JP3640460B2 - Cylinder liner mounting structure - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to dimension setting of a fitting portion between both flange portions and a cylinder block in a structure in which a cylinder liner having two flange portions having different diameters is attached to a cylinder block of an internal combustion engine.
[0002]
[Prior art]
  2. Description of the Related Art Conventionally, a structure in which two upper and lower flanges having a major axis on the upper stage and a minor axis on the lower stage are provided on the outer peripheral upper end of the cylinder liner for fitting to the cylinder block is known. Further, the cylinder liner has its upper end protruding slightly above the cylinder block and is suppressed by the cylinder head from above to fix the fitting.
[0003]
  This structure will be described with reference to a side cross-sectional view showing a structure for attaching the cylinder liner CL having the two-stage flange portion of FIG. 1 to the cylinder block CB. In FIG. 1, CL is a cylinder liner, CB is a cylinder block, and CH is a cylinder head, and an upper flange 1 and a lower flange 2 are formed on the outer periphery of the upper end of the cylinder liner CL. P is a piston.
[0004]
  Upper heel part 1 and lower heel part 2Between the cylinder block CB, the horizontal surface of the bottom of the upper flange 1 is pushed against the horizontal surface of the cylinder block CB by the suppression of the head bolts that fasten the cylinder head CH to the cylinder block CB and the dead weight of the cylinder liner CL. It is hit. The cylinder liner CL and the cylinder block CB have a tightening force by a head bolt, a thermal load due to combustion in the cylinder (causing thermal deformation of the cylinder liner CL), an in-cylinder pressure (bore internal pressure of the cylinder liner CL), Inertial force or the like due to the reciprocation of the piston is applied, and stress concentration occurs in the bent portion A of the cylinder block CB and the bent portion B of the cylinder liner CL shown in FIG. When this stress concentration becomes excessive, a crack may occur in the bent portion B at the upper part of the lower flange portion 2 of the cylinder liner CL. Among the factors of stress concentration in the bent portions A and B, the influence of the tightening force and the thermal load is the largest.
[0005]
  Regarding the thermal deformation of the cylinder liner CL during engine operation,Upper heel part 1Is a contact surface between the cylinder block CB and the cylinder block CBUpper buttockIt is a contact surface between the fitting part D1, the lower flange part 2 and the cylinder block CB.Lower buttockA small gap is provided in the fitting portion D2. Conventionally, in many cases, the amount of thermal deformation is suppressed because it is cooled in a cooling water pool just below the lower heel part 2, soLower buttockOn the other hand, the gap of the fitting portion D2 (hereinafter, the size of this gap is referred to as Δφ2) is reduced (if the gap is too large, it becomes free and does not play a role of stress distribution).Upper buttockThe fitting portion D1 has a large gap (hereinafter referred to as Δφ1) in consideration of the amount of thermal deformation (for example, Δφ1 = 0.05 mm). However, in consideration of the stress balance applied to the cylinder block CB and the cylinder liner CL, the size of the gaps (hereinafter, “gap size” is simply referred to as “gap”) Δφ1 · Δφ2 is set. Never before.
[0006]
  Further, a structure is known in which an O-ring is annularly fitted on the outer periphery of the cylinder liner to prevent water leakage from the upper flange portion at the upper end. The cylinder block of the cylinder liner CL fitted with the conventional O-ring shown in FIG. A side cross-sectional view showing the attachment structure to the CB will be described. As shown in FIG. 11, the O-ring 3 disposed on the lower heel part 2 is fitted into a fitting groove 2 a provided in an annular shape on the lower heel part 2, and the upper and lower sides thereof are sandwiched between the lower heel part 2, The thickness of the upper and lower lower flange 2 is the same (d1 = d2), and the gap between the cylinder block CB and the cylinder block CB has only a fitting tolerance. The cooling water chamber 4 formed between the cylinder block CB and the cylinder block CB is separated.
