JP2014145340A - Cylinder block for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cylinder block of an internal combustion engine capable of improving dimensional accuracy and strength by being manufactured by die casting, and further improving strength and rigidity of a top deck.SOLUTION: In a cylinder block for an internal combustion engine composed of a cylinder bore portion 57a for sliding a piston, and a block portion 57c including an external wall 57b covering the circumference of the cylinder bore portion 57a, and provided with a water jacket between itself and the cylinder bore portion 57a, a cover member 61 covering the water jacket and disposed over the cylinder bore portion 57a and the block portion 57c, is integrally joined to the cylinder bore portion 57a and the block portion 57c by frictional agitation bonding.

Description

  The present invention relates to a cylinder block for an internal combustion engine in which deck surfaces are connected and formed by friction stir welding.

  The cylinder block for an internal combustion engine includes a cylinder wall into which a piston is inserted and an outer wall surrounding the cylinder wall via a water jacket, and the cylinder wall and the outer wall are walls having a top deck to which a cylinder head is attached. A so-called closed deck type in which the water jacket is closed by being integrally connected is known (for example, see Patent Document 1).

JP 2007-315195 A

The cylinder block of the above closed deck structure can increase the strength and rigidity of the top deck side, but is manufactured by gravity casting at a relatively low pressure using a core to form a water jacket. It is difficult to select materials with high strength and to improve dimensional accuracy.
Thus, it is conceivable to increase the dimensional accuracy and strength by manufacturing the cylinder block by die casting. If the dimensional accuracy and strength are increased, it is possible to cope with higher output of the engine and weight reduction by making it thinner. However, in die casting, for example, it is easy to manufacture an open deck type cylinder block without a wall having a top deck surface, but it is difficult to increase the strength and rigidity of the top deck.

  The present invention has been made in view of the above-described circumstances, and by manufacturing by die casting, it is possible to select a material having high strength, to improve dimensional accuracy and strength, and to improve the strength and rigidity of the top deck. An object of the present invention is to provide a cylinder block for an internal combustion engine that can be increased.

In order to solve the above-described problem, the present invention provides a water jacket (41e) between the cylinder bore portion (57a) that slides the piston and the cylinder bore portion (57a) while covering the periphery of the cylinder bore portion (57a). In a cylinder block for an internal combustion engine comprising a block part (57c) having an outer wall (57b) provided, the cylinder block covers the water jacket (41e) and straddles the cylinder bore part (57a) and the block part (57c). The lid member (61) disposed on the cylinder bore is integrated with the cylinder bore part (57a) and the block part (57c) by bonding by friction stir welding.
According to this configuration, since the lid member is attached by friction stir welding so as to cover the water jacket between the cylinder bore portion and the block portion, the cylinder block is manufactured by die casting, so that the cylinder block has high strength. The material can be selected, and the dimensional accuracy and strength can be increased. Furthermore, the top deck strength and rigidity of the cylinder block can be increased.

The said cover member (61) is provided with the flat plate part (61f) which contact | connects the step part (57e, 57f) provided in the said cylinder bore part (57a) and the said block part (57c), and the said friction stirring. The flat plate portion (61f) may be bonded to the side surface (57j, 57m) and the bottom surface (57k, 57n) of the stepped portion (57e, 57f) by bonding. According to this configuration, since the flat plate portion has a structure that is integrated with not only the side surface of the step portion but also the bottom surface, the bonding strength can be further increased.
In the above configuration, the lid member (61) is joined to the bottom surface (57k, 57n) of the step portion (57e, 57f) after being joined to the side surface (57j, 57m) of the step portion (57e, 57f). You may be made to do. According to this configuration, the amount of deformation of the lid member can be reduced by joining first from the side surface on the top deck side, and distortion associated with joining on the bottom surface side, which is the next largest load, can be reduced.

Further, in the above configuration, the lid member (61) further protrudes from the center of the flat plate portion (61g) and extends between the cylinder bore portion (57a) and the step portions (57e, 57f) of the block portion (57c). To the water jacket (41e), and the side surfaces (61p, 61q) of the convex portion (61g) are connected to the cylinder bore portion (57a) and the block portion (57c) by the friction stir welding. You may make it join to. According to this configuration, the distortion at the time of joining the lid member can be reduced by the convex portion, and the side surface of the convex portion is joined, so that the coupling strength between the cylinder bore portion and the block portion can be further increased.
In the above configuration, the lid member (61) is joined to the bottom surface (57k, 57n) of the stepped portion (57e, 57f), and then the side surface (61p, 61q) of the convex portion (61g) is joined. You may make it. According to this configuration, it is possible to enhance the bondability of the bottom surface of the stepped portion by the convex portion of the lid member and to restrict the distortion caused by the joining of the cylinder bore portion and the block portion due to the projecting effect of the convex portion.

