JP2009299657A - Cooling device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a miniaturized cooling device for an internal combustion engine capable of sufficiently using heat taken away by a refrigerant when the refrigerant cools the internal combustion engine for heating intake air. <P>SOLUTION: This device is provided with a refrigerant chamber 1d positioned around a cylinder 1c, and a first injection valve 13 injecting liquid phase refrigerant to an upper part of the refrigerant chamber. The upper part of an inside of the refrigerant chamber is filled with a gas phase refrigerant of the same material as a liquid phase refrigerant, and a lower part of the refrigerant chamber is filled with the liquid phase refrigerant. Part of the liquid phase refrigerant in the refrigerant chamber takes heat away from an inside of a cylinder and changes it to a gas phase during an expansion stroke. The pressure of the gas phase refrigerant in the refrigerant chamber is controlled to an upper limit of set pressure higher than atmospheric pressure. Part of gas phase refrigerant in the refrigerant chamber heats intake air in the cylinder and changes to liquid phase during the intake stroke. When an engine load is larger than a set load, the liquid phase refrigerant is injected by the first injection valve during an exhaust phase. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a cooling device for an internal combustion engine.

  A cooling device has been proposed in which a liquid phase refrigerant is injected and supplied to a refrigerant chamber around a cylinder of an internal combustion engine, and the inside of the cylinder is cooled by heat of vaporization of the liquid phase refrigerant (see, for example, Patent Document 1). The apparatus can be reduced in size as compared with a conventional cooling apparatus having a large radiator and circulating cooling water around the cylinder.

JP 63-246409 A JP 2007-187112 A JP 61-20692 A JP-A-6-173680

  In the above-described cooling device, the refrigerant chamber around the cylinder is filled with the atmospheric-pressure gas phase refrigerant vaporized from the liquid phase refrigerant, and is injected into the liquid phase from the liquid phase refrigerant and the gas phase refrigerant that have not changed into the gas phase. The changed liquid phase refrigerant is returned to the refrigerant tank from the lower part of the refrigerant chamber.

  In such a configuration, the heat taken by the refrigerant when the internal combustion engine is cooled cannot be sufficiently utilized for intake air heating in the intake stroke.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a downsized cooling apparatus for an internal combustion engine that can sufficiently utilize the heat taken by the refrigerant when the internal combustion engine is cooled for intake air heating.

  According to a first aspect of the present invention, there is provided a cooling device for an internal combustion engine, comprising: a refrigerant chamber positioned around a cylinder; and a first injection valve that injects a liquid-phase refrigerant into an upper portion of the refrigerant chamber. The upper part is filled with a gas phase refrigerant of the same substance as the liquid phase refrigerant, the lower part of the refrigerant chamber is filled with a liquid phase refrigerant of the same substance as the liquid phase refrigerant, and a part of the liquid phase refrigerant in the refrigerant chamber is filled During the expansion stroke, heat is taken from the inside of the cylinder to change to a gas phase, and the pressure of the gas phase refrigerant in the refrigerant chamber is controlled at an upper limit to a set pressure higher than atmospheric pressure, and a part of the gas phase refrigerant in the refrigerant chamber is inhaled. During the stroke, the intake air in the cylinder is heated to change into the liquid phase, and when the engine load is higher than the set load, the liquid refrigerant is injected in the exhaust stroke by the first injection valve.

  According to a second aspect of the present invention, there is provided the internal combustion engine cooling apparatus according to the first aspect, wherein when the engine load is higher than the set load, the liquid refrigerant is expanded by the first injection valve. It is also characterized by injecting during the stroke.

  The cooling apparatus for an internal combustion engine according to claim 3 according to the present invention is the cooling apparatus for an internal combustion engine according to claim 1 or 2, wherein the liquid-phase refrigerant contains at least methanol, ammonia, or butane, A second injection valve for directly injecting the liquid-phase refrigerant into the cylinder is provided.

  According to a fourth aspect of the present invention, there is provided the internal combustion engine cooling apparatus according to the third aspect, wherein the liquid refrigerant is injected into the cylinder in the intake stroke by the second injection valve. Features.

