JP6342158B2 - Internal combustion engine - Google Patents

Description

  The present invention relates to an internal combustion engine including a cooling device and an EGR device.

  An internal combustion engine for a vehicle is generally water-cooled, and cooling water is circulated by a water pump. On the other hand, recent vehicle internal combustion engines are often provided with an EGR device that recirculates a portion of the exhaust gas to the intake system in order to promote purification of exhaust gas, improve fuel efficiency, and the like. In many cases, a water-cooled EGR cooler that cools the water is provided.

  Inside the EGR cooler, a heat exchange section consisting of a gas passage (element) such as a flat tube or a thin tube through which EGR gas passes is arranged, and the cooling water passes through a gap between adjacent gas passages. Thus, the heat of the EGR gas is absorbed by the cooling water. In this case, the EGR cooler is usually provided in the middle of the dedicated bypass passage, and is usually designed so that the cooling water passes through the heat exchange part evenly (for example, Patent Document 1).

JP 2000-45884 A

  As described above, the EGR cooler is usually provided in a dedicated bypass passage. However, if the EGR cooler and other equipment / equipment are to be cooled by a common pipe, the EGR cooler May be placed in the main pipeline of the cooling water passage. In this case, in the structure in which the cooling water passes through the heat exchanging portion as in Patent Document 1, the flow resistance is remarkably increased, and there is a high possibility that it cannot be used.

  The present invention has been made to improve the current situation.

The internal combustion engine of the present invention is
An EGR device having a water-cooled EGR cooler in the EGR pipe and a cooling device in which the cooling water circulates by a water pump are provided, and a heat exchanging portion that contacts the cooling water is disposed inside the EGR cooler. In the configuration that
By shifting the heat exchanging portion to one side across the axis of the cooling water inlet in the EGR cooler, the cooling water is transferred to the other side of the EGR cooler across the axis of the cooling water inlet. An escape passage that flows to the cooling water outlet without passing through the heat exchange section is formed .

  In the present invention, a part of the cooling water that has flowed into the EGR cooler performs heat exchange work through the heat exchange part, and the other remaining flows smoothly from the inlet to the outlet without passing through the heat exchange part. The flow resistance of the cooling water passing through the inside of the EGR cooler can be remarkably suppressed. Therefore, it is possible to flow the cooling water in the EGR cooler more than the amount of water necessary for heat exchange work without causing an increase in flow resistance.

As a result, it is possible or disposed or to cool the cooling and other cooling portion of the EGR cooler, an EGR cooler to the main line the entire amount of the cooling water passes in one pipe, the internal combustion engine Contributes to downsizing and cost reduction. Further, by eliminating the dedicated bypass passage of the EGR cooler and reducing the pressure loss, it becomes possible to reduce the burden on the water pump and improve fuel efficiency. Furthermore, since the cooling water more than the past can flow through the EGR cooler, the cooling performance of the EGR cooler can be improved.

Further, since the heat exchanging portion to form a passage relief by providing to bias on one side of the inside of the EGR cooler, the heat exchange unit is Ru can accept the existing ones. Therefore , it is advantageous in terms of cost.

1 is an overall side view of an internal combustion engine. It is the II-II front view of FIG. FIG. 3 is a sectional view taken along line III-III in FIG. 1. It is a IV-IV view of FIG. (A) is a cross-sectional view taken along the line VA-VA in FIG. 1, and (B) is a cross-sectional view taken along the line VB-VB in FIG.

  Next, an embodiment of the present invention will be described with reference to the drawings. In the following description, the terms “upper”, “left”, “right”, “front” and “rear” are used to identify the direction, but the “upper” and “lower” directions are perpendicular to the crankshaft and cylinder bore. It is the longitudinal direction of the shaft.

