JP2012092758A - Cylinder block cooling structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cylinder block cooling structure that can properly cool a bore wall according to an engine warmup state.SOLUTION: The cylinder block cooling structure 1 includes a groove 11 formed between the bore 13 and a water jacket 14 out of a cylinder block 10A of an engine, and a high heat conduction material 12 provided in the groove 11. The high heat conduction material has a coefficient of linear expansion higher than that of a base material of the cylinder block 10A and is provided in a contactless state with a wall surface of the groove 11 so that the heat conduction material 12 contacts with the wall surface of the groove 11 when a temperature of a coolant circulating into the water jacket 14 is higher than a predetermined value α. Moreover, the high heat conduction material 12 has thermal conductivity higher than that of the base material of the cylinder block 10A.

Description

  The present invention relates to a cooling structure for a cylinder block, and more particularly to a cooling structure for a cylinder block provided with a high thermal conductivity material.

  A technique for providing a high thermal conductivity material in an engine cylinder block or the like is known. Patent Document 1 discloses an internal combustion engine in which a high heat conduction member is disposed between an outer periphery of a cylinder liner and an inner periphery of a cylinder liner insertion hole of a cylinder block.

JP 2010-71246 A

  By providing a high thermal conductivity material that promotes heat transfer from the bore wall, cooling of the bore wall can be promoted. As a result, occurrence of knocking can be suppressed. However, it is desirable that the temperature rise of the bore wall can be promoted during engine warm-up from the viewpoint of reducing piston friction.

  In view of the above problems, an object of the present invention is to provide a cooling structure for a cylinder block that can appropriately cool a bore wall according to the engine warm-up state.

  The present invention includes a groove portion provided in a portion between a bore and a cooling medium passage in a cylinder block of an engine, and a high heat conductive material provided in the groove portion, wherein the high heat conductive material is the cylinder block. And has a linear expansion coefficient higher than that of the base material, and when the temperature of the cooling medium flowing through the cooling medium passage is higher than a predetermined value, the non-grooved wall surface is not in contact with the groove wall surface. It is the cooling structure of the cylinder block provided in the state of contact.

  In the present invention, it is preferable that the high thermal conductivity material has a higher thermal conductivity than the base material of the cylinder block.

  According to the present invention, the bore wall can be appropriately cooled according to the engine warm-up state.

It is a schematic block diagram of the cylinder block of Example 1. FIG. It is an enlarged view of the A section shown in FIG. It is a figure which shows the mode of the heat transfer in Example 1. FIG. It is a schematic block diagram of the cylinder block of Example 2. It is a figure which shows the relationship between Ni content rate of TiNi, and shape recovery temperature Af. It is explanatory drawing of a guidance | induction part. It is a figure which shows the mode of the heat transfer in Example 2. FIG. It is a figure which shows the mode of the distribution | circulation of the cooling water in Example 2. FIG.

  Embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic configuration diagram of a cylinder block 10A. FIG. 2 is an enlarged view of a portion A shown in FIG. The cylinder block 10A includes a cylinder block cooling structure (hereinafter referred to as a cooling structure) 1A. The cooling structure 1 </ b> A includes a groove 11 and a high thermal conductive material 12. A bore 13 and a water jacket (hereinafter referred to as W / J) 14 are formed in the cylinder block 10A. The cylinder block 10A is provided in an engine (not shown). The cylinder block 10A is an open deck type cylinder block in which W / J 14 is opened on the deck surface.

  The groove 11 is provided in a portion of the cylinder block 10A between the bore 13 and the W / J 14 that is the cooling medium passage. The groove 11 opens on the deck surface of the cylinder block 10 </ b> A and is provided corresponding to W / J 14 in the extending direction of the bore 13. For this reason, the groove part 11 and W / J14 have the same depth.

