JP2004225872A - Metal member uniting structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a metal member uniting structure in which a pair of metal members can be stably fastened to each other with appropriate fastening axial force and in which it is possible to surely prevent generation of clearance and deformation caused by excessive axial force in the vicinity of the position where the axial force affects when the temperature increases or decreases. <P>SOLUTION: A cylinder head (a first metal member) whose coefficient of linear expansion is the first coefficient A and a cylinder block (a second metal member) whose coefficient of linear expansion is the second coefficient B different from the first coefficient are united to each other by a bolt (a third metal member). The coefficient C of linear expansion of the third metal member is the third coefficient C between the first coefficient A and the second coefficient B. When a first distance between a first united portion p1 of the first metal member and the third metal member and a second united portion p2 of the first metal member and the second metal member is denoted by X and a second distance between a third united portion p3 of the second metal member and the third metal member and the second united portion p2 is denoted by Y, the following equation (A-C)X=(C-B)Y is fulfilled. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a metal member joining structure in which a pair of overlapping metal members are fastened by a third metal member to be integrated.
[0002]
[Prior art]
When integrally connecting a pair of metal members, for example, a cylinder block and a cylinder head of an internal combustion engine, usually a metal bolt is inserted from the cylinder head side, and the bolt is formed on the lower side of a bolt hole formed on the cylinder block side. The engine body is assembled and connected by screwing it onto the inner screw formed in the above and tightening it.
[0003]
The internal combustion engine adopting such a coupling structure has a gasket interposed between the cylinder block and the cylinder head, and this sealing function is also added to suppress the generation of a gap between the cylinder block and the cylinder head, and to prevent combustion. Gas leakage from the chamber, water leakage from the water jacket, oil leakage from the oil passage, and the like are prevented.
[0004]
By the way, the internal combustion engine undergoes a considerable temperature change between the cold state and the completion of warm-up, and the cylinder block and cylinder head made of metal members and the fastening bolts fitted to these joints have respective linear expansion coefficients. , And at this time, an axial force in the pulling direction is received between the positions where the fastening axial force is applied.
[0005]
For example, as shown in FIG. 7, it is assumed that the fastening bolt receives the axial force for fastening at the position (1) corresponding to the normal temperature of the engine. When the position (2) and the position (3) corresponding to the temperature are sequentially reached, the axial force increases. Conversely, when the engine is cooled and dropped in response to the engine stoppage or a relatively large drop in the ambient temperature, the axial force decreases at a position (4) corresponding to the dropped temperature. Such a rise and fall in temperature is thereafter repeated in the order of position (5) and position (6) corresponding to each temperature, and when the temperature reaches the normal temperature position (7) again, the settling on the cylinder head side is added. , The axial force decreases by about δ kgf. This decrease in axial force tends to increase over time.
[0006]
By anticipating such a decrease in the axial force in advance, and by sufficiently adding the initial tightening force of the fastening bolt in the axial direction, the gap between the mating surface of the cylinder block and the cylinder head, which are two metal members caused by the decrease in the axial force, In order to suppress the occurrence of gaps, especially in a low-temperature atmosphere where the amount of shrinkage deformation is relatively large, the fastening force disappears, and the relative displacement or occurrence of gaps is suppressed. I have.
However, when the reduction in the axial force of the fastening bolt is anticipated in advance, and the initial fastening force in the axial direction of the fastening bolt is excessively applied, the following problem occurs.
[0007]
For example, as shown in FIG. 9, a fastening bolt is inserted from the cylinder head side (upper side of the paper), and tightened and connected to the upper wall section 120 of the cylinder liner 110 which is a part of the lower cylinder block of the paper. And At this time, a state occurs in which a grommet of a gasket (not shown) is sandwiched between both opposing surfaces of the upper cylinder head and the lower end of the cylinder liner 110 in FIG. Then, the upper end of the cylinder liner 110 and the cylinder head side are displaced in the pressure contact direction in accordance with the increase in the axial force due to the tightening of the fastening bolts. At this time, the upper end of the cylinder liner 110 is moved toward the cylinder head side with the grommet as a lever. Displace. As a result, the upper portion of the cylinder liner 110 integrated with the upper wall portion is deformed as shown by a two-dot chain line in FIG. That is, the deformation amount b of the bore B of the cylinder liner 110 in the vicinity of the bolt tightening hole 100 increases at the level of μm and becomes the bore B ′. As shown in FIG. 8, the bore deformation amount μm increases in accordance with the increase in the axial tightening axial force kgf of the fastening bolt, and the deformation causes early uneven wear of the cylinder liner, This leads to a decrease in durability.
