JP2003301744A - Piston cooling device and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem wherein a conventional method for cooling a cooling cavity defined in a piston by means of an oil jet jetted from a single nozzle causes insufficient cooling and uneven cooling. <P>SOLUTION: Nozzles 58a and 58b for jetting oil are disposed on a crankshaft side of a piston 23. The nozzle 58a jets oil over an inlet/outlet 29a cut in the piston 23 to inject the oil into a cooling cavity 26 when the piston 23 is at the top dead center. The nozzle 58b jets oil over an inlet/outlet cut in the piston 23 to inject the oil into the cooling cavity 26 when the piston 23 is at the bottom dead center. The piston 23 is thus cooled with increased efficiency and cooled evenly. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and method for injecting cooling oil into a piston of an internal combustion engine, and more particularly to an apparatus and method for injecting oil into a cooling cavity formed in the piston and a back surface of the piston.

[0002]

2. Description of the Related Art The heat load on pistons has increased with the recent high performance of engines. To solve this problem, there is a method of providing a cooling cavity in the piston and injecting oil into the cooling cavity to cool the piston. However, if the heat load on the piston further increases, the efficiency cannot be kept up by cooling the piston by the above method, and the heat load on the connecting rod etc. increases due to the rise in the temperature on the back surface of the piston, causing burns. There is. This phenomenon is particularly remarkable in an internal combustion engine in which a supercharger or the like is provided in the intake system to achieve a high compression ratio.

To address this problem, for example, open technical report 91-
As described in No. 6590, a method of cooling the piston by providing an oil jet for injecting toward the opening of the cooling cavity and an oil jet for injecting toward the back surface of the piston and individually injecting oil is proposed. Has been done.

[0004]

However, in the above-mentioned method, the cooling efficiency is improved as a whole of the piston and the heat load can be suppressed. However, the oil is introduced into the cooling cavity from one direction. In order to inject and discharge oil from the other direction, the ambient temperature at the inlet and outlet of the cooling cavity is different, and if oil is injected to the pin boss surface from one direction, the connecting rod etc. connected to the pin boss surface will be obstructed. Therefore, because the piston cannot be sprayed with oil evenly on the pin boss surface, a part of the piston is not locally cooled, resulting in uneven cooling, resulting in poor cooling efficiency.

The present invention has been made in view of the above problems, and in an apparatus and method for cooling a piston by injecting cooling oil into the piston, the cooling efficiency of the piston is improved and the piston is made uniform. The task is to cool it.

[0006]

In order to solve the above-mentioned problems, a piston provided in a cylinder of an internal combustion engine, and a cooling cavity which is a cavity provided inside a starting body of the piston,
With respect to the piston of the cylinder, a plurality of inlet / outlet holes formed in the pin boss surface, which is the surface on which the pin boss of the piston is provided, and penetrating to the cooling cavity, and the ejection direction of the ejection hole are with respect to the lower surface of the pin boss. And a diagonally provided nozzle, wherein when the cooling liquid is jetted from the plurality of nozzles, the piston is located at a top dead center or a position near the top dead center from the first nozzle. At a certain time, the cooling liquid is injected toward the first inlet / outlet hole to inject the cooling liquid into the cooling cavity, and when the piston is at or near the bottom dead center from the second nozzle, the second A piston cooling device was used which injects the cooling liquid toward the inlet / outlet holes and injects the cooling liquid into the cooling cavity.

In this piston cooling device, the cooling liquid jetted from each of the plurality of nozzles is jetted alternately into the respective cooling liquid inlet / outlet holes drilled up to the cooling cavity. By alternately injecting the cooling liquid into the respective cooling liquid inlet / outlet holes, the flow direction of the cooling liquid passing through the cooling cavity can be changed alternately. As a result, it becomes possible to make the cooling efficiency around each inlet / outlet hole and inside the cooling cavity substantially uniform.

In order to cool the piston, a cavity is provided inside the piston, an injection hole for injecting a cooling liquid is provided in the cavity, and a cooling liquid is injected from the injection hole to cool the piston. The inlet / outlet hole for injecting the cooling liquid into the cooling cavity is composed of at least two holes for that purpose. However, with conventional piston cooling,
It is the injection of the cooling liquid from one direction. On the other hand, when the cooling liquid is injected into the cooling cavity through the two or more inlet / outlet holes, a plurality of nozzles are provided in the respective cooling liquid inlet / outlet holes in order to individually inject the cooling liquid from each inlet / outlet hole. Provided so that cooling liquid can enter and exit.

