JP6135706B2 - Engine cooling system - Google Patents

Description

  The present invention relates to an engine cooling apparatus.

  In recent years, a technique for improving the fuel efficiency by reducing the cooling loss by insulating the combustion chamber and thereby improving the thermal efficiency of the engine has been studied. For example, research on an engine structure including a cylinder liner formed of carbon fiber reinforced resin composite material (CFRP / Carbon Fiber Reinforced Plastics) is underway.

  According to this engine structure, since the cylinder liner is formed of the carbon fiber reinforced resin composite material having low thermal conductivity, heat dissipation to the cylinder block is suppressed. As a result, it contributes to a reduction in cooling loss of the engine and, in turn, an improvement in thermal efficiency.

  However, by suppressing the heat radiation to the cylinder block, the temperature rise of the cooling water and oil (cooling fluid) flowing outside the cylinder liner is also prevented. For this reason, for example, in a cold district, there is a possibility that the heating function using the thermal energy of the cooling water may be adversely affected.

  In order to prevent such adverse effects, for example, as described in Patent Document 1, a cooling structure that cools the cylinder liner by circulating cooling water in a water jacket formed along the outer periphery of the cylinder liner. In the cylinder block, an annular cooling pool portion for temporarily storing cooling water is formed in a portion around the water jacket in the cylinder block, and the annular cooling pool portion and the water jacket are communicated with each other by a plurality of cooling water passages. It can be considered that the cooling water in the cooling water passage collides with the wall surface of the water jacket substantially perpendicularly when viewed from the axial direction.

JP 2005-337035 A

  According to the cooling structure described in Patent Document 1, turbulent flow of cooling water is generated in the water jacket by causing the cooling water to collide with the wall surface of the water jacket substantially perpendicularly when viewed from the axial direction of the cylinder. be able to. As a result, since the heat transfer rate from the cylinder liner to the cooling water is increased, the temperature rise of the cooling water flowing outside the cylinder liner can be promoted even when the cylinder liner is made of a material having low thermal conductivity. Can do.

  However, since the cooling structure described in Patent Document 1 is formed by forming an annular cooling pool portion around the water jacket in the cylinder block, the structure of the cylinder block is complicated and the size of the cylinder block is increased. There is a risk of inviting. Furthermore, although the cooling structure described in Patent Document 1 can increase the heat transfer rate from the cylinder liner to the cooling water, it cannot suppress heat dissipation from the cylinder block and improve fuel efficiency.

  The present invention has been made in view of the above circumstances, and provides an engine cooling device capable of ensuring good fuel consumption performance and heating performance while avoiding the complexity and enlargement of the structure of a cylinder block. The purpose is to do.

In order to solve the above-described problems, the present invention provides a water jacket formed in a cylinder block so as to surround a cylinder bore wall of an engine, and a hollow shape that is accommodated in the water jacket with a space from the cylinder bore wall. A spacer member; an introduction passage for introducing cooling water into the internal space of the spacer member; and a lead-out passage for guiding cooling water from a space between the spacer member and the cylinder bore wall. The member has a bore side peripheral wall that faces and opposes the outer peripheral surface of the cylinder bore wall. The bore side peripheral wall extends from the outside to the inside, and cools water in the internal space to the cylinder bore wall. and ejection holes for ejecting is formed toward the out of the cylinder bore wall, around the site facing the ejection hole, said cylinder Toward the outer circumferential surface of the A wall to the bore side peripheral wall protrudes, characterized in that the ribs have a gap is formed between said bore side wall, to provide cooling system for an engine.

  According to the present invention, the cooling water introduced into the internal space of the spacer member (hereinafter referred to as “spacer inner space”) through the introduction passage is the space between the spacer member and the cylinder bore wall through the ejection holes in the bore side peripheral wall. (Hereinafter referred to as “bore side space”) and discharged from the bore side space through the outlet passage. The bore-side peripheral wall is close to the outer peripheral surface of the cylinder bore wall, and the ejection holes of the bore-side peripheral wall extend from the outside to the inside of the bore-side peripheral wall. Collide with. When the cooling water collides with the outer peripheral surface of the cylinder bore wall, turbulent flow is generated in the bore side space, particularly near the surface of the cylinder bore wall, and the temperature boundary layer near the surface of the cylinder bore wall becomes thin. Since the heat transfer rate from the wall to the cooling water increases, the heat of the cylinder bore wall is efficiently transferred to the cooling water. And the favorable heating performance can be ensured by utilizing the cooling water efficiently heated by the cylinder bore wall.

  In addition, since the cooling device has a simple structure in which the spacer member is accommodated in the water jacket, the structure of the cylinder block can be prevented from becoming complicated or enlarged.