[0007]
[Problems to be solved by the invention]
  First, in the mounting structure of the cylinder liner CL having the upper and lower two-stage flanges (upper-stage flange part 1 and lower-stage flange part 2), the stress generated in the bent parts A and B, which are two stress concentration parts, is biased. A lot of stress is applied to the cylinder block CB or the cylinder liner CL, and in the worst case, cracks are generated. That is, if stress is concentrated on the bent portion A, the load on the cylinder block CB increases, and if much stress is generated on the bent portion B, the load on the cylinder liner CL increases. The stress concentrates on the bent part A.Upper buttockThe gap Δφ1 of the fitting part D1 isLower buttockSmaller than the gap Δφ2 of the fitting portion D2, in the extreme,Upper buttockOnly the fitting part D1 is in the fitted state,Lower buttockThe fitting portion D2 is in a free state. On the other hand, the stress concentrates on the bent part B.Upper buttockThe gap Δφ1 of the fitting part D1 is large.Upper buttockThe fitting part D1 is free,Lower buttockThis is a state in which only the fitting part D2 is in a fitted state.
[0008]
  During engine operation, thermal expansion occurs in the cylinder liner CL. The temperature distribution of the cylinder liner CL during engine operation is higher on the upper inner diameter side and becomes lower as it goes outward and downward. The upper flange portion 1 having a large thermal expansion at a high temperature is configured to drag the cylinder liner CL main body portion that does not expand so much at a low temperature, and is high in the bent portion B that is a boundary between the upper flange portion 1 and the main body portion. Thermal stress is generated. here,Lower buttockWhen the thermal expansion of the main body is constrained at the fitting portion D2 (that is, the gap Δφ2 is reduced), the stress of the bent portion B further increases. During operation, this thermal stress is added to the bending stress due to the tightening force from the cylinder head CH side, so that the bent portion B becomes a portion having the highest stress in the cylinder liner CL.
[0009]
  One method for reducing the stress at the bent portion B of the cylinder liner CL during engine operation is to restrain the outer periphery of the flange portion 1 in the radial direction so as to suppress the amount of thermal expansion of the upper flange portion 1. It can be considered that the flange 1 reduces the force that drags the main body of the cylinder liner CL outward. Specifically, the outer periphery of the upper flange 1 is restrained by the inner periphery of the mounting hole of the upper flange 1 in the cylinder block CB. That is,Upper buttockThe gap Δφ1 in the fitting portion D1 is reduced. But in this case, of course, theUpper buttockA load in the radial direction due to thermal expansion of the upper flange portion 1 is applied to the inner periphery of the mounting hole of the cylinder block CB in the fitting portion D1, and as a result, the stress at the bent portion A of the cylinder block CB increases.
[0010]
  As described above, when the clamping force by the cylinder head CH, the temperature distribution of the cylinder liner CL, and the gap Δφ2 are made constant, the degree of supporting the thermal expansion of the upper flange 1 is related to the gap Δφ1, and the gap As Δφ1 is smaller, the degree of supporting the thermal expansion is higher, and the stress of the bent portion B of the cylinder liner CL is reduced, but the stress of the bent portion A of the cylinder block CB is increased. On the contrary, if it is increased, the stress of the bent portion A is lowered, but the stress of the bent portion B is increased by the thermal expansion of the cylinder liner CL main body portion due to the drag of the upper flange portion 1. On the other hand, when the clamping force by the cylinder head CH, the temperature distribution of the cylinder liner CL, and the gap Δφ1 are made constant, if the gap Δφ2 is reduced, the thermal expansion of the main body portion of the cylinder liner CL is restricted. Although the stress at the bent portion A of the cylinder block CB decreases, the stress at the bent portion B of the cylinder liner CL increases. On the other hand, if it is increased, the thermal expansion restraint of the cylinder liner CL main body portion is reduced, so that the stress of the bent portion B is reduced,Upper buttockThe inner periphery of the mounting hole of the cylinder block CB in the fitting part D1 must support not only the thermal expansion of the upper flange part 1 in the cylinder liner CL but also the thermal expansion of the main body part, and the stress of the bent part A is high. Become.