In order to increase the cooling efficiency of the piston,
The piston cooling device injects the cooling liquid at a position where the trajectory of the cooling liquid ejected from the first or second nozzle does not overlap the cooling liquid inlet / outlet hole formed in the pin boss surface of the piston.

When injecting the cooling liquid into the inlet / outlet hole of the piston, the cooling liquid is jetted from a nozzle provided in the cylinder. At this time, the injection direction of the nozzle is directed to the pin boss surface, and the oil injected obliquely hits the pin boss surface so that the piston moves up and down at a certain point. It is preferable that the entrance and exit holes provided in the surface overlap. As a result, not only can the cooling liquid be injected into the cooling cavity only at a predetermined position of the piston, but also at a position other than the predetermined position other than the inlet / outlet hole, for example, the piston pin boss located at a position distant from the cooling cavity. It becomes possible to inject the cooling liquid to the above. Therefore, not only the cooling cavity provided inside the piston but also the cooling from the pin boss surface can be performed.

In order to improve the cooling efficiency, when the piston is at the intermediate position between the top dead center and the bottom dead center, at least the locus of the cooling liquid sprayed from the first nozzle or the second nozzle is set. The third inlet / outlet holes arranged so as to be overlapped with each other, and when the piston is at an intermediate position between the top dead center and the bottom dead center, by the cooling liquid injected from either the first nozzle or the second nozzle. A piston cooling device can be provided in which the cooling liquid is injected into the cooling cavity through the third cooling liquid inlet / outlet hole.

The nozzle for injecting the cooling liquid is, as described above,
It is attached so as to jet the cooling liquid obliquely to the pin boss surface. Therefore, one inlet / outlet hole provided on the pin boss surface overlaps with the trajectory of the cooling liquid injected only at a certain position within the movable range of the piston, that is, the cooling liquid is injected from the inlet / outlet hole. Therefore, a third inlet / outlet hole is newly provided in the vicinity of the first or second inlet / outlet hole into which the cooling liquid is injected corresponding to the nozzle, and the first or second piston is moved when the piston moves to another position. It is possible to inject into the third inlet / outlet hole from a nozzle that injects into either of the inlet / outlet holes of This allows
It is possible to inject the cooling liquid into the cooling cavity at least twice from one nozzle as the piston moves.

Further, when cooling the piston, in order to prevent the deterioration of the combustion efficiency due to the decrease of the piston temperature, the number of nozzles for injecting the cooling liquid to the piston according to the temperature in the cylinder of the internal combustion engine. To change.

In an internal combustion engine of a type in which fuel is directly added to a combustion chamber in a cylinder such as a diesel engine, when the temperature of the piston is lowered, the fuel added to the upper surface of the piston constituting the combustion chamber is condensed. There is a problem that adversely affects flammability. Therefore, in order to prevent unnecessary cooling of the piston by the piston cooling method, it is preferable to change the number of nozzles that inject the cooling liquid according to the piston temperature.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION (Embodiment 1) Embodiment 1 according to the present invention will be described below. In FIG. 1, an internal combustion engine (hereinafter referred to as an engine) 1 includes a fuel supply system 10,
The in-line four-cylinder compression ignition type diesel engine system mainly includes a combustion chamber 20, an intake system 30, an exhaust system 35, a cooling system 50, a lubricating system 60 and the like. The configuration of the diesel engine system will be described below.

The fuel supply system 10 includes a supply pump 11,
A pressure accumulation chamber (common rail) 12, a fuel injection valve 13, an engine fuel passage P1 and the like are provided.

The supply pump 11 is a fuel tank (not shown)
The fuel drawn up is made into a high pressure and supplied to the common rail 12 through the engine fuel passage P1. The common rail 12 has a function of holding (accumulating) the high-pressure fuel supplied from the supply pump 11 at a predetermined pressure, and distributes the accumulated fuel to each fuel injection valve 13. The fuel injection valve 13 is an electromagnetic valve having an electromagnetic solenoid (not shown) inside, and is opened appropriately to supply and inject fuel into the combustion chamber 20.

