JP2007009743A - Cooling structure of water-cooled engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cooling structure of a water-cooled engine capable of preventing sealability at a head gasket from being impaired in a split type cylinder block and securing the high reliability of the sealability at the seal portion of a water jacket. <P>SOLUTION: This engine 11 comprises a cylinder liner part 25 and a cylinder outer wall part 31 which define a cylinder bore 20. The water jacket 24 is formed between the outer peripheral surface of the cylinder liner part and the inner peripheral surface of the cylinder outer wall part 31. Between the outer peripheral surface and the inner peripheral surface, seal members 41, 42 are fitted to the vertical end parts of the cylinder liner part 25. A cooling water hole 39 is formed in the cylinder outer wall part 31 so as to communicate its outside with the water jacket 24. The cooling water hole 39 is so formed that is aligned with the roughly axial center of the cylinder liner part 25. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a cooling structure for a water-cooled engine.

  In a water-cooled engine, a water jacket for circulating cooling water around a cylinder bore is formed. In such a water-cooled engine, the water pump is driven to circulate the cooling water in the water jacket, so that heat is taken away from the surroundings of the cylinder bore, which becomes hot as the air-fuel mixture burns, and the engine is kept at an appropriate temperature. I am doing so.

  Recently, a cylinder block that forms the main part of a water-cooled engine is divided into a cylinder liner part that defines a cylinder bore and a cylinder block body that includes a cylinder outer wall part, with a water jacket forming region as a boundary. There is. An example of such a split cylinder block is shown in FIG.

In the cylinder block 100 shown in FIG. 7, a cylinder liner portion 110 that defines the cylinder bore 101 and a cylinder block main body 120 including a cylinder outer wall portion 121 and a crankcase 122 are formed as separate structures. The cylinder block 100 is integrally assembled with the cylinder block main body 120 in a state where the cylinder liner portion 110 is inserted into the cylinder block main body 120 from above. In this case, the cylinder liner portion 110 is inserted to a position where the flat upper deck 111 provided at the upper end of the cylinder liner portion 110 comes into contact with the upper receiving surface 123 of the cylinder outer wall portion 121, and the outer peripheral surface 110 a of the cylinder liner portion 110. A protrusion 113 provided at the lower end of the cylinder is in contact with the inner peripheral surface 121 a of the cylinder outer wall 121. In the cylinder block 100 configured as described above, a water jacket 125 is formed between the outer peripheral surface 110 a of the cylinder liner portion 110 and the inner peripheral surface 121 a of the cylinder outer wall portion 121. In addition, a cooling water hole 126 is formed in the cylinder outer wall 121, and cooling water is supplied from the cooling water hole 126 into the water jacket 125.
JP-A-9-68041

  By the way, in the engine, a cylinder head 160 is assembled to an upper portion of an upper deck 111 provided in the cylinder liner portion 110 via a head gasket 150. In such an engine, the vicinity of the upper end portion of the cylinder liner portion 110 on which the cylinder head 160 is placed, that is, the vicinity of the upper end portion of the cylinder liner portion 110 in which the combustion chamber 170 is formed becomes the highest temperature as the air-fuel mixture burns. . Therefore, the cylinder liner portion 110 has a larger dimensional change due to thermal expansion in the vicinity of the upper end portion than in other portions (the center portion, the lower end portion, etc.), and the dimension due to the thermal contraction when cooled. Changes tend to be large. For this reason, the surface pressure acting on the head gasket 150 is likely to be non-uniform due to thermal contraction when the cylinder liner portion 110 is cooled. As a result, the sealing performance of the head gasket 150 is improved. There is a risk of damage.

  Further, in this cylinder block 100, between the outer peripheral surface 110a of the cylinder liner portion 110 and the inner peripheral surface 121a of the cylinder outer wall portion 121, seal members 131 and 132 are respectively provided at the end on the cylinder head 160 side and the end on the opposite side. Is intervening. However, since the cooling water hole 126 is formed in the vicinity of the seal member 131 in the cylinder outer wall 121, the portion of the seal member 131 is easily affected by the pressure of the cooling water, and the sealing performance of the portion may be reduced. There is.

