EP3839237A1

EP3839237A1 - Cylinder bore wall insulator, internal combustion engine, and automobile

Info

Publication number: EP3839237A1
Application number: EP19850392.2A
Authority: EP
Inventors: Junya Satoh; Tatsunori Kataoka
Original assignee: Nichias Corp
Current assignee: Nichias Corp
Priority date: 2018-08-13
Filing date: 2019-07-26
Publication date: 2021-06-23
Also published as: JP2020026778A; JP6793694B2; WO2020036052A1; EP3839237A4

Abstract

There is provided a thermal insulator for a cylinder bore wall for insulating a bore wall facing a coolant inflow port to the groove-like coolant passage, the thermal insulator including: a rubber member in contact with a wall surface on a cylinder bore side of the groove-like coolant passage and for covering the wall surface on the cylinder bore side of the groove-like coolant passage; and a metal base member to which the rubber member is fixed, wherein the metal base member includes: a rear surface pressing part; elastic parts; and a movement limiting part extending from a rear surface of the metal base member toward a lower portion of an inside of the coolant inflow port in the cylinder block, and having an extending end positioned outside a position of a wall surface outside the groove-like coolant passage, and for limiting a movement of the metal base member.

There can be provided a thermal insulator for a cylinder bore wall, for insulating a cylinder bore wall facing a coolant inflow port to a groove-like coolant passage, and capable of limiting a movement in an up-down direction and a circumferential direction of the groove-like coolant passage.

Description

[Technical Field]

The present invention relates to a thermal insulator disposed in contact with a wall surface on a groove-like coolant passage side of a cylinder bore wall of a cylinder block of an internal combustion engine, an internal combustion engine including the thermal insulator, and an automobile including the internal combustion engine.

[Background Art]

An internal combustion engine has a structure in which an explosion of fuel occurs at a top dead center of a piston in a bore and the piston is pushed down by the explosion, temperature rises on an upper side of a cylinder bore wall and temperature falls on a lower side of the cylinder bore wall. Therefore, a difference occurs in a thermal deformation amount between the upper side and the lower side of the cylinder bore wall. Expansion is large on the upper side and, on the other hand, expansion is small on the lower side.
As a result, frictional resistance between the piston and the cylinder bore wall increases. This causes a decrease in fuel efficiency. Therefore, there is a need to reduce the difference in the thermal deformation amount between the upper side and the lower side of the cylinder bore wall.
Therefore, in order to equalize a wall temperature of the cylinder bore wall, it has been conventionally attempted to set a spacer in the groove-like coolant passage for adjusting a flow of coolant in the groove-like coolant passage and controlling the cooling efficiency on the upper side and the cooling efficiency on the lower side of the cylinder bore wall by the coolant. For example, Patent Literature 1 discloses a heat medium passage partitioning member for cooling an internal combustion engine that is a passage partitioning member disposed in a groove-like heat medium passage for cooling formed in a cylinder block of the internal combustion engine, to thereby partition the groove-like heat medium passage for cooling into a plurality of passages, the passage partitioning member including: a passage dividing member that is formed at height smaller than the depth of the groove-like heat medium passage for cooling and functions as a wall section that divides the groove-like heat medium passage for cooling into a bore side passage and a counter-bore side passage; and a flexible lip member that is formed from the passage dividing member toward an opening of the groove-like heat medium passage for cooling and formed of a flexible material in a manner in which a distal edge portion extends beyond one inner surface of the groove-like heat medium passage for cooling, whereby, after completion of insertion into the groove-like heat medium passage for cooling, the distal edge portion comes into contact with the inner surface in an intermediate position in a depth direction of the groove-like heat medium passage for cooling with a deflection restoration force of the distal edge portion to separate the bore side passage and the counter-bore side passage.
In the heat medium passage partitioning member for cooling an internal combustion engine in Patent Literature 1, the wall temperature of the cylinder bore wall can be equalized to some extent. Therefore, it is possible to reduce the difference in the thermal deformation amount between the upper side and the lower side of the cylinder bore wall. However, a uniform control can only be performed on the entire cylinder bore wall.
However, the temperature conditions are not uniform in the entire cylinder bore wall, and actually the cylinder bore wall has some portions which need to be insulated and some portions which do not need to be insulated. As such, for example, Patent Literature 2 discloses a thermal insulator for selectively insulating only a bore wall of one cylinder bore among cylinder bores.

[Citation List]

[Patent Literature]

[Patent Literature 1] Japanese Patent Laid-Open No. 2008-31939 (Claims)
[Patent Literature 2] Japanese Patent Laid-Open No. 2007-162473 (Figure 4)

[Summary of Invention]

[Technical Problem]

Since in a vicinity of a cylinder bore wall near a coolant inflow port to a groove-like coolant passage of a cylinder block, coolant having a low temperature flows and a flow rate of the coolant is fast, the temperature is cooled more excessively than the other cylinder bore walls. Accordingly, it becomes necessary to set a thermal insulator that insulates selectively the cylinder bore wall near the coolant inflow port. Therefore, there is set the thermal insulator for the cylinder bore wall that insulates a portion facing a coolant inflow port.
However, since the vibration is applied to an engine during operation of an internal combustion engine, a thermal insulator for a cylinder bore wall disclosed in Patent Literature 2 moves in an up-down direction or a circumferential direction of the groove-like coolant passage, which tends to cause a displacement.
Therefore, an object of the present invention is to provide a thermal insulator for a cylinder bore wall, for insulating a cylinder bore wall facing a coolant inflow port to a groove-like coolant passage of a cylinder block, and capable of limiting a movement in an up-down direction and a circumferential direction of the groove-like coolant passage.

[Solution to Problem]

The above problems are solved by the present invention described below.
That is, the present invention (1) provides a thermal insulator for a cylinder bore wall set in a groove-like coolant passage of a cylinder block of an internal combustion engine including cylinder bores and for insulating a bore wall facing a coolant inflow port to the groove-like coolant passage,
the thermal insulator including: a rubber member in contact with a wall surface on a cylinder bore side of the groove-like coolant passage and for covering the wall surface on the cylinder bore side of the groove-like coolant passage; and a metal base member to which the rubber member is fixed, wherein
the metal base member includes: a rear surface pressing part for pressing the entire rubber member toward the wall surface on the cylinder bore side of the groove-like coolant passage from a rear surface side; elastic parts that urge the rear surface pressing part to press the rubber member toward the wall surface on the cylinder bore side of the groove-like coolant passage; and a movement limiting part extending from a rear surface of the metal base member toward a lower portion of an inside of the coolant inflow port in the cylinder block, and having an extending end positioned outside a position of a wall surface outside the groove-like coolant passage, and for limiting a movement of the metal base member.
The present invention (2) provides the thermal insulator for the cylinder bore wall according to (1), wherein the rubber member is a heat-sensitive expanding rubber or a water-swelling rubber.
The present invention (3) provides an internal combustion engine in which the thermal insulator for the cylinder bore wall according to any one of (1) and (2) is set in a groove-like coolant passage.
The present invention (4) provides an automobile including the internal combustion engine according to (3).