(1). Overview The internal combustion engine of the present embodiment includes an engine body having a cylinder block 1 and a cylinder head 2 fixed to the upper surface of the cylinder block 1. It is mounted on the vehicle in a horizontal direction (in FIG. 1, the crankshaft 3 is schematically indicated by a one-dot chain line). A cylinder head cover 4 is fixed to the upper surface of the cylinder head 2, and an oil pan 5 is fixed to the lower surface of the cylinder block 1.

  One chain case 6 is fixed to one of the left and right end surfaces (short side surfaces) of the cylinder block 1 and the cylinder head 2, and the chain case 6, the cylinder block 1, and the cylinder head 1 are connected to each other. A cam shaft drive mechanism such as a timing chain (not shown) is disposed in a space formed therebetween.

  One end of the crankshaft 3 protrudes to the outside of the chain case 6, and as shown in FIG. 2, an accessory driving pulley 7 is fixed to the protruding end, and the accessory driving belt 8 is wound around the accessory driving pulley 7. The alternator 9, the water pump 10, and the air conditioner compressor 11 are driven. The alternator 9, the water pump 10, and the air conditioner compressor 11 are close to the front side of the engine body. For this reason, the accessory drive belt 8 is hung on the back surface of the pulley 12 of the water pump 10. Reference numeral 13 shown in FIG. 2 is a tension pulley.

  The water pump 10 is fixed to the housing 14 that is a part of the chain case 6, the pump cover 15 that is fixed to the housing 10 from the pulley 12 side, and the housing 10 that is fixed to the housing 10 from the opposite side of the pulley 12. The inlet cover 16 is a main element, and cooling water is pumped from the discharge port provided inside to the main gallery provided in the cylinder block 1 by rotation of the built-in blade.

  The inlet cover 16 of the water pump 10 includes an inflow port 16 a parallel to the crankshaft 3, and the inflow port 16 a protrudes on the opposite side to the chain case 6. Note that the inlet 16 a may be provided integrally with the housing portion 14 without providing the inlet cover 16. A transmission 17 is fixed to the other end surface 1 b of the cylinder block 1 opposite to the chain case 6.

  As shown in FIG. 1, an exhaust joint 18 is fixed to a substantially middle portion of the front surface 2 c of the cylinder head 2, and a catalytic converter 19 is integrally provided on the exhaust joint 18. In the present embodiment, the collecting passage (exhaust manifold portion) for collecting the exhaust ports provided for each cylinder is provided inside the cylinder head 2, and only one exhaust port is open on the outer surface of the cylinder head 2. It is.

  Tapered portions are provided at the upper and lower portions of the catalytic converter 19, a joint pipe 20 is connected to the lower end of the lower taper section, and an exhaust pipe 21 is connected to the joint pipe 20. A flange plate 22 is fixed to the joint pipe 20. The flange plate 22 is fixed to the cylinder block 1 via a bracket (shown in the drawing).

As shown in FIG. 1, when viewed from a direction orthogonal to the crankshaft 3 and the cylinder bore, the catalytic converter 19 is inclined with respect to the vertical line so as to move away from the chain case 6 as it goes downward, and as shown in FIG. When viewed from the axial direction of the crankshaft 3, the crankshaft 3 is inclined with respect to the vertical line so as to move away from the cylinder block 1. The catalytic converter 19 is covered from the front with a thin plate insulator (not shown) (covers about a half circumference).

(2). Cooling water piping / EGR device A thermo valve unit 25 for controlling the flow of cooling water is provided on the other end surface 2b of the cylinder head 2 on the side opposite to the chain case 6. Although illustration is omitted, piping is provided from a location of the thermo valve unit 25 to a radiator, a heater, or the like.

  A cooling water outlet 26 opens at the end of the front surface 2c of the cylinder head 2 close to the thermo valve unit 25, and the cooling water outlet 26 and the inlet 16a of the water pump 10 return behind the catalytic converter 19. Connected by a tube 27.

