JP3814255B2 - Water-cooled V-type 2-cylinder engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a water-cooled V-type two-cylinder engine, and more particularly to the arrangement of cooling system piping and cooling equipment.
[0002]
[Prior art]
Conventionally, in a water-cooled V-type two-cylinder engine, the thermostat is disposed at the outlet of the cooling water jacket of the cylinder head and is attached to the cylinder so as to protrude toward one end in the crankshaft direction. Is provided. The thermostat measures the cooling water temperature at the outlet of the cooling water jacket at the time of warm-up operation or normal operation, opens when the temperature becomes higher than a predetermined temperature, returns the cooling water discharged from the cooling water jacket outlet to the radiator, The cooling water cooled in the radiator is supplied to the cooling water jacket of the cylinder.
[0003]
In such an outlet-side thermostat arrangement method, especially during the warm-up operation, when the water temperature reaches a predetermined temperature, the thermostat opens, and the cooling water cooled by the radiator is rapidly supplied to the cooling water jacket. As a result, the cylinder is rapidly cooled and water temperature hunting is likely to occur. In particular, when the outside air temperature is low or when the cooling fan of the radiator is always rotating, the difference in the hunting water temperature is extremely large.
[0004]
On the other hand, as shown in FIG. 5, there is a so-called inlet-side thermostat type engine in which a thermostat 110 is connected to the cooling water supply pipe 105 between the cooling water supply outlet 103 and the cooling water jacket inlet 107 of the radiator 102. It has been developed (see Patent Document 1).
[0005]
In such an inlet-side thermostat arrangement method, the temperature of the cooling water circulating from the cooling water jacket 106 through the bypass path 108 is detected, the thermostat 110 is opened and closed, and the low-temperature cooling water from the radiator 102 and the cooling water are High temperature cooling water circulating from the jacket 106 via the bypass path 108 is mixed so as to reach a substantially constant temperature by opening and closing the thermostat 110, and the adjusted cooling water is supplied to the cooling water jacket 106. Therefore, the rapid temperature change of the cylinder can be eliminated, and the water temperature hunting phenomenon can be prevented.
[0006]
[Patent Document 1]
Japanese Utility Model Publication No. 63-12626.
[0007]
[Problems to be solved by the invention]
However, in the inlet-side thermostat arrangement method as shown in FIG. 5, at the time of water injection, the cooling water stagnates in the thermostat 110 only by water injection from the water inlet 112 of the radiator 102, and water cannot be injected into the cooling water jacket 106. The auxiliary water injection port 120 is formed at the upper end of the jacket 16 and water must be injected from the auxiliary water injection port 120, and the efficiency of the water injection operation is not good.
[0008]
Further, even when the cooling water is drained, the water in the cooling water jacket 106 cannot be completely drained only by draining from the radiator drain port 113. Therefore, the auxiliary drain port 121 is also provided at the lower end of the cooling water jacket 106. It is also necessary to drain from the auxiliary drain port 121.
[0009]
OBJECT OF THE INVENTION
An object of the present invention is to prevent the hunting phenomenon and the like by stabilizing the cooling water temperature, and to facilitate the injection and drainage of the cooling water.
[0010]
[Means for Solving the Problems]
In the water-cooled V-type two-cylinder engine of the present application, a thermostat is connected between the lower-end cooling water feed outlet of the radiator and the cooling water jacket inlet of the cylinder, and the cooling water jacket lower end and the cooling water A water injection / drain bypass path that communicates the lower end between the delivery port and the thermostat is provided, and the water injection / drain bypass path prevents backflow of the cooling water from the cooling water jacket and from the cooling water delivery outlet to the cooling water jacket. A check valve that allows the flow of cooling water to the lower end is provided.
[0011]
In this way, by adopting the inlet side thermostat arrangement system, the cooling water temperature can be stabilized and the hunting phenomenon of the water temperature can be prevented, and the inside of the radiator and the cooling water jacket can be performed only by supplying water from the water inlet of the radiator. The inside can be filled at the same time, and the water injection work in the inlet side thermostat arrangement system can be performed efficiently.
[0012]
According to a second aspect of the present invention, in the water-cooled V-type two-cylinder engine according to the first aspect, a first cooling-cooling water supply pipe includes a lower-end cooling water feed outlet of the radiator and an inlet formed in a lower chamber of the thermostat. The outlet formed in the upper chamber of the thermostat and the suction side of the water pump communicating with the inlet of the cooling water jacket are connected by a second cooling water supply pipe, and the lower chamber of the thermostat is connected with the above water injection It is characterized by being connected to a cooling water jacket through a drain bypass path.