The intake system 30 forms a passage (intake passage) for intake air supplied into each combustion chamber 20. On the other hand, the exhaust system 35 forms a passage (exhaust passage) for the exhaust gas discharged from each combustion chamber 20.

The engine 1 is also provided with a known supercharger (turbocharger) 40. The turbocharger 40 includes a turbine wheel 42 and a compressor 43 that are connected via the shaft 4. One compressor 43 is exposed to intake air in the intake system 30, and the other turbine wheel 42 is exposed to exhaust gas in the exhaust system 35. The turbocharger 40 having such a configuration has an effect of increasing the intake pressure (supercharging effect) by rotating the compressor 43 using the exhaust flow (exhaust pressure) received by the turbine wheel 42.

In the intake system 30, the turbocharger 4
The intercooler 31 provided at 0 forcibly cools the intake air whose temperature has risen due to supercharging. The throttle valve 32, which is provided further downstream than the intercooler 31, is an electronically controlled on-off valve whose opening can be adjusted steplessly, and reduces the flow passage area of the intake passage under predetermined conditions. , Has a function of adjusting (reducing) the supply amount of the intake air.

Further, the engine 1 is provided with an exhaust gas recirculation passage (EGR passage) 45 that bypasses the upstream side (intake system 30) and the downstream side (exhaust system 35) of the combustion chamber 20. Specifically, the EGR passage 45 connects the exhaust collecting pipe 35 a upstream of the turbocharger 40 in the exhaust system 35 and the downstream side of the throttle valve 32 in the intake system 30. The EGR passage 45 has a function of appropriately returning a part of the exhaust gas to the intake system 30. The EGR passage 45 is opened and closed steplessly by electronic control, and an EGR valve 46 capable of freely adjusting the flow rate of exhaust gas flowing through the passage and the EGR passage 4 are provided.
EGR for cooling exhaust gas passing through 5 (circulation)
A cooler 47 is provided.

Further, in the exhaust system 35, an exhaust passage 35b is provided along the exhaust gas flow path downstream of the portion where the exhaust collecting pipe 40a connected to the combustion chamber and the turbine wheel 42 are provided, and a catalyst is provided downstream thereof. The casing 37 and an exhaust passage 35c are further connected downstream. The catalyst casing 37 accommodates a particulate filter that removes fine particles contained in the exhaust gas, and a catalyst that is carried on the particulate filter to purify harmful components such as NOx.

The cooling system 50 comprises a thermostat 51, a radiator 52, a cooling pump 53, a cooling fan 54 and a bypass pipe 55. Cooling water that has passed through the cooling water passage inside the engine 1 and is heated by engine waste heat or the like flows into the radiator 52 through the thermostat 51. The radiator 52 has a water passage 25 through which cooling water flows, and has a large number of heat dissipation plates (fins) outside the pipe forming the water passage. Therefore, the heated cooling water is forcibly cooled by the cooling fan 54 when passing through the inside of the radiator 52. The cooled cooling water is sent to the cooling water passage 25 inside the engine 1 by the cooling pump 53 to cool each part.

Further, the thermostat 51 is provided with a mechanism for opening and closing the valve by heat. By opening and closing the valve according to the temperature, the cooling water heated in the bypass pipe 55 is drained and the temperature of the cooling water is adjusted.

The lubrication system 60 includes an oil pan 61, an oil pump 62, an oil strainer 63, an oil cooler 64,
It is composed of an oil filter 65, an oil gallery 66, an injection pump 67, a nozzle 58a, and a nozzle 58b. The oil pan 61 stores the oil and cools the hot oil. Further, when sucking up the oil stored in the oil pan 61 by the oil pump 62 and the oil strainer 63, the oil pan 61 is made to prevent air entrapment due to the inertial force of the oil or the like.
Prevent the oil from being unintentionally biased by a partition plate. The oil sucked up by the oil pump 62 flows into the oil cooler 64 and is cooled. A pipe through which cooling water flows is provided inside the oil cooler 64, and heat exchange between the cooling water and oil is performed through this pipe. After that, it flows into the oil filter 65, and the filter paper in the oil filter 65 removes minute impurities contained in the oil. After that, oil gallery 6 which is the distribution channel of oil
After 6, the pressure is increased by the injection pump 67 and is injected as an oil jet from the nozzles 58a and 58b. The nozzles 58a and 58b are provided in the cylinder or the crankcase, and the ejection holes thereof are installed so as to obliquely eject toward the pin boss surface of the piston.