[Advantageous Effects of Invention]

The present invention can provide a thermal insulator for a cylinder bore wall, for insulating a cylinder bore wall facing a coolant inflow port to a groove-like coolant passage of a cylinder block, and capable of limiting a movement in an up-down direction and a circumferential direction of the groove-like coolant passage.

[Brief Description of Drawings]

[Figure 1] Figure 1 is a schematic plan view illustrating a form example of a cylinder block in which a thermal insulator for a cylinder bore wall of the present invention is set.
[Figure 2] Figure 2 is a cross-sectional view taken along a line x-x in Figure 1.
[Figure 3] Figure 3 is a perspective view of the cylinder block illustrated in Figure 1.
[Figure 4] Figure 4 is a top view of a coolant inflow port of the cylinder block illustrated in Figure 1.
[Figure 5] Figure 5 is a diagram illustrating the coolant inflow port of the cylinder block illustrated in Figure 1 as viewed from a groove-like coolant passage side.
[Figure 6] Figure 6 is a diagram illustrating a coolant supply port of the cylinder block illustrated in Figure 1 as viewed from outside.
[Figure 7] Figure 7 is a schematic perspective view illustrating a form example of the thermal insulator for the cylinder bore wall of the present invention.
[Figure 8] Figure 8 is a diagram illustrating the thermal insulator 30 for the cylinder bore wall in Figure 7 as viewed from a heat-sensitive expanding rubber side.
[Figure 9] Figure 9 is a rear view illustrating the thermal insulator 30 for the cylinder bore wall in Figure 7.
[Figure 10] Figure 10 is a top view illustrating the thermal insulator 30 for the cylinder bore wall in Figure 7.
[Figure 11] Figure 11 is an end view taken along a line x-x in Figure 10.
[Figure 12] Figure 12 is a diagram illustrating a way to stack each member of the thermal insulator 30 for the cylinder bore wall in Figure 7.
[Figure 13] Figure 13 is a diagram illustrating the way to stack each member of the thermal insulator 30 for the cylinder bore wall in Figure 7.
[Figure 14] Figure 14 is a diagram illustrating cut-off portions that are cut off from a metal plate to form an elastic part attaching member 31 illustrated in Figure 7.
[Figure 15] Figure 15 is a diagram illustrating a cut-off portion that is cut off from a metal plate to form a front-side stiffening plate 34 in Figure 7.
[Figure 16] Figure 16 is a schematic diagram illustrating a state in which the thermal insulator 30 for the cylinder bore wall is set in the cylinder block 11 illustrated in Figure 1.
[Figure 17] Figure 17 is a schematic plan view illustrating the state in which the thermal insulator 30 for the cylinder bore wall is set in the cylinder block 11 illustrated in Figure 1.
[Figure 18] Figure 18 is a schematic end view illustrating the state in which the thermal insulator 30 for the cylinder bore wall is set in the cylinder block 11 illustrated in Figure 1.
[Figure 19] Figure 19 is a diagram illustrating a state in which the heat-sensitive expanding rubber 33 in Figure 18 expands and is in contact with the bore wall.
[Figure 20] Figure 20 is a schematic plan view illustrating movement of the thermal insulator 30 for the cylinder bore wall and a coolant flow during operation of an internal combustion engine.
[Figure 21] Figure 21 is a schematic end view illustrating movement of the thermal insulator 30 for the cylinder bore wall and a coolant flow during operation of an internal combustion engine.

[Description of Embodiments]