[0013]
Thereby, the cooling water piping between a radiator, a thermostat, a water pump, and a cooling water jacket lower end part can be simplified.
[0014]
A third aspect of the present invention is the water-cooled V-type two-cylinder engine according to the first or second aspect, wherein the lower end of the water injection / drain bypass path is between the check valve and the lower end of the cooling water jacket. It is characterized by having a drain opening that can be opened and closed.
[0015]
Thereby, the inside of a radiator and the inside of a cooling water jacket can be drained simultaneously and completely by only drainage from one drain outlet, and drainage work can be performed efficiently.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a front view showing a water-cooled V-type two-cylinder engine to which the present invention is applied in a state where a radiator is not attached. A pair of cylinders 1 arranged in a V-type includes a cylinder 2 and a cylinder head as is well known. 3, a head cover 4, and the like, and a carburetor 6 and a bifurcated intake manifold 7 are disposed between the cylinders 1. Both ends of the intake manifold 7 are connected to the intake ports 10 of the cylinder heads 3, the common inlet portion at the center of the intake manifold 7 is connected to the carburetor 6, and the inlet of the carburetor 6 is connected to the upper side via the intake communication pipe 11. The air cleaner 12 is connected. The intake manifold 7 also serves as a cooling water collecting pipe. A cooling water passage is formed in parallel with the intake passage, and an overhanging portion 7a is formed to protrude obliquely upward, and is returned to the overhanging portion 7a. A cooling water outlet 15 and a bypass cooling water outlet 16 are opened. The intake manifold / cooling water collecting pipe 7 will be hereinafter simply referred to as “cooling water collecting pipe 7”.
[0017]
A starter 17 is disposed in the lower space of one cylinder 2, and a cooling water channel switching thermostat 18 integrally provided with a check valve 20 is disposed in the lower space of the other cylinder 2. The thermostat 18 includes a case 18 a and a valve body 34. The thermostat 18 is disposed in an inclined posture substantially parallel to the cylinder 2, and the flange portion 18 b of the case 18 a is fixed to the cylinder head 3 with bolts 19. The thermostat 18 is partitioned into an upper chamber 35 and a lower chamber 36 that are opened and closed by a valve body 34, and a check valve case 41 and a drain port 38 are formed at the lower end of the lower chamber 36. A bolt plug 43 is detachably screwed into the drain port 38.
[0018]
FIG. 2 is a right side view of FIG. 1 (II arrow view). The radiator 22 is arranged on the flywheel 24 arrangement side in the crankshaft direction, and the water pump 25 is arranged on the output shaft 23 arrangement side. The thermostat 18 is located between the radiator 22 and the water pump 25 in the crankshaft direction, and at least the center portion thereof is disposed within the crankshaft direction width of the cylinder 2.
[0019]
A water inlet 26 is formed on the upper end surface of the radiator 22, and a radiator cap 29 is covered. A cooling water return port 27 is formed at the upper end of the rear surface of the radiator 22, and the cooling water return port 27 is connected to the return cooling water outlet 15 of the cooling water collecting pipe 7 via the cooling water return pipe 28. . A cooling water outlet 30 is formed at the lower end of the rear surface of the radiator 22, and the cooling water outlet 30 is connected to an inlet 32 of the thermostat 18 via a first cooling water supply pipe 31.
[0020]
An outlet 39 and a bypass inlet 40 are formed in the upper chamber 35 of the thermostat 18, the inlet 32 is formed in the lower chamber 36, and a water injection and drain bypass port 42 is formed in the check valve case portion 41. .
[0021]
The upper bypass inlet 40 is connected to the bypass cooling water outlet 16 of the cooling water collecting pipe 7 via the bypass pipe 44, and the outlet 39 is connected to the suction inlet of the water pump 25 via the second cooling water supply pipe 45. The water injection / drain bypass 42 communicates with the cooling water jacket lower end 55 of the cylinder 2 via the water injection / drain bypass pipe 47.
[0022]
FIG. 4 is an enlarged view of the check valve 20 portion. The check valve 20 has an upward conical portion 20a protruding into the valve hole 50 and a plurality of passage grooves 51, and is shown when the engine is stopped. In this way, the valve hole 50 is opened by contacting the conical stopper 53 and the cooling water in the lower chamber 36 can be supplied to the water injection / drainage bypass port 42 via the passage groove 51. ing. On the other hand, when the pressure on the side of the water injection / drain bypass port 42 is high, the check valve 20 is pushed up to close the valve hole 50 so as to prevent the flow of cooling water from the bypass port 42 to the lower chamber 36. It has become. The drain port 38 is located at the lowermost end portion of the check valve case portion 41 and has an inclined posture that is directed obliquely downward.