[0008]
Therefore, in the cylinder block coupling structure disclosed in Japanese Patent Application Laid-Open No. H8-21299 (patent document 1), a cylinder liner made of cast iron is cast in a cylinder block body made of an aluminum alloy. A screw groove is formed in a lower portion sufficiently distant from the surface, and a bolt inserted from the cylinder head side is screwed into this, so that the cylinder head and the cylinder block body side are integrally connected. . With this structure, even if the cylinder block body expands and contracts due to a temperature change, the change in the axial force on the bolt screwed to the cylinder liner side is minimized, the axial force of the bolt is stabilized, and gas leakage etc. It can be prevented from occurring.
[0009]
[Patent Document 1]
JP-A-8-21299 (paragraphs "0013" to "0016", FIG. 2)
[0010]
[Problems to be solved by the invention]
As described above, when the linear expansion coefficient is different from the fastening bolt that is the fastening metal member, the pair of metal members that have been tightened and joined without a gap at a normal fastening temperature at normal temperature have a difference between the working positions of the fastening force. Depending on the length, expansion and contraction are repeated relatively greatly due to changes in temperature, and in some cases, gaps may occur in the polymerized surface, especially in a low-temperature atmosphere, and excessive axial force must be applied to cope with this. If added in advance, there is a problem that deformation occurs near the position where the axial force acts.
[0011]
Therefore, when the coupling structure of the cylinder block disclosed in Patent Document 1 described above is used to cope with this problem, there is a limited configuration in which a cylinder liner made of cast iron is cast inside a cylinder block body made of an aluminum alloy. Therefore, the technology cannot be applied to a cylinder block connecting structure that uses a combination of other materials. In particular, the technology cannot be applied to a cylinder block in which a cylinder liner is integrally cast. Further, the bearing is integrally cast not on the cylinder block body but on the lower part of the cylinder liner, and also in this respect, a special configuration is adopted, so that the versatility of implementation is put to use.
[0012]
As described above, when a pair of metal members having mutually different linear expansion coefficients are integrally joined by the fastening metal member, even if the linear expansion coefficients of the pair of metal members and the fastening metal member are different from each other. In addition, it is desired that the pair of metal members be fastened in a state where the fastening metal member always stably maintains an appropriate fastening axial force in response to a change in the ambient temperature. Accordingly, there is a demand for a joining structure of metal members that can prevent deformation near an operation position due to an excessive axial force without a gap with a predetermined fastening force.
[0013]
The present invention has been made on the basis of the above-described problems, and a fastening metal member can stably fasten a pair of metal members with an appropriate fastening axial force. An object of the present invention is to provide a joining structure of metal members that can reliably prevent deformation near an axial force acting position due to excessive axial force.
[0014]
[Means for Solving the Problems]
According to the first aspect of the present invention, a first metal member having a first coefficient of linear expansion and a second metal member having a second coefficient different from the first coefficient are connected by a third metal member. In the metal member coupling device, the third metal member is formed of a metal member whose linear expansion coefficient is a third coefficient between the first coefficient and the second coefficient, and the first coefficient is A; The second coefficient is B, the third coefficient is C, and the distance between the first joint between the first metal member and the third metal member and the second joint between the first metal member and the second metal member. When the first distance is X, and the second distance between the third joint between the second metal member and the third metal member and the second joint is Y, the first distance and the second The relationship between the two distances is
(A−C) X = (C−B) Y
Is set so as to satisfy the following.