  According to a fifth aspect of the present invention, there is provided the internal combustion engine cooling apparatus according to the third aspect, wherein the internal combustion engine compresses the fuel supplied into the cylinder in the intake stroke in the compression stroke. The self-ignition is performed, and a pressure increase rate when the maximum combustion pressure is reached is detected by a combustion pressure sensor. When the detected pressure increase rate is equal to or higher than a set value, the liquid phase is detected by the second injection valve. The refrigerant is injected in the compression stroke of the next cycle.

  According to a sixth aspect of the present invention, there is provided the internal combustion engine cooling apparatus according to the third aspect, wherein the internal combustion engine compresses the fuel supplied into the cylinder in the intake stroke in the compression stroke. It is self-ignited, and an ignition timing is detected by a combustion pressure sensor, and when the detected ignition timing is earlier than a set timing, the liquid refrigerant is immediately injected by the second injection valve.

  The internal combustion engine cooling device according to claim 7 according to the present invention is the internal combustion engine cooling device according to claim 1 or 2, wherein the gas-phase refrigerant is ammonia, and the gas-phase refrigerant is disposed in the engine exhaust system. It supplies to the selected selective reduction catalyst apparatus.

  An internal combustion engine cooling apparatus according to an eighth aspect of the present invention is the internal combustion engine cooling apparatus according to any one of the first to seventh aspects, wherein fins extend from a cylinder side wall of the refrigerant chamber into the refrigerant chamber. And a heat insulating layer is formed on a side wall of the refrigerant chamber opposite to the cylinder.

  According to the cooling device for an internal combustion engine of the first aspect of the present invention, the internal combustion engine cooling apparatus includes a refrigerant chamber positioned around the cylinder, and a first injection valve that injects liquid-phase refrigerant into the upper portion of the refrigerant chamber. The upper part is filled with the gas phase refrigerant of the same material as the liquid phase refrigerant, and the lower part of the refrigerant chamber is filled with the liquid phase refrigerant. During the expansion stroke, a part of the liquid phase refrigerant in the refrigerant chamber is in the cylinder during the expansion stroke. By taking heat from the inside and changing to the gas phase, the inside of the cylinder can be cooled well. Further, the upper limit of the pressure of the gas-phase refrigerant in the refrigerant chamber is controlled to a set pressure higher than the atmospheric pressure, so that the gas-phase refrigerant holds the heat taken from the cylinder in the expansion stroke not only by the temperature but also by the pressure. In addition, a part of the gas-phase refrigerant in the refrigerant chamber changes from the liquid phase to the gas phase during the intake stroke to sufficiently heat the intake air in the cylinder, and fuel vaporization can be promoted in the cylinder. Further, when the engine load is higher than the set load, the liquid refrigerant is injected in the exhaust stroke by the first injection valve. Thus, when the engine load is higher than the set load, the injected liquid-phase refrigerant takes the heat in the cylinder and evaporates in the upper part of the refrigerant chamber. Is sufficiently cooled, the intake air charging efficiency can be sufficiently increased.

  According to the cooling device for an internal combustion engine according to claim 2 of the present invention, in the cooling device for the internal combustion engine according to claim 1, when the engine load is higher than the set load, the liquid phase refrigerant is expanded by the first injection valve. The cylinder is also cooled during the stroke to cool the inside of the cylinder. Thus, when the engine load is higher than the set load, the liquid phase refrigerant evaporates in the upper part of the refrigerant chamber and cools the cylinder in the expansion stroke, thereby causing thermal deformation of the cylinder bore and piston meltdown due to excessive increase in the combustion temperature. Etc. can be prevented.

  According to the cooling device for an internal combustion engine according to claim 3 of the present invention, in the cooling device for the internal combustion engine according to claim 1 or 2, the liquid phase refrigerant contains at least methanol, ammonia, or butane. A second injection valve for directly injecting the liquid phase refrigerant into the cylinder is provided. Thereby, the liquid phase refrigerant can be injected into the cylinder as fuel as necessary.

  According to the cooling device for an internal combustion engine according to claim 4 of the present invention, in the cooling device for the internal combustion engine according to claim 3, the second injection valve injects the liquid refrigerant into the cylinder in the intake stroke. Thus, the in-cylinder temperature is lowered in the intake stroke due to the latent heat of vaporization of the liquid phase refrigerant, and the intake charge efficiency can be increased.