  As a technique for adjusting the flow of the cooling water, a protrusion is provided at a position corresponding to the cooling water hole on the outer peripheral surface of the inner wall of the cylinder forming the water jacket so that the flow of the cooling water supplied from the cooling water hole is the same. Patent Document 1 discloses a configuration in which the direction is changed in the axial direction of the cylinder along the outer peripheral surface.

  The present invention has been made in view of the above problems, and the object thereof is not to impair the sealing performance with the head gasket of the split-type cylinder block, and also has high sealing performance at the sealing portion of the water jacket. It is an object to provide a cooling structure for a water-cooled engine that can ensure reliability.

  In order to achieve the above object, the invention according to claim 1 includes a cylinder liner portion defining a cylinder bore and a cylinder outer wall portion, a cylinder head is assembled to the cylinder liner portion via a head gasket, and the cylinder liner is assembled. A water jacket is formed between the outer peripheral surface of the cylinder and the inner peripheral surface of the cylinder outer wall, and a seal member is provided between the outer peripheral surface and the inner peripheral surface at the end on the cylinder head side and the opposite end, respectively. A cooling structure for a water-cooled engine comprising a cooling water hole for supplying cooling water into the water jacket from the outside of the outer wall portion of the cylinder at a substantially axial center of the cylinder liner portion. The gist is that it was formed in correspondence.

  According to the above configuration, the cooling water hole for supplying cooling water into the water jacket from the outside of the cylinder outer wall portion is formed so as to correspond to the approximate center in the axial direction of the cylinder liner portion. Accordingly, the cooling water hole is separated from the end portion on the cylinder head side that becomes high temperature. Thereby, in the vicinity of the cylinder bore upper end portion of the cylinder liner portion, the supercooling by the cooling water supplied from the cooling water hole is suppressed, so that the size change due to the thermal contraction can be minimized. . For this reason, it is possible to prevent the surface pressure acting on the head gasket from becoming non-uniform due to the dimensional change due to the heat shrinkage and to prevent the sealing performance of the head gasket from being impaired. In addition, the cooling water hole is also separated from the end on the cylinder head side where the seal member is interposed and the end on the opposite side. Thereby, the influence of the pressure of the cooling water supplied from the cooling water hole can be prevented from being exerted as much as possible on these sealing members. Therefore, it is possible to ensure high reliability with respect to the sealing performance at the sealing portion of the water jacket.

Hereinafter, an embodiment in which the present invention is embodied in a cooling structure for an in-vehicle gasoline engine (hereinafter referred to as an engine) will be described with reference to FIGS.
As shown in FIG. 1, the engine 11 includes a cylinder block 12 and a cylinder head 16 that is assembled to the upper portion of the engine block 11 via a head gasket 15. A head cover (not shown) is attached above the cylinder head 16, and an oil pan (not shown) is attached below the cylinder block 12.

Next, the configuration of the cylinder block 12 will be described with reference to FIGS.
As shown in FIG. 2, in the cylinder block 12, four cylinder bores 20 are provided in the upper part, and a crankcase part 21 is provided in the lower part. The crankcase portion 21 forms a crankcase together with an oil pan attached below the crankcase portion 21. A flat upper deck 22 on which the cylinder head 16 shown in FIG. 1 is placed is provided at the top of the cylinder block 12.

  As shown in FIG. 3, the cylinder block 12 includes a water jacket 24 around each cylinder bore 20. The water jacket 24 is formed in a substantially annular shape so as to surround the outer periphery of each cylinder bore 20 while avoiding a connection portion between adjacent cylinder bores 20. The cylinder block 12 is divided into two structures shown below with a region forming the water jacket 24 as a boundary.

  As shown in FIG. 4, the cylinder block 12 is divided into a cylinder liner portion 25 that defines the cylinder bore 20 and a cylinder block body 30 that forms the outer wall of the water jacket 24. The cylinder liner portion 25 includes a cylinder coupling body 26 in which four cylinder liners 26a are integrally coupled, and the upper deck 22 provided on the upper portion thereof. The cylinder coupling body 26 is integrally formed so that cylindrical cylinder liners 26a serving as the respective cylinders are linearly arranged and their outer peripheral surfaces are connected to each other.