[0011]
  Note that the stress generated in both bent portions A and B (that is, the cylinder block CB and the cylinder liner CL) due to the thermal expansion of the cylinder liner CL during engine operation is a radial force, and as described above, the gap Although it is influenced by Δφ1 and Δφ2, the stress generated in both bent portions A and B due to the tightening force of the cylinder head CH during engine operation is a force in the vertical direction, and therefore has little relation to the gaps Δφ1 and Δφ2. Accordingly, both stresses at the bent portions A and B during engine operation, which is a load condition in which a thermal load is applied to the tightening force of the cylinder head CH, have an inversely proportional relationship with respect to the gap Δφ1 or Δφ2.
[0012]
  This will be described with reference to FIG. FIG. 2 illustrates the stress of the cylinder block CB (curved portion A) and the cylinder liner CL (curved portion B) obtained from the relationship between the gaps Δφ1 and Δφ2. Here, the stress allowable values of the bent portions A and B (that is, the cylinder block CB and the cylinder liner CL) are different, and the stress allowable value of the bent portion A is F._A0, The (stress) allowable value of the bent portion B is F_B0(Collectively F₀ And ), And the stress value applied to each bent portion is F_A , F_B (Collectively referred to as F). Φ is the bore diameter of the cylinder block CL.
[0013]
  Although there is a difference in the increase / decrease ratio due to the difference in the gap Δφ2 (here, Δφ2 / φ), if the gap Δφ1 is too small, stress exceeding the allowable value is concentrated in the bent portion A (cylinder block CB) (F_A / F_A0> 1). As the gap Δφ1 is increased, the stress at the bent portion A decreases and the stress at the bent portion B increases. However, if the gap Δφ1 is too large, the bent portion B (cylinder liner CL) has a stress exceeding an allowable value. Concentrate (F_B / F_B0> 1), eventually, no matter how much the gap Δφ1 is increased, the stress is not displaced.Upper buttockThe fitting part D1 is free,Lower buttockOnly the fitting portion D2 is in a fitted state. Especially stress F is allowable value F₀Exceeds the stress ratio (F / F) between the bent portion A and the bent portion B.₀ ) Is biased, defects such as cracks are likely to occur in the biased side, so that a balance of stress is ensured, that is, the stress ratio in both bent portions A and B is equalized (F_A/ F_A0= F_B/ F_B0)This is very important. Further, when the stress ratio is made uniform in this way, the stress ratio in both bent portions A and B is approximately 1 (F_A / F_A0= F_B/ F_B0It can be seen from the graph intersections P1, P2, P3, and P4 in FIG. 2 that the stress applied to both bent portions A and B exceeds the allowable value, but can be kept low. I understand.
[0014]
  Thus, in order to make the stress ratios of the two bent portions A and B uniform, it is necessary to analyze the relationship between the gap Δφ1 and the gap Δφ2 and to set the relationship between the two gaps Δφ1 and Δφ2 based on this. It is.
[0015]
  Furthermore, even if the stress ratios of the two bent portions A and B are equal, if the stress value is too large, both the bent portions A and B generate stress exceeding the strength, resulting in a problem. As can be seen from FIG. 2, the larger the gap Δφ2 (correctly, the bore diameter ratio of the gap Δφ2, that is, Δφ2 / φ), the greater the stress ratio of the two bent portions A and B, the graph intersections P1, P2, P3, The value of the stress ratio at P4 increases. Therefore, the upper limit of the gap Δφ2 (Δφ2 / φ) must be set to a limit that does not cause a problem. On the other hand, the smaller the gap Δφ2, the smaller the value of the stress ratio at the two bent portions A and B represented by the graph intersections P1 to P4, which is desirable in terms of the strength of the cylinder block CB and the cylinder liner CL. If it is too small (for example, Δφ2 / φ = 0), it becomes less than the fitting tolerance and the cylinder liner CL cannot be inserted into the cylinder block CB. It is desirable to set the gap Δφ2 based on these.
[0016]
  In the present invention, based on the above, by setting both gaps Δφ1 and Δφ2 within a certain range, a plurality of loads such as a tightening force from the cylinder head CH, a thermal load, an internal pressure in the cylinder liner CL, etc. During engine operation, the stresses generated at the two bent portions A and B (that is, the cylinder block CB and the cylinder liner CL) fall within an allowable range in design.