  According to the cooling device for an internal combustion engine according to claim 5 of the present invention, in the cooling device for an internal combustion engine according to claim 3, the internal combustion engine compresses the fuel supplied into the cylinder in the intake stroke in the compression stroke. The pressure increase rate when the maximum combustion pressure is reached is detected by the combustion pressure sensor, and when the detected pressure increase rate exceeds the set value, the second injection valve causes the liquid phase refrigerant to In the compression stroke of the next cycle, thereby reducing the temperature in the cylinder without increasing the intake charge efficiency due to the latent heat of vaporization of the liquid-phase refrigerant in the compression stroke, making it difficult for self-ignition to occur. The combustion noise can be suppressed by delaying the self-ignition timing.

  According to the cooling device for an internal combustion engine according to claim 6 of the present invention, in the cooling device for the internal combustion engine according to claim 3, the internal combustion engine compresses the fuel supplied into the cylinder in the intake stroke in the compression stroke. When the ignition timing is detected by the combustion pressure sensor and the detected ignition timing is earlier than the set timing, the liquid phase refrigerant is immediately injected by the second injection valve. In addition, the in-cylinder temperature can be lowered without increasing the intake charge efficiency by the latent heat of vaporization of the liquid-phase refrigerant, and the self-ignition combustion can be slowed to suppress the combustion noise.

  According to the cooling device for an internal combustion engine according to claim 7 of the present invention, in the cooling device for the internal combustion engine according to claim 1 or 2, the gas phase refrigerant is ammonia, and the gas phase refrigerant is disposed in the engine exhaust system. The selective reduction catalyst device is supplied to the selective reduction catalyst device, so that the temperature of the selective reduction catalyst device is not lowered by the latent heat of vaporization of liquid ammonia.

  According to the cooling device for an internal combustion engine according to claim 8 of the present invention, in the cooling device for an internal combustion engine according to any one of claims 1 to 7, fins extend from the cylinder side wall of the refrigerant chamber to the refrigerant chamber. There is a heat insulating layer on the side wall of the refrigerant chamber opposite to the cylinder. Accordingly, the fins facilitate the transfer of heat between the liquid-phase refrigerant and the gas-phase refrigerant in the refrigerant chamber and the inside of the cylinder, and the rigidity around the cylinder can be improved. Heat dissipation from the gas-phase refrigerant that has deprived of heat from the inside is suppressed, and the gas-phase refrigerant can heat the cylinder well in the intake stroke.

  FIG. 1 is a schematic view of an internal combustion engine equipped with a cooling device according to the present invention. In the figure, 1 is an engine body, 2 is an intake passage connected to an intake port 1a of the engine body 1, and 3 is an exhaust passage connected to an exhaust port 1b of the engine body 1. 1c is a cylinder, and 4 is a piston that slides in the cylinder. 5 is an intake valve, and 6 is an exhaust valve.

  1d is a refrigerant chamber having an annular cross section formed around the cylinder 1c. The refrigerant chamber 1d is preferably provided separately for each cylinder. The upper part of the refrigerant chamber 1d is filled with a gas phase refrigerant, and the lower part of the refrigerant chamber 1d is filled with a liquid phase refrigerant. The gas phase refrigerant and the liquid phase refrigerant are the same substance. The upper part of the refrigerant chamber 1 d filled with the gas phase refrigerant is connected to the gas phase refrigerant pressure accumulating chamber 7 by a pipe and to the upper part of the refrigerant tank 9 through the safety valve 8. The upper part of the refrigerant tank 9 is filled with a gas phase refrigerant.

  The safety valve 8 is opened at a set pressure higher than the atmospheric pressure and returns the gas-phase refrigerant to the refrigerant tank 9, so that the upper portions of the gas-phase refrigerant accumulator 7 and the upper portion of the refrigerant chamber 1d are controlled by the set pressure. Filled with gas phase refrigerant. The gas-phase refrigerant pressure accumulating chamber 7 is connected to the upper part of the refrigerant tank 9 via the first pump 10 by a pipe in which the check valve 11 is arranged, and the gas-phase refrigerant pressure in the gas-phase refrigerant pressure accumulating chamber 7 is However, when the pressure is slightly lower than the above-mentioned set pressure, the first pump 10 is operated to pump the gas-phase refrigerant in the refrigerant tank 9 into the gas-phase refrigerant pressure accumulating chamber 7 via the check valve 11. It has become. Thus, the upper portions of the gas-phase refrigerant pressure accumulating chamber 7 and the refrigerant chamber 1d are filled with the gas-phase refrigerant maintained at a substantially set pressure.