  In the present invention, the lid member arranged so as to cover the water jacket and straddle the cylinder bore portion and the block portion is integrated by the friction stir welding to the cylinder bore portion and the block portion, so that the cylinder bore portion and the block portion are integrated. Since the lid member is attached by friction stir welding so as to cover the water jacket between the cylinder block and the cylinder block, the cylinder block can be manufactured by die-casting, so that a material with high strength can be selected. The strength can be increased, and further, the top deck strength and rigidity of the cylinder block can be increased.

Further, the lid member includes a flat plate portion that comes into contact with a step portion provided in the cylinder bore portion and the block portion, and the flat plate portion is bonded to the side surface and the bottom surface of the step portion by friction stir welding. Since the structure is integrated with not only the side surface but also the bottom surface, the bonding strength can be further increased.
In addition, since the lid member is joined to the bottom surface of the step portion after being joined to the side surface of the step portion, the deformation amount of the lid member can be reduced by joining the side surface on the top deck side first, and the next largest It is also possible to reduce the distortion associated with the joining on the bottom surface side as a load.

The lid member further includes a convex portion that protrudes from the center of the flat plate portion and extends into the water jacket from between the stepped portions of the cylinder bore portion and the block portion, and the side surface of the convex portion is formed into the cylinder bore portion and the block portion by friction stir welding. Since it joins, while the distortion at the time of joining of a cover member can be reduced with a convex part, since the side surface of a convex part is joined, the joint strength of a cylinder bore part and a block part can further be raised.
In addition, since the lid member is joined to the bottom surface of the stepped portion, the side surface of the convex portion is joined, thereby improving the joining property of the bottom surface of the stepped portion at the convex portion of the lid member and due to the projecting effect of the convex portion. It is possible to regulate the distortion associated with the joining between the cylinder bore portion and the block portion.

1 is a left side view showing a motorcycle according to an embodiment of the present invention. It is a principal part side view which shows the front part of a vehicle body frame, and its periphery. It is a top view which shows the top deck of a cylinder block. It is a top view which shows a cylinder block raw material. It is a top view which shows a cover member. It is a top view which shows the state which fitted the cover member in the groove part of the cylinder block raw material. It is the VII-VII sectional view taken on the line of FIG. It is the 1st operation view showing the junction point of a cylinder block material and a lid member. It is a 2nd operation | movement figure which shows the joining procedure of a cylinder block raw material and a cover member. It is a 3rd operation | movement figure which shows the joining procedure of a cylinder block raw material and a cover member. It is a 4th operation figure which shows the joint point of a cylinder block raw material and a cover member.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the description, descriptions of directions such as front and rear, right and left and up and down are the same as directions with respect to the vehicle body unless otherwise specified. Further, in each figure, the symbol FR indicates the front of the vehicle body, the symbol UP indicates the upper side of the vehicle body, and the symbol LE indicates the left side of the vehicle body.
FIG. 1 is a left side view showing a motorcycle 1 according to an embodiment of the present invention.
The motorcycle 1 includes a body frame 2 serving as a skeleton. The body frame 2 is formed by integrally joining a plurality of types of metal parts by welding or the like, and includes a head pipe 11, a pair of left and right main frames 12 extending rearward and downward from the head pipe 11, and a lower side from the main frame 12. A pair of left and right down frames 13 that extend obliquely rearward and support the front end portion of the power unit P, a pair of left and right pivot frames 14 that are connected to the rear end portion of the main frame 12, and a rear portion that is connected to the rear portion of the pivot frame 14 A pair of left and right seat rails 15 extending obliquely upward, and a backstay 16 that connects the pivot frame 14 and the seat rail 15 are provided.

