JP4306560B2 - Engine cylinder block structure - Google Patents

Description

  The present invention relates to a cylinder block structure of an engine, and more particularly to a cylinder block structure capable of suppressing an increase in oil consumption associated with deformation of the inner wall of a cylinder bore, which is a problem in a water-cooled engine.

  In order to reduce the fuel consumption of automobiles, engines tend to be lighter and higher in compression. For this reason, the cylinder block is made thinner, and a cylinder head bolt for fastening the cylinder head to the cylinder block. As a problem associated with this, an increase in oil consumption due to deformation of the inner wall of the cylinder bore is known.

  Patent Document 1 proposes to devise the thickness of the partition wall between the cylinder bore and the water jacket as a means for solving this problem. Specifically, among the partition walls between the cylinder bore and the water jacket, the thickness of the partition wall portion below the cylinder head bolt is made thicker than the partition wall portion on the upper side based on the lower end position of the cylinder head bolt. It has been proposed to suppress an increase in oil consumption by suppressing the deformation of the inner wall of the cylinder bore.

  Further, in Patent Document 2, the cylinder bore inner wall has a long axis direction in addition to the four-dimensional deformation in which the vicinity of the four head bolts protrudes inward when each cylinder is viewed in plan by the axial force of the cylinder head bolt. It should be pointed out that there is an inflection point in the deformation amount of the cylinder, and considering the inflection point of the deformation amount of the inner wall of the cylinder bore, the partition wall between the cylinder bore and the water jacket should be thinned Therefore, it is proposed to reduce the weight while preventing deformation of the inner wall of the cylinder block. Specifically, it has been proposed to design the partition portion corresponding to the upper portion of the upper and lower heights of the water jacket to be thick and to design the partition portion corresponding to the lower portion to be thin.

  Further, Patent Document 3 provides a boss portion that crosses the water jacket, and by connecting the partition wall between the cylinder bore and the water jacket to the outer wall of the water jacket at this boss portion, the deformation of the inner wall of the cylinder bore is suppressed. Therefore, it is proposed to suppress an increase in oil consumption.

With respect to the design of the water jacket, conventionally, in general, the design is such that the bottom surface of the water jacket is substantially coincident with the lower end of the piston stroke. On the other hand, Patent Document 4 discloses a so-called shallow water jacket in which the bottom surface of the water jacket is set above the lower end of the piston stroke.
JP 10-339206 A JP 2003-83156 A Japanese Utility Model Publication No. 5-61435 JP 2002-115600 A

  One of the causes of oil consumption increase due to deformation of the inner wall of the cylinder bore, particularly deformation in the long axis direction will be described with reference to FIG. 1. As is well known, the piston 1 typically has three piston rings. 2-4. The uppermost piston ring 2, that is, the top ring and the next second ring 3 are compression rings for keeping the combustion chamber airtight. The lowermost piston ring 4 is an oil ring, and the oil ring 4 has a function of scraping off excess oil adhering to the cylinder bore inner wall 5 in the downward stroke of the piston 1. Here, the topland space 6 which leads to the combustion chamber and is defined by the top ring 2 is substantially equal to the pressure in the combustion chamber. The second land space 7 defined by the top ring 2 and the second ring 3 tends to maintain the combustion pressure in the combustion chamber as it is during the expansion process. The third land space 8 leading to the crank chamber and defined by the oil ring 4 is substantially equal to the pressure in the crank chamber.

  Referring to FIG. 2, in the process in which piston 1 descends during the expansion stroke, top land space 6 is at a relatively higher pressure than second land space 7 until halfway, but a reverse phenomenon occurs from the middle. The state in which the second land space 7 is relatively higher in pressure than the top land space 6 continues to the bottom dead center.

  The deformation of the cylinder bore inner wall 5 in the major axis direction is indicated by phantom lines in FIG. The piston rings 2 to 4 expand and contract in accordance with the deformation amount of the cylinder bore inner wall 5. For example, when the contact pressure of the top ring 2 with the cylinder bore inner wall 5 becomes weak or away from the cylinder bore inner wall 5, When the pressure is relatively higher than that of the top land space 6, the pressure escapes from the second land space 7 to the top land space 6, and this contributes to an increase in oil consumption.