  An upper deck 22 constituting the top of the cylinder block 12 is integrally formed at the upper end of the cylinder coupling body 26. The upper deck 22 has a flat plate shape, and the cylinder head 16 is placed on the upper surface of the upper deck 22 via the head gasket 15 (see FIG. 1). In the upper deck 22, a plurality of fastening holes 27 used for fastening the cylinder liner portion 25 and the cylinder block body 30 and a plurality of cooling water passages 28 communicating with the water jacket 24 are formed at predetermined positions. A support projection 29 is provided around the lower end of the cylinder coupling body 26 along the outer peripheral surface of each cylinder liner 26a.

  On the other hand, the cylinder block main body 30 includes a crankcase portion 21 and a cylinder outer wall portion 31 that surrounds the outer periphery of the cylinder coupling body 26. The cylinder block body 30 has a shape in which a cylinder outer wall portion 31 protrudes from an upper portion of the crankcase portion 21, and a plurality of reinforcing ribs 33 are formed on the outer periphery thereof so as to extend vertically and horizontally.

  The cylinder outer wall portion 31 has an opposing surface disposed on the inner side thereof so as to oppose the outer peripheral surface of the cylinder coupling body 26, and is formed in a substantially rectangular frame shape as a whole. A flange portion 35 is provided at the upper end portion of the cylinder outer wall portion 31, and the upper surface of the flange portion 35 is an upper receiving surface 35 a that abuts and supports the lower surface of the upper deck 22 of the cylinder liner portion 25. A fastening hole 37 used to fasten the cylinder liner portion 25 and the cylinder block body 30 is opened at the same position as the fastening hole 27 of the upper deck 22 in the upper receiving surface 35a.

  A cooling water hole 39 is formed in the cylinder outer wall portion 31 so as to communicate the outside and the inside thereof (see FIG. 6). The cooling water hole 39 is connected to a water pump (not shown) attached to the outer portion of the engine 11 through a cooling water pipe or the like. The engine 11 is a water-cooled engine. When the water pump is driven with the rotational force of the crankshaft 10, the cooling water discharged from the water pump is supplied to the water jacket 24 from the cooling water hole 39. It has become so.

Next, the configuration of the cylinder head 16 and the head gasket 15 will be described.
As shown in FIGS. 5 and 6, the cylinder head 16 is used for fastening with the intake / exhaust passages 61 and 62 communicating with the combustion chamber 60 formed at the upper end portion of the cylinder bore 20 and the cylinder block 12. Fastening holes 67 and the like are formed. Further, a water jacket 64 is formed in the cylinder head 16 so as to avoid these intake / exhaust passages 61 and 62, the fastening holes 67 and the like, and a cooling water passage 68 communicating with the water jacket 64 is provided in the cylinder head 16. It is opened on the lower surface of.

  A head gasket 15 serving as a sealing member that seals between the cylinder head 16 and the cylinder liner portion 25 constituting the cylinder block 12 is hermetically and liquid-tightly closed. The head gasket 15 has a hole 57 used for fastening the cylinder head 16 and the cylinder block 12, and a hole 58 for communicating the cooling water passage 68 of the cylinder head 16 and the cooling water passage 28 of the cylinder block 12. It is transparent.

The cylinder block 12, the cylinder head 16, and the head gasket 15 configured as described above are assembled by the fastening structure shown in FIG.
As shown in the figure, a fastening hole 67 of the cylinder head 16, a hole 57 of the head gasket 15, a fastening hole 27 of the upper deck 22, and a fastening hole 37 of the cylinder block body 30 are arranged coaxially. A head bolt 77 inserted from above the fastening hole 67 of the cylinder head 16 is inserted into the hole 57 of the head gasket 15 and the fastening hole 27 of the upper deck 22 and fastened to the fastening hole 37 of the cylinder block body 30. Yes. Through the fastening with the head bolt 77, the cylinder liner portion 25 is assembled to the cylinder block body 30, and the head gasket 15 and the cylinder head 16 are assembled to the top of the cylinder block 12, that is, the upper portion of the upper deck 22.

