Internal combustion engine

Abstract

To provide an internal combustion engine that prevents failure caused by freezing of condensation water in a recirculation gas pipe for recirculating gas generated in a combustion cycle to an intake side.SOLUTION: In an internal combustion engine 1 having a recirculation gas pipe 9 for recirculating gas generated in a combustion cycle to an intake side, the recirculation gas pipe 9 is a multi-layer pipe having an inner layer 26 located close to an axial center thereof and an outer layer 27 disposed on the outer diameter side of the inner layer 26, and is configured so that the gas can flow in both of the inner layer 26 and the outer layer 27.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to an internal combustion engine. [Background technology]

[0002] 2. Description of the Related Art An internal combustion engine may be provided with a recirculation gas pipe that recirculates gases generated in the combustion cycle, such as blow-by gas and exhaust gas, to the intake side.

[0003] For example, in a configuration in which blow-by gas generated in a combustion cycle is recirculated to the intake side (intake manifold 103 side) via a recirculation gas pipe 102 (Positive Crankcase Ventilation) connected to a valve 101 provided in an internal combustion engine 100 as shown in Fig. 6, the blow-by gas flowing through the recirculation gas pipe 102 is relatively warm and contains moisture, so that condensation may occur inside the recirculation gas pipe 102 cooled by low-temperature outside air. If this condensation water freezes inside the valve 101, the recirculation gas pipe 102 becomes clogged.

[0004] If the recirculation gas pipe 102 becomes clogged, the blow-by gas flows back through the breather path (not shown), and the condensed water generated in the breather path freezes and clogs the breather path as well. If both the recirculation gas pipe 102 and the breather path become clogged, the blow-by gas that has nowhere to go flows into the combustion chamber through the gaps in the cylinder block liner, causing poor combustion and possibly causing problems such as white smoke coming from the muffler.

[0005] Therefore, for example, in the internal combustion engine disclosed in Patent Document 1 below, a throttling member that retains condensed water that has condensed in the piping is provided in the air inlet passage that sends fresh air to the crank chamber, thereby preventing problems caused by condensed water. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2017-2737 A Summary of the Invention [Problem to be solved by the invention]

[0007] In the internal combustion engine described in Patent Document 1, the blow-by gas return passage through which the blow-by gas flows when the internal combustion engine is operating under low load conditions is not provided with a throttle member for retaining condensed water. Therefore, there is a risk that condensed water generated in the blow-by gas return passage cooled by low-temperature outside air will freeze in the valve, causing problems such as blocking of the blow-by gas return passage.

[0008] Therefore, an object of the present invention is to provide an internal combustion engine that prevents problems caused by condensed water freezing in a recirculation gas pipe that recirculates gas generated in the combustion cycle to the intake side. [Means for solving the problem]

[0009] In order to solve the above problems, the present invention provides: In an internal combustion engine having a recirculation gas pipe for recirculating gas generated in a combustion cycle to an intake side, The internal combustion engine is characterized in that the reflux gas pipe is a multi-layer pipe having an inner layer close to the axis and an outer layer disposed on the outer diameter side of the inner layer, and is configured so that the gas can flow through both the inner layer and the outer layer.

[0010] In the above configuration, The reflux gas pipe may be extended in the vertical direction, and a storage section capable of storing condensed water generated by cooling the gas may be formed in at least one location of the outer layer.

[0011] In the configuration in which the storage portion is formed, The gas may flow upward through the return gas pipe, and the storage section may be a check valve that opens upward due to the pressure of the gas flowing upward inside the return gas pipe.

[0012] In the configuration in which the storage portion is formed, The storage section may have a first wall extending from one radial side of the outer layer toward the other radial side, and a second wall extending from the other radial side of the outer layer above the first wall toward the one radial side, and the end of the first wall on the other radial side may be located on the other radial side and above the end of the second wall on the one radial side.

[0013] In a configuration in which the storage portion has the first wall and the second wall, The one radial side may be configured to be a radially outer side of the outer layer, and the other radial side may be configured to be a radially inner side of the outer layer.

