Engine unit

Abstract

To improve cooling efficiency while avoiding enlargement of a cylinder block.SOLUTION: A multi-cylinder engine unit includes a cylinder block 2 in which a plurality of cylinders 7a to 7d are disposed in a row, a water jacket 9 provided in the cylinder block 2, disposed around each of the cylinders 7a to 7d, and communicating with each other in a row direction of the cylinders 7a to 7d, a water pump 10 that supplies coolant so that the coolant flows through the water jacket 9 with one of the rows of the cylinders 7a to 7d as an upstream side and the other as a downstream side, and a pipe 11a and a that are connected to the cylinder block 2 and the water pump 10 and introduce the coolant supplied from the water pump 10 to a predetermined part of the water jacket 9. 11b.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a multi-cylinder engine unit. [Background technology]

[0002] In engine units installed in vehicles, cooling is performed by circulating coolant supplied from a water pump within the cylinder block. In recent years, in an effort to improve fuel efficiency, the exhaust temperature of internal combustion engines has tended to rise, which has resulted in higher cylinder block temperatures, and therefore there is a demand for improved cooling efficiency. Patent document 1 discloses a configuration in which a water gallery is formed along the side wall of the cylinder block in the direction of the cylinder row, and cooling water is introduced from this water gallery into the water jacket of the cylinder block through communication holes formed corresponding to each cylinder. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 8-158932 Summary of the Invention [Problem to be solved by the invention]

[0004] In a configuration such as that in Patent Document 1, in which a water gallery is formed along the side wall of the cylinder block in the cylinder row direction, the cylinder block becomes larger, which may cause problems such as restrictions on engine layout and an increase in the amount of cooling water.

[0005] The present invention has been made in view of the above circumstances, and has as its object to improve cooling efficiency while avoiding an increase in the size of the cylinder block. [Means for solving the problem]

[0006] The engine unit of the present invention is a multiple-cylinder engine unit comprising: a cylinder block in which multiple cylinders are arranged in a row; water jackets provided in the cylinder block, arranged around each of the cylinders and communicating with each other in the row direction of the cylinders; a water pump that supplies cooling water so that one of the rows of cylinders is on the upstream side and the other is on the downstream side, and a pipe connected to the cylinder block and the water pump, which introduces the cooling water supplied from the water pump to a predetermined location in the water jacket. [Effects of the Invention]

[0007] According to the present invention, it is possible to improve the cooling efficiency while avoiding an increase in the size of the cylinder block. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a diagram showing a schematic configuration of an engine unit according to an embodiment; [Figure 2] 1 is a perspective view showing a cylinder block of an engine unit according to an embodiment. [Figure 3] 1 is a plan view showing a part of a cylinder block of an engine unit according to an embodiment. [Figure 4] FIG. 10 is a diagram for explaining a heat transfer coefficient analysis. DETAILED DESCRIPTION OF THE INVENTION

[0009] An engine unit (1) according to one embodiment of the present invention is a multiple-cylinder engine unit (1) including: a cylinder block (2) in which a plurality of cylinders (7a to 7d) are arranged in a row; water jackets (9) provided in the cylinder block (2), arranged around each of the cylinders (7a to 7d), and interconnected in the row direction of the cylinders (7a to 7d); a water pump (10) that supplies cooling water so that one of the rows of the cylinders (7a to 7d) is upstream and the other is downstream, and pipes (11a, 11b) that connect the cylinder block (2) and the water pump (10) and introduce the cooling water supplied from the water pump (10) to a predetermined location in the water jacket (9). This makes it possible to improve the cooling efficiency while avoiding an increase in the size of the cylinder block (2). [Example]

[0010] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. Fig. 1 is a diagram showing a schematic configuration of an engine unit 1 according to an embodiment. Fig. 2 is a perspective view showing a cylinder block 2 of the engine unit 1. Fig. 3 is a plan view showing a part of the cylinder block 2 of the engine unit 1. The engine unit 1 is a unitized internal combustion engine that is mounted on a vehicle. As shown in Fig. 1, the engine unit 1 includes a cylinder block 2, a cylinder head 3 connected to the top of the cylinder block 2, a cylinder head cover 4 that covers the top of the cylinder head 3, and an oil pan 5 connected to the bottom of the cylinder block 2 and that stores lubricating oil.

[0011] In this embodiment, the engine unit 1 is a four-cylinder engine, with cylinders 1 (#1) through 4 (#4) arranged in series in the front-to-rear direction. As shown in FIGS. 2 and 3, four cylinders 7a through 7d are arranged in a line in the cylinder block 2. A piston (not shown) is housed in each of the cylinders 7a through 7d so that it can reciprocate. The reciprocating motion of the piston is converted into the rotational motion of the crankshaft 6 via a connecting rod, providing driving force for the vehicle.