A thermal insulator for a cylinder bore wall of the present invention and an internal combustion engine of the present invention will be described with reference to Figure 1 to Figure 15. Figure 1 to Figure 3 each illustrate a form example of a cylinder block in which the thermal insulator for the cylinder bore wall of the present invention is set. Figure 1 is a schematic plan view illustrating the cylinder block in which the thermal insulator for the cylinder bore wall of the present invention is set, Figure 2 is a cross-sectional view taken along a line x-x in Figure 1, and Figure 3 is a perspective view of the cylinder block illustrated in Figure 1. Figure 4 is a top view of a coolant inflow port of the cylinder block, Figure 5 is a diagram illustrating the coolant inflow port of the cylinder block as viewed from a groove-like coolant passage side, and Figure 6 is a diagram illustrating a coolant supply port as viewed from outside. Figure 7 is a schematic perspective view illustrating a form example of the thermal insulator for the cylinder bore wall of the present invention. Figure 8 is a diagram illustrating the thermal insulator 30 for the cylinder bore wall in Figure 7 as viewed from a heat-sensitive expanding rubber side. Figure 9 is a rear view illustrating the thermal insulator 30 for the cylinder bore wall in Figure 7. Figure 10 is a top view illustrating the thermal insulator 30 for the cylinder bore wall in Figure 7. Figure 11 is an end view taken along a line x-x in Figure 10. Figure 12 and Figure 13 each are a diagram illustrating a way to stack each member of the thermal insulator 30 for the cylinder bore wall in Figure 7. Figure 14 is a diagram illustrating cut-off portions that are cut off from a metal plate to form an elastic part attaching member 31 illustrated in Figure 7. Figure 15 is a diagram illustrating a cut-off portion that is cut off from a metal plate to form a front-side stiffening plate 34 in Figure 7.
As illustrated in Figure 1 to Figure 3, in an open deck type cylinder block 11 of a vehicle-mounted internal combustion engine in which the thermal insulator for the cylinder bore wall is set, a bore 12 in which a piston moves up and down, and a groove-like coolant passage 14 in which coolant flows are formed. A wall partitioning into the bore 12 and the groove-like coolant passage 14 is a cylinder bore wall 13. In the cylinder block 11, a coolant supply passage 15 for supplying the coolant to the groove-like coolant passage 14 and a coolant discharge port 16 for discharging the coolant from the groove-like coolant passage 14 are formed.
In the cylinder block 11, two or more bores 12 are formed side by side in series. Therefore, the bores 12 include end bores 12a1 and 12a2 adjacent to one bore and intermediate bores 12b1 and 12b2 sandwiched by two bores (note that, when the number of bores of the cylinder block is two, the bores 12 include only the end bores). Among bores formed side by side in series, the end bores 12a1 and 12a2 are bores at both ends. The intermediate bores 12b1 and 12b2 are bores formed between the end bore 12a1 at one end and the end bore 12a2 at the other end. Each of a wall between the end bore 12a1 and the intermediate bore 12b1, a wall between the intermediate bore 12b1 and the intermediate bore 12b2, and a wall between the intermediate bore 12b2 and the end bore 12a2 (inter-bore walls 191) is a portion sandwiched by two bores, to which heat is transmitted from two cylinder bores, resulting in the wall temperature being higher than that of the other walls. On a wall surface 17 on the cylinder bore side of the groove-like coolant passage 14, the temperature is the highest near the inter-bore walls 191. Therefore, the temperature of a boundary 192 of the bore walls of the cylinder bores and the vicinity of the boundary 192 is the highest in the wall surface 17 on the cylinder bore side of the groove-like coolant passage 14.
In the present invention, in a wall surface of the groove-like coolant passage 14, a wall surface on the cylinder bore 13 side is referred to as a wall surface 17 on the cylinder bore side of the groove-like coolant passage. In the wall surface of the groove-like coolant passage 14, a wall surface on an opposite side of the wall surface 17 on the cylinder bore side of the groove-like coolant passage is referred to as a wall surface 18 outside the groove-like coolant passage.
The coolant supply passage 15 formed in the cylinder block 11 includes a coolant supply port 151 for supplying the coolant from outside into the cylinder block 11, a front stage supply chamber 152 into which the coolant to be supplied into the cylinder block 11 is temporarily supplied, and a coolant inflow port 153 for allowing the coolant to flow from the front stage supply chamber 152 into the groove-like coolant passage 14. In the cylinder block 11, a coolant discharge port 16 for discharging the coolant from the groove-like coolant passage 14 to the outside of the cylinder block 11 is provided.
During operation of an internal combustion engine, the coolant supplied from the coolant supply port 151 to the cylinder block 11 flows through the front stage supply chamber 152, and into the groove-like coolant passage 14 from the coolant inflow port 153. The coolant flow is divided into the groove-like coolant passage 14 on an upper side on the drawing of Figure 1 and the groove-like coolant passage 14 on a lower side on the drawing of Figure 1. Then, the coolant flows toward the coolant discharge port 16, and is discharged from the coolant discharge port 16 to the outside of the cylinder block 11.
The thermal insulator 30 for the cylinder bore wall illustrated in Figure 7 to Figure 11 is a thermal insulator for insulating a bore wall facing the coolant inflow port 153 provided in the cylinder block 11 as illustrated in Figure 1, i.e., a bore wall 20 of the cylinder bore 12a2. Therefore, the thermal insulator 30 for the cylinder bore wall is set in the groove-like coolant passage 14 in a vicinity of the coolant inflow port 153.
The thermal insulator 30 for the cylinder bore wall includes the elastic part attaching member 31 that is provided with metal leaf springs 37 and a movement limiting metal plate 38 and is formed in an arcuate shape when viewed from above, a rear-surface-side pressing member 32 formed in an arcuate shape when viewed from above, a heat-sensitive expanding rubber 33, and the front-side stiffening plate 34 formed in an arcuate shape when viewed from above, in which the elastic part attaching member 31, the rear-surface-side pressing member 32, the heat-sensitive expanding rubber 33, and the front-side stiffening plate 34 are stacked in this order. As illustrated in Figure 8, bending sections 35a formed on an upper end of the elastic part attaching member 31, bending sections 35b formed on a lower end of the elastic part attaching member 31, bending sections 36a formed on a right end of the elastic part attaching member 31, and bending sections 36b formed on a left end of the elastic part attaching member 31 are bent to the front-side stiffening plate 34 side, whereby the rear-surface-side pressing member 32, the heat-sensitive expanding rubber 33, and the front-side stiffening plate 34 are held between the bending sections 35a, 35b, 36a, and 36b and the elastic part attaching member 31 to manufacture the thermal insulator 30 for the cylinder bore wall. That is, the thermal insulator 30 for the cylinder bore wall includes the heat-sensitive expanding rubber 33, and a metal base member 29 comprised of the elastic part attaching member 31, the rear surface pressing member 32, and the front-side stiffening plate 34. Note that in the form example illustrated in Figure 7, since the elastic part attaching member 31, the rear surface pressing member 32 and the front-side stiffening plate 34 cooperate to fix the heat-sensitive expanding rubber 33, the elastic part attaching member 31, the rear surface pressing member 32, and the front-side stiffening plate 34 serve as the metal base member.
The heat-sensitive expanding rubber 33 is a member that heat-sensitively expands in the groove-like coolant passage and is in direct contact with the bore wall 20 of the cylinder bore 12a2 to cover an insulating part of the bore wall 20 and insulate the bore wall 20.
The rear-surface-side pressing member 32 is formed in an arcuate shape when viewed from above. The rear-surface-side pressing member 32 has a shape conforming to the rear surface side (a surface on the opposite side of a contact surface 26 side) of the heat-sensitive expanding rubber 33 such that the rear-surface-side pressing member 32 can press the entire heat-sensitive expanding rubber 33 from the rear surface side of the heat-sensitive expanding rubber 33.
The elastic part attaching member 31 is formed in an arcuate shape when viewed from above. The elastic part attaching member 31 has a shape conforming to the rear surface side (a surface on the opposite side of the heat-sensitive expanding rubber 33) of the rear-surface-side pressing member 32. The elastic part attaching member 31 is provided with the metal leaf springs 37 which are elastic parts and the movement limiting metal plate 38 which is a movement limiting part. The metal leaf springs 37 are vertically long rectangular metal plates. One ends of the metal leaf springs 37 in the longitudinal direction are connected to the elastic part attaching member 31. The metal leaf springs 37 are attached to the elastic part attaching member 33 by being bent from the elastic part attaching member 31 on a side of the one ends connected to the elastic part attaching member 31 such that the other ends of the metal leaf springs 37 separate from the elastic part attaching member 31. The other ends of the metal leaf springs 37 are bent at positions of respective contact portions 371 such that the contact portions 371 come into contact with the wall surface 18 outside the groove-like coolant passage. The movement limiting metal plate 38 is a rectangular metal plate, and extends in the horizontal direction from the rear surface side of the elastic part attaching member 31 toward the outside to be attached to the elastic part attaching member 33.
The front-side stiffening plate 34 is formed in an arcuate shape when viewed from above. A rectangular opening 301 is formed in the front-side stiffening plate 34 when viewed from the front side. The bending sections 35a formed on the upper end of the elastic part attaching member 31, the bending sections 35b formed on the lower end of the elastic part attaching member 31, the bending sections 36a formed on the right end of the elastic part attaching member 31, and the bending sections 36b formed on the left end of the elastic part attaching member 31 are bent toward the front-side stiffening plate 34, and the rear-surface-side pressing member 32, the heat-sensitive expanding rubber 33, and the front-side stiffening plate 34 are held between the elastic part attaching member 31 and the bending sections 35a, 35b, 36a, and 36b, whereby these members are fixed. Note that in the heat-sensitive expanding rubber 33, a surface on the opposite side of the rear-surface-side pressing member 32 side serves as the contact surface 26 that is to be in contact with the wall surface 17 on the cylinder bore side of the groove-like coolant passage.
