Inter-bore structure of the engine

Abstract

To provide a more streamlined inter-bore structure of an engine so that cooling performance can be improved while maintaining dimensions between bores, such as increasing output without increasing an engine length by reviewing a structure between the bores, which have a severe thermal condition, and introducing new improvements.SOLUTION: In an inter-bore structure of an engine, a cooling waterway 1W formed in a cylinder block 1 is provided with an inter-bore waterway 1B between adjacent cylinders 1a, and an inter-bore waterway 1B is provided with a connection wall a that connects and integrates the adjacent cylinders 1a, where the connection wall a is configured to guide cooling water w flowing from a suction side to an exhaust side in the inter-bore waterway 1B to a cylinder head side on the exhaust side. The inter-bore waterway 1B is formed such that its cross-sectional area becomes smaller from the suction side to the exhaust side.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a structure of a water passage between bores between adjacent cylinders in a cooling water passage of a cylinder block of an engine, that is, a structure between bores of an engine.

Background Art

[0002] In a water-cooled engine, a cooling water passage (water jacket) for passing cooling water is provided in the cylinder block, specifically in the cylinder portion that fits the piston in the cylinder block, and specifically around the cylinder. And in an engine having a plurality of cylinders (cylinders) such as an in-line four-cylinder engine, as disclosed in Patent Document 1, many have a water passage also between adjacent cylinders, that is, between bores.

[0003] The thermal conditions between the bores of the cylinder portion are more severe than other parts. If the distance between the bores is increased to increase the heat capacity and a sufficient cooling water passage is provided, the engine length (the length of the cylinder portion in the cylinder in-line direction) becomes enlarged. If the cooling water passage is minimized to make the distance between the bores small and the engine length is made compact, the heat capacity becomes insufficient. Therefore, in the design between the bores, there is a point that it is difficult to balance the two originally.

[0004] For example, when trying to increase the output of the engine, it causes an increase in the heat generation amount and combustion pressure near the top dead center of the piston. Therefore, it is necessary to improve the cooling performance and strength of the cylinder. So, if the wall thickness between the bores is not changed (to avoid enlargement of the engine length) in order to prioritize compactness of the engine length, it is necessary to remove the connecting wall (a connecting wall that connects adjacent cylinders between the bores, see 4b in FIG. 2 of Patent Document 1) to enhance the cooling performance.

[0005] However, if the connecting wall is removed, the support for the liner (cylinder liner) at that location will be lost, which may lead to a decrease in the strength of the liner. Thus, the reality is that "when the wall thickness between bores is constant, cooling performance and strength are in a trade-off relationship."

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] In view of the above-described reality, an object of the present invention is to provide a more rationalized inter-bore structure of an engine such that, through a review of the structure between bores under severe thermal conditions and new ideas, the output can be increased without increasing the engine length, and the cooling performance can be improved while maintaining the dimensions between bores.

Means for Solving the Problems

[0008] The present invention relates to an inter-bore structure of an engine, a cooling water passage formed in a cylinder block is provided with an inter-bore water passage between adjacent cylinders, a connecting wall that connects and integrates adjacent cylinders is provided in the inter-bore water passage, the connecting wall is set to have a shape that guides cooling water flowing from the intake side to the exhaust side in the inter-bore water passage to the cylinder head side on the exhaust side, and the inter-bore water passage is characterized in that the cross-sectional area of the inter-bore water passage decreases from the intake side to the exhaust side.

[0009] For other aspects of the present invention Constituent elements refer to the Claims 1 to 5 claims.

Effects of the Invention

[0010] According to the present invention, since a connecting wall is provided to connect adjacent cylinders, the strength and rigidity of the portion between the bores of the cylinder block can be improved. And the cooling water flowing from the intake side to the exhaust side in the water passage between the bores is guided to the cylinder head side (piston head side) by the connecting wall, so that the cooling property (heat dissipation property) of the exhaust side and the cylinder head side portion where the thermal load is the most severe is greatly improved.

[0011] As a result, in the prior art, it was impossible to simultaneously improve the cooling property and the strength improvement of the upper portion between the bores by increasing the output. However, according to the present invention, for example, an engine with an increased output can be realized without changing the length in the cylinder series direction, and it is possible to provide a water passage structure between the bores that can simultaneously improve the cooling property and the strength improvement of the upper portion between the bores.