Furthermore, since the heat insulating effect is produced by providing the spacer member, it is possible to suppress the heat of the cylinder bore wall from being radiated to the cylinder block, thereby improving the thermal efficiency of the engine and ensuring good fuel efficiency. it can. Moreover, the heat insulation effect by the spacer member suppresses the heat of the cooling water from being radiated to the cylinder block, and as a result, the temperature rise of the cooling water can be promoted to ensure good heating performance.
In the bore side space, in the direction along the cylinder bore wall, the cooling water flow disturbance (turbulent flow state) gradually decreases with increasing distance from the cooling water collision site on the cylinder bore wall. The heat transfer rate from the cylinder bore wall to the cooling water gradually decreases as the distance from the part increases. However, according to this configuration, since the flow of the cooling water in the bore side space is disturbed by the rib, the disturbance of the cooling water flow is recovered at a position away from the cooling water collision site on the cylinder bore wall. Accordingly, the heat transfer rate from the cylinder bore wall to the cooling water can be recovered to a high level, and the decrease can be suppressed.
In the present invention, the cylinder bore wall is formed by a cylindrical cylinder liner fitted into the cylinder block, and the cylinder liner has a heat conductivity in the first direction along the axial direction along the thickness direction. It is preferable that the thermal jacket has a thermal conductivity anisotropy larger than the thermal conductivity in the second direction, and the water jacket is disposed only on the outer side of one end portion in the axial direction of the cylinder liner.
In this configuration, the “cylindrical cylinder liner fitted into the cylinder block” includes a cylinder liner press-fitted into the cylinder block and a cylinder liner cast into the cylinder block.
According to this configuration, since the cylinder liner has thermal conductivity anisotropy, the heat in the combustion chamber moves exclusively along the cylinder liner toward the water jacket, and the outside (the second direction outside) from the cylinder liner. Heat dissipation to is suppressed. Therefore, while maintaining the combustion chamber at a high temperature to increase the thermal efficiency of the engine, the temperature of the cooling water can be raised efficiently by efficiently transporting heat to the cooling water flowing in the water jacket.
Furthermore, since the water jacket is disposed only outside the one end portion in the axial direction of the main body, excessive heat transfer to the cooling water (increase in cooling loss) can be suppressed. Moreover, since the volume in a water jacket becomes small, it becomes possible to raise temperature of cooling water with a small amount of heat. Such a structure is particularly effective in a low heat capacity type engine having a relatively small calorific value.
In the present invention, the cylinder bore wall is formed by a cylindrical cylinder liner fitted into the cylinder block, and the cylinder liner has a heat conductivity in the first direction along the axial direction along the thickness direction. A main body portion having thermal conductivity anisotropy larger than the thermal conductivity in the second direction, and a heat induction portion connected to one end portion of the main body portion in the first direction so as to be capable of transferring heat, It is preferable that it is disposed only outside the heat induction part.
According to this configuration, it is possible to achieve the same effect as in the above case where the water jacket is disposed only outside the one end portion in the axial direction of the main body portion.
According to another aspect of the present invention, there is provided a water jacket formed in a cylinder block so as to surround a cylinder bore wall of an engine, and a hollow shape accommodated in the water jacket with a space from the cylinder bore wall. A spacer member; an introduction passage for introducing cooling water into the internal space of the spacer member; and a lead-out passage for guiding cooling water from a space between the spacer member and the cylinder bore wall. The member has a bore side peripheral wall that faces and opposes the outer peripheral surface of the cylinder bore wall. The bore side peripheral wall extends from the outside to the inside, and cools water in the internal space to the cylinder bore wall. The cylinder bore wall is formed in a cylindrical cylinder liner fitted into the cylinder block. The cylinder liner has a thermal conductivity anisotropy whose thermal conductivity in the first direction along the axial direction is greater than the thermal conductivity in the second direction along the thickness direction; And a heat induction part connected to one end of the body part in the first direction so as to be capable of transferring heat, and the water jacket is disposed only outside the heat induction part. A device is provided.
According to the present invention, the cooling water introduced into the internal space of the spacer member (hereinafter referred to as “spacer inner space”) through the introduction passage is the space between the spacer member and the cylinder bore wall through the ejection holes in the bore side peripheral wall. (Hereinafter referred to as “bore side space”) and discharged from the bore side space through the outlet passage. The bore-side peripheral wall is close to the outer peripheral surface of the cylinder bore wall, and the ejection holes of the bore-side peripheral wall extend from the outside to the inside of the bore-side peripheral wall. Collide with. When the cooling water collides with the outer peripheral surface of the cylinder bore wall, turbulent flow is generated in the bore side space, particularly near the surface of the cylinder bore wall, and the temperature boundary layer near the surface of the cylinder bore wall becomes thin. Since the heat transfer rate from the wall to the cooling water increases, the heat of the cylinder bore wall is efficiently transferred to the cooling water. And the favorable heating performance can be ensured by utilizing the cooling water efficiently heated by the cylinder bore wall.
In addition, since the cooling device has a simple structure in which the spacer member is accommodated in the water jacket, the structure of the cylinder block can be prevented from becoming complicated or enlarged.
Furthermore, since the heat insulating effect is produced by providing the spacer member, it is possible to suppress the heat of the cylinder bore wall from being radiated to the cylinder block, thereby improving the thermal efficiency of the engine and ensuring good fuel efficiency. it can. Moreover, the heat insulation effect by the spacer member suppresses the heat of the cooling water from being radiated to the cylinder block, and as a result, the temperature rise of the cooling water can be promoted to ensure good heating performance.
Moreover, since the water jacket is disposed only outside the one end portion in the axial direction of the main body, excessive heat transfer (increase in cooling loss) to the cooling water can be suppressed.
In the present invention, a rib that protrudes from the outer peripheral surface of the cylinder bore wall toward the bore side peripheral wall around the portion of the cylinder bore wall that faces the ejection hole and has a gap between the bore side peripheral wall Is preferably formed.
In the bore side space, in the direction along the cylinder bore wall, the turbulence of the cooling water flow (turbulent state) gradually decreases as the distance from the collision area of the cooling water on the cylinder bore wall decreases. As the distance increases, the heat transfer rate from the cylinder bore wall to the cooling water also tends to decrease. However, according to this configuration, since the flow of the cooling water in the bore side space is disturbed by the rib, the disturbance of the cooling water flow is recovered at a position away from the cooling water collision site on the cylinder bore wall. Accordingly, the heat transfer rate from the cylinder bore wall to the cooling water can be recovered to a high level, and the decrease can be suppressed.