[0014] In all of the above configurations: The outer layer may have a cross-sectional area, as cut along a plane perpendicular to the axis of the reflux gas pipe, that is larger at an upper side than at a lower side of the outer layer. Effect of the Invention

[0015] In this invention, the recirculation gas pipe installed in the internal combustion engine is a multi-layer pipe having an inner layer and an outer layer, and the blow-by gas can flow through both the inner layer and the outer layer, so that when there is no condensed water, the blow-by gas flows through both the inner layer and the outer layer, and a sufficient flow rate similar to that of the conventional method can be ensured, and even when the outer layer is clogged with condensed water, the blow-by gas flows at least through the inner layer, and a predetermined flow rate can be ensured. Therefore, the recirculation gas pipe is not completely clogged, and problems caused by condensed water freezing in the recirculation gas pipe that recirculates the blow-by gas generated in the combustion cycle to the intake side can be prevented. [Brief description of the drawings]

[0016] [Figure 1] 1 is a cross-sectional view that illustrates a schematic diagram of an internal combustion engine according to an embodiment of the present invention. [Diagram 2] 2 is a cross-sectional view showing an example of a recirculation gas pipe employed in the internal combustion engine shown in FIG. 1. [Diagram 3] 3 is a cross-sectional view showing an example of a storage section of the return gas pipe shown in FIG. 2. [Figure 4] 4 is a cross-sectional view showing another example of the storage section shown in FIG. 3. [Diagram 5] 4 is a cross-sectional view showing still another example of the storage portion shown in FIG. 3. [Figure 6] FIG. 1 is a cross-sectional view showing an example of a recirculation gas pipe of an internal combustion engine according to a conventional technique. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] An embodiment of an internal combustion engine 1 according to the present invention will be described with reference to the drawings. As shown in Fig. 1, the internal combustion engine 1 has an internal combustion engine body 2, a turbocharger 3, an intake manifold 4 and an exhaust manifold 5 connected to the internal combustion engine body 2, a breather path 8 capable of sending fresh air from an intake pipe 6 to the internal combustion engine body 2 (into a cylinder block 7), and a return gas pipe 9 (Positive Crankcase Ventilation) that returns blow-by gas generated in the combustion cycle of the internal combustion engine body 2 to the intake side (intake manifold 4).

[0018] A cylinder 10 is formed inside the cylinder block 7 that constitutes the internal combustion engine body 2, and a piston 11 moves up and down inside this cylinder 10. A connecting rod 12 is connected to the lower end of the piston 11, and the up and down movement of the piston 11 is converted into the rotational movement of a crankshaft 13 by the connecting rod 12. The connecting rod 12 and the crankshaft 13 are housed in the lower part of the cylinder block 7 (inside a crankcase 14). A cylinder head 15 is provided on the upper part of the cylinder block 7, and various parts such as an intake valve 16 and an exhaust valve 17 are provided in the cylinder head 15, and a combustion chamber 18 is formed between the cylinder block 7 and the cylinder head 15.

[0019] The intake pipe 6 has an air cleaner 19 for removing foreign matter in the intake air, an intercooler 21 for cooling the intake air compressed by a compressor 20 of the turbocharger 3, and a throttle valve 22, and is connected to the intake manifold 4. In addition, an exhaust pipe 23 connected to the exhaust manifold 5 is connected to a muffler (not shown) and the like via a turbine 24 of the turbocharger 3 and the like.

[0020] A breather path 8 branching off from the intake pipe 6 is connected to the cylinder head 15 and communicates with the space inside the crankcase 14. The recirculation gas pipe 9 is connected to the cylinder block 7 via a valve 25 and communicates with the space inside the crankcase 14. This valve 25 is an opening / closing valve that opens in response to negative pressure inside the intake manifold 4. The pressure state of the intake manifold 4 changes depending on the operating state of the vehicle; it becomes negative pressure when the internal combustion engine 1 is in a low load state, and becomes positive pressure when the internal combustion engine 1 is in a high load state.