  The object of the present invention is to realize an engine that can suppress an increase in oil consumption accompanying deformation of the cylinder bore inner wall, with the understanding that deformation of the cylinder bore inner wall due to the axial force of the head bolt is inevitable. The object is to provide a cylinder block structure.

  A further object of the present invention is to provide an engine cylinder block structure capable of suppressing deformation of the cylinder bore inner wall over the entire piston stroke while suppressing an increase in oil consumption accompanying deformation of the cylinder bore inner wall in the longitudinal direction. There is to do.

  The present invention relates to the fact that the position of the maximum deformation point (hereinafter referred to as “maximum deformation point”) of the inner wall of the cylinder bore depends on the depth of the water jacket disposed adjacent to the cylinder bore, When the upper end position of the threaded part of the cylinder block to which the bolt is screwed is located above the height position of the bottom surface of the water jacket, the maximum bore deformation point is from the top surface of the cylinder block to the bottom surface of the water jacket. It is based on the knowledge that it occurs at about 2/3 of the depth. Furthermore, the present invention is based on the viewpoint that if the piston speed when passing through the maximum deformation point is relatively slow, the diameter expansion operation of the piston ring can follow the shape change of the deformed cylinder bore inner wall. In other words, if the piston speed when passing through the maximum deformation point is high, a relative delay occurs in the operation of expanding the piston ring after passing through the maximum deformation point, which causes the contact pressure of the piston ring against the cylinder bore inner wall. The possibility that the piston ring becomes weak or the piston ring moves away from the inner wall of the cylinder bore increases.

According to the present invention, the above technical problem is
A cylinder block of an engine in which a cylinder head is fastened by a head bolt,
A head bolt receiving hole provided around the cylinder bore of the cylinder block and receiving the head bolt;
A water jacket that is disposed on the radially outer side of the cylinder bore via a partition wall and cools the engine by passing cooling water;
In the cylinder block structure, the head bolt receiving hole has a bolt insertion portion that opens to a top surface of the cylinder block, and a screw portion that is positioned below the bolt insertion portion and to which the cylinder head bolt is screwed.
The threaded portion so that the maximum deformation point of deformation of the inner wall of the cylinder bore that is deformed in the major axis direction by the fastening force of the cylinder head bolt is positioned above the midpoint of the piston stroke of the piston fitted in the cylinder bore. uppermost surface is set to an upper position than the bottom surface of the water jacket Rutotomoni, the bottom surface of the water jacket is set at a position above the bottom dead center of the piston,
The cylinder block further includes an oil gallery through which engine oil passes, provided at a lower region of the water jacket and at a height position where a piston ring of the piston is located when the piston is located at a bottom dead center. Have
This is achieved by providing a cylinder block structure for an engine , wherein a partition wall between the oil gallery and the cylinder bore inner wall is thinner than a partition wall between the water jacket and the cylinder bore inner wall .

Regarding the deformation in the major axis direction of the cylinder bore inner wall that occurs when the cylinder head is fastened by the head bolt, the maximum deformation point is set so that it is located above the midpoint of the piston stroke where the piston speed reaches the maximum speed. The maximum deformation point can be passed through the piston at a relatively slow speed. Therefore, according to the present invention, the expansion operation of the piston ring immediately after the piston passes through the maximum deformation point in the expansion stroke cannot follow the inclination of the inner wall of the cylinder bore and jumps from the maximum deformation point, which causes oil consumption. An increase in the amount can be suppressed. Even if the expansion operation of the piston ring immediately after passing through the maximum deformation point is delayed and the proper contact pressure of the piston ring cannot be maintained, if the expansion stroke is before the intermediate point of the piston stroke, the combustion chamber Because of the high pressure, the gas pressure in the land space between adjacent piston rings can be released in the direction of the crank chamber, causing the gas pressure in the land space to escape to the combustion chamber and increase oil consumption. Can be suppressed. In addition, the partition between the oil gallery and the cylinder bore inner wall has a thin-walled structure to reduce the rigidity of the lower end of the cylinder bore inner wall, thereby deforming the part in the diameter-expanding direction, so that the piston ring at the piston bottom dead center Since the inner land pressure can be released to the crank chamber side, it is possible to suppress the oil from escaping to the combustion chamber side and increasing the oil consumption.