Brief Description of the Drawings

[0012] [Fig. 1] Side view showing a schematic flow of cooling water in the engine [Fig. 2] Schematic diagram showing the structure of the cooling device [Fig. 3] Showing the flow of cooling water, (A) is the cylinder part in plan view, and (B) is the cylinder head in plan view [Fig. 4] A view showing the structure between the cylinder bores, (A) is a cross-sectional view taken along the Y-Y line of FIG. 3(A), (B) is a cross-sectional view taken along the B-B line of (A), and (C) is a cross-sectional view taken along the C-C line of (A) [Fig. 5] Plan view of the cylinder head [Fig. 6] Cross-sectional view taken along the Z-Z line of FIG. 5 (a transverse cross-sectional view showing the corresponding part between the bores) [Fig. 7] Cross-sectional view of the main part showing another embodiment of the water passage between the bores

Embodiments for Carrying Out the Invention

[0013] The following describes an embodiment of the bore - to - bore structure of the engine according to the present invention with reference to the drawings in the case of an industrial diesel engine. In an industrial diesel engine (hereinafter abbreviated as "engine") E, the side with the cooling fan 10 is the front, the side with the flywheel 7 is the rear, the side with the intake port 30 [the side with the intake manifold (not shown)] is the right, and the exhaust port 28 [the side with the exhaust manifold (not shown)] is the left.

[0014] As shown in FIG. 1, in the engine E [a vertical in - line 4 - cylinder (multi - cylinder) water - cooled engine], a cylinder head 2 is assembled on the cylinder block 1, a head cover 3 is assembled on the cylinder head 2, and an oil pan 4 is assembled under the cylinder block 1. The upper part of the cylinder block 1 is a cylinder part 1A into which the piston 6 is fitted. 5 is a crankshaft, 6 is a piston, 7 is a flywheel, 8 is a transmission belt, 9 is a water pump, 10 is a cooling fan, and 11 is a radiator. The upper part of the cylinder block 1 is formed as a cylinder part 1A into which the piston 6 is fitted.

[0015] As shown in FIGS. 1 to 3, the cooling water w in the cooling device R of the engine E generally flows in the following order of description. That is, water pump 9 → water inlet 31 → cylinder part 1A → cylinder head 2 → water outlet 32 → thermostat 12 → upper hose 13 → radiator 11 → lower hose 14 → water pump 9. The water inlet 31 of the cylinder part 1A is provided at a position slightly more central than the intake side in the width direction, and the water outlet 32 of the cylinder head 2 is provided at a position closer to the exhaust side in the width direction. Note that 34 in FIG. 2 is a reservoir tank.

[0016] As shown in Fig. 2, when the water temperature is lower than a predetermined temperature, such as immediately after the engine E is started, the thermostat 12 is closed, so that the cooling water w from the water outlet 32 returns to the water pump 9 without passing through the radiator 11 through the short - circuit hose 33. Also, a part of the cooling water w has a path that cools the oil cooler 16 through the supply path 15 of the dedicated route from the cylinder head 2 and then returns to the water pump 9 through the discharge path 17 (see Fig. 1). In Fig. 2, the thick white arrows indicate the flow of the cooling water w, and the arrow by the line indicates the flow of the air k during air bleeding, respectively.

[0017] As shown in Figs. 1 and 3, the cooling water w that enters the cylinder part 1A from the water inlet 31 on the front side of the cylinder part 1A basically flows backward but also flows upward for each cylinder bore (cylinder) 1a. Therefore, the cooling water w flows upward into the head cooling water passage 2W, which is the water jacket of the cylinder head 2, through a plurality of floating holes 2f from the cylinder cooling water passage 1W, which is the water jacket of the cylinder part 1A, and in the head cooling water passage 2W, it flows from the rear to the front (toward the front water pump 9) toward the water outlet 32.

[0018] As shown in Figs. 3(A) and 4(A), in the inter - bore water passage 1B formed between adjacent cylinder bores 1a, 1a of the cylinder part 1A, a connecting wall a that connects and integrates the adjacent cylinder bores 1a, 1a is provided. The connecting wall a is composed of a lower wall 35, a lower connecting wall 18, a middle connecting wall 19, an upper connecting wall 20, and an upper wall 36, and is formed in a state of crossing the inter - bore water passage 1B. The inter - bore water passage 1B and the head cooling water passage 2W above it are communicated by the communication holes 21, 22 on the intake and exhaust sides of the cylinder part 1A and the vertical hole water passage 21A and the inclined hole water passage 22A (both will be described later) of the cylinder head 2.