[0017]
  Also, regarding the size setting of the gap, the vertical length of the fitting part, in particular,Upper buttockThe upper heel part fitting depth L1 which is the vertical length of the fitting part D1 is a setting element. When the upper flange portion fitting depth L1 is increased, the stresses of both bent portions A and B are uniformly increased.Upper buttockIn the fitting portion D1, a radial load F1 is applied to the inner periphery of the mounting hole of the cylinder block CB that restrains the thermal expansion of the cylinder liner CL. This radial load F1 becomes a bending moment M around the bent portion A, and a bending stress is generated in the bent portion A. M = ∫F₁ -Since L1dL1, the load F₁Even when the upper heel portion fitting depth L1 is large, the stress of the bent portion A is high, and conversely, the stress is low.
[0018]
  On the other hand, the load F1 is also applied to the cylinder liner CL to become a bending moment about the bent portion B, and a bending stress is generated in the bent portion B. As described above, in order to reduce the thermal stress in the bent portion B,Upper buttockIt is effective to constrain thermal expansion at the fitting portion D1, that is, the load F₁However, if the load F is increased, the bending stress in the bent portion B is increased. Accordingly, in order to reduce the bending stress, it is effective to reduce the upper flange portion fitting depth L1.
[0019]
  In the conventional mounting structure of the O-ring 3 in the cylinder liner CL, as described above, since it is separated from the cooling water chamber 4 below, the engine liner is at a high temperature from the cylinder liner CL during engine operation. In order to cope with this, a heat-resistant O-ring must be used, resulting in high cost. Even with heat-resistant O-rings, the heat-resistant temperature has a limit, which is an obstacle to promoting higher engine output.
[0020]
[Means for Solving the Problems]
  The present invention is configured as follows.
  In claim 1, the upper stage has a long diameter with respect to the cylinder block CB of the internal combustion engine.Upper heel part 1And the bottom is the short diameterLower heel part 2In the structure in which the cylinder liner CL having the two-stage flange portion formed on the outer periphery of the upper end is fitted, between the outer surface of the upper-stage flange portion 1 and the inner surface of the cylinder block CB,MatingOf depth L1Upper buttock fitting part D1And the size of the gap of the upper flange fitting portion D1 is Δφ1And lower heel part 2Between the outer side of the cylinder and the inner side of the cylinder block CB,The lower heel part fitting part D2 is configured, and the size of the gap of the lower heel part fitting part D2 is Δφ2,If the bore diameter of the cylinder liner CL is φ, Δφ1 = Δφ2 + (4-8) × 10^-Fourφ, Δφ2 = (0.2 to 1.0) × 10^-3This is set to φ.
[0021]
  In claim 2, in the cylinder liner mounting structure according to claim 1,Upper buttock fitting part D1When the fitting height of L1 is L1, L1 = (0.02-0.05) φ.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
  Embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a side sectional view showing a mounting portion of a two-stage flange on the cylinder liner CL on the cylinder block CB, and FIG. 2 is a view of the bent portions A and B with respect to Δφ1 / φ when Δφ2 / φ is set in four stages. Each stress ratio F_A/ F_A0, F_B/ F_B0FIG. 3 is a table for explaining each stress ratio curve in FIG. 2. FIG. 4 is a diagram showing the change of Δφ1 / φ with respect to Δφ2 / φ when L1 / φ is set in three stages. 5 is a diagram showing a change of Δφ1 / φ with respect to Δφ2 / φ when L1 / φ = 2% and φ = φ ′, and FIG. 6 is a diagram showing Δφ2 / φ with respect to L1 / φ = 2% and φ = φ ″. It is a figure which shows the transition of (DELTA) phi1 / phi.