  Thus, in a state where the cylinder liner portion 25 is assembled to the cylinder block main body 30, the cylinder coupling body 26 is inserted inside the cylinder outer wall portion 31. Further, the lower surface of the upper deck 22 is brought into contact with the upper receiving surface 35 a of the cylinder outer wall portion 31 at the upper end portion of the cylinder liner portion 25, and the tip surface of the support protrusion 29 is brought into contact with the inner peripheral surface of the cylinder outer wall portion 31 at the lower end portion. Abutment is supported. And while the inner peripheral surface of the cylinder outer wall part 31 and the outer peripheral surface of the cylinder coupling body 26 of the cylinder liner part 25 are arranged facing each other, the inner peripheral surface of the cylinder outer wall part 31 and the outer peripheral surface of the cylinder coupling body 26 are arranged. The water jacket 24 is formed between the two.

  Further, a seal is provided between the lower surface of the upper deck 22 and the upper receiving surface 35 a of the cylinder outer wall portion 31 and between the tip surface of the support projection 29 of the cylinder coupling body 26 and the inner peripheral surface of the cylinder outer wall portion 31. Members 41 and 42 are interposed. By these seal members 41 and 42, sealing performance is ensured at the end portion of the water jacket 24 on the cylinder head 16 side and the end portion on the opposite side of the crankcase portion 21 side.

  In the assembled state as described above, the cooling water passage 68 of the cylinder head 16, the hole 58 of the head gasket 15, and the cooling water passage 28 of the cylinder block 12 are communicated. Thus, when the cooling water is supplied through the cooling water hole 39, the cooling water is introduced into the water jacket 24 of the cylinder block 12, and the cooling water passage 28 of the upper deck 22 and the hole 58 of the head gasket 15 are provided. After passing, it is also introduced into the water jacket 64 of the cylinder head 16 through the cooling water passage 68. In this way, the coolant is circulated through both the cylinder block 12 and the cylinder head 16, so that each part that becomes hot by driving the engine 11 is cooled.

  Further, since the surface pressure acting on both surfaces of the head gasket 15 is increased through the fastening with the head bolt 77, the space between the cylinder head 16 and the cylinder liner portion 25 is more airtightly and liquid tightly closed. Thus, the sealing performance by the head gasket 15 is suitably maintained. However, particularly when the engine 11 is driven, the vicinity of the combustion chamber 60 shown in FIG. 6, that is, the vicinity of the upper end of the cylinder liner portion 25 is hotter than the other portions. No. 25 has a large dimensional change due to thermal expansion in the vicinity of the boundary. Accordingly, the dimensional change due to heat shrinkage when cooled by cooling water tends to be large, and it becomes difficult to keep a high surface pressure acting on the head gasket 15 uniform. May be impaired.

  For this reason, in this embodiment, the hole position of the cooling water hole 39 for supplying the cooling water to the water jacket 24 is set to a position corresponding to the approximate center of the cylinder liner portion 25 in the axial direction. Specifically, the cooling water hole 39 is formed such that its center position corresponds to the axial center position of the cylinder liner portion 25. In this case, the cooling water hole 39 is formed substantially at the center of the cylinder outer wall 31 in the axial direction.

  The cooling water hole 39 is disposed in the vicinity of the upper end portion of the cylinder liner 26 a disposed to face the cooling water hole, that is, away from the vicinity of the combustion chamber 60 that becomes high temperature when the engine 11 is driven. Thereby, in the cylinder liner 26a, it is possible to avoid the cooling water supplied from the cooling water hole 39 to the water jacket 24 directly hitting the vicinity of the upper end portion having the largest dimensional change due to thermal expansion. For this reason, in the vicinity of the upper end portion of the cylinder liner 26a, the supercooling by the cooling water from the cooling water hole 39 is suppressed, and the size change due to the thermal contraction can be suppressed as small as possible. . For this reason, it is possible to prevent the surface pressure acting on the head gasket 15 from being locally reduced due to the dimensional change due to the heat shrinkage, and the sealing performance by the head gasket 15 is suitably maintained.

  Further, in this case, the cooling water hole 39 is provided at each end in the vertical direction of the cylinder liner portion 25 in which the seal members 41 and 42 are interposed, in other words, the opposite end of the water jacket 24 on the cylinder head 16 side. It is also spaced apart from the end of the crankcase portion 21 that is located on the side. Thereby, it is possible to prevent the cooling water supplied from the cooling water holes 39 from directly hitting each end portion of the cylinder liner portion 25 in which the seal members 41 and 42 are interposed. For this reason, the influence of the pressure of the cooling water supplied from the cooling water hole 39 can be prevented from being exerted on the seal members 41 and 42 as much as possible. For this reason, high reliability can be secured for the sealing performance at the sealing portion of the water jacket 24.