[0023]
FIG. 3 is a schematic piping diagram of the cooling system, and the cooling water path is expressed in an easy-to-understand manner. The discharge port 38 is disposed closer to the cooling water jacket than the check valve 20 and is positioned at the lowermost end of the cooling water path between the cooling water delivery port 30 of the radiator 22 and the cooling water jacket lower end 55. The discharge port of the water pump 25 communicates with the cooling water jacket inlet 56 of each cylinder 2.
[0024]
When the temperature of the cooling water flowing through the thermostat is lower than the set temperature, the thermostat 18 closes the chambers 35 and 36 so that only the bypass inlet 40 and the outlet 39 communicate with each other. 36, the cooling water supplied from the inlet 32 and the bypass inlet 40 is mixed, and the cooling water is supplied from the outlet 39 to each cooling water jacket 54 via the water pump 25. In addition, a check valve 34a is usually built in the thermostat case 18a between the upper and lower chambers 35 and 36.
[0025]
[Action]
In FIG. 3, when cooling water is poured before the first use after production, the radiator cap 29 is removed and water is poured only from the water inlet 26. The cooling water poured into the radiator 22 is also supplied to the cooling water jacket lower end 55 via the first cooling water supply pipe 31 at the lower end, the check valve 20, the water injection and drain bypass pipe 47. Therefore, the cooling water can be filled in the radiator 22 and each cooling water jacket simultaneously and quickly.
[0026]
During the warm-up operation, when the temperature of the cooling water flowing in the upper chamber 35 of the thermostat 18 is lower than the set temperature, the valve body 34 of the thermostat 18 is closed. Therefore, the cooling water discharged from the cooling water jacket outlet 57 at the upper end is sucked into the water pump 25 via the return bypass pipe 44, the upper chamber 35 of the thermostat 18 and the second cooling water supply pipe 45, and Supplied to water jacket inlet 56. In this case and during normal operation, the water injection and drainage bypass pipe 47 is pressurized by the pressure of the water pump 25, but the check valve 20 prevents backflow into the thermostat 18.
[0027]
When the temperature of the cooling water flowing in the upper chamber 35 of the thermostat 18 rises and the temperature of the valve body 34 of the thermostat 18 exceeds the set temperature, the valve body 34 of the thermostat 18 opens and the chambers 35 and 36 communicate with each other. . As a result, the cooling water cooled by the radiator 22 and the cooling water returning from the return bypass pipe 44 are mixed in the thermostat 18 and sucked into the water pump 25 via the second cooling water supply pipe 45 to cool the cooling water. Supplied to the water jacket.
[0028]
When the cooling water is drained during maintenance, the lower outlet 38 is opened. The discharge port 38 is located at the lowermost end of the cooling water path (the cooling water supply pipe 31 and the water injection / drainage bypass pipe 47) between the lower end cooling water outlet 30 of the radiator 22 and the cooling water jacket lower end 55. Therefore, the cooling water in the cooling water jacket is discharged from the discharge port 38 through the bypass pipe 47, and the cooling water in the radiator 22 is discharged from the discharge port 38 through the first cooling water supply pipe 31 and the check valve 20. Is done. The cooling water in the return bypass pipe 44, the cooling water supply pipe 45 and the upper chamber 35 of the thermostat case 18 a is passed from the check valve 34 a built in the thermostat 18 through the thermostat inlet 32 and the check valve 20. At the same time.
[0029]
As shown in FIG. 2, in the inlet-side thermostat arrangement method, since the thermostat 18 is arranged in the lower space of the cylinder 2 between the radiator 22 and the water pump 25 in the crankshaft direction, the lower end cooling of the radiator 22 is performed. Pipings extending from the water outlet 30 to the water pump 25 through the thermostat 18, that is, the cooling water supply pipes 31 and 45 can be simply and simply disposed in the engine lower space. In addition, the bypass pipe 47 for water injection and drainage can be compactly disposed in the lower space of the cylinder 2.
[0030]
[Other Embodiments]
(1) The case portion of the check valve 20 can be arranged separately from the case 18 a of the thermostat 18. Further, the thermostat case 18a can be integrally formed with the outer wall of the cylinder.