[0015]
As described above, the linear expansion coefficients of the first metal member and the second metal member and the third metal member for fastening, and the length between the positions where the fastening force is applied by the third metal member for fastening, are used. , The second distances X and Y satisfy (A−C) X = (C−B) Y. Therefore, even if there is a change in the ambient temperature, the excess of the extension of the first metal member with respect to the third metal member is equal to the third distance. Since the portion of the third metal member opposed to the second metal member is relatively extended, the excess can be canceled out, the fastening axial force applied to the third metal member for fastening is always stable, and the third metal member is applied at the time of fastening at room temperature. The initial fastening axial force can be maintained. For this reason, the first metal member and the second metal member are always fastened with the fastening metal member stably maintaining the fastening axial force, and the tightened connection state is stably maintained with no gap by the initial fastening axial force. In addition, it is possible to prevent generation of an excessive fastening axial force and prevent deformation of the fastening seat surface.
[0016]
According to a second aspect of the present invention, in the first aspect, the first metal member is a cylinder head of the engine, and the second metal member is a cylinder block of the engine. The three metal members are cylinder head bolts that couple the cylinder head to the cylinder block, and are applied to a coupling structure between the cylinder head and the cylinder block of the engine. As described above, even when the cylinder head and the cylinder block are fastened with the cylinder head bolt, the excessive extension of the cylinder head with respect to the cylinder head bolt is excessive because the portion of the cylinder head bolt facing the cylinder block is relatively extended. The cylinder head and the cylinder block are always fastened with the cylinder head bolts stably maintaining the fastening axial force, and the tightened connection state can be maintained without any gap with the initial fastening axial force, and gas leakage and oil Leakage can be prevented 0, and excessive tightening axial force can be prevented from being generated, and deformation of the tightening seat surface on the cylinder head side can be prevented.
[0017]
According to a third aspect of the present invention, in the metal member coupling structure according to the second aspect, the cylinder head bolt is disposed along an axial direction of the cylinder liner, and the coupling portion between the cylinder head bolt and the cylinder block is provided. A water jacket is formed axially downward.
In this way, even if the connecting portion where the cylinder head and the cylinder block are fastened with the cylinder head bolt is located above the water jacket, the cylinder head bolt always keeps the fastening axial force stable. Since the cylinder head and the cylinder block are fastened, it is possible to reliably prevent the cylinder liner in the vicinity of the joint from being excessively deformed.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
FIGS. 1 to 3 show schematic views of an engine 1 assembled by applying a metal member connecting structure according to an embodiment of the present invention. This engine 1 is an in-line four-cylinder vertical engine, and outputs a gas pressure of high-pressure combustion gas generated in a combustion explosion process in a fuel chamber of each cylinder as a rotational force by the action of a piston and a crankshaft (not shown). The configuration of a four-cycle internal combustion engine is adopted. In the main body of the engine 1, a cylinder head 3 is superposed on a cylinder block 2 and a sheet metal oil pan 4 is superposed on a lower side, and these are integrally connected to each other. In particular, the cylinder block 2 and the cylinder head 3 are integrally joined by applying the joining structure of the metal member as one embodiment of the present invention.
[0019]
The cylinder block 2 is made of cast iron FC, and has a vertically-extending outer wall 6 continuously formed in a substantially rectangular shape in front, rear, left and right directions. Are arranged in series in the longitudinal direction X of the cylinder block 2 in a state of being oriented vertically. Moreover, the upper end and the lower end of each cylinder liner 5 are interconnected by an upper wall 7 and a lower wall 8 and are formed integrally with the outer wall side. Such a cylinder block 2 forms a water jacket 9 between the outer wall 6 and each cylinder liner 5, and this water jacket 9 is connected to a cooling water circulation system.
[0020]
A predetermined vertical direction is formed on the upper side of each cylinder liner 5 in the cylinder block 2 so as to swell toward the water jacket 9 side from the center of each cylinder liner 5 and downward from the upper wall 7 side. The boss 11 is formed with the width h1 secured.
The boss 11 is formed with a vertical hole 14 that opens toward the upper wall 7. In particular, the vertical hole 14 is formed as a hole having a relatively longer vertical length than the opening on the upper wall side, and a screw hole 13 for screwing a fastening bolt 12 described later is formed on a lower portion thereof.