  A fuel injection valve 12 is disposed in the intake passage 2 and injects gasoline as fuel in synchronization with intake air or asynchronously with intake air. The fuel injected in this way is supplied into the cylinder 1c in the intake stroke to become a homogeneous mixture, and starts self-ignition combustion when it is compressed in the compression stroke to reach the ignition temperature. The engine body 1 is not limited to such self-ignition combustion, but may have a spark plug to spark-ignite a homogeneous mixture.

  During combustion in the cylinder 1c, a part of the liquid-phase refrigerant in the refrigerant chamber 1d is good so that it takes heat from the cylinder 1c during the expansion stroke and changes to a gas phase, and the temperature inside the cylinder 1c does not increase excessively. Cool down. Further, the pressure of the gas-phase refrigerant in the refrigerant chamber 1d is maintained at a set pressure higher than the atmospheric pressure, so that the gas-phase refrigerant holds the heat taken from the cylinder in the expansion stroke not only by the temperature but also by the pressure. A part of the gas-phase refrigerant in the refrigerant chamber 1d changes from the liquid phase to the gas phase during the intake stroke to sufficiently heat the intake air in the cylinder, and fuel vaporization is promoted in the cylinder 1c. .

  Reference numeral 13 denotes a first injection valve that injects the liquid phase refrigerant in the liquid phase refrigerant pressure accumulation chamber 14 to the upper portion of the refrigerant chamber 1d. The liquid-phase refrigerant pressure accumulating chamber 14 is connected to the lower part of the refrigerant tank 9 via a second pump 16 by a pipe in which the check valve 15 is arranged, and the liquid-phase refrigerant pressure in the liquid-phase refrigerant pressure accumulating chamber 14 is increased. When the pressure is slightly lower than the set injection pressure, the second pump 16 is operated so that the lower liquid phase refrigerant in the refrigerant tank 9 is pumped into the liquid phase refrigerant pressure accumulating chamber 14 via the check valve 15. It has become. Thus, the liquid-phase refrigerant pressure accumulating chamber 14 is filled with the liquid-phase refrigerant maintained at the set injection pressure, and the liquid-phase refrigerant can be injected at any time via the first injection valve 13.

  FIG. 2 is an enlarged cross-sectional view in the vicinity of the first injection valve 13. When the engine load is higher than the set load, as shown in FIG. 2, the first injection valve 13 causes the liquid refrigerant L to be injected into the upper part of the refrigerant chamber 1d in the exhaust stroke, preferably in the early stage of the exhaust stroke. Colliding with the cylinder side wall of 1d, a part thereof evaporates to become a gas phase refrigerant, and cools the inside of the cylinder 1c well. Thus, when the intake stroke is reached, the inside of the cylinder is sufficiently cooled, so that the intake charging efficiency can be sufficiently increased.

  Further, when the engine load is higher than the set load, the liquid refrigerant may be injected by the first injection valve 13 even in the expansion stroke, preferably in the initial stage of the expansion stroke when the temperature in the cylinder is highest. Thereby, even in the expansion stroke, the liquid phase refrigerant is evaporated in the upper part of the refrigerant chamber 1d and the inside of the cylinder is cooled, so that the combustion temperature rises excessively at high loads, causing thermal deformation of the cylinder bore, melting of the piston 4, etc. This can be surely prevented.

  If the material of the liquid phase refrigerant and the gas phase refrigerant is methanol, ammonia, or butane, or contains at least one of them, it can be injected into the cylinder 1c as fuel. Reference numeral 17 denotes a second injection valve that directly injects such a liquid phase refrigerant into the cylinder 1c. The second injection valve 17 is connected to the liquid phase refrigerant pressure accumulation chamber 14 by a pipe.

  If liquid phase refrigerant is injected into the cylinder 1c in the intake stroke by the second injection valve 17 in addition to the fuel injected by the fuel injection valve 12, the inside of the cylinder 1c in the intake stroke due to the latent heat of vaporization of the liquid phase refrigerant. The temperature is lowered and the intake charge efficiency can be increased.