  In this invention, it is preferable that the said ejection hole is extended in the direction which makes a substantially perpendicular | vertical on the said outer peripheral surface with respect to the tangent which touches the outer peripheral surface of the said cylinder bore wall seeing from the axial direction of a cylinder.

  According to this configuration, when cooling water in the spacer inner space is introduced into the bore side space through the ejection holes, the cooling water is viewed from the axial direction of the cylinder with respect to a tangent line that contacts the outer peripheral surface of the cylinder bore wall. As a result, the cooling water collides with the outer peripheral surface of the cylinder bore wall substantially perpendicularly. When the cooling water collides with the outer peripheral surface of the cylinder bore wall substantially perpendicularly, the degree of occurrence of turbulent flow in the bore side space increases, and the temperature boundary layer near the surface of the cylinder bore wall becomes very thin. The heat transfer rate from the cylinder bore wall to the cooling water can be further increased.

  In the present invention, it is preferable to further include a water pump for supplying cooling water to the internal space through the introduction passage.

  According to this configuration, a pressure difference is generated between the spacer inner space and the bore side space by the pumping force of the water pump (the pressure in the spacer space is higher than the pressure in the bore side space), and cooling water is supplied. It can be made to collide with the outer peripheral surface of a cylinder bore wall reliably.

  In the present invention, the spacer member is preferably made of a heat insulating material.

  According to this configuration, the heat of the cylinder bore wall is further suppressed from being radiated to the cylinder block. Thereby, the thermal efficiency of the engine can be further improved, and good fuel efficiency can be ensured. Moreover, it is further suppressed that the heat of the cooling water is radiated to the cylinder block. Thereby, the temperature increase of the cooling water can be promoted, and good heating performance can be ensured.

  As described above, according to the present invention, good fuel economy performance and heating performance can be ensured while avoiding the complexity and enlargement of the structure of the cylinder block.

1 is a cross-sectional view of a multi-cylinder engine to which a cooling device according to a first embodiment of the present invention is applied. It is sectional drawing which expands and shows the principal part of the engine shown by FIG. It is sectional drawing which expands and shows the peripheral part of the ejection hole shown by FIG. FIG. 2 is a cross-sectional view of the engine shown in FIG. It is sectional drawing which expands and shows the principal part of the engine shown by FIG. It is a graph which shows the improvement of the heat transfer rate in 1st Embodiment. It is sectional drawing which shows the principal part of the cooling device which concerns on 2nd Embodiment of this invention. It is a figure which shows the 1st example (a) and 2nd example (b) of the rib in 2nd Embodiment of this invention. It is a graph which shows the improvement of the heat transfer rate in 2nd Embodiment. It is a figure which shows the modification of the rib in 2nd Embodiment.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. FIG. 4 is a cross-sectional view taken along line AA in FIG. 1, but shows only one of the four cylinders. Moreover, the arrow in FIG.3, 5 has shown an example of the flow of a cooling water.