Various sensors are attached to each part of the engine 1 to output signals relating to the environmental conditions of the part and the operating state of the engine 1.

That is, the rail pressure sensor 70 outputs a detection signal corresponding to the pressure of the fuel stored in the common rail 12. The air flow meter 72 uses the intake system 30.
A detection signal corresponding to the flow rate of intake air (intake air amount) is output upstream of the throttle valve 32. The water temperature sensor 71 outputs a detection signal corresponding to the temperature of the cooling water warmed inside the engine 1.

Further, the accelerator opening sensor 76 is attached to an accelerator pedal (not shown) and outputs a detection signal which is a basis of a work amount required in the engine 1 in accordance with a depression amount of the pedal. The crank angle sensor 77 is the engine 1
A detection signal (pulse) is output every time the output shaft (crank shaft) of the above rotates by a certain angle. Each of these sensors 70-
79 is electrically connected to an electronic control unit (ECU) 80.

As shown in FIG. 2, the ECU 80 includes a central processing unit (CPU), a read-only memory (ROM),
A random access memory (RAM), a backup RAM that does not erase stored information even after operation is stopped, a timer counter, etc., an input port including an A / D converter, and an output port are connected by a bidirectional bus. And a logical operation circuit.

The ECU 80 inputs the detection signals of the various sensors through the input port, and based on these signals, E
In the CPU of the CU 80, the program stored in the ROM is used to perform basic control of the fuel injection of the engine 1 and the like, and the supply of fuel injection related to addition of a reducing agent (fuel that functions as a reducing agent) accompanying exhaust gas purification Various controls related to the operating state of the engine 1 such as the amount are performed.

A lubrication system 60 for supplying oil as a coolant to each cylinder through the nozzles 58a and 58b, and a lubrication system 50 for cooling the engine 1 as well as the oil.
The ECU 80 and the like that control the functions of the above together constitute a cooling device for the engine 1 according to the present embodiment. The cooling control or the like is an ECU 80 that outputs a command signal related to the control.
Including the above, the operation is performed through the operation of various members constituting this cooling device.

The method of cooling the heat generated by the combustion of the fuel in the combustion chamber 20 will be described below. The diesel engine highly compresses the air taken into the combustion chamber and burns the fuel injected into the combustion chamber with the compression heat generated during this compression to obtain power. That is, the volume expansion of the gas in the combustion chamber 20 caused by igniting and burning the fuel by raising the temperature in the combustion chamber to the ignition point is used as the power.

The fuel as the combustion source is generally injected into the combustion chamber before the piston reaches the top dead center and diffused into the combustion chamber. The piston ignites the fuel and starts combustion for the first time near the top dead center, and the expansion of the internal gas by this combustion promotes the volume expansion of the combustion chamber.

When the normal combustion process is performed with the wall temperature in the combustion chamber being high, the gas in the combustion chamber is compressed and becomes high in temperature, and heat higher than the wall temperature of the combustion chamber is supplied to the piston. Combustion may start before reaching the top dead center. At this time, a back pressure, that is, a force opposite to the direction in which the crankshaft rotates acts on the piston. As a result, the combustion efficiency, which is the efficiency with which the fuel changes into momentum, decreases, and in some cases, the connecting rod that connects the piston and the crankshaft is damaged.

In addition, as the temperature around the combustion chamber becomes high, the coefficient of thermal expansion changes between the outside air side and the combustion chamber side of the vehicle body forming the combustion chamber, causing deformation of the vehicle body and deterioration of the airtightness of the joint. Etc. may occur. Therefore, cool around the combustion chamber,
It is necessary to operate the engine normally.

FIG. 2 shows a schematic sectional view of the periphery of the combustion chamber 20. The combustion chamber 20 is formed by penetrating a cylinder-shaped cylinder liner 24 inside a cylinder block 21, joining a cylinder head 22 above this, and inserting a piston 23 into the cylinder liner 24 from below. ing.

Cylinder liner 2 of cylinder block 21
A cooling water passage 25 is provided in a portion in contact with the outer side of 4, and cooling water flows through the inside.