[0023]
  FIG. 7 is a diagram showing the displacement of the stress ratio with respect to Δφ2 / φ when L1 / φ is set to three stages when the stress ratios of both bent portions A and B are equal, and FIG. 8 is the upper stage collar portion when Δφ2 = 0. Each stress ratio F in the bent portions A and B with respect to the bore diameter φ when the fitting portion is not present in 1_A / F_A0, F_B/ F_B09 is a side sectional view showing a cooling structure of the O-ring 3 attached to the cylinder liner CL of the present invention. FIG. 10 is a partial view of the cooling water chamber 4 in a partial range of the entire circumference of the cylinder liner CL of the present invention. FIG. 9 is a sectional view taken along the line ZZ in FIG. 9 showing an embodiment in which a communication passage 4a from the O-ring 3 is provided, and FIG. 11 is a view showing a cooling structure of a conventional cylinder liner CL provided with an O-ring.
[0024]
  In the cylinder liner CL shown in FIG. 1 according to the embodiment of the present invention, the thickness of the upper flange 1 is (0.08 to 0.12) φ, and the outer diameter of the upper flange 1 is (1.25 to 1.35). ) Φ, the thickness of the main body is (0.07 ~ 0.12) φ, and the thickness of the upper collar 1 is not so large compared to the thickness of the main body, etc., and communicates with the bore from the outer surface It is not a type that has drilled cooling water holes. (This type of bore cooling structure is often used for types with a large bore diameter φ.)
[0025]
  In the cylinder liner mounting structure shown in FIG. 1, the description of the graphs shown in FIGS. 2 and 3 is given in the above-mentioned prior art, and the problem and solving means of the present invention are explained from among them. As a supplementary explanation, the gap Δφ2 is set in four stages of 0, 0.0005φ, 0.001φ, and 0.01φ. In FIG. 2, the cylinder liner CL (the bent portion B) is set in accordance with each stage of the gap Δφ2. ) Stress ratio graphs X1, X2, X3, and X4, and stress ratio graphs Y1, Y2, Y3, and Y4 of the cylinder block CB (curved portion A).
[0026]
  In the present invention, first, the stress ratios of the two bent portions A and B indicated by the graph intersections P1 to P4 in FIG._A/ F_A0= F_B/ F_B0) For obtaining the relationship between the two gaps Δφ1 and Δφ2, and the other is to set the gap Δφ2 so that the stress does not greatly exceed the allowable value.
[0027]
  First, the stress ratio of both the bent portions A and B becomes equal (F_A / F_A0= F_B / F_B0In order to obtain the relationship between the two gaps Δφ1 and Δφ2, the relationship between the two gaps Δφ1 and Δφ2 in the case where the stress ratios of the two bent portions A and B shown in FIG.
  The upper heel part fitting depth L1 is set to three stages, and the graphs are shown under the respective settings. In any case, the gap Δφ1 (Δφ1 / φ) is relative to the gap Δφ2 (Δφ2 / φ). When the gap Δφ2 (Δφ2 / φ) reaches a certain size, the gap Δφ1 (Δφ1 / φ) at which the two stress ratios are equal is constant.
  This is because the gap Δφ1 exceeds the amount of thermal deformation of the cylinder liner CL,Upper buttockThe fitting portion D1 is in a free state, and although the stress ratio applied to both the bent portions A and B is equal, this portion is excluded. That is, the range of both gaps Δφ1 and Δφ2 exhibiting a linear relationship in each graph of FIG. 4 is adopted. The relationship between the two gaps Δφ1 and Δφ2 in this range is expressed as in Equation 1.
[0028]
[Expression 1]
[0029]
  In addition, the relationship shown in Equation 1 isUpper buttockThe vertical length of the fitting portion D1, that is, the upper flange portion fitting depth L1 shown in FIG. 1, the in-cylinder pressure, the tightening force of the head bolt (cylinder head CH), the member temperature of the cylinder liner CL and the cylinder block CB (ie , Cooling structure in the vicinity of the cylinder liner CL mounting portion). Among these factors, the upper buttock fitting depth L1 has the most influence on the relationship shown in Equation 1. Also in FIG. 4, the diameter ratio of the upper flange portion fitting depth L1 to the bore is set to 2%, 5%, and 10%, and the cylinder liner CL and the cylinder block CB (both bent portions) are set in each step. The graph is shown to show the relationship between the gaps Δφ1 and Δφ2 at which the stress ratio of A and B) is equal.