[0021] The recirculation gas pipe 9 extends in the vertical direction, with its lower end connected to the cylinder block 7 and its upper end connected to the intake manifold 4. During the combustion cycle, blow-by gas that has leaked from the combustion chamber 18 to the crankcase 14 side through the gap between the liner of the cylinder 10 and the piston 11 flows upward through the recirculation gas pipe 9 together with fresh air introduced into the crankcase 14 from the breather path 8 when the intake manifold 4 is under negative pressure. On the other hand, when the intake manifold 4 is under positive pressure, the valve 25 is closed, so that the blow-by gas flows through the breather path 8 toward the intake pipe 6.

[0022] The details of the return gas pipe 9 are shown in FIG. 2. The return gas pipe 9 is a multi-layer pipe (two-layer pipe in this embodiment) having an inner layer 26 close to its axis and an outer layer 27 arranged on the outer diameter side of the inner layer 26. The gas (a mixture of blow-by gas and fresh air. Hereinafter, simply referred to as blow-by gas) is configured to flow in both the inner layer 26 and the outer layer 27. In this embodiment, the return gas pipe 9 and the valve 25 are connected by extending the outer wall, which is the radially outer wall of the outer layer 27, from the inner wall, which is the radially inner wall of the outer layer 27, and connecting the valve 25 so that the end of the valve 25 is covered at the extended portion of the outer wall. The return gas pipe 9 and the intake manifold 4 are connected by providing an opening in the intake manifold 4 with a diameter approximately equal to that of the outer wall of the outer layer 27, and attaching a flange provided on the outer side of the outer wall of the outer layer 27 to the intake manifold 4 so that the opening and the outer layer 27 are aligned. This allows the blow-by gas to flow through both the inner layer 26 and the outer layer 27. The cross-sectional area of ​​the inner layer 26 (the area of ​​the portion through which the blow-by gas flows when cut along a plane perpendicular to the axis of the return gas pipe 9) is almost constant over its entire length, whereas the cross-sectional area of ​​the outer layer 27 employs a non-circular pipe that is gradually larger at its upper side than at its lower side.

[0023] Storage sections 28 capable of storing liquid (hereinafter referred to as condensed water) formed from condensed moisture and the like contained in the blow-by gas flowing through the return gas pipe 9 are formed in two locations near the lower end and the upper end of the outer layer 27. As shown in Fig. 3, the storage section 28 has a first wall 29 extending from a radially outer wall (hereinafter referred to as the outer wall) of the outer layer 27 on one radial side of the outer layer 27 toward a radially inner wall (hereinafter referred to as the inner wall) of the outer layer 27 on the other radial side, and a second wall 30 extending from the inner wall on the other radial side of the outer layer 27 toward the outer wall on one radial side.

[0024] The first wall 29 and the second wall 30 are both formed in an arc shape in cross section cut along a plane including the axis of the return gas pipe 9. The first wall 29 is formed so that a portion extending from the outer wall of the outer layer 27 toward the inner wall and a portion extending further upward are continuously formed, and the second wall 30 is formed so that a portion extending from the inner wall of the outer layer 27 above the first wall 29 toward the outer wall and a portion extending further downward are continuously formed. The inner wall side end of the first wall 29 is located on the inner wall side and above the outer wall side end of the second wall 30, and a labyrinth is formed by the first wall 29 and the second wall 30. When condensed water accumulates up to the height of the end of the first wall 29, the end of the second wall 30 is immersed in the condensed water. In a state where there is no condensed water, the blow-by gas flows upward along the arrow shown in FIG. 3. In this embodiment, the first wall 29 is curved downward and the second wall 30 is curved upward, so that condensed water can easily accumulate in the first wall 29 and the blow-by gas can flow smoothly.