Similarly, the cylinder head 22 is also provided with a cooling water passage 25 through which cooling water is circulated in order to cool the fuel injection valve 13, the intake valve 27a, the exhaust valve 27b, etc. provided in the vehicle body. . By the cooling water flowing in the cooling water passage 25, the cylinder head 22 and the cylinder block 21 are cooled by burning the fuel to a high temperature.

The cylinder head 22 has a combustion chamber 2
Intake port 33 for inhaling the atmosphere to 0, and exhaust port 38 for exhausting gas that burns fuel in the combustion chamber 20
The intake port 33 and the exhaust port 38 are opened and closed by an intake valve 27a and an exhaust valve 27b, respectively, so that intake and exhaust are performed in the combustion chamber 20.

A piston 23 is inserted into a cylinder liner 24 below the combustion chamber 20. The piston 23 is pin-joined to a connecting rod 90 via a pin boss 28, and the connecting rod 90 is connected to a crankshaft (not shown). The connecting rod 90 includes the piston 23.
Plays the role of converting the linear motion of the robot into the rotational motion of the crankshaft. Therefore, when the crankshaft rotates, the piston 23 makes a linear reciprocating motion inside the cylinder liner 24.

The piston 23 forms the lower surface of the combustion chamber 20 and serves as an operating surface when the combustion chamber 20 expands due to combustion. Further, fuel is injected onto the upper surface of the piston 23 and burns. Therefore, the driving body is heated by the combustion heat to be in an overheated state, and cooling is required to improve the overheated state of the piston 23 due to this combustion heat. Therefore, the piston 23 has a cooling cavity 26 therein, and also has inlet / outlet holes 29a, 29b for letting oil as a cooling liquid into and out of the cooling cavity 26. Further, below the piston 23, there are provided nozzles 58a and 58b for injecting oil obliquely upward. Hereinafter, cooling of the piston 23 by this oil injection will be described.

As described above, by circulating the cooling water inside, the cylinder block 21 and the cylinder head 22 forming the combustion chamber 20 can be directly cooled by this cooling water. However, since the piston 23 is always operating, it is impossible to extend the cooling water passage from the cylinder block 21 or the like. Therefore, it is difficult to directly cool the piston 23 with cooling water. Therefore, the piston 23 is cooled by injecting into the piston 23 oil that serves as lubricating oil that has been cooled in advance with cooling water.

Specifically, the nozzle 58a and the nozzle 58b
The oil is injected from the bottom to the lower surface of the piston 23, and the oil is injected into the cooling cavity 26 provided in the piston 23 through the inlet / outlet holes 29a and 29b penetrating the cooling cavity 26. Further, the nozzles 58a and 58b for injecting oil are attached so as to be oblique with respect to the axis line along which the piston 23 reciprocates.

As shown in FIGS. 2 and 3, the nozzle 58b injects oil toward the periphery of the pin boss 28 when the piston 23 is near the top dead center. Again piston 2
When 3 is near the bottom dead center, oil is injected toward the inlet / outlet hole 29b to fill the inside of the cooling cavity 26 with oil.

As shown in FIGS. 4 and 5, the nozzle 58a has an inlet / outlet hole 29 when the piston 23 is near the top dead center.
Oil is injected toward a to fill the inside of the cooling cavity 26 with oil. When the piston 23 is near the bottom dead center, the lower surface of the piston 23 is sprayed to cool the entire lower surface.

That is, the nozzles 58a and 58b are installed obliquely so that when the piston 23 moves, the lower surface of the piston 23 and the trajectory of the oil injected from the nozzle intersect at different positions. did. Further, when the piston 23 is near the top dead center, the inlet / outlet hole 29
Oil is injected from a and discharged from 29b, and when it is near the bottom dead center, oil is injected from an inlet / outlet hole 29b to 29a.
Eject more. Generally, the temperature of the place where the oil is discharged becomes higher than the temperature where the oil is injected. Therefore, it is possible to uniformly cool the piston 23 by alternately injecting oil into the inlet / outlet hole 29a and the inlet / outlet hole 29b.