  In the case where the engine body 1 is a compression self-ignition internal combustion engine, a rate of increase in pressure when the maximum combustion pressure is reached can be detected by providing a combustion pressure sensor in the cylinder 1c. As shown in FIG. 3, a pressure increase rate immediately before the maximum combustion pressure Pmax immediately after the compression top dead center TDC is detected, and this pressure increase rate is a set value as in the case of a sudden pressure increase as shown by a solid line in FIG. If it is above, very high noise will generate | occur | produce. At this time, in the next cycle of the same cylinder, the liquid refrigerant is injected by the second injection valve 17 in the compression stroke.

  As a result, the temperature in the cylinder 1c is lowered without increasing the intake charging efficiency due to the latent heat of vaporization of the liquid-phase refrigerant in the compression stroke, the self-ignition hardly occurs and the self-ignition timing is delayed, as shown by a dotted line in FIG. The combustion noise is suppressed by lowering the maximum combustion pressure. When the combustion pressure sensor is provided in only one cylinder, when the rate of pressure increase exceeds the set value in the cylinder provided with the combustion pressure sensor, the cylinder in the next compression stroke is changed to all cylinders. On the other hand, the liquid phase refrigerant may be injected in the compression stroke by the second injection valve 17.

  Further, the combustion pressure sensor detects the ignition timing, that is, the timing at which the heat generation rate becomes a set value (for example, 10%) based on the corresponding in-cylinder pressure P0, and is detected as indicated by the solid line in FIG. When the ignition timing T is earlier than the set timing (set timing immediately after the compression top dead center), a large noise is generated as it is, so that the second injection valve 17 immediately injects the liquid phase refrigerant into the cylinder. Anyway. Thereby, the in-cylinder temperature can be lowered without increasing the intake charging efficiency due to the latent heat of vaporization of the liquid-phase refrigerant, and the subsequent self-ignition combustion can be slowed to suppress combustion noise.

By the way, the selective catalytic reduction device occludes NO _x in the exhaust gas, and reduces and purifies the occluded NO _x with supplied ammonia before the NO _x occlusion amount is saturated. As shown in FIG. 1, in the case where such a selective catalytic reduction device 18 is disposed in the exhaust passage 3, if the supplied ammonia is a liquid, the selective catalytic reduction device 18 is lowered in temperature by latent heat of vaporization, absorbing performance of the reduced purification performance and the new NO _X occluded NO _X is reduced.

Accordingly, if the refrigerant is ammonia, a supply means 19 (ammonia injection valve) for supplying ammonia to the selective reduction catalyst device 18 is connected to the gas phase refrigerant pressure accumulating chamber 7, and the selective reduction catalyst device 18 is connected to the gas phase. Ammonia can be supplied. Thereby, it is possible to prevent the selective reduction catalyst 18 absorbing performance of the reduction purification performance and the new NO _X decrease in temperature to occluded NO _X by latent heat of vaporization of the liquid ammonia is lowered.

  FIG. 4 is a cross-sectional view showing the structure of another refrigerant chamber 1d ', and FIG. 5 is a view taken along arrow A in FIG. 4 from which the heat insulating layer 1h' and the outer member 1j 'have been removed. As shown in these drawings, the refrigerant chamber 1d ′ is formed outside the cylindrical portion 1e ′ of the cylinder block around the cylinder 1c ′, and the cylindrical portion 1e ′ includes vertical ribs 1f ′ having the same height and The lateral ribs 1g ′ are welded in a lattice shape. The outer sides of the vertical ribs 1f ′ and the horizontal ribs 1g ′ are covered with a heat insulating layer 1h ′ made of ceramic or the like, and an outer member 1j ′ is disposed around the heat insulating layer 1h ′ to provide the airtightness of the refrigerant chamber 1d ′. It has become so. The lateral ribs 1f ′ and 1g ′ are made of, for example, an aluminum alloy having excellent heat conductivity, and the chambers formed by the lattice-like longitudinal ribs 1f ′ and the lateral ribs 1g ′ communicate with each other. A communication hole 1k ′ is formed in the vertical rib 1f ′ and the horizontal rib 1g ′.