  The frame (the head pipe 11, the main frame 12, the down frame 13, the seat rail 15, and the back stay 16) excluding the pivot frame 14 of the vehicle body frame 2 is formed of a metal pipe made of a metal material such as a steel material. Reference numeral 14 denotes a plate-like member made of a metal material. In the figure, reference numeral 17 denotes an upper reinforcing frame that connects the head pipe 11 and the main frame 12, and 18 denotes a lower reinforcing frame that connects the main frame 12 and the down frame 13.

The left and right main frames 12 extend obliquely rearward and downward in a side view from the lower left and right of the head pipe 11, extend outward in the vehicle width direction and extend obliquely downward rearward, and their rear ends are in front of the left and right pivot frames 14. Connected to the top.
The left and right pivot frames 14 extend downward from the rear portions of the left and right main frames 12 and support a pivot shaft 24 at the upper and lower intermediate portions thereof. The pivot shaft 24 is supported along the vehicle width direction, the swing arm 26 is supported on the pivot frame 14 via the pivot shaft 24 so as to be swingable up and down, and the rear wheel 25 is provided at the rear end of the swing arm 26. It is mounted rotatably. Reference numeral 39 denotes a rear fender that covers the rear wheel 25 from above.

  The head pipe 11 is disposed so as to incline rearwardly at the vehicle width direction center of the front portion of the vehicle, and supports the front fork 20 so as to be steerable left and right. A front wheel 21 is rotatably supported at the lower end portion of the front fork 20, and a steering handle 22 is supported at the upper end portion of the front fork 20. That is, the head pipe 11 supports a steering device that constitutes the steering system of the motorcycle 1. Reference numeral 38 denotes a front fender that covers the front wheel 21 from above.

The seat 27 is formed as an integrated seat that extends forward and backward so that a driver and a passenger can sit on each other and is supported by a pair of left and right seat rails 15. Reference numeral 28 denotes a grab rail which is held by the passenger.
The motorcycle 1 includes a vehicle body cowl 3 that covers substantially the entire vehicle body frame 2, and a center stand 4 and a side stand 5 that are attached to the lower portion of the vehicle body frame 2.

  The vehicle body cowl 3 is a full cover type that covers substantially the entire vehicle body frame 2, and includes a front cowl 31 that covers the front of the vehicle body including the head pipe 11, and a pair of left and right that covers the front of the occupant's feet. Leg shield 32, a pair of left and right footrests 33 extending rearward from the lower part of leg shield 32, an under cover 34 covering the lower part of footrest 33, a center tunnel part 35 for covering main frame 12 from above, A side cover 36 that covers the seat rail 15 and the backstay 16 is connected to the placement portion 33 and the center tunnel portion 35.

FIG. 2 is a side view of the main part showing the front part of the vehicle body frame 2 and the periphery thereof.
A vehicle driving power unit P is supported in an area at the lower front of the vehicle body surrounded by the main frame 12, the down frame 13, and the pivot frame 14, and a seat 27 (see FIG. 1) is supported above the power unit P.
The power unit P is integrally provided with a multi-cylinder (two cylinders in this configuration) internal combustion engine E in which the cylinder portion 41 is erected from the front portion of the crankcase 42 and the crankcase 42 of the internal combustion engine E. The unit includes a transmission M, and is supported by the vehicle body frame 2 via a plurality of brackets 50.
The cylinder portion 41 includes a cylinder block 41A connected to the front portion of the crankcase 42, a cylinder head 41B coupled to the cylinder block 41A, and a head cover 41C coupled to the cylinder head 41B. An oil pan 43 is coupled to the lower part of the crankcase 42.

A throttle body 45 is connected to the upper surface of the cylinder portion 41 (the upper surface of the cylinder head 41B) via an intake pipe, and an air-fuel mixture obtained by mixing fuel and air is supplied to the internal combustion engine E via the throttle body 45. The An exhaust pipe 46 is connected to the lower surface of the cylinder portion 41 (the lower surface of the cylinder head 41B). The exhaust pipe 46 extends rearward below the power unit P and is located on the right side of the rear wheel 25 (see FIG. 1). Is connected to an exhaust muffler 47 (see FIG. 1). A catalytic converter 48 is provided in the middle of the exhaust pipe 46 (in the vicinity of the cylinder portion 41).
The crankcase 42 supports the crankshaft 51 along the vehicle width direction. The crankcase 42 is configured by combining an upper case half body 42A and a lower case half body 42B that can be divided into upper and lower portions along a split surface along a horizontal plane that passes through the axis of the crankshaft 51. It is integrally formed with the case half 42A.