[0021]
As shown in FIG. 2, such boss portions 11 are provided at four corners of each cylinder liner 5 in a plan view. The bolt 12 is inserted into the vertical hole 14 of each boss portion 11, and the bolt 12 is screwed into the screw hole 13 thereunder, whereby the cylinder head 3 is fastened to the cylinder block. For this reason, the explosion pressure generated in the fuel chamber can be distributed to each of the four square bolts 12 so as to be evenly received, and the fastening force is applied to the cylinder block 2 and the cylinder head 3 via the bolts 12 so that mutual fluctuation does not occur. Each boss 11 can be evenly provided.
[0022]
A downward overlapping surface f2 of the cylinder head 3 is overlapped with an upward overlapping surface f1 of the upper wall 7 of the cylinder block 2 via a gasket 15.
Here, the cylinder head 3 covers the entire upward overlapping surface f1 of the cylinder block 2 and forms the fuel chamber of each cylinder by closing the upper part of the cylinder liner 5 of each cylinder.
The cylinder head 3 is die-cast from an aluminum alloy, accommodates a valve train (not shown), and has an upper water jacket (not shown) formed at a portion that does not interfere with these valve trains.
[0023]
The upper water jacket communicates with the water jacket 9 on the cylinder block 2 side through a plurality of cooling water passages 16 formed on the upper wall of the cylinder block.
Further, an oil circulation path (not shown) for supplying oil to a valve train (not shown) in the cylinder head 3 is formed in the cylinder head 3.
The cylinder head 3 has a flange 17 projecting from the outer peripheral edge thereof. The flange 17 is overlapped on the upper wall 7 of the cylinder block 2 via the gasket 15, and is connected to the cylinder block 2 at a plurality of positions, that is, each of the boss portions 11 by using a joining structure of metal members to which the present invention is applied. They are integrally connected at the opposing position.
[0024]
As shown in FIGS. 1 and 3, the flange 17 of the cylinder head 3 has a vertical width X, and a through hole 18 is formed at a position facing each boss 11. The through hole 18 is opposed to the vertical hole 14 of the boss portion 11, and a fastening bolt 12 is fitted into the through hole 18 from above and screwed into the screw hole 13. Note that the connection structure of the cylinder block 2 and the cylinder head 3 which are the metal members is similarly configured at the fastening positions by the bolts 12 which are the metal members for fastening. And duplicate explanations are omitted.
[0025]
As shown in FIGS. 1 and 3, when the bolt 12 is fastened, a joint between the bolt 12 and the upper surface of the flange 17 is defined as an axial force acting position p <b> 1. The force acting position P3 is defined as the position where the cylinder block 2 and the cylinder head 3 are opposed to the overlapping surfaces f1 and f2, that is, the central portion in the thickness direction of the gasket 15 is defined as the intermediate axial force acting position p2.
[0026]
Here, the bolt 12 which is a metal member for fastening is subjected to a tightening process with respect to the screw hole 13 of the boss portion 11 at room temperature atmosphere so that the axial force becomes an appropriate value, and the cylinder block which is a pair of metal members is formed. 2 and the cylinder head 3 are integrally connected.
Further, the fastening of the cylinder block 2 and the cylinder head 3 by the bolts 12 will be described in detail.
Here, as shown in FIG. 5, a cylinder head (a) made of an aluminum alloy is used as a first metal member, and its linear expansion coefficient is set to a first coefficient A (21 × 10 ^-6 ).
[0027]
The cylinder block (b) cast by the cast iron FC is used as a second metal member, and its linear expansion coefficient is set to a second coefficient B (10 × 10 ^-6 ).
A steel bolt (c) is used as a third metal member for fastening, and its linear expansion coefficient is set to a third coefficient C (12 × 10 ^-6 ).
Here, the coefficient of linear expansion A of the cylinder head (a) is different from the coefficient of linear expansion B of the cylinder block (b). In addition, the linear expansion coefficient C of the bolt was selected as a coefficient between the first coefficient A and the second coefficient B, that is, A>C> B.