  In such a configuration of the refrigerant chamber 1d ′, rib-shaped fins extend from the cylinder side wall 1e ′ of the refrigerant chamber 1d ′ into the refrigerant chamber 1d ′, and a heat insulating layer is formed on the anti-cylinder side wall 1j ′ of the refrigerant chamber 1d ′. 1h ′ is formed. As a result, the fins can easily transfer heat between the liquid-phase refrigerant and gas-phase refrigerant in the refrigerant chamber 1d ′ and the cylinder, and can improve the rigidity around the cylinder. 1h ′ suppresses heat radiation from the gas-phase refrigerant that has taken heat from the inside of the cylinder, and the gas-phase refrigerant can heat the inside of the cylinder satisfactorily in the intake stroke. In the refrigerant chamber 1d ', the fins are formed in a lattice shape by the vertical ribs 1f' and the horizontal ribs 1g ', but the fins around the refrigerant chamber may be formed in a honeycomb shape or a diamond shape.

1 is a schematic view of an internal combustion engine equipped with a cooling device according to the present invention. It is an expanded sectional view near the 1st injection valve. It is a figure which shows the relationship between a crank angle and a cylinder internal pressure. It is sectional drawing which shows another structure of a refrigerant | coolant chamber. It is A arrow directional view of FIG. 4 which removed the heat insulation layer and the outer side member.

Explanation of symbols

1c, 1c ′ cylinder 1d, 1d ′ refrigerant chamber 13 first injection valve 17 second injection valve

Claims (8)

  A refrigerant chamber located around the cylinder; and a first injection valve that injects liquid phase refrigerant into the upper portion of the refrigerant chamber, the upper portion of the refrigerant chamber being filled with a gas phase refrigerant of the same material as the liquid phase refrigerant. The lower part of the refrigerant chamber is filled with a liquid phase refrigerant of the same material as the liquid phase refrigerant, and a part of the liquid phase refrigerant in the refrigerant chamber takes heat from the inside of the cylinder during the expansion stroke and changes to a gas phase. The pressure of the gas-phase refrigerant in the refrigerant chamber is controlled at an upper limit to a set pressure higher than the atmospheric pressure, and a part of the gas-phase refrigerant in the refrigerant chamber heats the intake air in the cylinder during the intake stroke to change the phase to the liquid phase When the engine load is higher than the set load, the internal combustion engine cooling device is characterized in that the liquid refrigerant is injected in the exhaust stroke by the first injection valve.   2. The cooling device for an internal combustion engine according to claim 1, wherein when the engine load is higher than the set load, the first injection valve also injects the liquid phase refrigerant in the expansion stroke.   The liquid phase refrigerant includes at least methanol, ammonia, or butane, and a second injection valve that directly injects the liquid phase refrigerant into a cylinder is provided. The internal combustion engine cooling device according to claim 2.   The cooling device for an internal combustion engine according to claim 3, wherein the liquid-phase refrigerant is injected into the cylinder in the intake stroke by the second injection valve.   The internal combustion engine compresses the fuel supplied into the cylinder in the intake stroke and self-ignites in the compression stroke, and detects the pressure increase rate when the maximum combustion pressure is reached by the combustion pressure sensor, and detects the detected 4. The cooling apparatus for an internal combustion engine according to claim 3, wherein when the rate of pressure increase is equal to or greater than a set value, the liquid refrigerant is injected in the compression stroke of the next cycle by the second injection valve.   The internal combustion engine compresses the fuel supplied into the cylinder in the intake stroke and self-ignites it in the compression stroke, detects the ignition timing by a combustion pressure sensor, and when the detected ignition timing is earlier than the set timing The cooling device for an internal combustion engine according to claim 3, wherein the liquid refrigerant is immediately injected by the second injection valve.   The cooling apparatus for an internal combustion engine according to claim 1 or 2, wherein the gas-phase refrigerant is ammonia, and the gas-phase refrigerant is supplied to a selective reduction catalyst device disposed in an engine exhaust system.   8. The fin according to claim 1, wherein a fin extends from the cylinder side wall of the refrigerant chamber to the refrigerant chamber, and a heat insulating layer is formed on the anti-cylinder side wall of the refrigerant chamber. Cooling device for internal combustion engine.

Images