[0025] Storage sections 28 are provided around the entire circumference of the outer layer 27 at two locations, near the lower end and near the upper end of the outer layer 27, and condensed water accumulates in the storage sections 28, trapping gas between the vicinity of the lower end and the vicinity of the upper end of the outer layer 27 and forming a heat insulating layer between the inner layer 26 and the outside of the return gas pipe 9. Furthermore, when the condensed water freezes due to the low temperature of the outside air, it is possible to prevent the condensed water accumulated in the storage sections 28 from overflowing due to vibrations while the vehicle is running.

[0026] 2, the storage portion 28 is provided in two places, near the lower end and near the upper end of the outer layer 27, but it may be provided in at least one place in the outer layer 27. When the storage portion 28 is provided in one place, it is not possible to confine gas inside the outer layer 27, but it is possible that the storage portion 28 can function as a heat insulating layer by stopping the flow of gas inside the outer layer 27. In this case, it is preferable to provide the storage portion 28 in the vicinity of the lower end of the outer layer 27.

[0027] 4, the first wall 29 may be a cone-shaped member extending obliquely upward from the outer wall of the outer layer 27, and the second wall 30 may be a cone-shaped member extending obliquely downward from the inner wall of the outer layer 27 above the first wall 29, and the inner wall end of the first wall 29 may be located on the inner wall side and above the outer wall end of the second wall 30. With this configuration, condensed water can be efficiently stored in the storage section 28 in the same manner as above.

[0028] 5, the storage section 28 may be a check valve. This check valve has a valve body 31 provided on the outer wall side of the outer layer 27, and a valve seat 32 provided on the inner wall side of the outer layer 27 on which the valve body 31 can be seated. When the pressure of the blow-by gas flowing upward in the return gas pipe 9 is small, the valve body 31 is seated on the valve seat 32. When the pressure of the blow-by gas becomes greater than a predetermined value, the valve body 31 opens upward due to the pressure, and the blow-by gas flows through the outer layer 27. When condensed water accumulates in the storage section 28, the weight of the condensed water presses the valve body 31 downward, preventing the valve body 31 from opening due to the pressure of the blow-by gas.

[0029] It should be noted that the configuration of the reservoir 28 shown in FIGS. 3 to 5 is merely an example, and can be modified as appropriate as long as the condensed water can be efficiently stored in the reservoir 28.

[0030] In the above internal combustion engine 1, the recirculation gas pipe 9 for recirculating the blow-by gas from the crankcase 14 to the intake manifold 4 is a multi-layer pipe having an inner layer 26 close to its axis and an outer layer 27 disposed on the outer diameter side of the inner layer 26, and the blow-by gas can flow through both the inner layer 26 and the outer layer 27. Therefore, in a state where no condensed water is generated, the blow-by gas flows through both the inner layer 26 and the outer layer 27, and a sufficient flow rate similar to that of the conventional method can be ensured, while even when the outer layer 27 is clogged with condensed water, the blow-by gas flows at least through the inner layer 26, and a predetermined flow rate can be ensured. Therefore, the recirculation gas pipe 9 is not completely clogged, and problems caused by condensed water freezing in the recirculation gas pipe 9 for recirculating the blow-by gas generated in the combustion cycle to the intake side can be prevented.

[0031] In addition, the above-mentioned internal combustion engine 1 is configured such that the return gas pipe 9 extends in the vertical direction and a storage section 28 capable of storing a liquid formed from condensed components of the blow-by gas is formed in at least one location of the outer layer 27. Therefore, an insulating layer of gas is formed in the outer layer 27, and the generation of condensed water from the blow-by gas flowing through the inner layer 26 can be suppressed.

[0032] Moreover, in the above-described internal combustion engine 1, the storage section 28 has a first wall 29 extending from one radial side of the outer layer 27 toward the other radial side, and a second wall 30 extending from the other radial side of the outer layer 27 toward one radial side, and the end portion on the other radial side of the first wall 29 is located on the other radial side and above the end portion on the one radial side of the second wall 30, so that the condensed water can be reliably stored in the storage section 28. Moreover, since the one radial side is the outer wall side of the outer layer 27 and the other radial side is the inner wall side of the outer layer 27, it is possible to promote the generation and freezing of condensed water on the outer wall of the outer layer 27, which is easily affected by cold air from the outside.