[0028]
Next, as shown in FIG. 3, the first coupling portion between the cylinder head 3 as the first metal member and the bolt 12 as the third metal member for fastening is connected to the axial force acting position p1 on the upper surface of the flange 17 here. And The second joint between the cylinder head 3 as the first metal member and the cylinder block 2 as the second metal member is connected to the intermediate axial force acting position p2 between the overlapping surfaces f1 and f2 of the cylinder block 2 and the cylinder head 3. I do. A third joint between the cylinder block 2 as the second metal member and the bolt 12 as the third metal member is defined as an axial force acting position p3 at the center of the screw hole 13.
[0029]
Further, the distance between the axial force acting position p1 which is the first joint and the intermediate axial force acting position p2 which is the second joint is a first distance X, and the axial force actuated position p3 which is the third joint is the second distance X. A second distance between the connecting portion and the intermediate axial force acting position p2 is Y.
In this case, in the fastening structure of the bolt 12 shown in FIGS. 1 and 3, the relationship between the first distance X and the second distance Y is expressed by the following equation (A).
(A−C) X = (C−B) Y (1)
Is set to meet.
[0030]
That is, rewriting equation (a),
(21 × 10 ^-6 ―12 × 10 ^-6 ) X = (12 × 10 ^-6 -10 x 10 ^-6 ) Y
9X = 2Y
Ｙ Y = 4.5X
Thus, the distance (X + Y) between the axial force acting position p1 which is the bearing surface of the bolt 12 and the axial force acting position p3 at the center of the screw hole 13 of the boss portion 11 is the thickness of the flange 17 of the cylinder head 3. The first distance X between the axial force acting position p1 and the intermediate axial force acting position p2 is 5.5 times. That is, when the thickness of the flange 17 is defined as the first distance X, the distance (X + Y) between the bearing surface of the bolt 12 and the third coupling portion between the cylinder block 2 and the bolt 12 is equal to the first distance X of 5 Formula (A) is satisfied by providing the boss portion 11 having the vertical hole 14 having a length that can be fitted and screwed with the bolt 12 and the subsequent screw hole 13 so as to be five times larger.
[0031]
In the coupling structure that satisfies the equation (a), the bolt is (c), the cylinder head is (a), the cylinder block is (b), and the relationship between the relative length and position is shown in the center of FIG. Indicated as position.
Here, in a normal temperature state, when the bolt (c), the cylinder head (a), and the cylinder block b in the coupling structure satisfying the expression (a) are in a high temperature state (temperature change amount Δt), the right side of FIG. As shown, a first coupling portion (axial force acting position p1) between the bolt (c) and the cylinder head (a) and a third coupling portion (axial force acting position p3) between the bolt (c) and the cylinder block (b). ) Is elongated by C (X + Y) · Δt.
[0032]
On the other hand, a third coupling portion (axial force acting position p3) between the bolt (c) and the cylinder block (b) and a second coupling portion (axial force acting position) between the cylinder head (a) and the cylinder block (b). p2) is changed to BY · Δt, and the distance X between the first joint (axial force acting position p1) and the second joint (axial force acting position p2) is AX · Δt. Elongation and deformation are relatively large with Δt.
[0033]
That is, the aluminum alloy cylinder head (a) having a relatively large coefficient of linear expansion A expands relatively greatly, and the bolt () at a portion facing the distance X between the axial force acting positions p1 and p2 at normal temperature. It is larger by an excess amount α than the elongation (CX · Δt) of c). However, the excess α here is caused by the fact that the portion opposite to the distance Y between the normal temperature axial force acting positions p2 and p3 of the bolt 12 extends a relatively long distance (CY · Δt) with respect to the cylinder block (b). , The excess α can be canceled.
[0034]
That is, an axial force acting position P1, which is a first joint between the bolt (c) and the cylinder head (a), and an axial force acting position P3, which is a third joint between the bolt (c) and the cylinder block (b). In the meantime, the bolt (c) extends from X + Y to C (X + Y) △ t and is deformed. On the other hand, the flange 17 of the cylinder head (a) also extends and deforms in accordance with the high temperature change, and the axial force acting position P1, which is the first connection portion between the bolt (c) and the cylinder head (a), and the cylinder head ( The distance X between the a) and the axial force acting position P2, which is the second joint between the cylinder block (b), changes to AX · Δt. Further, the cylinder block (b) also extends and deforms in accordance with the change in high temperature, and the axial force acting position P2, which is the second connection portion between the cylinder head (a) and the cylinder block (b), the bolt (c), and the cylinder block (b) ) And the axial force acting position p3 which is the third coupling portion changes to BY · Δt.