  The high thermal conductive material 12 is provided in the groove 11. The high thermal conductive material 12 has a plate shape and is provided from the opening to the bottom of the groove 11. The high thermal conductive material 12 has a higher linear expansion coefficient than the base material of the cylinder block 10A, and the groove portion 11 when the temperature of cooling water (cooling water temperature) that is a cooling medium flowing through the W / J 14 is higher than a predetermined value α. Are provided in a non-contact state with respect to the wall surface of the groove 11 so as to be in contact with the wall surface (specifically, the wall surface on the bore side and the wall surface on the W / J 14 side).

  Therefore, the high thermal conductive material 12 is provided so that a gap is formed between the groove 11 and the wall surface of the groove 11 when the cooling water temperature is equal to or lower than the predetermined value α. The gap is a slight gap having a size of about several μm to several tens of μm, for example. For example, the cooling water temperature at the completion of engine warm-up can be applied to the predetermined value α. The high heat conductive material 12 may be provided in a non-contact state with any one of the wall surface on the bore side and the wall surface on the W / J 14 side.

  The high thermal conductive material 12 has a higher thermal conductivity than the base material of the cylinder block 10A. The base material of the cylinder block 10A is, for example, aluminum die cast, and the material of the high thermal conductive material 12 is, for example, zinc. For example, when the base material of the cylinder block 10A is aluminum die cast, the material of the high heat conductive material 12 may be an aluminum alloy having a larger linear expansion coefficient and higher thermal conductivity than aluminum die cast. In this regard, aluminum die casts used in casting have many additives such as Si. For this reason, an aluminum alloy with few additives has a thermal conductivity that is, for example, about twice that of aluminum die casting.

  Next, the function and effect of the cooling structure 1A will be described. FIG. 3 is a view showing a state of heat transfer in the cooling structure 1A. (A) shows the state of heat transfer during engine warm-up, and (b) shows the state of heat transfer after engine warm-up. (A) shows a state where the cooling water temperature is lower than the predetermined value α, and (b) shows a state where the cooling water temperature is higher than the predetermined value α.

  As shown to (a), a clearance gap is formed between the wall surface of the groove part 11, and the high heat conductive material 12 during engine warm-up. As a result, as schematically shown by the arrow H1, heat transfer from the wall portion of the bore 13 to the cooling water flowing through the W / J 14 is suppressed by the heat insulating effect by air. For this reason, the cooling structure 1A can reduce the friction of the piston provided in the bore 13 during engine warm-up.

  On the other hand, as the engine warms up, the high thermal conductive material 12 thermally expands. As a result, as shown in (b), the wall surface of the groove 11 and the high thermal conductive material 12 come into contact after the engine is warmed up. For this reason, the cooling structure 1A can promote heat transfer from the wall portion of the bore 13 to the cooling water flowing through the W / J 14 after the engine is warmed up, as schematically shown by the arrow H2. And thereby, cooling of the bore 13 wall part can be promoted. As a result, specifically, this can suppress the occurrence of knocking. Thus, the cooling structure 1A can appropriately cool the wall portion of the bore 13 according to the engine warm-up state.

  Further, according to the cooling structure 1A for promoting the cooling of the wall portion of the bore 13 in this manner, it is possible to suppress the occurrence of knocking without particularly increasing the cooling performance of the cylinder head provided in the cylinder block 10A. . Specifically, for example, by providing the cylinder head to the cylinder block 10A via a head gasket having high heat insulation properties, it is possible to suppress the cooling performance of the cylinder head while promoting cooling of the wall portion of the bore 13. In this regard, it has been found that the cooling of the cylinder head is accompanied by a large cooling loss. For this reason, the cooling structure 1A is suitable for suppressing the occurrence of knocking while suppressing an increase in cooling loss.

  FIG. 4 is a schematic configuration diagram of the cylinder block 10B. The cylinder block 10B is substantially the same as the cylinder block 10A except that a cooling structure 1B is provided instead of the cooling structure 1A. The cooling structure 1 </ b> B includes a shape memory material 15 shown below instead of the groove 11 and the high thermal conductive material 12.