[0033] In addition, in the above-mentioned internal combustion engine 1, the ventilation cross-sectional area of ​​the outer layer 27 cut by a plane perpendicular to the axis of the recirculation gas pipe 9 is larger on the upper side than on the lower side of the outer layer 27, so that it is possible to promote the falling of a plurality of small-diameter condensed water generated on the upper side of the outer layer 27 while combining them, and therefore the condensed water can be smoothly stored in the storage section 28. On the other hand, because the upper side of the outer layer 27 is opened larger than the lower side, the condensed water stored in the storage section 28 can be sucked up by the negative pressure of the intake manifold 4 or quickly evaporated, so that the ventilation state of the outer layer 27 can be smoothly restored.

[0034] In the internal combustion engine 1 according to this embodiment, the recirculation gas pipe 9 is a pipe (Positive Crankcase Ventilation) for recirculating blow-by gas to the intake side, and is intended to prevent moisture in the blow-by gas from condensing in the recirculation gas pipe 9 and freezing to block the recirculation gas pipe 9. In an internal combustion engine 1 equipped with an exhaust gas recirculation device, the recirculation gas pipe 9 can be used as a pipe for recirculating exhaust gas that has passed through the exhaust manifold 5 to the intake side.

[0035] In the above embodiment, the reflux gas pipe 9 is a two-layer pipe composed of the inner layer 26 and the outer layer 27, but it may be a multi-layer pipe composed of three or more layers. In this case, it is preferable to provide a reservoir 28 in the outermost layer.

[0036] The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. Therefore, the scope of the present invention is defined by the claims, not the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0037] 1. Internal combustion engine 2. Internal combustion engine body 3. Turbocharger 4. Intake manifold 5 Exhaust manifold 6 Intake pipe 7 Cylinder block 8 Breather Path 9 Return gas pipe 10 Cylinders 11 Piston 12 Connecting rod 13 Crankshaft 14 Crankcase 15 Cylinder head 16 Intake valve 17 Exhaust valve 18 Combustion chamber 19 Air cleaner 20 Compressor 21 Intercooler 22 Throttle valve 23 Exhaust pipe 24 Turbine 25 Valve 26 Inner Layer 27 Outer layer 28 Storage section 29 First wall 30 Second wall 31 Valve body 32 Valve seat

Claims

1. In an internal combustion engine having a recirculation gas pipe for recirculating gas generated in a combustion cycle to an intake side, The internal combustion engine is characterized in that the reflux gas pipe is a multi-layer pipe having an inner layer close to an axial center thereof and an outer layer disposed on the outer diameter side of the inner layer, and is configured so that the gas can flow through both the inner layer and the outer layer.

2. 2. The internal combustion engine according to claim 1, wherein the recirculation gas pipe is provided extending in a vertical direction, and a storage portion capable of storing condensed water generated by cooling the gas is formed in at least one location of the outer layer.

3. 3. The internal combustion engine according to claim 2, wherein the gas flows upward through the recirculation gas pipe, and the reservoir is a check valve that opens upward by pressure of the gas flowing upward through the recirculation gas pipe.

4. 3. The internal combustion engine according to claim 2, wherein the storage portion has a first wall extending from one radial side of the outer layer toward the other radial side, and a second wall extending from the other radial side of the outer layer above the first wall toward the one radial side, and an end portion of the first wall on the other radial side is located on the other radial side and above an end portion of the second wall on the one radial side.

5. 5. An internal combustion engine according to claim 4, wherein the one radial side is a radially outer side of the outer layer, and the other radial side is a radially inner side of the outer layer.

6. 6. The internal combustion engine according to claim 2, wherein a cross-sectional area of ​​the outer layer cut along a plane perpendicular to an axis of the reflux gas pipe is larger at an upper side than at a lower side of the outer layer.

Images