When the thermal insulator 30 for the cylinder bore wall is set in the groove-like coolant passage 14 of the cylinder block 11, the heat-sensitive expanding rubber 33 expands and comes into contact with the wall surface 17 on the cylinder bore side of the groove-like coolant passage 14, so that the heat-sensitive expanding rubber 33 covers the wall surface 17 on the cylinder bore side of the groove-like coolant passage 14. At this time, the metal leaf springs 37 projecting toward the opposite side of the heat-sensitive expanding rubber 33 come into contact with the wall surface on the opposite side of the wall surface 17 on the cylinder bore side, i.e., the wall surface 18 outside the groove-like coolant passage 14, thereby generating an urging force. The rear surface pressing member 32 presses the heat-sensitive expanding rubber 33 from the rear surface side toward the wall surface 17 on the cylinder bore side of the groove-like coolant passage 14 with the generated urging force of the metal leaf springs 37, to cause the heat-sensitive expanding rubber 33 to adhere to the wall surface 17 on the cylinder bore side of the groove-like coolant passage 14.
A manufacturing procedure of the thermal insulator 30 for the cylinder bore wall will be described. As illustrated in Figure 12 and Figure 13, the front-side stiffening plate 34 is joined to the contact surface side of the heat-sensitive expanding rubber 33. The rear surface pressing member 32 and the elastic part attaching member 31 in which the metal leaf springs 37, the movement limiting metal plate 38, and the bending sections 35a, 35b, 36a, and 36b are formed are joined in this order to the rear surface side of the heat-sensitive expanding rubber 33. Subsequently, the bending sections 35a, 35b, 36a, and 36b are bent. As illustrated in Figure 7 to Figure 11, the rear surface pressing member 32, the heat-sensitive expanding rubber 33 and the front-side stiffening plate 34 are held by the elastic part attaching member 31 and the bending sections 35a, 35b, 36a and 36b, whereby the heat-sensitive expanding rubber 33 is fixed to the metal base member 29 comprised of the elastic part attaching member 31, the rear surface pressing member 32 and the front stiffening plate 34, to manufacture the thermal insulator 30 for the cylinder bore wall.
Note that, as a manufacturing procedure of the elastic part attaching member 33, as illustrated in Figure 14, a metal plate 51 is prepared, and portions indicated by oblique lines in Figure 14 are cut off to form the metal leaf springs 37, the movement limiting metal plate 38, and the bending sections 35a, 35b, 36a, and 36b, whereby a punched product 52 of the metal plate is manufactured. Subsequently, the entire punched product 52 of the metal plate is formed in an arcuate shape. The metal leaf springs 37 are bent to project to the rear surface side and furthermore are bent at the distal ends of the metal leaf springs 37. The movement limiting metal plate 38 is bent to extend in the horizontal direction. In this way, the elastic part attaching member 31 is manufactured. In addition, as a manufacturing procedure of the front-side stiffening plate 33, as illustrated in Figure 15, a metal plate 53 is prepared, and a portion indicated by oblique lines in Figure 15 are cut off to form an opening 301, whereby a punched product 54 of the metal plate is manufactured. Subsequently, the punched product 54 of the metal plate is formed in an arcuate shape, whereby the front-side stiffening plate 34 is manufactured.
The thermal insulator 30 for the cylinder bore wall is set in the groove-like coolant passage 14 of the cylinder block 11 illustrated in Figure 1, for example. Figure 16 is a schematic diagram illustrating a state in which the thermal insulator 30 for the cylinder bore wall is set in the cylinder block 11 illustrated in Figure 1. As illustrated in Figure 16, the thermal insulator 30 for the cylinder bore wall is inserted into a position at which the coolant inflow port 153 is formed in the groove-like coolant passage 14 of the cylinder block 11. As illustrated in Figure 17 and Figure 18, the thermal insulator 30 for the cylinder bore wall is set in the groove-like coolant passage 14. At this time, as illustrated in Figure 17 and Figure 18, the thermal insulator 30 for the cylinder bore wall is set so that the movement limiting metal plate 38 of the thermal insulator 30 for the cylinder bore wall is inserted into the coolant inflow port 153.
As illustrated in Figure 17 and Figure 18, in the state before the coolant is supplied into the groove-like coolant passage 14, the movement limiting metal plate 38 extends toward a lower portion of the inside of the coolant inflow port 153, and an extending end 382 of the movement limiting metal plate 38 is positioned outside the position of the wall surface 18 outside the groove-like coolant passage 14. Note that Figure 17 and Figure 18 each are an enlarged schematic view illustrating the vicinity of a setting position of the thermal insulator 30 for the cylinder bore wall in the state in which the thermal insulator 30 for the cylinder bore wall is set in the cylinder block 11 illustrated in Figure 1. Figure 17 is a plan view, and Figure 18 is an end view.
When the internal combustion engine is operated after the thermal insulator 30 for the cylinder bore wall is set in the groove-like coolant passage 14 of the cylinder block 11, the heat-sensitive expanding rubber 33 is heated and heat-sensitively expands. As illustrated in Figure 19, the heat-sensitive expanding rubber 33 expands through the opening 301 formed in an inner portion of the front-side stiffening plate 34 toward the wall surface 17 on the cylinder bore side, and the contact surface 26 comes into contact with the wall surface 17 on the cylinder bore side. The heat-sensitive expanding rubber 33 continues to expand even after the contact surface 26 comes into contact with the wall surface 17 on the cylinder bore side, and expands to an open state. Therefore, a force is applied to the contact portions 371 of the metal leaf springs 37 in a direction toward the elastic part attaching member 31. Consequently, the metal leaf springs 37 are deformed such that the contact portions 371 approach the elastic part attaching member 31 side. Therefore, a restoring elastic force is generated in the metal leaf springs 37. The elastic part attaching member 31 is pushed toward the wall surface 17 on the cylinder bore side of the groove-like coolant passage with the elastic force. As a result, the heat-sensitive expanding rubber 33 is pressed against the wall surface 17 on the cylinder bore side of the groove-like coolant passage by the rear-surface-side pressing member 32 pushed by the elastic part attaching member 31. That is, the thermal insulator 30 for the cylinder bore wall is set in the groove-like coolant passage 14, whereby the heat-sensitive expanding rubber 33 is heated and heat-sensitively expands, resulting that the metal leaf springs 37 are deformed. The rear-surface-side pressing member 32 is urged by the restoring elastic force of the deformation to press the heat-sensitive expanding rubber 33 against the wall surface 17 on the cylinder bore side of the groove-like coolant passage. In this way, the heat-sensitive expanding rubber 33 of the thermal insulator 30 for the cylinder bore wall comes into contact with the wall surface 17 on the cylinder bore side of the groove-like coolant passage. Figure 19 is a diagram illustrating a state in which the heat-sensitive expanding rubber 33 in Figure 18 expands and is in contact with the bore wall.
As illustrated in Figure 19, in the state after the internal combustion engine is operated and the heat-sensitive expanding rubber 33 expands, the movement limiting metal plate 38 extends toward the lower portion of the inside of the coolant inflow port 153, and the extending end 382 of the movement limiting metal plate 38 is positioned outside the position of the wall surface 18 outside the groove-like coolant passage 14.
Next, the limitation on movement of the thermal insulator for the cylinder bore wall during operation of the internal combustion engine will be described. As illustrated in Figure 20, for the lateral direction, the thermal insulator 30 for the cylinder bore wall moves in a circumferential direction (denoted by reference numeral 41) of the groove-like coolant passage due to vibration during operation of the internal combustion engine. However, since the movement limiting metal plate 38 of the thermal insulator 30 for the cylinder bore wall extends to the inside of the coolant inflow port 153, the movement of the thermal insulator 30 for the cylinder bore wall to the left side in the circumferential direction of the groove-like coolant passage in Figure 20 is limited, by the movement limiting metal plate 38, to a range up to a position at which a lateral side end section 381a of the movement limiting metal plate 38 comes into contact with an inner wall 154a of the coolant inflow port 153. Similarly, the movement of the thermal insulator 30 for the cylinder bore wall to the right side in the circumferential direction of the groove-like coolant passage in Figure 20 is limited, by the movement limiting metal plate 38, to a range up to a position at which a lateral side end section 381b of the movement limiting metal plate 38 comes into contact with an inner wall 154b of the coolant inflow port 153.
As illustrated in Figure 21, the thermal insulator 30 for the cylinder bore wall moves in an up-down direction (denoted by reference numeral 42) due to vibration during operation of the internal combustion engine. However, since the movement limiting metal plate 38 of the thermal insulator 30 for the cylinder bore wall extends to the inside of the coolant inflow port 153, the movement of the thermal insulator 30 for the cylinder bore wall in the downward direction in Figure 21 is limited when a bottom surface 383 of the movement limiting metal plate 38 comes into contact with an inner wall 155 of the coolant inflow port 153.
Furthermore, as illustrated in Figure 20 and Figure 21, after flowing from the front stage supply chamber 152 toward the coolant inflow port 132, coolant 40 flows from the extending end 382 of the movement limiting metal plate 38 through a top surface of the movement limiting metal plate 38 toward the lateral side end sections 381a and 381b of the movement limiting metal plate 38, and then flows toward the lower side of the groove-like coolant passage 14. Therefore, the coolant flow in the downward direction from the upper side of the movement limiting metal plate 38 through the lateral sides of the movement limiting metal plate 38 creates a state in which the movement limiting metal plate 38 is pressed downward. Such a coolant flow limits the movement of the thermal insulator 30 for the cylinder bore wall in the upward direction as illustrated in Figure 21.
As described above, the movement limiting metal plate 38 is attached to the rear surface side of the thermal insulator 30 for the cylinder bore wall, the movement limiting metal plate 38 extending toward the lower portion of the inside of the coolant inflow port 153 and having the extending end 382 positioned outside the position of the wall surface 18 outside the groove-like coolant passage 14, thereby limiting the movement of the thermal insulator 30 for the cylinder bore wall in the up-down direction and the circumferential direction of the groove-like coolant passage. Figure 20 and Figure 21 each are an enlarged schematic view illustrating the movement of the thermal insulator 30 for the cylinder bore wall and the coolant flow during operation of the internal combustion engine, in the vicinity of the setting position of the thermal insulator 30 for the cylinder bore wall. Figure 20 is a plan view, and Figure 21 is an end view.
A thermal insulator for a cylinder bore wall of the present invention is a thermal insulator set in a groove-like coolant passage of a cylinder block of an internal combustion engine including cylinder bores and for insulating a bore wall facing a coolant inflow port to the groove-like coolant passage,
the thermal insulator including: a rubber member in contact with a wall surface on a cylinder bore side of the groove-like coolant passage and for covering the wall surface on the cylinder bore side of the groove-like coolant passage; and a metal base member to which the rubber member is fixed, wherein