  On the other hand, an EGR pipe 28 that recirculates exhaust gas to the intake system is connected to the joint pipe 20 of the catalytic converter 19, and the end of the EGR pipe 28 is directly below the cooling water outlet 26 in the front surface of the cylinder head 2. It is connected via a flange plate 29. The cylinder head 2 has an EGR internal passage communicating with the EGR pipe 28, and EGR gas is sent from the EGR internal passage to the intake system via the EGR valve.

An EGR cooler 30 is inserted in the middle of the EGR pipe 28, and the EGR cooler 30 is also inserted in the return pipe 27 of the cooling water . Therefore, the cooling water return pipe 27 is separated into an inflow pipe 27 a located on the upstream side of the EGR cooler 30 and an outlet pipe 27 b located on the downstream side of the EGR cooler 30.

  The EGR pipe 28 is also divided by the EGR cooler 30, but the upstream portion of the EGR cooler 30 includes a first portion 28 a fixed to the joint pipe 20 of the catalytic converter 19 and a first portion fixed to the EGR cooler 30. The two parts 28b are separated from each other, and both are connected by fastening the first and second flanges 31 and 32 fixed to the end portions with bolts 33. The first portion 28a has a slightly larger diameter than the second portion 28b.

The portion of the EGR pipe 28 downstream of the EGR cooler 30 is composed of one third portion 28c, and the flange plate 29 is fixed to the end of the third portion 28c. It is fixed to the cylinder head 2 in a simplified manner). The second portion 28 b of the EGR pipe 28 is connected to the lower surface of the EGR cooler 30, and the third portion 28 c is connected to the upper surface of the EGR cooler 30. Accordingly, the EGR gas flows through the EGR cooler 30 from the bottom to the top. The third portion 28 c passes behind the return pipe 27.

  A flange plate 35 is also fixed to the start end of the inflow pipe 27 a in the return pipe 27 of the cooling water, and the flange plate 35 is fixed to the cylinder head 2 with a bolt 36. As shown in FIGS. 3 and 4, the portion of the cylinder head 2 where the return pipe 27 and the EGR pipe 28 are fixed is stepped down to the rear side of the portion where the exhaust joint 18 is fixed ( More precisely, the portion where the return pipe 27 and the EGR pipe 28 are fixed is the reference front surface of the cylinder head 2, and the exhaust plate is formed by fixing the cover plate to the reference front surface. The exhaust joint 18 is fixed.).

  The EGR cooler 30 has an upper and lower surface, a front and rear surface, and a left and right surface, and has a substantially square shape, and is disposed between the catalytic converter 19 and the water pump 10 as shown in FIG. Accordingly, the inflow pipe 27a constituting the return pipe 27 is connected to the side surface of the EGR cooler 30 located on the catalytic converter 19 side, and the outlet pipe 27b is connected to the surface of the EGR cooler 30 facing the water pump 10. It is connected. In this case, it arrange | positions so that the connection part (cooling water exit) of the exit pipe 27b may become lower than the connection part (cooling water inlet) of the inflow pipe 27a. Therefore, the cooling water flows from the top to the bottom while flowing in the EGR cooler 30 sideways.

  Further, the EGR cooler 30 is disposed close to the catalytic converter 19. Further, as clearly shown in FIG. 5, the EGR cooler 30 is arranged closer to the cylinder block 1 than the catalytic converter 19. Furthermore, the EGR cooler 30 is arranged in an inclined posture that approaches the cylinder block 1 as it is farther from the water pump 10 in plan view.

As shown in FIG. 5, inside the EGR cooler 30, a heat exchanging portion 37 composed of a large number of flat tube-like gas passages (fins, elements) 37a is arranged, and a gap between adjacent gas passages 37a is arranged. The EGR gas is cooled by passing cooling water through.
In this case, the inflow pipe 27a and the outlet pipe 27b are moved closer to each other and connected to the EGR cooler 30, and the heat exchanging portion 37 is moved closer to the rear side (cylinder block 1 side). In other words, the heat exchanging part 37 is arranged so as to be shifted to one side (rear side) with the axis of the cooling water inlet 30a interposed therebetween.
Therefore, the front side of the heat exchange portion 37 (in other across the axis of the cooling water inlet 30a other side (the opposite side to the heat exchange unit 37), the cooling water without the cooling water through the heat exchange portion 37 The escape passage 38 flowing from the inlet 30a to the cooling water outlet 30b is vacant, and the relief passages 38 are vacant on both the left and right sides of the heat exchange unit 37. The relief passages 38 on the left and right sides of the heat exchange unit 37 are cooled. It functions as a buffer space for flowing water through the entire heat exchanging section 37.