[0019] As shown in FIG. 4(A), the lower wall 35 is formed as a cornered overhanging wall that protrudes slightly upward from the lower end of the inter-bore water passage 1B. The lower connecting wall 18 is formed as an independent wall with a substantially trapezoidal cross-section having an ascending inclined surface 18a that slopes upward as it goes from the intake side (right side) to the exhaust side. The left-right width of the ascending inclined surface 18a is set to about half of the left-right width of the entire lower connecting wall 18, but this is not the limit.

[0020] The middle connecting wall 19 has an intake-side inclined wall 19a having substantially the same angle as the ascending inclined surface 18a and an exhaust-side horizontal wall 19b, and is formed as a wall with a flat bent shape in a "C" shape that bulges upward as a whole. The upper connecting wall 20 has a start-side downward wall portion 20a with a gentler inclination angle and a shorter left-right length than the intake-side inclined wall 19a and a horizontal main body wall portion 20b. The upper wall 36 is a downwardly flat convex overhanging wall, and connecting holes 21 and 22 are formed at both left and right ends thereof.

[0021] Therefore, the inter-bore water passage 1B has a horizontal first passage 41 between the upper and lower portions of the lower wall 35 and the lower connecting wall 18, a second passage 42 that bends between the upper and lower portions of the lower connecting wall 18 and the middle connecting wall 19 and is positioned higher on the exhaust side as a whole, a third passage 43 in which only the intake-side end between the upper and lower portions of the middle connecting wall 19 and the upper connecting wall 20 is upwardly inclined, and a flat fourth passage 44 with a small vertical width between the upper and lower portions of the upper connecting wall 20 and the upper wall 36. That is, the connecting walls 35, 18 to 20, 36 are set in a shape that guides the cooling water w flowing from the intake side to the exhaust side in the inter-bore water passage 1B formed by the first to fourth passages 41 to 44 to the cylinder head 2 side on the exhaust side.

[0022] By setting the cross-sectional areas of the lower connecting wall 18 and the middle connecting wall 19 (the area of the cross-section cut by a plane extending in the vertical direction and the cylinder in-line direction) to increase from the intake side to the exhaust side, the cross-sectional area of the inter-bore water passage 1B is configured to decrease from the intake side to the exhaust side. The lower connecting wall 18 and the middle connecting wall 19 are set to a bent shape that protrudes toward the cylinder head 2 side when viewed in the front-rear direction (the cylinder arrangement direction), and the cross-sectional area of the entire five connecting walls 35, 18 to 20, 36 is set such that the cross-sectional area of the upper half (the half on the cylinder head 2 side) is smaller than the cross-sectional area of the lower half (the half on the side opposite to the cylinder head 2). Also, by making the diameter of the exhaust-side communication hole 21 larger than the diameter of the intake-side communication hole 22, etc., the flow passage area of the exhaust-side communication passage (an example of the exhaust-side communication passage) 21 is set to be larger than the flow passage area of the intake-side communication passage (an example of the intake-side communication passage) 22.

[0023] As shown in FIGS. 1 and 5, a head cooling water passage 2W through which cooling water w passes is formed inside the cylinder head 2, and an inter-bore corresponding portion 2b located directly above the inter-bore water passage 1B between adjacent cylinder bores 1a, 1a in the cylinder head 2 is shown in FIGS. 3(B) and 4. In the inter-bore corresponding portion 2b, a portion surrounded by a pair of insertion walls 24 on the left and right having insertion holes 2c through which tightening bolts 23 pass, and the cylinder head bottom wall 26 and the head upper wall 25 is formed in the head cooling water passage 2W.

[0024] The bottom surface 26a of the cylinder head bottom wall 26 is the surface that is placed on the upper surface 1b of the cylinder part 1A via the gasket G, and the head upper wall 25 is the upper wall of the cylinder head on which the head cover 3 is placed. Note that 28 in FIGS. 5 and 6 is an exhaust port, and the head cooling water passage 2W is also formed at each of the upper and lower portions thereof and on the right side of the right insertion wall 24.