  The shape memory material 15 is provided in W / J14. The shape memory material 15 has a plate shape, and is provided from the opening to the bottom of the W / J 14. The shape memory material 15 provided in the W / J 14 functions as a water jacket spacer that improves the heat transfer coefficient by decreasing the flow path cross-sectional area and increasing the flow rate of the cooling water.

  When the cooling water temperature is higher than the predetermined value α ′, the shape memory material 15 changes its shape so as to be located on the opposite side of the bore 13 from the bore 13 side. For example, the coolant temperature at the completion of engine warm-up can be applied to the predetermined value α ′. The predetermined value α ′ and the predetermined value α may be the same value. In this respect, the predetermined value α ′ is used instead of the predetermined value α because, as will be described later, when the cooling structure 1B and the cooling structure 1A are used in combination, the predetermined value α and the shape memory material related to the high thermal conductive material 12 This is because the predetermined value α ′ according to 15 may actually be slightly different.

  When the shape memory material 15 is located on the bore 13 side, the shape memory material 15 is provided so as to be in close contact with the wall surface on the bore 13 side among the wall surfaces of the W / J 14. Moreover, when located in the opposite side to the bore 13, it is provided so that it may closely_contact | adhere to the wall surface on the opposite side to the bore 13 among the wall surfaces of W / J14.

  FIG. 5 is a graph showing the relationship between the Ni content of TiNi and the shape recovery temperature Af. When the material of the shape memory material 15 is TiNi, the shape memory material 15 can be deformed as described above when the cooling water temperature is higher than the predetermined value α ′ due to the composition of TiNi. The composition of TiNi can be set according to the ease of warming up of the engine, that is, according to the coolant temperature when the engine warm-up is completed.

  When the engine is easily warmed up, for example, the composition of TiNi can be set so that the shape memory material 15 is deformed between 60 ° C. and 80 ° C. When the engine is difficult to warm up, the composition of TiNi can be set so that the shape memory material 15 is deformed at 80 ° C., for example. For these, for example, the range indicated by the range R is suitable. In this regard, the composition of TiNi is preferably a composition in which, for example, the Ni content is 50 at%.

  The thermal conductivity of TiNi is greatly reduced to about 12 W / mK, whereas the thermal conductivity of aluminum die cast is about 100 W / mK.

  FIG. 6 is an explanatory diagram of the guiding portion 15a. (A) shows cylinder block 10B in top view. (B) expands and shows the B section shown to (a). The shape memory material 15 further includes a guide portion 15a that guides the cooling water flowing through the W / J 14 to the first distribution path P1 or the second distribution path P2 according to the cooling water temperature. The guiding portion 15a guides the cooling water to the first flow path P1 when the cooling water temperature is lower than the predetermined value α ′. Further, when the cooling water temperature is higher than the predetermined value α ′, the cooling water is guided to the second flow path P2. The guide part 15a is provided in the inlet part In of cooling water among W / J14.

  The distribution paths P1 and P2 are both paths through which the cooling water flows from the inlet part In to the cooling water outlet part Out. Of the plurality of bores 13 arranged in series, the first distribution path P1 extends from the inlet portion In to the outlet portion Out along the side of the bore 13 provided at the end on the inlet portion In and outlet portion Out side. It is a route for circulating cooling water. The second circulation path P2 is a path for circulating cooling water in a U shape from the inlet portion In to the outlet portion Out along the plurality of bores 13 arranged in series.

  On the other hand, the induction | guidance | derivation part 15a deform | transforms as shown in (b) between engine warm-up and after engine warm-up. Then, by controlling the flow of the cooling water at the inlet portion In, the cooling water flowing into the W / J 14 is guided to the first distribution path P1 or the second distribution path P2. The guiding portion 15a can circulate the cooling water so that the flow rate is larger than that of the other cooling path when the cooling water is guided to one of the distribution paths P1 and P2. The guiding part 15a does not have to circulate the cooling water through the other cooling path when the cooling water is guided to any one of the distribution paths P1 and P2.