[0012] Combustion chambers are formed above the cylinders 7a to 7d by connecting the cylinder head 3 to the cylinder block 2. The cylinder head 3 is also provided with a plurality of intake ports, a plurality of intake valves that open and close the intake ports, a plurality of exhaust ports, and a plurality of exhaust valves that open and close the exhaust ports. Although not shown, the engine unit 1 is equipped with an intake device that supplies air from an air cleaner and an exhaust device that discharges exhaust gas after combustion.

[0013] In engine unit 1 configured as above, air is introduced from the intake system into the intake port of each cylinder, and fuel is injected to create an air-fuel mixture. The air-fuel mixture is compressed in the combustion chamber and ignited. The resulting combustion pressure pushes the piston down, producing power via crankshaft 6. Exhaust gases after combustion are discharged from the exhaust port of each cylinder through the exhaust system to the outside. In this way, in engine unit 1, each cylinder undergoes a series of four strokes consisting of the intake stroke, compression stroke, expansion stroke, and exhaust stroke, burning the fuel and outputting power.

[0014] 2 and 3, four cylinders 7a to 7d that are open at the upper end surface are provided in the cylinder block 2. These cylinders 7a to 7d are arranged in a line, and connecting portions 8a to 8c made of partition walls are provided between adjacent cylinders 7a to 7d.

[0015] The cylinder block 2 is also provided with a water jacket 9. The water jackets 9 are arranged around the cylinders 7a to 7d and communicate with each other in the column direction of the cylinders 7a to 7d. The water jackets 9 are arc-shaped grooves that follow the cylinders 7a to 7b and have approximately the same width. Figure 4 is a diagram for explaining the analysis of the heat transfer coefficient, as will be described later, and corresponds to the shape of the water jacket 9.

[0016] A water pump 10 is installed on the intake (IN) side at the front upper part of the cylinder block 2. As shown by arrow W in Figure 2, the water pump 10 supplies cooling water to the water jacket 9, with the front (FR) of the row of cylinders 7a to 7d as the upstream side and the rear (RR) as the downstream side.

[0017] Additionally, pipes (hoses) 11a and 11b are installed that connect the cylinder block 2 and the water pump 10 and introduce the cooling water supplied from the water pump 10 to predetermined locations in the water jacket 9. Details of the pipes 11a and 11b will be described later.

[0018] Here, in the cylinder block 2 without the pipes 11a and 11b installed, when temperature analysis was performed, it was found that between adjacent cylinders 7a to 7d, the temperature tended to be high at the upper ends of the cylinders 7a to 7d, and the temperature was found to be higher towards the rear. Specifically, the highest temperature T1 is shown at the upper end of the connection part 8c between the cylinder 7c of the third cylinder (♯3) and the cylinder 7d of the fourth cylinder (♯4). And, the second highest temperature T2 (<T1) is shown at the upper end of the connection part 8b between the cylinder 7c of the third cylinder (♯3) and the cylinder 7b of the second cylinder (♯2), and the third highest temperature T3 (<T2) is shown at the upper end of the connection part 8a between the cylinder 7b of the second cylinder (♯2) and the cylinder 7a of the first cylinder (♯1). In addition, although the temperature around each of the cylinders 7a to 7d (excluding the connection parts 8a to 8c) also becomes higher towards the rear, it was confirmed that the temperature T3 at the upper end of the connection part 8a between the cylinder 7b of the second cylinder (♯2) and the cylinder 7a of the first cylinder (♯1) is higher than the temperature T4 around the cylinder 7d of the fourth cylinder (♯4) (T3>T4).

[0019] Also, in the cylinder block 2 without the pipes 11a and 11b installed, an analysis of the heat transfer coefficient (HTC: Heat Transfer Coefficient) between the cooling water in the water jacket 9 and the cylinder block 2 was performed. FIG. 4 is a diagram for explaining the analysis of the heat transfer coefficient and shows the distribution of the heat transfer coefficient. Note that in FIG. 4, the actual analysis results (distribution of the heat transfer coefficient) are roughly shown. As shown in FIG. 4, the relationship is such that the heat transfer coefficient in region HTC-1 > the heat transfer coefficient in region HTC-2 > the heat transfer coefficient in region HTC-3 > the heat transfer coefficient in region HTC-4, and the result was obtained that the heat transfer coefficient is large at the front which is the upstream side of the cooling water and small at the rear which is the downstream side of the cooling water. This can be cited as one of the factors that the temperature difference between the cylinder block 2 decreases due to the temperature rise of the cooling water flowing in the rear of the water jacket 9, resulting in a decrease in the heat transfer efficiency. Also, although it depends on the shape of the head gasket, since the head gasket holes are smaller on the intake side compared to the exhaust (EX) side, it is difficult to form the flow of the cooling water, and it was confirmed that the heat transfer coefficient on the intake side tends to be smaller compared to the exhaust side.