FIG. 3 is a plan view showing the top deck 41d of the cylinder block 41A.
The cylinder block 41A is made of an aluminum alloy die-cast, and the top deck 41d to which the cylinder head 41B (see FIG. 2) is attached via a head gasket (not shown) is an internal cooling water at the stage of the material after die-casting. It is processed into a closed structure in which a water jacket 41e serving as a passage is covered.
In the figure, reference numerals 41f and 41g denote cooling water passages processed in the top deck 41d so that the inside of the water jacket 41e communicates with the cylinder head 41B side, and 41h denotes a bolt insertion for passing a bolt for fastening the cylinder head 41B to the cylinder block 41A. A hole 41j is a knock pin hole into which the knock pin is fitted, and 41k is a chain insertion hole through which the timing chain is passed.

FIG. 4 is a plan view showing the cylinder block material 57.
The cylinder block material 57, which is a material for forming the cylinder block 41A (see FIG. 3), is manufactured by die casting, which is one of the die casting methods. In die casting, the dimensional accuracy of the cast product is increased. In addition, the strength can be increased, and further, a material having high strength can be selected. Therefore, it can be employed in a high-power internal combustion engine, and when securing a predetermined strength and rigidity, the wall of the cylinder block 41A can be made thin, and the weight can be reduced. .

  The cylinder block material 57 includes a cylinder bore portion 57a on which a piston slides, and a block portion 57c having an outer wall 57b surrounding the cylinder bore portion 57a. Between the cylinder bore portion 57a and the outer wall 57b, a cylinder block 41A (see FIG. 3), a water jacket 41e (see FIG. 3) is formed with a groove portion 57d having a substantially 8-shape in plan view, which will be formed later. Since this cylinder block material 57 has an open deck structure in which the opening of the groove 57d is opened on the surface that becomes the top deck after the cylinder block material 57, it can be manufactured by die casting.

  A cylinder bore side step 57e is formed along the groove 57d at the edge of the cylinder bore 57a, which is the edge of the groove 57d, and an outer wall along the groove 57d is formed at the edge of the outer wall 57b, which is the edge of the groove 57d. A side step portion 57f is formed. In the figure, reference numeral 57g denotes a wide groove provided in a part of the groove 57d, and 57h denotes a cylinder material hole formed inside the cylinder bore 57a.

FIG. 5 is a plan view showing the lid member 61. FIG. 6 is a plan view showing a state in which the lid member 61 is fitted to the cylinder block material 57.
As shown in FIG. 5, the lid member 61 is made of an aluminum alloy die cast, is made of the same material as the cylinder block material 57 (see FIG. 4), and has an approximately 8 shape as a whole, and has two C-shaped rings 61 a. , 61b are combined to form an integrated shape, and one C-shaped ring 61a is provided with a wide portion 61e at a position facing the opening 61c.
FIG. 6 shows a state in which the lid member 61 is fitted in the cylinder bore portion side step portion 57e, the outer wall side step portion 57f, and the groove portion 57d of the cylinder block material 57. The opening of the groove portion 57d is closed by the lid member 61.

7 is a cross-sectional view taken along line VII-VII in FIG.
The lid member 61 includes a flat plate portion 61f that is flattened in an endless shape (approximately 8 ring shape), and an endless (approximately 8 ring shape) convex portion 61g that protrudes from one end surface of the flat plate portion 61f. Are integrally molded members.
The flat plate portion 61f is fitted to the cylinder bore portion side step portion 57e and the outer wall side step portion 57f, and the convex portion 61g is fitted to the edge portion of the groove portion 57d.

The procedure for joining the cylinder block material 57 and the lid member 61 described above will be described next.
FIG. 8 is a first operation view showing a joining procedure between the cylinder block material 57 and the lid member 61. 8A is a diagram showing a state before friction stir welding, and FIG. 8B is a diagram showing a state during friction stir welding.
As shown in FIG. 8A, first, a joining tool 63 is prepared. The basic structure of the joining tool 63 includes a cylindrical tool body 63a and a stirring pin 63b that projects integrally from the tool body 63a. And the joining tool 63 is arrange | positioned on the extension line | wire of the matching part 65 of the side surface 57j of the outer wall side step part 57f, and the outer surface 61j of the flat plate part 61f.