According to the above embodiment, the following effects can be obtained.
(1) Since the cooling water hole 39 for supplying cooling water to the water jacket 24 from the outside of the cylinder outer wall portion 31 is formed so as to correspond to the approximate center of the cylinder liner portion 25 in the axial direction, the engine 11 is driven. The cooling water hole 39 is separated from the end portion on the cylinder head 16 side, which sometimes becomes high temperature as the air-fuel mixture burns. Thereby, in the vicinity of the upper end portion of the cylinder bore 20 of the cylinder liner portion 25, since the supercooling by the cooling water supplied from the cooling water hole 39 is suppressed, the size change due to the thermal contraction is minimized. be able to. For this reason, it is possible to prevent the surface pressure acting on the head gasket 15 from becoming non-uniform due to the dimensional change due to the thermal contraction, and the sealing performance of the head gasket 15 can be prevented from being impaired. Further, the cooling water holes 39 are also separated from the respective end portions in the vertical direction of the cylinder liner portion 25 in which the seal members 41 and 42 are interposed, respectively. Thereby, the influence of the pressure of the cooling water supplied from the cooling water hole 39 can be prevented from being exerted on the sealing members 41 and 42 as much as possible. For this reason, high reliability can be secured for the sealing performance at the sealing portion of the water jacket 24.

In addition, you may change the said embodiment as follows.
In the present embodiment, the cooling water hole 39 is formed so that the center position thereof corresponds to the center position in the axial direction of the cylinder liner portion 25, but the present invention is not limited to this, and the cylinder liner portion 25 is not limited thereto. The center position of the cooling water hole 39 may be changed to a position shifted upward or downward from the center position. For example, in the engine 11 in which the water jacket 24 is formed on the upper end side of the cylinder liner portion 25, it is more desirable to set the hole position of the cooling water hole 39 above the center position. In this case, the cooling water hole 39 is set at a position above the approximate center of the cylinder outer wall portion 31 in the axial direction.

In the present embodiment, one cooling water hole 39 is formed in the cylinder outer wall portion 31; however, the number of the cooling water holes 39 may be changed to two or more.
In the present embodiment, the cooling water hole 39 is formed corresponding to one of the four cylinder liners 26a constituting the cylinder liner portion 25 and disposed at the end portion. You may change so that it may form corresponding to what was arrange | positioned near the center.

  In the present embodiment, the cooling water hole 39 is formed at substantially the center in the extending direction of the crankshaft 10 with respect to the cylinder liner 26a disposed corresponding to the cooling water hole 39. You may change to the arbitrary positions except the connection site | part with the cylinder liner 26a adjacent about the circumferential direction.

The perspective view which shows the whole structure of the water-cooled engine in this embodiment. The perspective view of the cylinder block which also makes the principal part of a water-cooled engine. The top view of a cylinder block similarly. The disassembled perspective view which similarly shows the division | segmentation structure of a cylinder block. AA sectional drawing of FIG. BB sectional drawing of FIG. Sectional drawing which shows schematic structure of the conventional water-cooled engine.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 15 ... Head gasket, 16 ... Cylinder head, 20 ... Cylinder bore, 24 ... Water jacket, 25 ... Cylinder liner part, 31 ... Cylinder outer wall part, 39 ... Cooling water hole, 41, 42 ... Seal member.

Claims (1)

A cylinder liner portion defining a cylinder bore and a cylinder outer wall portion; a cylinder head is assembled to the cylinder liner portion via a head gasket; and between the outer peripheral surface of the cylinder liner portion and the inner peripheral surface of the cylinder outer wall portion. A water-cooled engine cooling structure in which a water jacket is formed, and a seal member is interposed between an end portion on the cylinder head side and an end portion on the opposite side between the outer peripheral surface and the inner peripheral surface,
A cooling structure for a water-cooled engine, wherein a cooling water hole for supplying cooling water into the water jacket from the outside of the cylinder outer wall portion is formed so as to correspond to a substantially center in the axial direction of the cylinder liner portion. .

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