  In a preferred embodiment of the present invention, the depth of the water jacket is about 0.6 times the piston stroke, and a shallow water jacket with such a depth can be used in a conventional engine cooling mechanism. The cooling performance of the engine can be maintained by increasing the flow rate of the cooling water due to the shallow water jacket, and the increase in oil consumption described above can be suppressed.

  The cylinder block of a preferred embodiment of the present invention is a closed deck type having a top deck that closes the upper portion of the water jacket and constitutes the top surface of the cylinder block. The top deck has a deck portion provided at the shortest distance between the head bolt receiving hole and the cylinder bore adjacent to the head bolt receiving hole. According to this, since the rigidity of the cylinder bore upper end portion that is easily influenced by the axial force of the head bolt can be locally increased by the deck portion, deformation of the cylinder bore upper end portion due to the axial force of the head bolt can be suppressed.

  In the cylinder block according to a preferred embodiment of the present invention, the uppermost surface of the threaded portion of the head bolt receiving hole is set at a height position substantially in the middle of the vertical height of the water jacket. Further, the lower end of the screw portion is set at a position lower than the bottom surface of the water jacket and at a height position near the piston top surface at the piston bottom dead center. According to this, the maximum deformation point of the cylinder bore can be generated at a position about 2/3 of the depth of the water jacket by setting the uppermost surface of the screw part at a substantially middle part of the vertical height of the water jacket. In addition, by setting the lower end of the threaded portion to a height position near the piston top surface at the bottom dead center of the piston, the axial force of the head bolt can be adjusted to the cylinder without increasing the length of the threaded portion more than necessary. Since the deformation of the cylinder bore inner wall can be suppressed by transmitting to the lower rigid portion, the deformation of the cylinder bore inner wall can be suppressed over the entire piston stroke region.

  Since the water jacket of the preferred embodiment has a shallow bottom structure, the thickness of the partition wall between the oil gallery and the bottom surface of the water jacket is set between the water jacket and the inner wall of the cylinder bore using the lower region of the water jacket. It is designed to be approximately equal to the wall thickness of the partition wall. The water jacket having a shallow bottom structure according to the embodiment has an effect of quickly increasing the temperature of the engine cooling water when the engine is warmed up. In addition, by arranging an oil gallery adjacent to the bottom surface of the water jacket. Since the engine oil can be warmed up by the heat of the engine coolant, the oil warm-up performance can be improved.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

  FIG. 3 is a plan view of the cylinder block 10 of the embodiment. The cylinder block 10 has four cylinders S1 to S4 arranged in series. That is, the cylinder block 10 is for an in-line four-cylinder engine, and more specifically, a cylinder block for a gasoline engine made of an aluminum alloy.

  4 is a longitudinal sectional view of the cylinder block taken along line IV-IV in FIG. 3, and FIG. 5 is a longitudinal sectional view of the cylinder block taken along line VV. With reference to FIG. 4, an aluminum alloy cylinder head 11 is mounted on the cylinder block 10, and the cylinder head 11 is fastened to the cylinder block 10 by a head bolt 12.

  Returning to FIG. 3, five bolt receiving holes 13 for receiving the head bolts 12 are opened on both sides of the top surface 10 a of the cylinder block 10 in a row in the same manner as in the past. In this arrangement, four bolt receiving holes 13 are positioned at approximately equal intervals around each of the cylinders S1 to S4. Referring to FIG. 4, each bolt receiving hole 13 is composed of a bolt insertion portion 13a that opens to the top surface 10a of the cylinder block 10, and a screw portion 13b below the bolt insertion portion 13a. Screwed.