Furthermore, the overall heat exchange section 37, rather than shifting back from the flow path toward the cooling water outlet 30b from the cooling water inlet 30a of the EGR cooler 30, a portion of the front side of the heat exchanger 37, EGR The cooler 30 protrudes from the flow path from the cooling water inlet 30a to the cooling water outlet 30b. Therefore, a part (about half) of the front side of the heat exchanging portion 37 is exposed to a water flow from the cooling water inlet 30a toward the cooling water outlet 30b.

Therefore, some of the cooling water that has flowed into the EGR cooler 30 from the inflow pipe 27a passes through the heat exchanging portion 38 and functions to cool the EGR gas. There is a considerable proportion of cooling water that passes almost without any effect. The gap between the adjacent gas passages 37a extends long in the flow direction and the direction of the cooling water (is open to the side of the side of the cooling water inlet 30a cooling water outlet 30b.).

  As shown in FIG. 5A, the outlet pipe 27 b of the return pipe 27 has a connection structure that is simply inserted into the inlet 16 a of the water pump 10 from the inside. Therefore, the EGR cooler 30 is disposed on the axial center of the water pump 10.

  In this case, an inward annular protrusion 39 is provided at the opening edge of the inflow port 16a, while an outward annular groove 40 that fits the annular protrusion 39 is formed in the outlet pipe 27b. It is inserted into the inlet 16a by press fitting. Since the annular protrusion 39 and the annular groove 40 are fitted to each other, the outlet pipe 27b is allowed to be slightly inclined with respect to the inflow port 16a, and the sealing performance is secured even if it is slightly inclined.

(3) Summary In the above configuration, since the EGR cooler 30 is inserted in the middle of the return pipe 27, it is not necessary to provide a bypass passage. Therefore, it is possible to suppress the cost, is released from the constraint of space, it is possible to improve the freedom of the arrangement of the parts material. In many cases, the EGR cooler 30 is arranged in the dead space in the present embodiment, although the portion between the catalytic converter 19 (or other auxiliary machine) is often a dead space that should not be arranged. Therefore, the internal combustion engine can be made compact.

  Since there is not much cooling heat required for cooling the EGR gas, it is not necessary to pass the entire amount of cooling water flowing through the return pipe 27 through the heat exchanging portion 37. Therefore, providing the escape passage 38 inside the EGR cooler 30 as in the embodiment is preferable because it can prevent an increase in flow resistance. In this case, when the escape passage 38 is provided on the near side as in the embodiment, the heat (radiant heat) of the catalytic converter 19 is absorbed by the water in the escape passage 38, so that the heat shielding property is excellent.

  If the inflow pipe 27a of the return pipe 27 is arranged behind the catalytic converter 19 as in the embodiment, the heat of the catalytic converter 19 is also absorbed by the inflow pipe 27a, so that the cooling performance of the cylinder block 1 is improved. Contributes to improved fuel efficiency.

  Further, in the EGR cooler 30, the cooling water flows in from the opposite side of the water pump 10 and flows out to the water pump 10, so that the cooling water passes smoothly through the EGR cooler 30. For this reason, the cooling water flows toward the water pump 10 without resistance, and the return pipe 27 does not become long, so that the weight does not increase. In this case, since the end of the inflow pipe 27a is set to be higher than the start end of the outlet pipe 27b, the cooling water also flows from the top to the bottom inside the catalytic converter 19. For this reason, the cooling property of the heat exchange part 37 is high.