[0025] That is, as shown in FIGS. 3 to 6, on a cylinder head 2 assembled on a cylinder block 1 by a plurality of tightening bolts 23, insertion walls 24, 24 for passing the tightening bolts 23, 23 arranged on both sides between adjacent cylinder bores 1a, 1a in the cylinder block 1, a head upper wall 25 connecting the upper end portions of the pair of insertion walls 24, 24, and a cylinder head bottom wall 26 are provided, and a head cooling water passage 2W surrounded by the pair of insertion walls 24, 24, the head upper wall 25, and the cylinder head bottom wall 26 is formed. A vertical wall 27 that straddles the head upper wall 25 and the cylinder head bottom wall 26 and extends in a direction connecting the pair of insertion walls 24, 24 to block the head cooling water passage 2W is formed between the pair of insertion walls 24, 24.

[0026] As shown in FIGS. 4(A), 5, and 6, the vertical wall 27 is continuously connected and integrated to the left end of the insertion wall 24 on the right side (intake port side), and the horizontal position i of the right end 27a (the end on the opposite side of either one) of the vertical wall 27 is formed in a state of existing in the central region C between the pair of insertion walls 24, 24. As an example of the range of the central region C, when the center-to-center distance between the left and right insertion walls 24 is D, ±10% of the left and right centers (C: 0.4D ≦ i < 0.6D) can be mentioned, but other ranges (such as 30% to 70%) may also be acceptable.

[0027] If the horizontal width of the vertical wall 27 is the length d between the center and the left end 27a of the insertion wall 24 on the right side, the length d of the vertical wall 27 is set to about half the distance between the pair of insertion walls 24, 24, that is, the center-to-center distance D (0.4D ≦ d ≦ 0.6D). As shown in FIG. 6, it is advantageous to form a reinforcing wall 29 that protrudes upward in a rib shape and extends horizontally (in the direction connecting the pair of insertion walls 24, 24) on the cylinder head bottom wall 26 at the bore-to-bore corresponding portion 2b.

[0028] The left end of the reinforcing wall 29 rises obliquely upward and is connected to the insertion wall 24 on the left side. A vertical hole water channel (hole-shaped cooling water channel) 21A is formed in the inclined reinforcing wall portion 29a (see FIGS. 4(A), (C) and FIG. 6). The vertical hole water channel 21A communicates with the communication hole 21 on the left side of the cylinder portion 1A with the gasket G interposed therebetween. The vertical hole water channel 21A and the communication hole 21 vertically communicate the cylinder cooling water channel 1W and the head cooling water channel 2W.

[0029] As shown in FIGS. 4(A), (B) and FIG. 6, the head cooling water channel 2W on the front (one) side of the vertical wall 27 and the bottom surface 26a directly below the vertical wall 27, that is, directly below, are communicated by an inclined hole water channel 22A formed to extend forward and upward from the bottom surface 26a. That is, an inclined hole water channel 22A (inclined hole-shaped cooling water channel) straddling the head cooling water channel 2W on one side partitioned by the vertical wall 27 and the bottom surface 26a of the lower end or the other side of the cylinder head bottom wall 26 of the vertical wall 27 is provided at the lower part of the vertical wall 27. The cylinder cooling water channel 1W and the head cooling water channel 2W are also vertically communicated by the inclined hole water channel 22A and the right communication hole 22 which are communicated with the gasket G interposed therebetween.

[0030] 〔Regarding the effects〕 Since the stress at the upper part of the cylinder increases due to the increase in combustion pressure by increasing the output, it is necessary to reduce the stress by narrowing the wall interval (the interval between adjacent cylinder bores 1a, 1a) that supports the cylinder bore 1a (liner) at the upper part between the bores with a thin wall thickness. However, when the wall interval is narrowed, there is a problem that the cooling performance at the upper part between the bores, which needs to be improved in cooling performance, deteriorates. Therefore, in order to increase the cross-flow (the flow of the cooling water w from the intake side to the exhaust side) at the upper part between the bores where the deterioration occurs, the following configurations 1) to 3) seem to be effective.

[0031] 1) Reduce or omit the cross-flow at the lower part between the bores with a cooling margin 2) Provide a guide wall for increasing the water flow to the portion choked by the boss (insertion wall 24) of the tightening bolt 23 3) In order to promote the cross-flow above the bores, the rising water passage (intake-side communication hole 22) to the cylinder head 2 on the intake side is made smaller, and the rising water passage (exhaust-side communication hole 21) to the cylinder head 2 on the exhaust side is made larger.