Therefore, when the temperature change amount Δt, the change amounts of the cylinder head (a), the cylinder block (b), and the bolt (c) are as follows.
(1) The amount of change in the cylinder head (a) between the first joint between the cylinder head (a) and the bolt (c) and the second joint between the cylinder head (a) and the cylinder block (b) ： AX ・ △ t
(2) The amount of change in the cylinder block (b) between the second joint between the cylinder head (a) and the cylinder block (b) and the third joint between the cylinder block (b) and the bolt (c) ： BY ・ △ t
(3) A change amount of the bolt (c) between the first joint between the cylinder head (a) and the bolt (c) and the third joint between the cylinder block (b) and the bolt (c): C (X + Y) · Δt
The relationship between the cylinder head (a), the cylinder block (b), the bolt (c), and the amount of strain change δ of the bolt (c) is represented by the following equation.
[0035]
AX △ t + BY △ t = C (X + Y) △ t + δ (2)
To sort this out,
((A−C) X + (B−C) Y) · △ t = δ ··· (c)
In equation (c), if the amount of strain change δ of the bolt (c) is set to zero, the expansion of the cylinder head (a), the cylinder block (b), and the bolt (c) due to a temperature change causes the bolt (c) to deform. The cylinder head (a) and the cylinder block (b) can be integrally connected with the same fastening axial force as at room temperature without increasing or decreasing the fastening axial force.
[0036]
That is, the linear expansion coefficient A of the cylinder head (a), the linear expansion coefficient B of the cylinder block (b), the linear expansion coefficient C of the bolt (c), and the first joint between the bolt (c) and the cylinder head (a). , And the distance X between the axial force acting position P2, which is the second joint between the cylinder head (a) and the cylinder block (b), and the cylinder head (a) and the cylinder block (b). The relationship between the axial force acting position P2, which is the second joint portion with the axial force acting position P3, which is the third joint portion between the bolt (c) and the cylinder block (b), and the distance Y between the bolt and the cylinder block (b) are as follows. When the formula (a) is satisfied, the amount of strain change δ of the bolt (c) can be set to zero, and the cylinder head (a) and the cylinder block can be connected with the same axial force as at room temperature regardless of the temperature change. (B) can be integrally connected.
[0037]
Conversely, when the temperature becomes lower than the normal temperature (temperature change amount -Δt), the cylinder head (a), the cylinder block (b), and the bolt (c) contract and deform as shown on the left side of FIG. In this case, the respective amounts of deformation are based on the above equation (b).
[0038]
That is, the cylinder head (a) made of an aluminum alloy having a relatively large linear expansion coefficient A is relatively largely contracted (AX .-. DELTA.t), so that it faces the distance X between the axial force acting positions p1 and p2 at normal temperature. In this case, the bolt (c) in the portion to be shrunk is excessively reduced by an excess β from the amount of change in contraction (CX · −Δt) of the bolt (c). However, the excess β here is relatively large in the portion opposed to the distance Y between the normal temperature axial force acting positions p2 and p3 of the bolt 12 with respect to the shrinkage change amount (BY · −Δt) of the cylinder block (b). By setting the contraction change amount (CY · −Δt), the excess β can be canceled.
[0039]
That is, also in this case, since the configuration satisfies the above equation (a), the amount of change in strain δ of the bolt (c) becomes zero, and the increase or decrease in the fastening axial force of the bolt (c) due to contraction deformation. This does not occur, and the cylinder head (a) and the cylinder block (b) can be integrally connected with the same fastening axial force as at room temperature.