(First embodiment)
The engine cooling device according to the first embodiment (hereinafter referred to as “cooling device”) is applied to a vehicle engine such as an automobile.

  An outline of the cooling device will be described.

  As shown in FIGS. 1 to 4, the cooling device includes a water jacket 36 formed in the cylinder block 5 so as to surround the cylinder liner 51 of the engine 1, and a space 33 (see FIG. 2) from the cylinder liner 51 to the water jacket 36. , 3) and a hollow spacer member 26 accommodated with a space therebetween, an introduction passage 34 (see FIG. 4) for introducing cooling water into the internal space 26f (see FIGS. 2 and 3) of the spacer member 26, Leading passages 38 and 39 for leading cooling water from a space 33 between the spacer member 26 and the cylinder liner 51 (hereinafter referred to as “bore side space 33”, see FIGS. 2 and 3), and an introduction passage 34 are provided. A water pump 37 (see FIG. 4) for supplying cooling water to the internal space 26f, water jackets 27 and 28 formed on the cylinder head 4, And a eta and the heater core, the circulation path of the cooling water is constituted by these members.

  Hereinafter, this cooling device will be described in detail.

(Overall structure of engine 1)
The engine 1 to which the cooling device is applied is an in-line four-cylinder gasoline engine in which four cylinders are arranged in a direction perpendicular to the paper surface of FIG.

  The engine 1 includes an engine body 2 and auxiliary equipment such as an unillustrated intake / exhaust manifold and various pumps assembled thereto.

  The engine body 2 includes a cam cap 3, a cylinder head 4, a cylinder block 5, a crankcase (not shown), and an oil pan (not shown) that are connected vertically.

  Four cylinder bores 7 are formed in the cylinder block 5, and pistons 8 are slidably accommodated in the respective cylinder bores 7. A chamber 10 is formed for each cylinder. Each piston 8 is connected via a connecting rod 9 to a crankshaft (not shown) that is rotatably supported by the crankcase.

  The cylinder head 4 is provided with the same number of recesses 4 a as the cylinder bore 7 for forming the combustion chamber 10. The cylinder head 4 is provided with an intake port 12 and an exhaust port 13 that open to the combustion chamber 10 at the position of each recess 4a for each cylinder, and an intake valve 14 and an exhaust valve that open and close the intake port 12 and the exhaust port 13, respectively. 15 is installed in each of the ports 12 and 13, respectively.

  The intake valve 14 and the exhaust valve 15 are urged in the direction of closing the ports 12 and 13 (upward in FIG. 1) by return springs 16 and 17, respectively, and are provided on the outer periphery of the camshafts 18 and 19. Each port 12 and 13 is configured to be opened by being pressed by the cam portions 18a and 19a. Specifically, as the cam shafts 18 and 19 rotate, the cam portions 18a and 19a push down the cam followers 20a and 21a provided at the center of the swing arms 20 and 21, so that the swing arms 20 and 21 have one end thereof. The top of the pivot mechanism of the hydraulic lash adjusters 24 and 25 provided on the side is swung around the fulcrum, and the other end of the swing arms 20 and 21 resists the biasing force of the return springs 16 and 17 along with this swing. Then, the intake valve 14 and the exhaust valve 15 are pressed down. As a result, the ports 12 and 13 are opened.

  The cylinder head 4 and the cylinder block 5 are provided with a water jacket. Specifically, the cylinder block 5 is provided with a water jacket 36 so as to integrally surround the four cylinder bores 7. Further, the cylinder head 4 is provided with a water jacket 27 at a position on the intake side (right side in FIG. 1) of the combustion chamber 10 and below the intake port 12, and also on the exhaust side (in FIG. 1). A water jacket 28 is provided at a position below the exhaust port 13 on the left side.

  Although not shown in detail, the water jacket 36 of the cylinder block 5 and the water jackets 27 and 28 of the cylinder head 4 are connected to a gasket communication hole (not shown) interposed between the cylinder head 4 and the cylinder block 5. Are communicated with each other.

(Detailed structure of cylinder block 5)
As shown in FIGS. 1 and 2, the cylinder block 5 includes a block main body 50 that is a cast product of an aluminum alloy, and a cylindrical cylinder liner 51 that is cast or press-fitted into the block main body 50 (the present invention). The cylinder bore 7 is formed by the inner peripheral surface of the cylinder liner 51.

  The block main body 50 includes four cylinder portions 55 (see FIGS. 1 to 4), a skirt portion 56 (see FIG. 1) connected to the lower side of the cylinder portion 55 to form a crank chamber, and an inner side of the skirt portion 56. The crankshaft bearing portion 57 is provided. A cylinder liner 51 is disposed inside each cylinder portion 55.