[0030]
  In FIG. 4, when the three graphs are compared and examined, the slope of the linear relationship does not change. Therefore, the proportional constant of Δφ1 / φ with respect to Δφ2 / φ in Formula 1 (in this case, 1) is the upper heel fitting depth L1. However, the value of K representing the vertical axis intercept depends on the upper buttock fitting depth L1.
[0031]
  This is the same when the bore diameter φ is different, and both FIG. 5 and FIG.Upper buttockWhen the bore diameter ratio of the fitting portion D1 is constant (both are 2%), the relationship between the gaps Δφ1 and Δφ2 in which the stress ratio between the two bent portions A and B, that is, the cylinder liner CL and the cylinder block CB is equal. FIG. 5 shows a bore diameter φ set to φ ′, and FIG. 6 shows a bore diameter φ set to φ ″ (> φ ′). Comparing both graphs of FIG. 5 and FIG. It can also be seen that the vertical axis intercept only changes and the proportionality constant does not change, that is, the value of the bore diameter φ is a determinant of K in Equation 1.
[0032]
  In view of the above, the upper flange portion fitting depth L1 and the bore diameter φ are taken into account in Equation 1, which is a setting equation for the bore diameter ratio of the gap Δφ1 for equalizing the stresses of the cylinder liner CL and the cylinder block CB. K = (4-8) × 10^-FourIt becomes. When Formula 1 is replaced with an expression for obtaining the size of the gap Δφ1, Formula 2 is obtained.
[0033]
[Expression 2]
[0034]
  Here, if the upper flange portion fitting depth L1 is too large as in the above-described prior art, the stresses of the bent portions A and B increase, and the burden on the cylinder liner CL and the cylinder block CB increases. If it ’s too small,Upper buttockThere is a problem that the contact pressure at the fitting portion D1 becomes too high. Therefore, as in Equation 1, K = (4-8) × 10^-FourThe upper flange fitting depth L1 is set so that When the upper heel part fitting depth L1 is limited within this allowable range, Equation 3 is obtained.
[0035]
[Equation 3]
[0036]
  Next, the size of the gap Δφ2 is set in relation to the size of the stress ratio between the cylinder liner CL and the cylinder block CB (both bent portions A and B). Assuming that the stress ratio applied to the cylinder liner CL and the cylinder block CB (both bent portions A and B) is uniform, the magnitude of the stress ratio F / F₀(= F_A / F_A0= F_B / F_B0) Has an acceptable range. Stress ratio F / F₀ 7 increases in proportion to the gap Δφ2 (Δφ2 / φ) within a certain range, and increases as the upper flange fitting depth L1 (L1 / φ) increases. Therefore, in order to make the stress ratio within the allowable range, the gap Δφ2 and the upper flange fitting depth L1 must be set. Among these, about the upper collar part fitting depth L1, it can be made into a tolerance | permissible_range by the setting value by said Formula 3.
[0037]
  Therefore, the setting of the gap Δφ2 will be described. As can be seen in FIG. 7, Δφ2 / φ = (2-3) × 10^-3Then, the stress ratio F / F₀ Is a constant value. This is because the clearance Δφ2 is larger than the amount of thermal deformation of the cylinder liner CL and is free, so this portion is excluded and Δφ2 / φ is set as small as possible within a smaller range. It is desirable to do. The intermediate value of Δφ2 / φ within the range from 0 to the convergence value for obtaining the maximum stress value varies depending on the size of the upper buttock fitting depth L1 ((2-3) × 10^-3) About 1 × 10 of something slightly different^-3It is. In the present invention, Δφ2 / φ is set below this value. On the other hand, if the gap Δφ2 is too small, the cylinder liner CL cannot be fitted into the cylinder block CB at the time of assembly depending on how to obtain the dimensional tolerance. Therefore, Δφ2 / φ ≧ 2 × 10^-FourIt is said. That is, the size of the gap Δφ2 is set as shown in Equation 4.