[0020] In this configuration, where one row of cylinders 7a to 7d is upstream and the other is downstream, and the cooling water flows in one direction through the water jacket 9, the temperature of the cooling water rises toward the latter half of the cooling water circuit formed by the water jacket 9, reducing the cooling efficiency compared to the first half of the cooling water circuit, and leading to an increase in the temperature of the cylinder block 2.

[0021] Therefore, in this embodiment, the outlet circuit of the water pump 10 is branched, and cooling water at a temperature equivalent to that of the first half of the cooling water circuit is introduced into the second half of the cooling water circuit via pipes 11a and 11b, thereby improving the cooling efficiency.

[0022] The pipe 11a is disposed on the intake side of the row of cylinders 7a to 7d, and introduces cooling water into the water jacket 9 near a connection 8c between the most downstream cylinder 7d and the adjacent cylinder 7c (arrow w in FIG. 2). a As described above, the upper end of the connection portion 8c exhibits the highest temperature T1, and therefore, by using this as a predetermined location to introduce coolant (coolant at a temperature equivalent to that in the first half of the coolant circuit) from the water pump 10, the cooling efficiency can be improved.

[0023] The pipe 11b is disposed on the intake side of the row of cylinders 7a to 7d, and introduces cooling water into the water jacket 9 near a connection 8b between the cylinder 7c and the adjacent upstream cylinder 7b (arrow w in FIG. 2). b As described above, the upper end of the connection portion 8b shows the second highest temperature T2, and therefore, by using this as a predetermined location to introduce coolant (coolant at a temperature equivalent to that in the first half of the coolant circuit) from the water pump 10, the cooling efficiency can be improved.

[0024] When installing the pipes 11a and 11b, holes may be formed in the cylinder block 2, and the pipes 11a and 11b may be inserted therethrough so that the tips of the pipes 11a and 11b protrude into the water jacket 9, as shown in Fig. 2. This configuration makes it easier to apply the cooling water to a targeted position. Alternatively, the tips of the pipes 11a and 11b may have a nozzle structure so that the cooling water can be jetted or sprayed.

[0025] The pipes 11a and 11b may also be angled to communicate with the water jacket 9 to generate a flow of cooling water. For example, by introducing cooling water from the pipes 11a and 11b at an angle from the bottom to the top of the cylinder block 2, it is possible to aim for cooling within the longitudinal range of the cylinder. Furthermore, by locating the holes through which the pipes 11a and 11b are inserted at a lower position, it may be possible to obtain the effect of making it easier to install drain holes during casting, for example.

[0026] As described above, the configuration including pipes 11a, 11b that connect the cylinder block 2 and the water pump 10 and introduce the cooling water supplied from the water pump 10 to a predetermined location in the water jacket 9 makes it possible to improve cooling efficiency. Furthermore, because the configuration does not require a water passage separate from the water jacket 9 to be provided in the cylinder block 2, it is possible to avoid an increase in the size of the cylinder block 2. Although installation space is required for the pipes 11a, 11b, there is a degree of freedom in their installation, and compared to an increase in the size of the cylinder block 2, there are fewer restrictions on the engine layout and less of an impact on the amount of cooling water required.

[0027] Although the embodiments of the present invention have been described in detail above with reference to the drawings, each embodiment merely shows a specific example of how the present invention can be implemented. The technical scope of the present invention is not limited to each embodiment. Various modifications of the present invention are possible within the scope of the gist of the present invention, and these modifications are also included within the technical scope of the present invention. In this embodiment, a four-cylinder engine unit is used as an example, but the number of cylinders is not limited. In this embodiment, the two pipes 11a and 11b are used to introduce cooling water to two predetermined locations, but the number of predetermined locations is not limited. It is preferable to install the pipes so that cooling water is introduced at least near the connection between the most downstream cylinder and the adjacent cylinder in the water jacket. [Explanation of symbols]

[0028] 1: engine unit, 2: cylinder block, 7a to 7d: cylinders, 8a to 8c: connections, 9: water jacket, 10: water pump, 11a, 11b: pipes

Claims

1. A multi-cylinder engine unit, a cylinder block in which a plurality of cylinders are arranged in a line; a water jacket provided in the cylinder block, the water jacket being disposed around each of the cylinders and communicating with each other in the column direction of the cylinders; a water pump that supplies cooling water to the water jacket with one of the rows of cylinders acting as an upstream side and the other of the rows of cylinders acting as a downstream side; an engine unit comprising: a pipe connected to the cylinder block and the water pump, for introducing cooling water supplied from the water pump to a predetermined location in the water jacket;

2. 2. The engine unit according to claim 1, wherein the pipe is arranged on either the intake side or the exhaust side of the row of cylinders, and introduces cooling water into the water jacket near the connection between the most downstream cylinder and the adjacent cylinder.

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