  The cylinder block 10 is also provided with water jackets 15 on both sides thereof, and the water jacket 15 includes a top deck 16 that closes the upper side and constitutes the top surface 10a of the cylinder block 10 (FIG. 5). ). That is, the cylinder block 10 is a closed deck type. The top deck 16 particularly relates to each of the three bolt insertion holes 13M sandwiched by the bolt insertion holes 13E located at one end and the other end of the cylinder block 10, and is adjacent to each bolt insertion hole 13M. It includes a deck portion 16a (FIG. 3) provided at the shortest distance from the cylinders S1 to S4.

  Thus, by providing the deck portion 16a in the portion of the shortest distance between the bolt insertion hole 13M and the cylinders S1 to S4 adjacent thereto, the rigidity of the upper portion of the cylinders S1 to S4 can be locally increased. Deformation of the upper portion of the cylinder bore inner wall 5 due to the fastening of the cylinder head 11 by the cylinder head bolt 12 can be suppressed.

  Engine cooling water supplied from a radiator (not shown) is pumped into the water jacket 15 from one end of the cylinder block 10 as indicated by an arrow in FIG. 3, and the cooling water that has passed through the water jacket 15 The other end of the block is returned to the radiator through the water jacket of the cylinder head. The cylinder block 10 is also provided with an oil gallery 17 adjacent to the lower side of the water jacket 15 (FIG. 4).

  The engine made from the cylinder block 10 of the embodiment has (1) bore diameter X piston stroke: 87.5 mm × 94 mm, and (2) the top surface of the screw portion 13b of the head bolt receiving hole 13 from the top surface 10a of the cylinder block (head bolt). Seat) The depth L1 to T is 43 mm (L1 = 43 mm). (3) The depth L2 from the cylinder block top surface 10a to the lower end of the threaded portion 13b is 88 mm which is substantially equal to the piston stroke (L1 = 88 mm), this height position is substantially equal to the height position at which the top surface of the piston 1 is located when the piston 1 is located at the bottom dead center.

  FIG. 6 shows a first embodiment relating to the design of the water jacket 15. In this embodiment, the depth L3 from the cylinder block top surface 10a to the lower end of the water jacket 15 is set to 63 mm (corresponding to about “2/3” of the piston stroke), and the screw of the head bolt receiving hole 13 is set. The height position of the uppermost surface (cylinder head bolt seat) T of the portion 13 b is set so as to be approximately in the middle of the vertical height of the water jacket 15. A symbol M shown in FIG. 6 and the like indicates an intermediate point of the piston stroke (47 mm from the cylinder block top surface 10a). Further, the illustrated imaginary line 5 a shows a state of deformation of the cylinder bore inner wall 5 due to the axial force of the head bolt 12. The cylinder bore inner wall 5 is constituted by a cylinder liner as in the prior art. From this figure, it will be understood that the maximum deformation point P of the cylinder bore inner wall 5 is located above the piston stroke intermediate point M.

  FIG. 7 shows a second embodiment relating to the design of the water jacket 15. In this embodiment, the depth L3 from the cylinder block top surface 10a to the lower end of the water jacket 15 is set to 47 mm (corresponding to “1/2” of the piston stroke). The illustrated imaginary line 5a shows the state of deformation of the cylinder bore inner wall 5. From the figure, it will be understood that the maximum deformation point P of the cylinder bore inner wall 5 is located above the case of the first embodiment.

  FIG. 8 shows a third embodiment relating to the design of the water jacket 15. In this embodiment, the depth L3 from the cylinder block top surface 10a to the bottom surface of the water jacket 15 is set to 55 mm (corresponding to about “0.6” times the piston stroke). From this figure, it will be understood that the maximum deformation point P of the cylinder bore inner wall 5 is located between the first and second embodiments.

  For comparison, FIG. 9 shows a state of the deformation 5a of the cylinder bore inner wall 5 when the lower end position of the water jacket 15 is set to the position of the top surface of the piston 1 at the bottom dead center. It will be understood from the figure that the maximum deformation point P of the cylinder bore inner wall 5 is located below the intermediate point M of the piston stroke.