the metal base member includes: a rear surface pressing part for pressing the entire rubber member toward the wall surface on the cylinder bore side of the groove-like coolant passage from a rear surface side; elastic parts that urge the rear surface pressing member to press the rubber member toward the wall surface on the cylinder bore side of the groove-like coolant passage; and a movement limiting part extending from a rear surface of the metal base member toward a lower portion of an inside of the coolant inflow port in the cylinder block, and having an extending end positioned outside a position of a wall surface outside the groove-like coolant passage, and for limiting a movement of the metal base member.
The thermal insulator for the cylinder bore wall of the present invention is set in the groove-like coolant passage of the cylinder block of the internal combustion engine. The cylinder block in which the thermal insulator for the cylinder bore wall of the present invention is set is a cylinder block of an open deck type in which two or more cylinder bores are formed side by side in series. When the cylinder block is a cylinder block of an open deck type in which two cylinder bores are formed side by side in series, the cylinder block includes cylinder bores including two end bores. When the cylinder block is a cylinder block of an open deck type in which three or more cylinder bores are formed side by side in series, the cylinder block includes cylinder bores including two end bores and one or more intermediate bores. Note that, in the present invention, among the cylinder bores formed side by side in series, bores at both ends are referred to as end bores and a bore sandwiched by other cylinder bores on both sides is referred to as an intermediate bore.
In the cylinder block in which the thermal insulator for the cylinder bore wall of the present invention, a groove-like coolant passage in which coolant flows is formed. A wall partitioning into a bore and the groove-like coolant passage is a cylinder bore wall. In the cylinder block, a coolant supply passage for supplying the coolant to the groove-like coolant passage and a coolant discharge port for discharging the coolant from the groove-like coolant passage are formed. In the coolant supply passage, the position and shape of a coolant supply port for supplying the coolant into the cylinder block, the position and shape of a coolant inflow port to the groove-like coolant passage, the shape of the passage connecting between the coolant supply port and the coolant inflow port, and the like are selected as appropriate. Since the temperature rises on an upper side of the cylinder bore wall, the position of the coolant inflow port in the up-down direction is normally positioned above the groove-like coolant passage. The coolant supply port to the cylinder block is normally provided below. Since the position of the coolant supply port to the cylinder block is normally different in the up-down direction from the position of the coolant inflow port to the groove-like coolant passage, a passage connecting between the coolant supply port and the coolant inflow port (the front stage supply chamber 152 of the coolant in the form example illustrated in Figure 1) is provided.
Since the temperature of the coolant is low immediately after the coolant has flowed from the coolant inflow port and the flow rate of the coolant is fast in the groove-like coolant passage in the vicinity of the coolant inflow port, the cylinder bore wall facing the coolant inflow port is cooled more excessively than the other bore walls. Then, the thermal insulator for the cylinder bore wall of the present invention is set so that the cylinder bore wall facing the coolant inflow port is prevented from being excessively cooled. Therefore, the thermal insulator for the cylinder bore wall of the present invention is set at a position in the vicinity of the position at which the coolant inflow port is formed, in the groove-like coolant passage. The position of the cylinder bore wall in the up-down direction, the cylinder bore wall being insulated by the thermal insulator for the cylinder bore wall of the present invention, and the size and setting range of the rubber member are selected as appropriate.
The thermal insulator for the cylinder bore wall of the present invention includes the rubber member and the metal base member.
The rubber member is a member that is in direct contact with the wall surface on the cylinder bore side of the groove-like coolant passage, covers the wall surface on the cylinder bore side of the groove-like coolant passage, and insulates the cylinder bore wall. The rubber member is pressed against the wall surface on the cylinder bore side of the groove-like coolant passage by the metal base member with an urging force of the elastic parts. Therefore, the rubber member is formed into a shape conforming to the wall surface facing the coolant inflow port in the wall surface on the cylinder bore side of the groove-like coolant passage, that is, an arcuate shape when viewed from above. The shape of the rubber member viewed from a side is selected as appropriate according to a portion of the wall surface on the cylinder bore side of the groove-like coolant passage to be covered by the rubber member.
Examples of the material of the rubber member include a rubber such as a solid rubber, an expanding rubber, a foamed rubber, and a soft rubber and a silicone-based gelatinous material. A heat-sensitive expanding rubber or a water-swelling rubber that can expand a rubber member portion in the groove-like coolant passage after setting of the thermal insulator for the cylinder bore wall is desirable in that the rubber member can strongly come into contact with the cylinder bore wall to be prevented from being shaved when the thermal insulator for the cylinder bore wall is set in the groove-like coolant passage. Note that when the material of the rubber member is a material that does not expand in the groove-like coolant passage, the urging force is generated exclusively by the elastic parts. When the material of the rubber member is a material that expands in the groove-like coolant passage, the urging force is generated in cooperation with the elastic parts and the expanding rubber.
Examples of a composition of the solid rubber include a natural rubber, a butadiene rubber, an ethylene propylene diene rubber (EPDM), a nitrile butadiene rubber (NBR), a silicone rubber, and a fluorocarbon rubber.
Examples of the expanding rubber include a heat-sensitive expanding rubber. The heat-sensitive expanding rubber is a composite body obtained by impregnating a base foam material with a thermoplastic substance having a melting point lower than that of the base foam material, and compressing the resulting product. The heat-sensitive expanding rubber is a material, a compressed state of which is maintained by a cured product of the thermoplastic substance present at least in a surface layer part thereof at the normal temperature and is released when the cured product of the thermoplastic substance is softened by heating. Examples of the heat-sensitive expanding rubber include a heat-sensitive expanding rubber disclosed in Japanese Patent Laid-Open No. 2004-143262 . When the material of the rubber member is the heat-sensitive expanding rubber, the heat-sensitive expanding rubber expands to be deformed into a predetermined shape when the thermal insulator for the cylinder bore wall of the present invention is set in the groove-like coolant passage and heat is applied to the heat-sensitive expanding rubber.
Examples of the base foam material related to the heat-sensitive expanding rubber include various polymeric materials such as a rubber, an elastomer, a thermoplastic resin, and a thermosetting resin. Specifically, examples of the base foam material include a natural rubber, various synthetic rubbers such as a chloropropylene rubber, a styrene butadiene rubber, a nitrile butadiene rubber, an ethylene propylene diene terpolymer, a silicone rubber, a fluorocarbon rubber, and an acrylic rubber, various elastomers such as soft urethane, and various thermosetting resins such as rigid urethane, a phenolic resin, and a melamine resin.
As the thermoplastic substance related to the heat-sensitive expanding rubber, a thermoplastic substance, any one of a glass transition point, a melting point, and a softening temperature of which is lower than 120°C, is desirable. Examples of the thermoplastic substance related to the heat-sensitive expanding rubber include a thermoplastic resin such as polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, polyacrylic ester, a styrene butadiene copolymer, chlorinated polyethylene, polyvinylidene fluoride, an ethylene-vinyl acetate copolymer, an ethylene vinyl acetate vinyl chloride acrylate ester copolymer, an ethylene-vinyl acetate acrylate ester copolymer, an ethylene-vinyl acetate vinyl chloride copolymer, nylon, an acrylonitrile-butadiene copolymer, polyacrylonitrile, polyvinyl chloride, polychloroprene, polybutadiene, a thermoplastic polyimide, polyacetal, polyphenylene sulfide, polycarbonate, and thermoplastic polyurethane and various thermoplastic compounds such as a low-melting point glass frit, starch, a solder, and a wax.
Examples of the expanding rubber include a water-swelling rubber. The water swelling rubber is a material obtained by adding a water-absorbing substance to a rubber and is a rubber material that swells by absorbing water and has firmness for retaining an expanded shape. Examples of the water-swelling rubber include rubber materials obtained by adding water-absorbing substances such as a crosslinking substance of a polyacrylic acid neutralized product, a starch acrylic acid graft copolymer cross linking substance, a cross-linked carboxymethyl cellulose salt, and polyvinyl alcohol to a rubber. Examples of the water-swelling rubber include a water-swelling rubber containing a ketiminated polyamide resin, glycidyl ethers, a water-absorbing resin, and a rubber disclosed in Japanese Patent Laid-Open No. 9-208752 . When the material of the rubber member is the water-swelling rubber, the water-swelling rubber expands to be deformed into a predetermined shape when the thermal insulator for the cylinder bore wall of the present invention is set in the groove-like coolant passage and the coolant is supplied to the groove-like coolant passage and the water-swelling rubber absorbs the water.
The foamed rubber is a porous rubber. Examples of the foamed rubber include a sponge-like foamed rubber having a continuous cell structure, a foamed rubber having a closed cell structure, and a foamed rubber having a semi-closed cell structure. Specifically, examples of the material of the foamed rubber include an ethylene propylene diene terpolymer, a silicone rubber, a nitrile butadiene copolymer, a silicone rubber, and a fluorocarbon rubber. An expansion ratio of the foamed rubber is not limited to a particular value and is selected as appropriate. The water content of the rubber member can be adjusted by adjusting the expansion ratio. Note that the expansion ratio of the foamed rubber indicates a density ratio before and after foaming represented by ((density before foaming - density after foaming)/density before foaming) × 100.
When the material of the rubber member is a material that can absorb water such as the water-swelling rubber or the foamed rubber, the rubber member absorbs water when the thermal insulator for the cylinder bore wall of the present invention is set in the groove-like coolant passage and the coolant is supplied to the groove-like coolant passage. In which range the water content of the rubber member is set when the coolant is supplied to the groove-like coolant passage is selected as appropriate according to operation conditions and the like of the internal combustion engine. Note that the water content indicates a weight water content represented by (coolant weight / (filler weight + coolant weight)) × 100.