  The cylinder liner 51 includes a first liner portion 52 (corresponding to the “main body portion” of the present invention) that forms the lower portion of the cylinder bore 7 and a second liner portion 53 (corresponding to “the main portion” of the present invention). Equivalent to “heat induction part”. In the example shown in FIG. 1, the second liner portion 53 forms a certain region of the cylinder bore 7 including the position of the piston ring of the piston 8 that has reached the top dead center.

  The first liner portion 52 is formed of a high thermal conductivity carbon fiber reinforced resin composite material (CFRP) and has thermal conductivity anisotropy. More specifically, the first liner portion 52 is made of, for example, a carbon fiber reinforced resin composite material obtained by impregnating and laminating pitch-based carbon fibers in an epoxy resin or the like, and the carbon fibers of the cylinder liner 51 (first liner portion 52). It is formed in a cylindrical shape so as to be parallel to the center line (axis). Thereby, the first liner portion 52 has a thermal conductivity equal to or higher than that of the metal material, and the thermal conductivity in the vertical direction (direction parallel to the center line / corresponding to the “first direction” of the present invention) is thick. The structure has a heat conduction characteristic larger than the heat conductivity in the direction (direction perpendicular to the center line / corresponding to the “second direction” of the present invention), that is, heat conduction anisotropy. In the present embodiment, for example, the thermal conductivity in the vertical direction is about 300 W / mK, whereas the thermal conductivity in the thickness direction is about 2.0 W / mK, and the first liner portion 52 is The thermal conductivity is 150 times the thermal conductivity in the thickness direction.

  On the other hand, the second liner portion 53 is in contact with the upper surface of the first liner portion 52 in a state where heat can be transferred. The second liner portion 53 is formed of a metal material. In the present embodiment, the second liner portion 53 is formed of cast iron which is a general material of a cylinder liner. The thermal conductivity of cast iron is about 48 W / mK.

  As shown in FIGS. 1 to 5, the water jacket 36 is provided on the radially outer side (outer periphery) of the second liner portion 53. The water jacket 36 is formed by the outer peripheral surface of the second liner portion 53, the wall surface of the stepped portion 50a (see FIGS. 2 and 3) formed in the block body 50, and the gasket.

  As shown in FIG. 2, the spacer member 26 includes a bore side peripheral wall 26b, an anti-bore side peripheral wall 26a, an upper wall 26c, and a lower wall 26d, and these walls 26a to 26d are integrally formed. Has been. The material of the spacer member 26 is not particularly limited, but in the present embodiment, it is glass fiber reinforced plastic (GFRP) using an aromatic polyamide. This material has high heat insulation.

  As shown in FIGS. 2 to 5, the bore-side peripheral wall 26 b is disposed so as to face the outer peripheral surface of the second liner portion 53 (cylinder liner 51) close to the second liner portion 53. The bore side space 33 is formed in the upper part. The bore side space 33 is a space through which cooling water flows. That is, the outer peripheral surface of the second liner portion 53 of the cylinder liner 51 is in direct contact with the cooling water. The bore-side peripheral wall 26b forms an internal space 26f (hereinafter referred to as “spacer-internal space 26f”) between the anti-bore-side peripheral wall 26a. The spacer inner space 26f is a space through which cooling water flows.

  The bore-side peripheral wall 26b is formed with a plurality of cylindrical ejection holes 26e. The ejection hole 26e is a through hole that extends linearly from the outside to the inside of the bore-side peripheral wall 26b, and communicates the bore-side space 33 and the spacer inner space 26f. The ejection holes 26 e are for ejecting the cooling water in the spacer inner space 26 f toward the second liner portion 53. As shown in FIGS. 4 and 5, the ejection hole 26 e extends in a direction substantially perpendicular to a tangent line that contacts the outer peripheral surface of the second liner portion 53 when viewed from the axial direction of the cylinder (cylinder bore 7). In other words, the ejection hole 26e extends from the outside of the bore side peripheral wall 26b toward the center of the cylinder (cylinder bore 7).

  In the present embodiment, as shown in FIG. 4, three ejection holes 26e are formed on each of the intake side and the exhaust side of each cylinder. That is, six ejection holes 26e are formed for each cylinder. As shown in FIG. 2, each ejection hole 26 e is formed at the center in the vertical direction of the bore-side peripheral wall 26 b. In the three ejection holes 26e formed on the intake side of each cylinder, the intervals between adjacent ones are set to be substantially the same. The same applies to the three ejection holes 26e formed on the exhaust side of each cylinder.