[0031]
【The invention's effect】
As explained above, according to the present invention,
(1) The water-cooled V-type two-cylinder engine employs a structure in which the thermostat 18 is arranged on the inlet side of the cooling water jacket of the cylinder, so that the cooling water temperature is stable compared to the outlet-side thermostat arrangement method. The cooling water temperature during the warm-up operation is stabilized, and the water temperature hunting phenomenon can be prevented.
[0032]
(2) The thermostat 18 is connected between the cooling water outlet 30 of the radiator 22 and the cooling water jacket inlet 56 of the cylinder 1, and the cooling water jacket lower end 55 and the lower end between the cooling water outlet 30 and the thermostat 18 are connected. The water injection / drain bypass pipe 47 is connected to the water injection / drain bypass pipe 47 to prevent the reverse flow of the cooling water from the cooling water jacket and to cool the cooling water jacket 30 from the cooling water outlet 30 to the lower end of the cooling water jacket. Since the check valve 20 that allows the flow of water is provided, the radiator 22 and the cooling water jacket can be filled at the same time only by supplying water from the water inlet 26 of the radiator 22, and the water injection work in the inlet side thermostat system is efficiently performed. And can be done completely.
[0033]
(3) The lower end cooling water delivery port 30 of the radiator and the inlet 32 formed in the lower chamber 36 of the thermostat 18 are connected by the first cooling cooling water supply pipe 31 and formed in the upper chamber 35 of the thermostat 18. The outlet 39 and the suction side of the water pump 25 communicating with the cooling water jacket inlet 56 are connected by a second cooling water supply pipe, and the lower chamber 36 of the thermostat 18 is connected via the water injection and drain bypass path. When connected to the cooling water jacket 2, the cooling water piping between the radiator 22, the thermostat 18, the water pump 25, and the cooling water jacket lower end 55 can be simplified.
[0034]
(4) When a drainage port 38 that is openable and closable between the check valve 20 and the cooling water jacket lower end 55 is provided at the lower end of the water injection / drain bypass path, Therefore, the cooling water in the radiator 22 and the cooling water jacket 2 can be drained simultaneously and completely, and the draining work can be performed efficiently.
[Brief description of the drawings]
FIG. 1 is a front view of a V-type 2-cylinder engine to which the present invention is applied with a radiator removed.
FIG. 2 is a right side view (II view) of FIG. 1 showing a radiator attached state.
FIG. 3 is a schematic piping diagram of a cooling water path.
FIG. 4 is an enlarged vertical sectional view of a check valve portion.
FIG. 5 is a schematic piping diagram of a conventional example.
[Explanation of symbols]
2 Cylinder 3 Cylinder head 7 Cooling water collecting pipe 18 Thermostat 20 Check valve 22 Radiator 27 Radiator cooling water return port 30 Radiator cooling water feed port 31 First cooling water supply pipe 32 Thermostat inlet 35 Upper chamber 36 Lower chamber 38 Water outlet 39 Thermostat outlet 42 Water injection / drain bypass 45 Second cooling water supply pipe 47 Water injection / drain bypass pipe 55 Cooling water jacket lower end 56 Cooling water jacket inlet 57 Cooling water jacket outlet

Claims (3)

A thermostat is connected between the lower end cooling water feed outlet of the radiator and the cooling water jacket inlet of the cylinder, and a bypass path for water injection and drainage that connects the lower end of the cooling water jacket and the lower end between the cooling water feed outlet and the thermostat. Provided with a check valve that prevents the flow of cooling water from the cooling water jacket and allows the flow of cooling water from the cooling water delivery outlet to the lower end of the cooling water jacket in the bypass passage for water injection and drainage. A water-cooled V-type 2-cylinder engine. The lower end cooling water feed outlet of the radiator and the inlet formed in the lower chamber of the thermostat are connected by a first cooling cooling water supply pipe,
The outlet formed in the upper chamber of the thermostat and the suction side of the water pump communicating with the inlet of the cooling water jacket are connected by a second cooling water supply pipe,
The water-cooled V-type two-cylinder engine according to claim 1, wherein a lower chamber of the thermostat is connected to a cooling water jacket through the water injection and drain bypass paths. The water-cooled type according to claim 1 or 2, wherein a drainage port that is openable and closable is provided between the check valve and the lower end of the cooling water jacket at the lower end of the water injection and drainage bypass path. V-type 2-cylinder engine.

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