In this manner, even if there is a temperature change, the excess amount α of the first metal member with respect to the third metal member is increased by the fact that the portion of the third metal member facing the second metal member is relatively extended. Can be countered,
That is, the cylinder head 2 and the cylinder block 3 shown in FIG. 1 are integrally connected with each other with the same fastening axial force as that at normal temperature regardless of a change in temperature, and a gap is generated between both overlapping surfaces f1 and f2, gas leakage, Water leakage, oil leakage, and the like can be prevented, and deformation of the tightening seat surface on the cylinder head 3 side due to excessive increase in the fastening axial force due to expansion and contraction can be prevented.
[0040]
Further, as shown in FIGS. 1 and 3, an axial force acting position p3, which is a third coupling portion between the bolt 12 and the cylinder block 2, is formed in the boss portion 11, and is located laterally and axially below the boss portion 11. In this case, when an excessive fastening axial force (upward pulling force) is originally applied to the cylinder block 2 as described with reference to FIGS. 5 may be deformed. However, in the present embodiment, the cylinder liner 5 shown in FIGS. 1 and 3 does not apply an excessive fastening axial force to the boss portion 11 integrated therewith at normal temperature, high temperature, and low temperature. Since the axial force can be stably maintained, it is possible to reliably prevent the cylinder liner 5 from being excessively deformed in the vicinity of the axial force acting position p3, which is the third coupling portion, and uneven wear of the cylinder liner 5 can be prevented. It is possible to reliably prevent the occurrence of the deterioration and the reduction in the durability.
[0041]
FIG. 1 shows a connecting structure of metal members to which the present invention is applied, in which a cylinder block 2 and a cylinder head 3 constituting an engine body are fastened by bolts 12 serving as fastening metal members so that the ambient temperature can be increased or decreased. In the above description, the configuration has been described in which an appropriate fastening axial force can be maintained. Alternatively, the configuration shown in FIG. 6 may be employed.
[0042]
The connecting structure of metal members shown in FIG. 6 is a structure in which a pipe 18 made of cast iron and a pipe 19 made of an aluminum alloy are integrally connected as a first metal member with steel bolts 20. It is assumed that steam used as a high temperature fluid is used intermittently in a cold region.
Here, the flange 18a of the pipe 18 made of cast iron and the flange 19a of the aluminum pipe 19 made of an aluminum alloy are overlapped with each other. A nut 23 is screwed into the nut and tightened with an appropriate fastening axial force to be integrally joined.
[0043]
Also in this case, the linear expansion coefficient of the flange 19a of the aluminum pipe 19 is the first coefficient A, the linear expansion coefficient of the flange 18a of the cast iron pipe 18 is the second coefficient B, and the linear expansion coefficient of the steel bolt 20 is the third coefficient C. A coefficient having a characteristic of A>C> B is adopted for each linear expansion coefficient.
Further, the distance between the axial force acting position p1 of the flange 19a of the aluminum pipe 19 and the intermediate axial force acting position p2 where both flanges overlap is defined as a first distance X, and the intermediate axial force acting position p2 where both flanges overlap and the cast iron pipe 18 The distance between the axial force acting position p3 of the flange 18a and the flange 18a of the cast iron pipe 18, the flange 19a of the aluminum pipe 19 made of an aluminum alloy, and the bolt are set so as to satisfy the above-mentioned formula (A). A length of 20 or the like is selected and formed.
[0044]
During use, high-temperature steam flows through the cast-iron pipe 18 and the aluminum-alloy pipe 19 shown in FIG. 6, and is cooled to extremely low temperatures when not in use. However, since the pipe 18 made of cast iron and the pipe 19 made of an aluminum alloy are formed so as to satisfy the above-mentioned equation (a), regardless of the increase or decrease of the temperature, both pipes 18 are formed with the same fastening axial force as at normal temperature. The flanges 18a and 19a are integrally connected, and it is possible to reliably prevent a gap from being generated between the two overlapped surfaces f1 and f2 and to prevent steam leakage.
[0045]
In the above description, the first metal member is made of aluminum alloy, the second metal member is made of cast iron, and the third metal member for fastening is made of steel bolt. However, the present invention is not limited to this. As long as the respective linear expansion coefficients A, B, and C of the third metal member have a relationship of A>C> B, the same can be adopted, and their coupling structure can maintain the characteristics of the formula (A). In this case, the same effect as that of the connection structure of the metal members shown in FIG. 1 can be obtained.