[0038]
[Expression 4]
[0039]
  Next, the numerical values of the gaps Δφ1 and Δφ2 of the fitting portions D1 and D2 and the upper flange portion fitting depth L1 as in the present invention are adopted for a cylinder liner having any range of bore diameters. 8 will be described with reference to FIG. FIG. 8 shows a cylinder block CB and a cylinder liner CL (when the clearance Δφ2 in the lower flange portion fitting portion D2 of the lower flange portion 2 is 0 and no fitting portion is provided in the upper flange portion 1 (that is, in a free state). Each stress ratio F of each bent part A, B)_A/ F_A0, F_B/ F_B0This is the analysis result. From both graphs, the cylinder liner CL, that is, the stress ratio F of the bent portion B_B/ F_B0Changes with respect to the bore diameter φ is the stress ratio F of the cylinder block CB, that is, the bent portion A._A/ F_A0It increases as the bore diameter φ increases. Among them, the stress of the bent portion A is not so large (the stress ratio is not large), but the bent portion B is subjected to very high stress, the bore diameter φ is φα, and the stress F_B Is the tolerance F_B0(Stress ratio F_B / F_B0= 1) If the bore diameter becomes smaller than this, the stress applied to the bent portion B is less than the allowable value, so that the cylinder liner mounting structure considering the stress balance as in the present invention may not be adopted. On the other hand, the upper limit of the stress ratio is about 1.1. From the above, the numerical setting as in the present invention may be applied to a cylinder liner having a bore diameter φ of α ≦ φ ≦ β and having no cooling water hole as described above, as shown in FIG. .
[0040]
  The cylinder liner mounting structure in consideration of the stress balance is as described above. Next, the cooling structure of the O-ring 3 arranged on the outer periphery of the lower flange 2 will be described with reference to FIG. With respect to the cylinder liner CL shown in FIG. 9, the sealing structure with respect to the cylinder head CH may be a spigot type or a gasket type, and the upper and lower two-step flange structure has the same shape as that shown in FIG. The same code | symbol is used for the part 1, the lower collar part 2, etc.
[0041]
  As described in the prior art illustrated in FIG. 11, the O-ring 3 and the cooling water chamber 4 below the lower ridge portion 2 were separated. In the embodiment shown in FIG. 9, the thickness below the fitting groove 2a for fitting the O-ring in the lower flange portion 2 is slightly reduced, that is, the relationship between the upper and lower thicknesses d1 and d2 is d1> d2 (for example, d2 = d1 × (0.99 to 0.995), and between the lower flange 2 and the cylinder block CB (between cylinders), from directly below the fitting groove 2a to the upper end of the cooling water chamber 4 The communication path 4a is formed on the entire circumference of the cylinder liner CL, and the communication path 4a may be formed at least at a part between the cylinders as shown in FIG. Cooling water in the cooling water chamber 4 flows into the communication passage 4a and reaches the fitting groove 2a.If the O-ring 3 is fitted in the fitting groove 2a, the bottom surface of the O-ring 3 The cooling water flowing in from the communication path 4a will be hit. By allowing the cooling water to hit a part of the O-ring 3, the heat resistance of the O-ring 3 can be afforded, and the low-cost O-ring 3 can be used without being highly heat-resistant. Even an O-ring will be able to cope with higher engine output.
[0042]
  In addition, the sealing structure with respect to the cylinder head of a cylinder liner has a spigot type and a gasket type, FIG. 1 employs the former, FIG. 11 employs the latter, and FIG. 9 is not limited to either. For both structures, the upper and lower two-step flange structure comprising the upper-stage flange portion 1 and the lower-stage flange portion 2 is applied, and the gaps Δφ1 and Δφ2, the upper-stage flange portion fitting depth L1, and O according to the present invention are applied. The cooling structure of the ring 3 can be adopted.
[0043]
【The invention's effect】
  Since the present invention is configured as described above, the following effects can be obtained.