  Here, reference numeral 66 denotes a mating portion of the bottom surface 57k of the outer wall side stepped portion 57f and the outer bottom surface 61k of the flat plate portion 61f, and 67 denotes a mating portion of the side surface 57m of the cylinder bore portion side stepped portion 57e and the inner side surface 61m of the flat plate portion 61f. 68 is a mating portion of the bottom surface 57n of the cylinder bore portion side step portion 57e and the inner bottom surface 61n of the flat plate portion 61f, 69 is a mating portion of the outer surface 57p of the groove portion 57d and the outer surface 61p of the convex portion 61g, and 70 is the groove portion 57d. The inner side surface 57q of the convex portion 61g and the inner side surface 61q of the convex portion 61g.

Next, the welding tool 63 is rotated at a high speed as indicated by an arrow, moved to the mating portion 65 as indicated by an outlined arrow, and the stirring pin 63b is pressed against the mating portion 65 with a predetermined pressing force.
Thereby, the part which contacted the stirring pin 63b of the cylinder block raw material 57 and the cover member 61 becomes high temperature by friction. As a result, the base material of the cylinder block material 57 and the lid member 61 is agitated to be in a flowable state (a state in which plastic flow is possible), and the agitation pin 63b gradually moves into the base material.

  FIG. 8B shows a state in which the tool main body 63 a of the joining tool 63 has reached the surfaces of the cylinder block material 57 and the base material of the lid member 61. Reference numeral 62 denotes a plastic flow portion of the base material. In this state, the above-described progress of the joining tool 63 is stopped, and this time, the joining tool 63 is moved in the front / back direction of the drawing, that is, in the direction of approximately 8 along the mating portion 65 (see also FIG. 9). After the joining tool 63 moves, the base material that has been plastically flowed is cooled and solidified, and the mating portion 65 is gradually joined. At this time, in addition to the mating portion 65, a part of the mating portion 66 is also joined. After the mating portion 65 close to the surface is joined, the mating portion 66 is joined. The mating portions 67 and 68 are also joined in the same manner as the mating portions 66 and 69.

FIG. 9 is a second action diagram showing a joining procedure between the cylinder block material 57 and the lid member 61, and shows a moving path of the joining tool 63.
First, the joining tool 63 (see FIG. 8B) is moved along the outermost mating portion 65. The joining tool 63 starts moving from the start point S1 indicated by a black circle, and ends moving at the end point G1 indicated by a white circle.
Next, the joining tool 63 is moved along the innermost mating portion 67. The joining tool 63 starts moving from the start point S2 indicated by a black circle, and ends moving at the end point G2 indicated by a white circle.

Next, the joining tool 63 is moved along the second mating portion 69 from the outermost side. The welding tool 63 starts moving from the start point S3 indicated by a black circle, and ends moving at the end point G3 indicated by a white circle.
Finally, the joining tool 63 is moved along the second mating portion 70 from the innermost side. The joining tool 63 starts moving from the start point S4 indicated by a black circle, and ends moving at the end point G4 indicated by a white circle.

The start point S1 is set on the mating portion 65, and the end point G1 is set on the outer wall 57b. The start point S2 is set on the mating portion 67, and the end point G2 is set on the cylinder bore portion 57a. The start point S3 is set on the mating portion 69, and the end point G3 is set on the outer wall 57b. The start point S4 is set on the mating portion 70, and the end point G4 is set on the lid member 61.
The end points G1, G2, G3, and G4 are set to portions that are removed by processing when processing is performed to complete the cylinder block 41A.

  As described above, in the mating portions 65, 67, 69, 70, the outermost mating portions 65, 67 are first joined, and then the inner mating portions 69, 70 are joined. Since the pressing force at 63 is large, first, the mating portions 65 and 67 which are both edges of the lid member 61 are joined to increase the rigidity of the lid member 61, and then the mating portion 69 inside the lid member 61 is arranged. If 70 is joined, even if it presses the matching parts 69 and 70 with a big pressing force, the bending of the cover member 61 can be suppressed and it becomes possible to join stably. Since the lower portions of the mating portions 65 and 67 are supported by the edge portions of the cylinder bore portion 57a and the outer wall 57b, they are not easily bent even by a large pressing force.