  Next, the effect of the cooling structure 1B will be described. FIG. 7 is a diagram showing a state of heat transfer in the cooling structure 1B. FIG. 8 is a view showing a state of circulation of the cooling water in the cooling structure 1B. 7 and 8, (a) shows the state of heat transfer during engine warm-up, and (b) shows the state of heat transfer after engine warm-up. And (a) shows a mode when the cooling water temperature is lower than the predetermined value α ′, and (b) shows a mode when the cooling water temperature is higher than the predetermined value α ′. In FIG. 8, the thickness of the arrows of the distribution paths P1 and P2 schematically shows the magnitude of the flow rate.

  As shown in FIG. 7A, the shape memory material 15 is located on the bore 13 side during engine warm-up. As a result, as schematically indicated by the arrow H1 ′, heat transfer from the wall of the bore 13 to the cooling water flowing through the W / J 14 is suppressed. For this reason, the cooling structure 1B can reduce piston friction during engine warm-up.

  On the other hand, the shape memory material 15 is deformed after the engine is warmed up. As a result, as shown in FIG. 7B, the shape memory material 15 is located on the opposite side to the bore 13. For this reason, the cooling structure 1B can promote heat transfer from the wall portion of the bore 13 to the cooling water flowing through the W / J 14 after the engine is warmed up, as schematically shown by the arrow H2 ′. And thereby, cooling of the bore 13 wall part can be promoted.

  The cooling structure 1B can appropriately cool the wall portion of the bore 13 according to the engine warm-up state by the deformation of the shape memory material 15 as described above. Further, by making the material of the shape memory material 15 TiNi, it is possible to realize appropriate deformation according to the ease of engine warm-up. Furthermore, by making the material of the shape memory material 15 TiNi, it is possible to improve the heat insulation of the wall portion of the bore 13 during engine warm-up due to low thermal conductivity.

  As shown to Fig.8 (a), the guidance part 15a guides the cooling water which flows in into W / J14 to the 1st distribution path P1 during engine warming-up. As a result, the cooling water mainly circulates through the first distribution path P1. For this reason, the cooling structure 1B can reduce the friction of the piston during engine warm-up by suppressing the cooling of the wall portion of the bore 13.

  On the other hand, the guiding portion 15a guides the cooling water flowing into the W / J 14 after the engine is warmed up to the second circulation path P2. As a result, as shown in FIG. 8B, the cooling water preferentially flows through the second distribution path P2. For this reason, the cooling structure 1B can promote the cooling of the wall portion of the bore 13. And the cooling structure 1B can cool the bore 13 wall part more appropriately according to the engine warm-up state by controlling the flow of the cooling water flowing through the W / J 14 by the guide part 15a.

  Further, the cooling structure 1B is used in combination with the cooling structure 1A. In other words, the cooling structure 1B further includes the groove portion 11 and the high thermal conductive material 12, thereby further appropriately cooling the wall portion of the bore 13 according to the engine warm-up state.

  Although the embodiments of the present invention have been described in detail above, the present invention is not limited to such specific embodiments, and various modifications and changes can be made within the scope of the gist of the present invention described in the claims. It can be changed.

Cooling structure 1A, 1B
Cylinder block 10A, 10B
Groove 11
High thermal conductivity material 12
Bore 13
W / J 14
Shape memory material 15
Guide part 15a

Claims (2)

Of the cylinder block of the engine, a groove provided in a portion between the bore and the cooling medium passage,
A high thermal conductivity material provided in the groove,
The high thermal conductivity material has a higher linear expansion coefficient than the base material of the cylinder block, and contacts the wall surface of the groove when the temperature of the cooling medium flowing through the cooling medium passage is higher than a predetermined value. The cooling structure of the cylinder block provided in the non-contact state with respect to the wall surface of the said groove part. A cooling structure for a cylinder block according to claim 1,
The cylinder block cooling structure, wherein the high thermal conductivity material has a higher thermal conductivity than the base material of the cylinder block.

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