  As shown in FIGS. 2 to 5, the anti-bore side peripheral wall 26 a is disposed outside the bore side peripheral wall 26 b so as to face the bore side peripheral wall 26 b. As shown in FIG. 4, a cutout hole 26g for communicating the spacer inner space 26f and the introduction passage 34 is formed in the counter-bore side peripheral wall 26a.

  As shown in FIG. 4, the introduction passage 34 is formed in the block body 50. More specifically, the introduction passage 34 is formed in the cylinder portion 55 located at one end portion in the cylinder row direction among the four cylinder portions 55 constituting the block body 50. The upstream end (outer end) of the introduction passage 34 is connected to the discharge port of the water pump 37. The downstream end portion (inner end portion) of the introduction passage 34 is connected to the notch hole 26g of the counter bore side peripheral wall 26a.

  The lead-out passage 38 is a passage that allows the water jacket 27 and the bore-side space 33 to communicate with each other (see FIG. 1), and is formed in the cylinder head 4. The lead-out passage 39 is a passage that allows the water jacket 28 and the bore-side space 33 to communicate with each other (see FIG. 1), and is formed in the cylinder head 4. The water jacket 27 and the water jacket 28 are disposed downstream of the bore-side space 33 in the cooling water circulation path and upstream of the heater core.

  The radiator is disposed on the downstream side of the water jackets 36, 27, and 28 in the cooling water circulation path. The radiator cools the cooling water heated by the water jackets 36, 27, and 28 and returns the cooled cooling water to the water pump 37.

  The heater core is disposed on the downstream side of the water jackets 36, 27, and 28 in the cooling water circulation path and on the upstream side of the radiator. The heater core exchanges heat between the cooling water heated in the water jackets 36, 27, and 28 and the air in the passenger compartment to warm the air in the passenger compartment.

  Next, the operation and effects of the cooling device according to this embodiment will be described.

  When the water pump 37 is operated, the cooling water is introduced into the spacer inner space 26f through the introduction passage 34 and the cutout hole 26g by the pressure feeding force. Part of the cooling water introduced into the spacer inner space 26f is introduced into the bore side space 33 through the ejection holes 26e (see FIGS. 3 and 5), and the remaining cooling water flows through the spacer inner space 26f of each cylinder. All of the cooling water introduced into the spacer inner space 26f is finally introduced into the bore side space 33 through the ejection holes 26e. Since the speed of the cooling water increases when passing through the ejection hole 26e, the cooling water is ejected from the ejection hole 26e toward the outer peripheral surface of the second liner portion 53 when being introduced into the bore side space 33 (see FIGS. 3 and 5). ).

  2-5, the bore side peripheral wall 26b is close to the outer peripheral surface of the second liner portion 53, and the ejection hole 26e of the bore side peripheral wall 26b extends from the outside to the inside of the bore side peripheral wall 26b. Therefore, the cooling water ejected from the ejection hole 26 e collides with the outer peripheral surface of the second liner portion 53. When the cooling water collides with the outer peripheral surface of the second liner portion 53, a turbulent flow is generated in the bore-side space 33, particularly near the surface of the second liner portion 53, and the temperature near the surface of the second liner portion 53. The boundary layer becomes thin, and as a result, the heat transfer rate from the second liner portion 53 to the cooling water increases, so that the heat of the second liner portion 53 is efficiently absorbed by the cooling water.

  FIG. 6 is a graph showing that the heat transfer rate from the second liner portion 53 to the cooling water is increased in the present embodiment. A solid line G1 in FIG. 6 is a graph showing the relationship between the heat transfer coefficient and the distance from the cooling water collision center in the present embodiment. A broken line G2 in FIG. 6 is a graph showing a heat transfer coefficient when turbulent flow due to collision is not generated (when cooling water flows in a laminar flow state along the second liner portion 53).

  As shown in FIG. 6, when no turbulent flow due to a collision is generated, the heat transfer coefficient from the second liner portion 53 to the cooling water is constant at a low level. On the other hand, when the turbulent flow due to the collision is generated as in the present embodiment, the heat transfer coefficient is very high in the collision portion of the cooling water (about 6 times that when no turbulent flow is generated). (See arrow K1 in FIG. 6). Although the heat transfer coefficient gradually decreases as the distance from the collision site increases, the heat transfer coefficient is higher than the former as a whole. Accordingly, in the present embodiment, the cooling water that is efficiently warmed by the second liner portion 53 quickly rises in temperature. The raised cooling water is guided to the heater core through the outlet passages 38, 39 and the like. The heater core can exhibit good heating performance by the cooling water that is efficiently heated.

  In addition, since the cooling device has a simple structure in which the spacer member 26 is accommodated in the water jacket 36, the structure of the cylinder block 5 can be prevented from becoming complicated or enlarged.