[0046]
【The invention's effect】
As described above, according to the present invention, even when there is a change in the ambient temperature, the fastening axial force of the third metal member for fastening is stable, and can be maintained equal to the initial fastening axial force applied at the time of fastening at room temperature. Therefore, the first metal member and the second metal member are always fastened in a state where the fastening metal member stably maintains the fastening axial force, and the tightened and joined state can be maintained without a gap with an appropriate fastening axial force. In addition, it is possible to prevent excessive fastening axial force from being generated and to prevent deformation of the fastening seat surface.
[0047]
According to the second aspect of the present invention, even when the cylinder head and the cylinder block are fastened with the cylinder head bolt, the cylinder head and the cylinder block are always fastened while the fastening axial force of the cylinder head bolt is stably maintained. The tightened connection state can be maintained without a gap with a sufficient fastening axial force, and gas leakage and oil leakage can be prevented. Further, generation of excessive fastening axial force can be prevented and deformation of the fastening seat surface on the cylinder head side can be prevented.
[0048]
According to the third aspect of the present invention, since the cylinder head and the cylinder block are always fastened while the fastening axial force of the cylinder head bolt is stably maintained, it is ensured that excessive deformation occurs in the cylinder liner near the joint. Can be prevented.
[Brief description of the drawings]
FIG. 1 is a schematic side view of an engine to which a metal member coupling structure according to an embodiment of the present invention is applied.
FIG. 2 is a top view of a cylinder block of the engine of FIG.
FIG. 3 is an enlarged sectional view of a cylinder liner of the engine of FIG. 1 and a boss portion of a main part thereof.
FIG. 4 is an explanatory diagram illustrating a temperature change in a coupling structure of a cylinder head and a cylinder block of the engine of FIG. 1;
FIG. 5 is a diagram illustrating a coefficient of linear expansion of a material in a coupling structure of a cylinder head and a cylinder block of the engine of FIG. 1;
FIG. 6
FIG. 9 is a cutaway sectional view of a main part of a joint structure of a pair of pipes according to another embodiment of the present invention.
FIG. 7 is a characteristic diagram showing the relationship between axial force and temperature change of a conventional fastening bolt.
FIG. 8 is a characteristic diagram showing a relationship between a bore deformation amount and a change in axial force of a conventional cylinder liner.
FIG. 9 is a diagram illustrating a modification of a bore of a conventional cylinder liner.
[Explanation of symbols]
1 engine
2 Cylinder block (second metal member)
3 Cylinder head (first metal member)
12 bolts (third metal member)
p1 Axial force action position (first joint)
p2 Intermediate axial force action position (second joint)
p3 Axial force action position (third joint)
A First coefficient (linear expansion coefficient)
B Second coefficient (linear expansion coefficient)
C Third coefficient (linear expansion coefficient)
X 1st distance
Y Second distance

Claims (3)

In a metal member joining apparatus, a first metal member having a first coefficient of linear expansion and a second metal member having a second coefficient different from the first coefficient are joined by a third metal member.
The third metal member is a metal member having a coefficient of linear expansion that is a third coefficient between the first coefficient and the second coefficient,
The first coefficient is A,
The second coefficient is B,
The third coefficient is C,
X represents a first distance between a first joint between the first metal member and the third metal member and a second joint between the first metal member and the second metal member.
A second distance between a third joint between the second metal member and the third metal member and the second joint is Y,
, The relationship between the first distance and the second distance is expressed by the following equation (AC) X = (CB) Y
Characterized by being set so as to satisfy the following. The first metal member is a cylinder head of the engine, the second metal member is a cylinder block of the engine, and the third metal member is a cylinder head bolt for coupling the cylinder head to the cylinder block. ,
The metal member coupling structure according to claim 1, wherein the metal member coupling structure is applied to a coupling structure between a cylinder head and a cylinder block of the engine. The cylinder head bolt is disposed along the axial direction of the cylinder liner,
3. The metal member connecting structure according to claim 2, wherein a water jacket is formed below the connecting portion between the cylinder head bolt and the cylinder block in the axial direction.

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