  The uppermost surface T (head bolt seat) of the screw portion 13b of the head bolt receiving hole 13 is set above the lower end position of the water jacket 15 (particularly, the height position of the uppermost surface T of the screw portion 13b is set to the water jacket 15). In addition, by setting the lower end of the screw portion 13b near the bottom dead center of the piston, the deformation 5a of the cylinder bore inner wall 5 due to the axial force of the head bolt 12 is changed to the piston stroke. Although it can be reduced over the entire area, when the uppermost surface T of the screw portion 13b is located above the bottom surface of the water jacket 15 (L3> L1), it is about 2/3 of the water jacket depth. Since the maximum deformation point occurs at the position of, the position of the maximum deformation point P of the cylinder bore inner wall 5 depends on the depth L3 of the water jacket 15. It is seen from Togazu 6-9. Incidentally, in the embodiment, the height position of the uppermost surface T (head bolt seat) of the screw portion 13b is set in the vicinity of the intermediate point M of the piston stroke.

  Since the piston 1 fitted in the cylinders S1 to S4 transmits power to the engine output shaft via a crankshaft (not shown), the piston speed becomes the highest at an intermediate point M of the piston stroke. In the first to third embodiments in which the water jacket 15 is set to a shallow bottom, as described above, the maximum deformation point P is located above the intermediate point M of the piston stroke. Therefore, in the expansion stroke, the piston 18 passes through the maximum deformation point P at a relatively slow speed before reaching the maximum speed, so that the diameter expansion operation of the piston rings 2 to 4 after passing through the maximum deformation point P. Can descend while following the inclination of the cylinder bore inner wall 5 while maintaining an appropriate contact pressure with the cylinder bore inner wall 5.

  Even if the diameter expansion operation of the piston rings 2 to 4 after passing through the maximum deformation point P cannot follow the inclination of the cylinder bore inner wall 5 and the contact pressure against the cylinder bore inner wall 5 becomes weak, the intermediate point of the piston stroke At a position above M, as described above with reference to FIG. 2, the topland space 6 has a relatively higher pressure than the secondland space 7, and the secondland space 7 is the thirdland space. Since the pressure is relatively higher than 8, the pressure in the top land space 6 and the second land space 7 escapes to the third land space 8, and the engine oil can be returned to the crank chamber accordingly.

  From the above, by setting the depth L3 of the water jacket 15 so that the maximum deformation point P is located above the intermediate point M of the piston stroke, the piston 1 is allowed to reach the maximum deformation point P at a relatively slow speed. Thus, the delay in the diameter expansion operation of the piston rings 2 to 4 after passing through the maximum deformation point P in the expansion stroke can be suppressed. Therefore, the diameter expansion operation of the piston rings 2 to 4 follows the inclination of the cylinder bore inner wall 5 in the major axis direction, and the contact pressure of the piston rings 2 to 4 with respect to the cylinder bore inner wall 5 can be properly maintained.

  Further, even if a delay occurs in the diameter expansion operation of the piston rings 2 to 4 and the pressure escapes from the piston rings 2 to 4, the maximum deformation point P that is the factor is located above the intermediate point M of the piston stroke. Because the pressure in the spaces 6 to 8 defined by the piston rings 2 to 4 is the highest in the top land space 6 and the second land space 7 and the third land space 8 in this order. The direction of pressure relief can be directed toward the crank chamber, thereby reducing the possibility of engine oil entering the combustion chamber due to the deformation 5a of the cylinder bore inner wall 5.

  As described above, when the water jacket 15 is set to a shallow bottom, a design freedom is provided in a lower region of the water jacket 15. As is well known, the cylinder block 10 is provided with a crank chamber 20 (FIG. 5) in the lower region of the cylinder bores S1 to S4, and the oil gallery 17 is generally located below the water jacket 15 and in the vicinity of the crank chamber 20. Installed.

  FIG. 10 shows a first enlarged portion that uses the lower region of the shallow water jacket 15 to cause the oil gallery 17 to enlarge upward to the vicinity of the bottom dead center position to approach the lower end of the water jacket 15. 17a. The partition wall 21 between the first enlarged portion 17 a and the bottom surface of the water jacket 15 preferably has a wall thickness substantially equal to the partition wall 22 between the water jacket 15 and the cylinder bore inner wall 5.