  Furthermore, since a high heat insulating effect is produced by providing the spacer member 26 made of a heat insulating material, the heat of the second liner portion 53 is suppressed from radiating to the block main body 50, and as a result, the thermal efficiency of the engine 1 is improved. Thus, good fuel efficiency can be ensured. Moreover, the heat insulation effect by the spacer member 26 suppresses the heat of the cooling water from being radiated to the block main body 50. As a result, the temperature rise of the cooling water can be promoted to ensure good heating performance. .

  Further, since the first liner portion 52 has thermal conductivity anisotropy, the heat in the combustion chamber 10 moves exclusively along the first liner portion 52 toward the water jacket 36, and thus the first liner portion 52. Heat dissipation from the outside to the outside is suppressed. Therefore, while maintaining the combustion chamber 10 at a high temperature to increase the thermal efficiency of the engine 1, the heat can be efficiently transported to the cooling water flowing in the water jacket 36 to efficiently raise the temperature of the cooling water. .

  Furthermore, since the water jacket 36 is disposed only outside the second liner portion 53, excessive heat transfer to the cooling water (increase in cooling loss) can be suppressed. Moreover, since the volume in the water jacket 36 becomes small, it is possible to raise the temperature of the cooling water with a small amount of heat. Such a structure is particularly effective in a low heat capacity type engine having a relatively small calorific value.

(Second Embodiment)
A second embodiment of the present invention will be described with reference to FIGS. The solid line G1 in FIG. 9 is a graph showing the relationship between the heat transfer coefficient and the distance from the collision center of the cooling water in the second embodiment, and the broken line G2 shows the heat transfer coefficient when turbulent flow due to the collision is not generated. It is a graph to show.

  In the engine cooling device according to the second embodiment, as shown in FIGS. 7 and 8A, the second liner portion 53 is disposed around the portion of the second liner portion 53 that faces the ejection hole 26 e. A rib 35a that protrudes from the outer peripheral surface toward the bore-side peripheral wall 26b and that has a gap with the bore-side peripheral wall 26b is formed.

  As shown in FIG. 8A, the rib 35 a is formed in an annular shape so as to surround the collision site 40 at a certain distance from the collision site 40 of the cooling water in the second liner portion 53. .

  Next, the effect of the cooling device according to the second embodiment will be described.

  In the bore side space 33, in the direction along the second liner portion 53, the turbulence (turbulent flow state) of the cooling water gradually decreases as the distance from the collision portion 40 of the cooling water in the second liner portion 53 decreases. Accordingly, the heat transfer coefficient from the second liner portion 53 to the cooling water gradually decreases as the distance from the cooling water collision site 40 increases (see arrow Y in FIG. 9).

  However, according to the second embodiment, the flow of the cooling water in the bore-side space 33 is disturbed by the ribs 35a, so that the flow of the cooling water at a position away from the cooling water collision site 40 in the second liner portion 53. (See the arrow K2 in FIG. 9), and accordingly, the heat transfer rate from the second liner portion 53 to the cooling water can be recovered to a high level and the decrease can be suppressed.

  The first and second embodiments described above are exemplifications of preferred embodiments of the engine cooling device according to the present invention, and the specific configuration thereof is appropriately changed without departing from the gist of the present invention. Is possible.

  For example, in the first embodiment, the spacer member 26 is made of glass fiber reinforced plastic using aromatic polyamide, but may be made of other materials.

  In the first embodiment, the first liner portion 52 is made of a thermally conductive anisotropic material, but may be made of another material, for example, the same material as the second liner portion 53.

  In the example shown in FIG. 1, the length of the first liner portion 52 and the length of the second liner portion 53 in the vertical direction (axial direction of the cylinder) are substantially the same, but the present invention is not limited to this. For example, the upper end portion of the cylinder liner 51 may be configured by the second liner portion 53 and the portion other than the upper end portion of the cylinder liner 51 may be configured by the first liner portion 52 (CFRP).

  Further, the entire cylinder liner 51 may be configured by the first liner portion 52 (CFRP). In this case, for example, the water jacket 36 is disposed outside the upper end portion of the first liner portion 52, and the spacer member 26 is accommodated in the water jacket 36.

  Moreover, in the said 2nd Embodiment, although the shape of a rib is made into an annular | circular shape, it is not limited to this. For example, as shown in FIG. 8B, four ribs 35b are arranged on the upper side, the lower side, the right side, and the left side of the collision part 40 so as to surround the collision part 40 of the cooling water, and each rib You may form 35b so that it may become linear shape seeing from the direction orthogonal to the axial direction of a cylinder (cylinder bore 7).