[0032] In the present invention, Configuration 1 is achieved by setting the cross-sectional area of the entire connecting walls 35, 18 to 20, 36 such that the cross-sectional area of the upper half is smaller than that of the lower half. Configuration 2 is achieved by guiding the cooling water w flowing from the intake side to the exhaust side in the inter-bore water passage 1B mainly to the cylinder head side on the exhaust side by devising the shapes and dimensions of the lower connecting wall 18 and the middle connecting wall 19. Configuration 3 is achieved by making the flow passage area of the exhaust-side communication passage 21 larger than that of the intake-side communication passage 22.

[0033] That is, while providing the connecting walls 35, 18 to 20, 36 in the inter-bore water passage 1B composed of the first to fourth passages 41 to 44 to improve the strength between the bores of the cylinder part 1A, the water flow mainly on the exhaust side and the cylinder head side in the inter-bore water passage 1B is also improved. As a result, in the prior art, it was not possible to simultaneously improve the coolability and strength of the upper part between the bores by increasing the output, but according to the present invention, it becomes possible to improve them simultaneously. For example, there is an advantage that an engine can be provided in which the output can be increased without difficulty while maintaining the engine length. Further, since the cross-sectional area of the inter-bore water passage becomes smaller from the intake side to the exhaust side, the flow velocity of the cooling water increases as it goes from the intake side to the exhaust side, and the effect of further improving the coolability on the exhaust side can also be obtained.

[0034] 〔Alternative Embodiment〕 As the connecting wall a provided in the inter-bore water passage 1B, as simply shown in FIG. 7, triangular connecting walls 37, 38 having a cross-sectional area (the area of the cross-section cut by a plane expanding in the vertical and horizontal directions) that becomes larger toward the exhaust side, a lower side wall 39 with a constant thickness in an oblique direction, and an upper side wall 40 having an inverted triangular shape with a slightly thicker intake side may be a combined wall a. In this case, a fifth passage 45 (1B) is formed between the upper side wall 40 and the upper wall 36 in the vertical direction.

[0035] As shown in Fig. 7, the upper side 37a of the connecting wall 37 such as the lower side may be formed into a concave curved surface so as to be concave upward. Also, the number of the connecting walls a may be one (singular) or two or more (plural).

Explanation of Signs

[0036] 1 Cylinder block 1B Water passage between bores 1W Cooling water passage 1a Cylinder (cylinder bore) 2 Cylinder head 2W Head cooling water passage 21 Exhaust side communication passage 22 Intake side communication passage a Connecting wall w Cooling water

Claims

1. A cooling water passage formed in a cylinder block is provided with an inter-bore water passage between adjacent cylinders, and a connecting wall for connecting and integrating adjacent cylinders is provided in the inter-bore water passage. The connecting wall is set in a shape that guides the cooling water flowing from the intake side to the exhaust side in the inter-bore water passage to the cylinder head side on the exhaust side, and the inter-bore water passage is formed in a state where the cross-sectional area of the inter-bore water passage becomes smaller from the intake side to the exhaust side, wherein the connecting wall has an inter-bore structure of an engine that is set in a bent shape convex toward the cylinder head side when viewed in the cylinder arrangement direction.

2. The inter-bore structure of the engine according to claim 1, wherein the cross-sectional area of the connecting wall is set to be larger from the intake side to the exhaust side, so that the cross-sectional area of the inter-bore water passage becomes smaller from the intake side to the exhaust side.

3. A cooling water passage formed in a cylinder block is provided with an inter-bore water passage between adjacent cylinders, and a connecting wall for connecting and integrating adjacent cylinders is provided in the inter-bore water passage. The connecting wall is set in a shape that guides the cooling water flowing from the intake side to the exhaust side in the inter-bore water passage to the cylinder head side on the exhaust side, and the inter-bore water passage is formed in a state where the cross-sectional area of the inter-bore water passage becomes smaller from the intake side to the exhaust side, wherein an intake side communication passage and an exhaust side communication passage that communicate with the intake side and the exhaust side at the cylinder head side end of the inter-bore water passage in the cylinder block and a head cooling water passage provided in the cylinder head are provided, and the flow passage area of the exhaust side communication passage is set to be larger than the flow passage area of the intake side communication passage.

4. The inter-bore structure of the engine according to claim 3, wherein the cross-sectional area of the connecting wall is set to be larger from the intake side to the exhaust side, so that the cross-sectional area of the inter-bore water passage becomes smaller from the intake side to the exhaust side.

5. The inter-bore structure of the engine according to any one of claims 1 to 4, wherein the cross-sectional area of the connecting wall is set such that the cross-sectional area of the half on the cylinder head side is smaller than the cross-sectional area of the half on the anti-cylinder head side.

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