The shape and thickness of the rubber member are not limited to particular values and are selected as appropriate.
The metal base member is a member to which the rubber member is fixed. The metal base member includes at least the rear surface pressing part, the elastic parts, and the movement limiting part. The metal base member may be a member in which the rear surface pressing part, the elastic parts and the movement limiting part are integrally formed, or may be comprised of a combination of two or more members. For example, as in the form example illustrated in Figure 7, the metal base member may be comprised of a combination of a member serving as the rear surface pressing part, fixing parts (the bending sections, the front-side stiffening plate, and the like) for fixing the rubber member, and a member provided with the elastic parts and the movement limiting part, or may be a member in which the elastic part and the movement limiting part are attached, by welding, to the member serving as the rear surface pressing part in which the fixing parts (the bending sections, the front-side stiffening plate, and the like) for fixing the rubber member are formed.
The material of the metal base member is not limited to a particular material. However, stainless steel (SUS), an aluminum alloy, or the like is desirable because LLC resistance is high and strength is high.
The rear surface pressing part is a part for pressing the entire rubber member toward the wall surface on the cylinder bore side of the groove-like coolant passage from the rear surface side. The rear surface pressing part is formed in an arcuate shape when viewed from above. The rear surface pressing part has a shape conforming to the rear surface side (a surface on the opposite side of the contact surface side) of the rubber member and a shape covering the entire rear surface side or substantially the entire rear surface side of the rubber member such that the rear surface pressing part can press the entire rubber member from the rear surface side of the rubber member. The thickness of the rear surface pressing part is selected as appropriate. The material of the rear surface pressing part is selected as appropriate. However, a metal plate of stainless steel, an aluminum alloy, or the like is desirable.
The elastic parts are attached to the rear surface side of the thermal insulator for the cylinder bore wall of the present invention. The elastic parts are members elastically deformed when the thermal insulator for the cylinder bore wall of the present invention is set in the groove-like coolant passage and for urging the rear surface pressing member with an elastic force to press the rubber member toward the wall surface on the cylinder bore side of the groove-like coolant passage.
It is only required that at least one elastic part is attached to the thermal insulator for the cylinder bore wall of the present invention. However, preferably two or more elastic members, particularly preferably three or more elastic members are attached in the arc direction of the thermal insulator for the cylinder bore wall of the present invention when the thermal insulator for the cylinder bore wall of the present invention is viewed from above.
A form of the elastic part is not limited to a particular form. Examples of the form of the elastic part include a tabular elastic member, a coil-like elastic member, a leaf spring, a torsion spring, and an elastic rubber. As the elastic part, a metal elastic member such as a metal leaf spring, a coil spring, a leaf spring, or a torsion spring is desirable.
As the elastic part, it is desirable that a portion in contact with the wall surface on the opposite side of the wall surface on the cylinder bore side of the groove-like coolant passage and the vicinity of the portion are formed into a curved surface shape swelling to the wall surface on the opposite side of the wall surface on the cylinder bore side of the groove-like coolant passage because it is possible to prevent the wall surface on the opposite side of the wall surface on the cylinder bore side of the groove-like coolant passage from being damaged by contact portions with the wall surface of the elastic parts when the thermal insulator for the cylinder bore wall of the present invention is inserted into the groove-like coolant passage.
In the thermal insulator for the cylinder bore wall of the present invention, a form, a shape, a size, a setting position, a setting number, and the like of the elastic parts are selected as appropriate according to the shape and the like of the groove-like coolant passage such that the rubber member is urged by an appropriate pressing force by the elastic parts when the thermal insulator is set in the groove-like coolant passage.
In the thermal insulator 30 for the cylinder bore wall illustrated in Figure 7, the elastic part attaching member and the metal leaf springs, which are the elastic parts, are integrally formed and the rubber member and the rear surface pressing member are fixed to the elastic part attaching member in which the metal leaf springs are formed, whereby the elastic parts are attached to the thermal insulator for the cylinder bore wall. However, a method of attaching the elastic parts to the thermal insulator for the cylinder bore wall is not limited to a particular method. Examples of other methods include a method of welding metal elastic members such as metal leaf springs, metal coil springs, leaf springs, or torsion springs to the rear surface pressing member made of a metal plate to fix the rubber member to the rear surface pressing member to which the elastic parts are welded.
The movement limiting part is attached to the rear surface side of the thermal insulator for the cylinder bore wall of the present invention. A portion on the extending end side of the movement limiting part is inserted into the lower portion of the inside of the coolant inflow port during operation of the internal combustion engine. That is, during operation of the internal combustion engine, the extending end of the movement limiting part is positioned outside the wall surface outside the groove-like coolant passage. The portion on the extending end side of the movement limiting part is inserted into the lower portion of the inside of the coolant inflow port, whereby the movement limiting part serves as a member for limiting a movement of the thermal insulator for cylinder bore wall of the present invention in the groove-like coolant passage, the movement being caused by vibration during operation of the internal combustion engine.
The shape of the movement limiting part is not limited to a particular shape. The shape may be any shape that extends from the rear surface side of the thermal insulator for the cylinder bore wall of the present invention toward the lower portion of the inside of the coolant inflow port so that the extending end is positioned outside the wall surface outside the groove-like coolant passage. Examples of the shape include a rectangular plate-like shape, a T plate-like shape in which side portions on the extending end side project laterally, and an L plate-like shape.
The material of the movement limiting part is not limited to a particular material. However, stainless steel (SUS), an aluminum alloy, or the like is desirable because LLC resistance is high and strength is high.
The setting position of the movement limiting part on the rear surface side of the thermal insulator for the cylinder bore wall of the present invention is not limited to a particular position. The position is selected as appropriate according to the forming position and the shape of the coolant inflow port.
A method of fixing the rubber member to the metal base member is not limited to a particular method. Examples of the method include a method of fixing the rubber member by holding the rubber member between the metal base member and the bending sections provided in the metal base member (in the form example illustrated in Figure 7, the bending sections are provided in the elastic part attaching member which is a component of the metal base member), and a method of bonding the rubber member to the metal base member using an adhesive. When the rubber member is held by the bending sections provided in the metal base member, the rubber member may be directly held by the bending sections. Alternatively, when the rubber is an expanding rubber, as in the form example illustrated in Figure 7, the front-side stiffening plate may be provided on the contact surface side of the rubber member, so that the rubber member is held by the bending sections via the front-side stiffening plate.
The metal base member includes at least the elastic parts, the movement limiting part, and the rear surface pressing part. All of the elastic parts, the movement limiting part, and the rear surface pressing part may be provided in one member. Alternatively, all or some of the elastic parts, the movement limiting part, and the rear surface pressing part may be provided in different members, so that the metal base member is formed by combining the different members in which the elastic parts, the movement limiting part, and the rear surface pressing part are provided.
The thermal insulator for the cylinder bore wall of the present invention moves in an up-down direction and a circumferential direction of the groove-like coolant passage due to vibration during operation of the internal combustion engine. However, in the thermal insulator for the cylinder bore wall of the present invention, since the movement limiting part extends to the inside of the coolant inflow port, the movement of the thermal insulator in the circumferential direction of the groove-like coolant passage is limited, by the movement limiting part, to a range up to a position at which a lateral side end section of the movement limiting part comes into contact with an inner wall of the coolant inflow port. Furthermore, since the movement limiting part extends to the inside of the coolant inflow port, the movement of the thermal insulator for the cylinder bore wall of the present invention in the downward direction is limited when a bottom surface of the movement limiting part comes into contact with the inner wall of the coolant inflow port. The coolant that has flowed from the coolant flow port flows on the top surface of the movement limiting part, and then flows through the lateral sides of the movement limiting part toward the lower side of the groove-like coolant passage, whereby the coolant flow creates a state in which the movement limiting part is pressed downward. In this way, the movement of the thermal insulator for the cylinder bore wall of the present invention in the upward direction is limited by such a coolant flow.
As described above, when the movement limiting part is provided on the rear surface side of the thermal insulator for the cylinder bore wall of the present invention, the movement limiting part extending toward the lower portion of the inside of the coolant inflow port and having the extending end positioned outside the position of the wall surface outside of the groove-like coolant passage, thereby limiting the movement of the thermal insulator for the cylinder bore wall of the present invention in the up-down direction and the circumferential direction of the groove-like coolant passage.
An internal combustion engine of the present invention is an internal combustion engine in which the thermal insulator for the cylinder bore wall of the present invention is set.
An automobile of the present invention is an automobile including the internal combustion engine of the present invention.