  First, in a structure in which a cylinder liner having two upper and lower flange portions is fitted to the cylinder block, as in claim 1, first, by setting a gap between the upper flange portion 1 and the cylinder block, the cylinder liner and the cylinder The stress applied to the block can be made uniform, and further, the stress can be suppressed to an allowable range by setting a gap between the lower flange 2 and the cylinder block. This avoids excessive stress on at least one of the cylinder block and the cylinder liner, and the durability of the cylinder liner and cylinder block can be maintained even when a high-bore cylinder liner with a large bore diameter is installed. Can be secured.
[0044]
  The stress applied to the cylinder block and the cylinder liner is kept within a permissible range by setting the vertical height of the fitting portion between the outer surface of the upper flange and the inner surface of the cylinder block. It can be done.
[Brief description of the drawings]
FIG. 1 is a side cross-sectional view showing a mounting portion of a two-stage flange on an upper part of a cylinder liner CL to a cylinder block CB.
FIG. 2 shows stress ratios F at the bent portions A and B with respect to Δφ1 / φ when Δφ2 / φ is set in four stages._A / F_A0, F_B / F_B0FIG.
FIG. 3 is a chart for explaining each stress ratio curve in FIG. 2;
FIG. 4 is a diagram showing a change of Δφ1 / φ with respect to Δφ2 / φ when L1 / φ is set in three stages.
FIG. 5 is a diagram showing a change of Δφ1 / φ with respect to Δφ2 / φ when L1 / φ = 2% and φ = φ ′.
FIG. 6 is a diagram showing a change of Δφ1 / φ with respect to Δφ2 / φ when L1 / φ = 2% and φ = φ ″.
FIG. 7 is a diagram showing a displacement of the stress ratio with respect to Δφ2 / φ when L1 / φ is set in three stages when the stress ratios of both bent portions A and B are made equal.
FIG. 8 shows stress ratios F in the bent portions A and B with respect to the bore diameter φ when Δφ2 = 0 and there is no fitting portion in the upper flange portion 1._A/ F_A0, F_B/ F_B0FIG.
FIG. 9 is a side sectional view showing a cooling structure of an O-ring attached to the cylinder liner CL of the present invention.
10 is a cross-sectional view taken along the line ZZ in FIG. 9 showing an embodiment in which a communication path 4a from the cooling water chamber 4 to the O-ring 3 is provided in a partial range of the entire circumference of the cylinder liner CL of the present invention.
FIG. 11 is a view showing a cooling structure of a cylinder liner CL provided with a conventional O-ring.
[Explanation of symbols]
CL cylinder liner
CB Cylinder block
CH Cylinder head
1 Upper buttock
2 Lower heel
2a Fitting groove
3 O-ring
4 Cooling water chamber
4a communication path
D1 collar (upper collar) fitting part
D2 Lower buttock fitting part
Δφ1The size of the gap in the upper flange fitting part D1
Δφ2The size of the gap in the lower buttock fitting portion D2
φ Bore diameter
L1 Upper buttock fitting depth L1

Claims (2)

A structure in which a cylinder liner CL having a two-stage flange part on the outer periphery of the upper end of the cylinder block CB of the internal combustion engine is provided with a two-stage flange part whose upper part is an upper flange part 1 having a long diameter and the lower part is a lower flange part 2 having a short diameter. In
Between the outer surface of the upper flange portion 1 and the inner surface of the cylinder block CB, an upper flange portion fitting portion D1 having a fitting depth L1 is formed, and the size of the gap between the upper flange portion fitting portion D1 is configured. Is Δφ1 ,
Between the outer side surface of the lower heel part 2 and the inner side surface of the cylinder block CB , a lower heel part fitting part D2 is configured, and the size of the gap of the lower heel part fitting part D2 is Δφ2,
If the bore diameter of the cylinder liner CL is φ,
Δφ1 = Δφ2 + (4-8) × 10 ⁻⁴ φ,
Δφ2 = (0.2 to 1.0) × 10 ⁻³ φ
Cylinder liner mounting structure, characterized in that In the cylinder liner mounting structure according to claim 1, when the fitting height of the upper flange part fitting part D1 is L1,
L1 = (0.02-0.05) φ
Cylinder liner mounting structure characterized by