axis of the horizontal pipe section is a long axis direction and a direction substantially perpendicular to the axis of the horizontal pipe section is a short axis direction. An elbow pipe for a cooling water inlet in an internal combustion engine, wherein an inner diameter in an axial direction is larger than an inner diameter of the horizontal pipe section, and an inner diameter in a short axis direction is substantially equal to an inner diameter of the horizontal pipe section.