Further, oil is supplied to the nozzle 58a and the nozzle 58.
The output ejected from b depends on the output of the engine 1. Therefore, when the output of the engine 1 is reduced, the output for discharging the oil is also reduced. Further, in the state where the engine output is reduced, that is, in the low load state, the temperature in the combustion chamber is also reduced, so that the necessity of cooling is reduced as compared with the high load state of the engine. Therefore, the number of nozzles that inject oil is changed according to the load state of the engine 1. That is, during acceleration,
The nozzle 58a and the nozzle 58b are in a high load state such as when climbing a slope.
Both are used for cooling. When the load is relatively low, such as when traveling at a constant speed, oil injection is performed from any one of the nozzles 58a and 58b. In a low load state during idling, oil is not injected from any nozzle.

As described above, by changing the number of the oil injection nozzles according to the load state of the engine 1, it is possible to prevent the supercooling of the piston 23 due to the oil injection when the load is low.

(Second Embodiment) In the first embodiment, oil injection is performed toward the inside of the cooling cavity 26 when the piston 23 is at the top dead center or the bottom dead center. In addition to this, it is also possible to cool the inside of the cooling cavity 26 by injecting oil near the intermediate position between the top dead center and the bottom dead center of the piston 23. In the second embodiment, an example in which cooling at such an intermediate position is possible will be described.

In this apparatus, as shown in FIG. 6, an inlet / outlet hole 129c is provided on the inlet / outlet hole 129a side. More precisely, as shown in FIG. 7, the inlet / outlet hole 129a is provided at the nozzle 5 when the piston 23 is located at the bottom dead center and in the vicinity of the bottom dead center.
8a overlaps the trajectory of the oil injected from
c is provided at a position overlapping the trajectory of the oil ejected from the nozzle 58a when the piston 23 is located at the top dead center and near the top dead center. Further, regarding the inlet / outlet hole 129b, see FIG.
As shown in FIG. 5, when the piston 23 is located near the middle position between the top dead center and the bottom dead center, the locus of oil sprayed from the nozzle 58b and the inlet / outlet hole 129b are provided so as to overlap each other.

The inlet / outlet hole 129a and the inlet / outlet hole 129 are located at the above positions
b, the inlet / outlet hole 129c is provided, and when the piston 23 is located at the top dead center and in the vicinity of the top dead center, oil is jetted from the nozzle 58a toward the inlet / outlet hole 129a, and from the nozzle 58b toward the pin boss surface. To do. Next, when the piston 23 is near the intermediate position between the top dead center and the bottom dead center, oil is jetted from the nozzle 58a toward the pin boss surface, and oil is jetted from the nozzle 58b toward the inlet / outlet hole 129b. Then, when the piston 23 is located at the bottom dead center and in the vicinity of the bottom dead center, the nozzle 58a causes the inlet / outlet hole 12
Oil is jetted toward 9c, and oil is jetted from the nozzle 58b toward the pin boss surface. As a result, it is possible to inject the cooling oil into the cooling cavity 26 at any position of the piston 23 near the top dead center, near the middle position between the top dead center and the bottom dead center, and near the bottom dead center. Becomes

As shown in the first embodiment, the nozzle 58a
Compared with the case of cooling by injecting oil onto the pin boss surface, oil can be injected into the cooling cavity 26 and cooling can be performed at a position closer to the combustion chamber 20 that is a heat source, so that the cooling performance is more excellent. Will be things. As described above, by providing the inlet / outlet hole 129c on the lower surface of the piston 23 and injecting the oil into the inlet / outlet hole 129c, the piston 23 can be cooled more effectively.

[0053]

According to the present invention, by alternately injecting the oil into the cooling cavity from the two nozzles, the cooling efficiency of the piston can be improved and the piston can be cooled uniformly. Further, by further providing an oil inlet / outlet hole and injecting the oil from any of the nozzles into this inlet / outlet hole, the amount of oil flowing in the cooling cavity can be increased, and the cooling effect can be further enhanced. it can.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing a diesel engine system according to an embodiment of the present invention.

FIG. 2 is a cross-sectional schematic configuration diagram (a piston top dead center position) around a combustion chamber according to the first embodiment of the present invention.

FIG. 3 is a cross-sectional schematic configuration diagram (a piston bottom dead center position) around a combustion chamber according to the first embodiment of the present invention.

FIG. 4 is a cross-sectional schematic configuration diagram (a piston top dead center position) around a combustion chamber according to the first embodiment of the present invention.