[Reference Signs List]

11 Cylinder block
12 Bore
12a1, 12a2 End bore
12b1, 12b2 Intermediate bore
13 Cylinder bore wall
14 Groove-like coolant passage
15 Coolant supply passage
16 Coolant discharge port
17 Wall surface on cylinder bore side of groove-like coolant passage 14
18 Wall surface outside groove-like coolant passage 14
20 Cylinder bore wall facing coolant inflow port
26 Contact surface
29 Metal base member
30 Thermal insulator for cylinder bore wall
31 Elastic part attaching member
32 Rear-surface-side pressing member
33 Heat-sensitive expanding rubber
34 Front-side stiffening plate
35a, 35b, 36a, 36b Bending section
37 Metal leaf spring
38 Movement limiting metal plate
40 Coolant
41 Circumferential direction of groove-like coolant passage
42 Up-down direction
51, 53 Metal plate
52, 54 Punched product
151 Coolant supply port
152 Front stage supply chamber
153 Coolant inflow port
154a, 154b, 155 Inner wall of coolant inflow port
191 Inter-bore portion
192 Boundary of bore walls of cylinder bores of wall surface on cylinder bore side of groove-like coolant passage
301 Opening
371 Contact portion
381a, 381b Lateral side end section
382 Extending end
383 Bottom surface of movement limiting metal plate