  In this way, by providing the first enlarged portion 17a in which the oil gallery 17 is enlarged upward and brought close to the vicinity of the water jacket 15, the oil gallery is heated by the heat of the engine cooling water passing through the water jacket 15 when the engine is warmed up. The temperature of the engine oil passing through 17 can be quickly raised. In particular, since the shallow water jacket 15 can reduce the amount of engine cooling water by the amount of the shallow bottom, the function of improving the warming-up performance of raising the engine cooling water to a predetermined temperature at the time of warming up is improved. However, the warm-up performance of the oil can be improved by utilizing the heat of the cooling water whose temperature rises early by such a shallow water jacket 15.

  The oil gallery 17 also has a second enlarged portion 17b that is brought close to the piston stroke bottom dead center in the cylinder bore inner wall 5. The partition wall 23 between the second enlarged portion 17b and the cylinder bore inner wall 5 is preferably thinner than the partition wall 22 between the water jacket 15 and the cylinder bore inner wall 5.

  As described above, by providing the oil gallery 17 with the second enlarged portion 17b close to the cylinder bore inner wall 5, the heat in the cylinders S1 to S4 is easily transferred to the engine oil, thereby further improving the engine oil warm-up performance. Can be improved.

  Further, since the partition wall 23 between the second enlarged portion 17b and the cylinder bore inner wall 5 is made thin, the rigidity in the vicinity of the bottom dead center of the piston stroke is lowered, and thereby the bore inner wall 5 is deformed outward in the radial direction. To do. The deformation of the bore inner wall 5 is indicated by a virtual line 5a in FIG.

  Regarding the setting of the arrangement position of the second enlarged portion 17b, it is preferable that the second land space defined by the top ring 2 and the second ring 3 as shown in FIG. It is preferable to set the arrangement position of the second expansion chamber 17b and the thickness of the partition wall 23 so that the oil consumption can be reduced by releasing the pressure of 7 to the crank chamber. As a result, the pressure in the second land space 7 that is relatively higher than the top land space 6 is released to the crank chamber side, so that the gas in the second land space 7 enters the top land space 6 with oil. Can be suppressed.

  FIG. 12 shows the oil jet 27. As is well known, this oil jet 27 is a member for cooling the piston 1 by injecting engine oil toward the inner wall of the piston 1 during high-speed rotation. The oil jet 27 is assembled in a hole 26 drilled in the bottom wall of the oil gallery 17 and fastened to the cylinder block 10 with a bolt 28.

  The cylinders S1 to S4 of the engine are subjected to honing in order to smooth the inner wall surface. However, when the second enlarged portion 17b is provided in the oil gallery 17 and the partition wall 23 is thinned to reduce rigidity. May not be able to withstand the honing process. In this case, when the oil gallery 17 is molded, it is preferable to provide a column 25 that crosses the oil gallery 17. The support wall 25 can support the partition wall 23 during the honing process. The support column 25 is preferably disposed on the axis of the hole 26 formed in the bottom wall of the oil gallery 17. Thereby, after the honing process, when the hole 26 is drilled in the bottom wall of the oil gallery 17, the pillar 25 can be cut using the drill.

  By carrying out such a processing procedure, the thinned partition wall 23 provided with the second enlarged portion 17b can have sufficient rigidity at the time of honing, and on the other hand, after the engine is assembled, the rigidity is reduced. The oil consumption mentioned above can be reduced by the reduced thin partition wall 23.