FIG. 5 is a cross-sectional schematic configuration diagram (a piston bottom dead center position) around a combustion chamber according to the first embodiment of the present invention.

FIG. 6 is a schematic diagram showing a positional relationship between inlet and outlet holes provided in the piston according to the second embodiment of the present invention.

FIG. 7 is a schematic sectional configuration diagram around a combustion chamber according to a second embodiment of the present invention.

FIG. 8 is a schematic sectional configuration diagram around a combustion chamber according to a second embodiment of the present invention.

[Explanation of symbols]

1 engine 10 Fuel supply system 11 Supply pump 12 common rail 13 Fuel injection valve 14 Shut-off valve 17 Fuel addition nozzle 20 Combustion chamber 21 cylinder block 22 cylinder head 23 pistons 24 cylinder liner 25 cooling channels 26 cooling cavities 27a intake valve 27b exhaust valve 28 pin boss 29a Entry / Exit hole 29b Entry / Exit hole 30 Intake system 31 Intercooler 32 Throttle valve 33 Intake port 35 Exhaust system 35a Exhaust collecting pipe 35b exhaust passage 35c exhaust passage 37 Catalyst casing 38 Exhaust port 40 turbocharger 40a Exhaust collecting pipe 42 turbine wheel 43 Compressor 45 EGR passage 46 EGR valve 47 EGR cooler 50 cooling system 51 thermostat 52 radiator 53 Cooling pump 54 Cooling fan 55 Bypass pipe 58a nozzle 58b nozzle 60 Lubrication system 61 oil pan 62 oil pump 63 Oil strainer 64 oil cooler 65 oil filter 66 Oil Gallery 67 injection pump 70 Rail pressure sensor 71 Water temperature sensor 72 Air flow meter 76 Accelerator position sensor 77 Crank angle sensor 80 ECU 90 connecting rod 129a Entry / Exit hole 129b Entry / Exit hole 129c Entry / Exit hole P1 engine fuel passage

Claims (5)

[Claims] 1. A piston provided in a cylinder of an internal combustion engine, a cooling cavity that is a cavity provided inside a piston body, and a pin boss surface that is a surface provided with a pin boss of the piston. A cooling device comprising: a plurality of inlet / outlet holes that are provided to penetrate to the cooling cavity; and a nozzle in which the ejection direction of the ejection hole is obliquely provided with respect to the lower surface of the pin boss with respect to the piston, When the cooling liquid is sprayed from the plurality of nozzles, the cooling liquid is sprayed toward the first inlet / outlet hole from the first nozzle when the piston is at or near the top dead center, thereby cooling the cavity. Cooling liquid is injected into the inside of the cooling cavity, and when the piston is at the bottom dead center or a position near the bottom dead center from the second nozzle, the cooling liquid is injected toward the second inlet / outlet hole to cool into the cooling cavity. Piston cooling device to inject liquid. 2. A coolant is jetted at a position where the locus of the coolant jetted from the first or second nozzle and the coolant inlet / outlet hole formed in the pin boss surface of the piston do not overlap each other. The piston cooling device according to claim 1. 3. When the piston is located at an intermediate position between the top dead center and the bottom dead center, at least one of the first and second nozzles is arranged so as to overlap the trajectory of the cooling liquid injected from the nozzle. 3 is an inlet / outlet hole, when the piston is at an intermediate position between the top dead center and the bottom dead center,
The cooling liquid injected from the third cooling liquid inlet / outlet hole is injected into the cooling cavity by the cooling liquid ejected from the first or second nozzle. Piston cooling device. 4. The piston cooling device according to claim 1, wherein the number of nozzles for injecting cooling liquid to the piston is changed according to the temperature in the cylinder of the internal combustion engine. 5. A cooling cavity connected to the inlet / outlet holes by alternately ejecting a cooling liquid from a plurality of nozzles toward a plurality of inlet / outlet holes formed in a piston provided in a cylinder of an internal combustion engine. The cooling liquid is made to flow into the cooling cavity, and different cooling liquid flows are alternately formed in the cooling cavity to uniformly cool the piston.
A piston cooling method for cooling a piston by injecting a cooling liquid onto the wall surface of the piston from the plurality of nozzles.