  Moreover, in the said 2nd Embodiment, as FIG. 7 showed, although the cross-sectional shape of the rib 35a was made into the rectangular shape (or square shape), it is not limited to this. For example, as illustrated in FIG. 10, the cross-sectional shape of the rib 35 c may be a trapezoid in which the downstream side in the cooling water flow direction is inclined toward the second liner portion 53. As shown in FIG. 7, when the downstream side in the cooling water flow direction is substantially perpendicular to the outer peripheral surface of the second liner portion 52, the cooling water flow is separated from the side. As a result, there is a possibility that the heat transfer rate may be reduced (see the portion indicated by arrow P in FIG. 9). On the other hand, as shown in FIG. 10, when the side on the downstream side in the cooling water flow direction is inclined, the flow of the cooling water is suppressed from being separated from the side, so that the heat transfer coefficient Can be suppressed.

DESCRIPTION OF SYMBOLS 1 Engine 5 Cylinder block 26 Spacer member 26a Anti-bore side peripheral wall 26b Bore side peripheral wall 26e Ejection hole 26f Spacer inside space (internal space)
33 Bore side space 34 Inlet passage 35a-35c Rib 36 Water jacket 37 Water pump 38, 39 Outlet passage 51 Cylinder liner (cylinder bore wall)
52 1st liner part (main part)
53 2nd liner part (heat induction part)

Claims (8)

A water jacket formed on the cylinder block so as to surround the cylinder bore wall of the engine;
A hollow spacer member accommodated in the water jacket with a space from the cylinder bore wall;
An introduction passage for introducing cooling water into the internal space of the spacer member;
An outlet passage for extracting cooling water from the space between the spacer member and the cylinder bore wall;
The spacer member has a bore-side peripheral wall that faces and opposes the outer peripheral surface of the cylinder bore wall. An ejection hole that ejects toward the cylinder bore wall is formed ,
Of the cylinder bore wall, a rib that protrudes from the outer peripheral surface of the cylinder bore wall toward the bore side peripheral wall and has a gap between the bore side peripheral wall is formed around a portion facing the ejection hole . A cooling device for an engine. The cylinder bore wall is formed by a cylindrical cylinder liner fitted into the cylinder block,
The cylinder liner has a thermal conductivity anisotropy in which the thermal conductivity in the first direction along the axial direction is larger than the thermal conductivity in the second direction along the thickness direction;
2. The engine cooling apparatus according to claim 1, wherein the water jacket is disposed only outside an axial end portion of the cylinder liner. 3. The cylinder bore wall is formed by a cylindrical cylinder liner fitted into the cylinder block,
The cylinder liner has a main body portion having a thermal conductivity anisotropy having a thermal conductivity in a first direction along an axial direction larger than a thermal conductivity in a second direction along a thickness direction thereof, and the first direction. A heat induction part connected to one end of the main body part so that heat can be transferred,
The engine cooling apparatus according to claim 1, wherein the water jacket is disposed only outside the heat induction unit. A water jacket formed on the cylinder block so as to surround the cylinder bore wall of the engine;
A hollow spacer member accommodated in the water jacket with a space from the cylinder bore wall;
An introduction passage for introducing cooling water into the internal space of the spacer member;
An outlet passage for extracting cooling water from the space between the spacer member and the cylinder bore wall;
The spacer member has a bore-side peripheral wall that faces and opposes the outer peripheral surface of the cylinder bore wall. The bore-side peripheral wall extends from the outside to the inside, and the cooling water in the internal space is supplied to the bore-side peripheral wall. An ejection hole that ejects toward the cylinder bore wall is formed,
The cylinder bore wall is formed by a cylindrical cylinder liner fitted into the cylinder block,
The cylinder liner has a main body portion having a thermal conductivity anisotropy having a thermal conductivity in a first direction along an axial direction larger than a thermal conductivity in a second direction along a thickness direction thereof, and the first direction. A heat induction part connected to one end of the main body part so that heat can be transferred,
The engine cooling apparatus according to claim 1, wherein the water jacket is disposed only outside the heat induction part. Of the cylinder bore wall, a rib that protrudes from the outer peripheral surface of the cylinder bore wall toward the bore side peripheral wall and has a gap between the bore side peripheral wall is formed around a portion facing the ejection hole. The engine cooling device according to claim 4 , wherein The said ejection hole is extended in the direction which makes a substantially perpendicular | vertical on the said outer peripheral surface with respect to the tangent which contact | connects the outer peripheral surface of the said cylinder bore wall seeing from the axial direction of a cylinder . The engine cooling device according to any one of the above. The engine cooling device according to any one of claims 1 to 6 , further comprising a water pump for supplying cooling water to the internal space through the introduction passage. The engine cooling device according to any one of claims 1 to 7 , wherein the spacer member is made of a heat insulating material.

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