Claims

A thermal insulator for a cylinder bore wall set in a groove-like coolant passage of a cylinder block of an internal combustion engine including cylinder bores and for insulating a bore wall facing a coolant inflow port to the groove-like coolant passage,
the thermal insulator comprising: a rubber member in contact with a wall surface on a cylinder bore side of the groove-like coolant passage and for covering the wall surface on the cylinder bore side of the groove-like coolant passage; and a metal base member to which the rubber member is fixed, wherein
the metal base member includes: a rear surface pressing part for pressing the entire rubber member toward the wall surface on the cylinder bore side of the groove-like coolant passage from a rear surface side; elastic parts that urge the rear surface pressing part to press the rubber member toward the wall surface on the cylinder bore side of the groove-like coolant passage; and a movement limiting part extending from a rear surface of the metal base member toward a lower portion of an inside of the coolant inflow port in the cylinder block, and having an extending end positioned outside a position of a wall surface outside the groove-like coolant passage, and for limiting a movement of the metal base member.
The thermal insulator for the cylinder bore wall according to claim 1, wherein
the rubber member is a heat-sensitive expanding rubber or a water-swelling rubber.
An internal combustion engine in which the thermal insulator for the cylinder bore wall according to any one of claims 1 and 2 is set in a groove-like coolant passage.
An automobile including the internal combustion engine according to claim 3.