JP4619998B2 - Exhaust gas recirculation device - Google Patents

Description

  The present invention relates to the technology of an exhaust gas recirculation (EGR) device of a four-cycle engine, and more particularly to the technology of a device that efficiently recirculates exhaust gas (EGR gas) to a combustion chamber.

Conventionally, in an internal combustion engine such as a diesel engine, an EGR device is known in order to reduce nitrogen oxide (NOx) generated during combustion as a countermeasure against environmental pollution. NOx, which is a harmful component, is generated when nitrogen in the air is oxidized as the combustion temperature in the engine combustion chamber increases. The EGR device recirculates a part of the exhaust gas (EGR gas) that has become an inert (low oxygen content) gas to the intake manifold and mixes it with the intake air, thereby reducing the combustion temperature in the combustion chamber. This is intended to reduce NOx. In such an EGR device, a technique for directly connecting an exhaust communication pipe from an exhaust manifold to an intake manifold is known (see, for example, “Patent Document 1” and “Patent Document 2”).
JP-A-8-261072 JP 2002-180914 A

  However, in the above-described prior art and the like, an exhaust manifold and an intake manifold extending in opposite directions as viewed from the combustion chamber are connected and a cooling device or the like is disposed, so that the handling becomes large and an extra space is required. In addition, when the EGR gas pipe that is at a high temperature is disposed on the air supply side, it is necessary to newly wrap a heat insulating material.

  In order to solve the above-described problems, the present invention provides an EGR device that completes EGR inside the engine, does not require a large space outside the engine, and can reduce the cost of newly added parts. is there.

  The problem to be solved by the present invention is as described above. Next, means for solving the problem will be described.

  In claim 1, a communication passage that communicates the inside of the crankcase and the combustion chamber is provided, and the opening of the combustion chamber that communicates with the communication passage is arranged in the exhaust stroke, the expansion stroke, and the later stage of the intake stroke in the combustion cycle. It is provided at the opening position.

  According to a second aspect of the present invention, a cam chamber is provided in the middle of the communication passage, a valve body is disposed on the cam shaft that is rotationally driven by the crankshaft, and the communication passage is provided by the valve body only in the exhaust stroke. In addition to being configured to open, a breather path that communicates the inside of the crankcase to the intake side is provided.

  According to a third aspect of the present invention, a cam chamber is provided in the middle of the communication passage, a valve body is disposed on the cam shaft that is rotationally driven by the crankshaft, and the communication passage is provided only by an intake stroke by the valve body. While being configured to open, an exhaust passage communicating with the exhaust manifold is provided in the crankcase.

According to a fourth aspect of the present invention, an oil drain hole communicating with the cam chamber and the inside of the crankcase is provided so as to extend downward, and a groove is formed on the cam chamber side of the oil drain hole on the front side in the rotation direction of the valve body. It is a thing.

According to a fifth aspect of the present invention, the communication path is configured by a piston and a groove formed on a contact surface between the piston of the cylinder block.

According to a sixth aspect of the present invention, a cylindrical member is disposed at a portion of the groove portion that contacts the piston.

  As effects of the present invention, the following effects can be obtained.

In claim 1, a communication passage that communicates the inside of the crankcase and the combustion chamber is provided, and the opening of the combustion chamber that communicates with the communication passage is arranged in the exhaust stroke, the expansion stroke, and the later stage of the intake stroke in the combustion cycle. Since it is provided at the open position, the EGR device has a simple structure, and a part of the exhaust gas is discharged from the combustion chamber into the crankcase during the exhaust stroke, and the exhaust gas is transferred from the crankcase into the combustion chamber during the intake stroke. It becomes possible to supply. In addition, the EGR device can be configured at low cost without adding new parts, and the EGR device can be provided without changing the layout outside the engine. Absent.
Furthermore, since the breather can be recirculated from the crankcase to the combustion chamber together with the exhaust gas, the cost for the breather can be reduced by reducing the number of breather parts. The exhaust gas to be recirculated becomes a part of the latter part of the exhaust stroke and has a lower temperature than that of the conventional one, so that it does not need to be cooled and efficiency is improved.