FIG. 10 is a third action diagram showing the joining procedure between the cylinder block material 57 and the lid member 61, and shows the joining procedure at the mating portions 69 and 70. FIG. 10A is a diagram showing a state before friction stir welding, and FIG. 10B is a diagram showing a state during friction stir welding. In FIGS. 10A and 10B, reference numerals 62A and 62A denote solidified portions formed by solidifying the plastic flow portions 62 and 62 (see FIG. 8B).
As shown in FIG. 10A, since the mating portions 69 and 70 are deeper than the mating portions 65 and 67, another joining tool 73 is prepared. The joining tool 73 includes a cylindrical tool body 73a and a stirring pin 73b protruding integrally from the tool body 73a. The stirring pin 73b is a joining tool 63 (see FIG. 8A). The stirring pin 63b (see FIG. 8A) is longer.

First, the joining tool 73 is disposed on the extension line of the mating portion 69.
Next, the welding tool 73 is rotated at a high speed as indicated by an arrow, moved to the mating portion 69 as indicated by an outlined arrow, and the stirring pin 73b is pressed against the mating portion 69 with a predetermined pressing force.
Thereby, the part which contacted the stirring pin 73b of the cylinder block raw material 57 and the cover member 61 becomes high temperature by friction. As a result, the base material of the cylinder block material 57 and the lid member 61 is melted and agitated to be in a flowable state (a state in which plastic flow is possible), and the agitation pin 73b gradually moves into the base material.

  FIG. 10B shows a state in which the tool main body 73 a of the joining tool 73 has reached the surfaces of the cylinder block material 57 and the base material of the lid member 61. Reference numeral 74 denotes a plastic flow portion of the base material. In this state, the above-described progress of the welding tool 73 is stopped, and this time, the welding tool 73 is moved in the front-back direction of the drawing, that is, in the direction of approximately 8 along the mating portion 69 (see also FIG. 9). After the joining tool 73 is moved, the base material that has been plastically flowed is cooled and solidified, and the mating portion 69 is gradually joined. At this time, in addition to the mating portion 69, the remaining portion of the mating portion 66 is also joined. After the mating portion 66 close to the surface is joined, the mating portion 69 is joined. The mating portions 68 and 70 are joined in the same manner as the mating portions 66 and 69.

FIG. 11 is a fourth operation view showing a joining procedure between the cylinder block material 57 and the lid member 61.
When the plastic flow portions 74 and 74 of the mating portions 66 and 68 to 70 (see FIG. 8) between the cylinder block material 57 and the lid member 61 are solidified, the friction stir welding between the cylinder block material 57 and the lid member 61 is completed. .
Thereafter, the joined end face is cut to the position of the straight line 76 to form the top deck 41d.

As shown in FIGS. 3, 4 and 6, the cylinder bore portion 57a for sliding the piston and the outer wall 57b that covers the periphery of the cylinder bore portion 57a and is provided with the water jacket 41e between the cylinder bore portion 57a. In a cylinder block 41A for an internal combustion engine E (see FIG. 2) comprising a block portion 57c provided with a lid member 61 that covers the water jacket 41e and is disposed so as to straddle the cylinder bore portion 57a and the block portion 57c. The cylinder bore part 57a and the block part 57c are integrated with each other by agitation joining.
According to this configuration, since the lid member 61 is attached by friction stir welding so as to cover the water jacket 41e between the cylinder bore portion 57a and the block portion 57c, the cylinder block 41A is manufactured by die casting. The material having a high strength of 41A can be selected, and the dimensional accuracy and strength can be increased. The top deck strength and rigidity of the cylinder block 41A can be increased. Therefore, when the strength and rigidity of the cylinder block 41A are secured, the weight of the cylinder block 41A can be reduced.

  Further, as shown in FIGS. 7, 8 and 10, the lid member 61 includes a cylinder bore portion side step portion 57e and an outer wall side step portion 57f as step portions provided on the cylinder bore portion 57a and the block portion 57c. The flat plate portion 61f includes a flat plate portion 61f that comes into contact, and the flat plate portion 61f is formed by friction stir welding so that the side surface 57j of the cylinder bore portion side step portion 57e, the side surface 57m of the outer wall side step portion 57f, the bottom surface 57k of the cylinder bore portion side step portion 57e Since it is joined to the bottom surface 57n of 57f, the flat plate portion 61f can be integrated with not only the side surfaces 57j and 57m but also the bottom surfaces 57k and 57n, so that the joining strength can be further increased.