  In the embodiment, since the EGR gas flows upward and the cooling water flows downward inside the EGR cooler 30, the EGR gas whose temperature has decreased is cooled with cooling water having a low temperature to promote the temperature decrease of the EGR gas. it can. For this reason, it is excellent in the cooling performance of EGR gas. Therefore, it is possible to contribute to an improvement in fuel consumption through an improvement in filling efficiency.

In the embodiment, while the EGR gas flows from the bottom to the top inside the EGR cooler 30, the cooling water flows approximately sideways. Therefore, the flow direction of the EGR gas and the flow direction of the cooling water However, since the escape passage 38 is provided on both the cooling water inlet 30a side and the cooling water outlet 30b side with the heat exchanging portion 37 interposed therebetween, the cooling water passes the heat exchanging portion 37 in its upper and lower overall length. Pass through evenly. For this reason, it is possible to ensure high cooling efficiency by bringing the cooling water into contact with the entire heat exchanging portion 37 evenly. As a result, it can contribute to improvement of fuel consumption.

Now, the rotation speed of the water pump 10 increases in proportion to the engine rotation speed. Accordingly, the flow rate of the cooling water flowing through the EGR cooler 30 increases as the engine speed increases. And like this embodiment, a part of heat exchange part 37 is exposed to the flow path which goes to the cooling water outlet 30b from the cooling water inlet 30a of the EGR cooler 30, and a part of heat exchange part 37 is exposed to a water flow. With this configuration, when the engine rotates at a high speed and the flow rate of the cooling water increases, the resistance to the heat exchange unit 37 increases, so that the amount (ratio) of the cooling water flowing through the escape passage 38 at a high speed increases.

  In other words, the higher the engine speed, the greater the amount of cooling water that flows through the escape passage 38 without resistance, thereby suppressing the pressure loss and improving fuel efficiency while ensuring the amount of water required for cooling each cooling section. Can contribute.

  Further, in the present embodiment, since the escape passage 38 is located on the catalytic converter 19 side, the heat exchanging portion 37 does not receive the heat of the catalytic converter 19. For this reason, the cooling performance of EGR gas can be improved and it can contribute to the improvement of a fuel consumption.

The present invention can be embodied in various ways other than the above-described embodiment. Anyway, a part of the water flow flowing from the cooling water inlet towards the cooling water outlet is arranged to meet the heat exchange unit. In addition, it is preferable to provide a buffer space for flowing the cooling water through the entire heat exchanging portion at least at a location on the inlet side.

For example, the EGR cooler can be provided in the middle of a pipe to which another cooling unit is connected (that is, the EGR cooler and the other cooling unit may be connected in series). The mode and degree of deviation (shift) of the heat exchange part can be arbitrarily set as necessary. It is also possible to set the flow direction of the EGR gas and the flow direction of the cooling water to be substantially the same.

  The present invention can be embodied in an internal combustion engine. Therefore, it can be used industrially.

1 Cylinder Block 2 Cylinder Head 10 Water Pump 19 Catalytic Converter (Catalyst Case)
25 Thermo valve unit 27 Cooling water return pipe 27a Inflow pipe 27b Outlet pipe 28 EGR pipe 28a 1st part 28b 2nd part 28c 3rd part 30 EGR cooler 30a Cooling water inlet 30b Cooling water outlet 37a Gas passage (element)
37 Heat Exchanger 38 Escape Passage

Claims (1)

An EGR device having a water-cooled EGR cooler in the EGR pipe and a cooling device in which the cooling water circulates by a water pump are provided, and a heat exchanging portion that contacts the cooling water is disposed inside the EGR cooler. The configuration
By shifting the heat exchanging portion to one side across the axis of the cooling water inlet in the EGR cooler, the cooling water is transferred to the other side of the EGR cooler across the axis of the cooling water inlet. An escape passage that flows to the cooling water outlet without passing through the heat exchange part is formed,
Internal combustion engine.

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