It is a figure for demonstrating one of the causes of the increase in the oil consumption accompanying the deformation | transformation of the long axis direction of a cylinder bore inner wall with the axial force of a head bolt. It is a figure which shows the pressure state of each land space of a piston ring corresponding to operation | movement of an engine. It is a top view of a cylinder block. It is a longitudinal cross-sectional view of the cylinder block along the IV-IV line of FIG. It is a longitudinal cross-sectional view of the cylinder block along the VV line of FIG. It is a figure for demonstrating the position of the maximum deformation point of the cylinder bore inner wall in the case of the shallow water jacket of 1st Example. It is a figure for demonstrating the position of the maximum deformation point of the cylinder bore inner wall in the case of the shallow water jacket of 2nd Example. It is a figure for demonstrating the position of the largest deformation point of the cylinder bore inner wall in the case of the shallow water jacket of 3rd Example. As a comparative example, it is a figure for demonstrating the maximum deformation | transformation point of the cylinder bore inner wall at the time of setting the bottom face of a water jacket to the bottom dead center vicinity. An example in which the oil gallery is enlarged to the vicinity of the bottom surface of the shallow water jacket and the oil gallery is enlarged to the vicinity of the cylinder bore inner wall so that the partition wall between the cylinder bore inner wall and the oil gallery near the bottom dead center is thinned will be described. FIG. It is a figure for demonstrating an effect when the partition wall of a cylinder bore near a bottom dead center and an oil gallery is made thin. It is a figure for demonstrating one method for eliminating the problem when the partition wall of the cylinder bore near the bottom dead center and the oil gallery is thinned.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Piston 2 Top ring 3 Second ring 4 Oil ring 5 Cylinder bore inner wall 10 Cylinder block 10a Top surface of a cylinder block 11 Cylinder head 12 Head bolt 13 Head bolt receiving hole 13a Bolt insertion part 13b Screw part 15 Water jacket 16 Top deck 16a Deck part 17 Oil gallery 17a First enlarged portion of oil gallery adjacent to water jacket 17b Second enlarged portion of oil gallery adjacent to cylinder bore 21 Bulkhead between oil gallery and water jacket 22 Bulkhead between water jacket and cylinder bore 23 Bulkhead between oil gallery and cylinder bore L1 Depth from top of cylinder block to top surface of screw part L2 From bottom to top of cylinder block Is L3 maximum deformation point of the uppermost P bore inner wall of the depth T threaded portion of the cylinder block top surface to the bottom surface of the water jacket M piston stroke midpoints

Claims (5)

A cylinder block of an engine in which a cylinder head is fastened by a head bolt,
A head bolt receiving hole provided around the cylinder bore of the cylinder block and receiving the head bolt;
A water jacket that is disposed on the radially outer side of the cylinder bore via a partition wall and cools the engine by passing cooling water;
In the cylinder block structure, the head bolt receiving hole has a bolt insertion portion that opens to a top surface of the cylinder block, and a screw portion that is positioned below the bolt insertion portion and to which the cylinder head bolt is screwed.
The threaded portion so that the maximum deformation point of deformation of the inner wall of the cylinder bore that is deformed in the major axis direction by the fastening force of the cylinder head bolt is positioned above the midpoint of the piston stroke of the piston fitted in the cylinder bore. uppermost surface is set to an upper position than the bottom surface of the water jacket Rutotomoni, the bottom surface of the water jacket is set at a position above the bottom dead center of the piston,
The cylinder block further includes an oil gallery through which engine oil passes, provided at a lower region of the water jacket and at a height position where a piston ring of the piston is located when the piston is located at a bottom dead center. Have
A cylinder block structure for an engine , wherein a partition wall between the oil gallery and the cylinder bore inner wall is thinner than a partition wall between the water jacket and the cylinder bore inner wall . The thickness of the partition wall between the bottom surface of the oil gallery and the water jacket, the engine according to claim 1, wherein the thickness substantially equal to the partition wall between the water jacket and the cylinder bore inner wall Cylinder block structure. The cylinder block structure for an engine according to claim 1 or 2 , wherein the depth of the water jacket is about 0.6 times the piston stroke. The cylinder block is a closed deck type cylinder block provided with a top deck that closes the upper portion of the water jacket to form the top surface of the cylinder block, and the top deck includes the head bolt receiving hole and the top deck receiving hole. The engine cylinder block structure according to any one of claims 1 to 3, further comprising a deck portion provided at a portion of a shortest distance from the cylinder bore adjacent to the cylinder bore. The uppermost surface of the screw portion of the head bolt receiving hole is set to a height position at a substantially middle portion of the vertical height of the water jacket, and the lower end of the screw portion is lower than the bottom surface of the water jacket. a cylinder block structure for an engine according to any one of claims 1 to 4, characterized in that there is and set to a height position of the piston top surface vicinity of the piston bottom dead center is.

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