  Further, the lid member 61 is joined to the side surface 57j of the cylinder bore portion side step portion 57e and the side surface 57m of the outer wall side step portion 57f, and then is attached to the bottom surface 57k of the cylinder bore portion side step portion 57e and the bottom surface 57n of the outer wall side step portion 57f. Since it is joined, the deformation amount of the lid member 61 can be reduced by joining the side surfaces 57j and 57m on the top deck side first, and the distortion accompanying joining on the bottom surfaces 57k and 57n side, which is the next largest load, can be reduced. .

  The lid member 61 further includes a projecting portion 61g that protrudes from the center of the flat plate portion 61f and extends into the groove portion 57d (water jacket 41e) from between the cylinder bore portion side step portion 57e and the outer wall side step portion 57f. Since the outer surface 61p and the inner surface 61q of the convex portion 61g are joined to the cylinder bore portion 57a and the block portion 57c, the convex portion 61g can reduce distortion when the lid member 61 is joined, and the outer surface 61p of the convex portion 61g. Since the inner surface 61q is joined, the coupling strength between the cylinder bore portion 57a and the block portion 57c can be further increased.

Further, since the lid member 61 is joined to the bottom surface 57k of the cylinder bore portion side step portion 57e and the bottom surface 57n of the outer wall side step portion 57f, the outer side surface 61p and the inner side surface 61q of the convex portion 61g are joined. The convex portion 61g enhances the bondability between the bottom surface 57k of the cylinder bore portion side step portion 57e and the bottom surface 57n of the outer wall side step portion 57f, and also joins the cylinder bore portion 57a and the block portion 57c by the tension effect of the convex portion 61g. The accompanying distortion can be regulated.
The above-described embodiment is merely an aspect of the present invention, and can be arbitrarily modified and applied without departing from the gist of the present invention.

41A Cylinder block 41e Water jacket 57a Cylinder bore part 57b Outer wall 57c Block part 57d Groove part 57e Cylinder bore part side step (step part)
57f External wall side step (step)
57j Side surface of outer wall side stepped portion 57k Bottom surface of outer wall side stepped portion 57m Side surface of cylinder bore portion side stepped portion 57n Bottom surface of cylinder bore portion side stepped portion 61 Lid member 61f Flat plate portion 61g Protruding portion 61p Outer surface of protruding portion (side surface)
61q Inside surface (side surface) of convex part
E Internal combustion engine

Claims (5)

A block portion (57b) having a cylinder bore portion (57a) for sliding the piston and an outer wall (57b) covering the periphery of the cylinder bore portion (57a) and provided with a water jacket (41e) between the cylinder bore portion (57a). 57c), the internal combustion engine cylinder block
A lid member (61) which covers the water jacket (41e) and is disposed so as to straddle the cylinder bore part (57a) and the block part (57c) is connected to the cylinder bore part (57a) and the block by friction stir welding. A cylinder block for an internal combustion engine, which is integrated with the portion (57c) by bonding.   The lid member (61) includes a flat plate portion (61f) in contact with stepped portions (57e, 57f) provided in the cylinder bore portion (57a) and the block portion (57c), and the flat plate portion (61f) is formed by the friction stir welding. The cylinder block for an internal combustion engine according to claim 1, wherein the portion (61f) is joined to the side surface (57j, 57m) and the bottom surface (57k, 57n) of the stepped portion (57e, 57f).   The lid member (61) is joined to the bottom surface (57k, 57n) of the step portion (57e, 57f) after being joined to the side surface (57j, 57m) of the step portion (57e, 57f). A cylinder block for an internal combustion engine according to claim 2.   The lid member (61) further protrudes from the center of the flat plate portion (61g) and extends between the cylinder bore portion (57a) and the step portions (57e, 57f) of the block portion (57c) to the water jacket (41e). ) And a side surface (61p, 61q) of the convex portion (61g) is joined to the cylinder bore portion (57a) and the block portion (57c) by the friction stir welding. The cylinder block for an internal combustion engine according to claim 2 or 3, characterized by the above.   The lid member (61) is joined to the bottom surface (57k, 57n) of the stepped portion (57e, 57f), and then the side surface (61p, 61q) of the convex portion (61g) is joined. A cylinder block for an internal combustion engine according to claim 4.

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