According to a second aspect of the present invention, a cam chamber is provided in the middle of the communication passage, a valve body is disposed on the cam shaft that is rotationally driven by the crankshaft, and the communication passage is provided by the valve body only in the exhaust stroke. Since it is configured to open and a breather path that communicates the inside of the crankcase to the intake side is provided, the EGR device has a simple structure, and a part of the exhaust gas is transferred from the combustion chamber into the crankcase during the exhaust stroke. In the intake stroke, the exhaust gas can be supplied to the combustion chamber from the intake side using the breather path. Further, the amount of exhaust gas to be recirculated can be adjusted by the shape of the cam.

According to a third aspect of the present invention, a cam chamber is provided in the middle of the communication passage, a valve body is disposed on the cam shaft that is rotationally driven by the crankshaft, and the communication passage is provided only by an intake stroke by the valve body. Since it is configured to open and an exhaust passage that communicates with the exhaust manifold is provided in the crankcase, the EGR device has a simple structure, and a part of the exhaust gas is transferred from the combustion chamber into the crankcase during the exhaust stroke. In the intake stroke, the exhaust gas can be supplied to the combustion chamber from the intake side using the breather path.
Further, the amount of exhaust gas to be recirculated can be adjusted by the shape of the cam. In addition, breather parts can be eliminated.

According to a fourth aspect of the present invention, an oil drain hole communicating with the cam chamber and the inside of the crankcase is provided so as to extend downward, and a groove is formed on the cam chamber side of the oil drain hole on the front side in the rotation direction of the valve body. As a result, excess lubricating oil can be removed from the cam, the flow of exhaust gas in the communication hole can be made smooth, and the lubricating oil can be scraped efficiently from the cam.

In Claim 5, since the said communicating path was comprised with the groove part formed in the contact surface with the piston and the piston of a cylinder block, the process at the time of an EGR structure is formed by previously forming a groove part in a cylinder block. The cost can be reduced by reducing the stroke.

According to the sixth aspect of the present invention, since the cylindrical member is disposed at the portion of the groove that contacts the piston , gas leakage from the ring on the piston surface can be prevented.

  Next, embodiments of the invention will be described. It should be noted that the technical scope of the present invention is not limited to the embodiments, but extends to the entire scope of the technical idea that the present invention truly intends, as will be apparent from the matters described in the present specification and drawings. It is.

  FIG. 1 is a front sectional view showing a diesel engine according to an embodiment of the present invention.

  FIG. 2 is a side sectional view showing a diesel engine according to an embodiment of the present invention. FIG. 3 is another side cross-sectional view showing a diesel engine according to an embodiment of the present invention. FIG. 4 is a schematic view showing an operation process of the diesel engine according to the first embodiment. 4A shows the transition period from the compression stroke to the expansion stroke, FIG. 4B shows the initial stage of the exhaust stroke, FIG. 4C shows the transition period from the exhaust stroke to the intake stroke, and FIG. 4D shows the late stage of the intake stroke.

  FIG. 5 is a schematic view showing an operation stroke of the diesel engine according to the second embodiment. About A, B, C, and D, it is the same process as FIG.

  FIG. 6 is a schematic view showing an operation stroke of the diesel engine according to the third embodiment. About A, B, C, and D, it is the same process as FIG.

  FIG. 7 is a schematic view showing an operation stroke of the diesel engine according to the fourth embodiment. About A, B, C, and D, it is the same process as FIG.

  FIG. 8 is a schematic view showing an operation stroke of the diesel engine according to the fifth embodiment. About A, B, C, and D, it is the same process as FIG.

  FIG. 9 is a schematic view showing an operation process of the diesel engine according to the sixth embodiment. About A, B, C, and D, it is the same process as FIG.

  FIG. 10 is a schematic view showing an operation stroke of the diesel engine according to the seventh embodiment. About A, B, C, and D, it is the same process as FIG.

  FIG. 11 is a schematic view showing an operation stroke of the diesel engine according to the eighth embodiment. About A, B, C, and D, it is the same process as FIG.

  FIG. 12 is a schematic view showing the structure of a diesel engine according to the ninth embodiment. FIG. 13 is a schematic view showing the structure of the diesel engine according to the tenth embodiment. FIG. 14 is a schematic view showing the structure of a diesel engine according to the eleventh embodiment.

  An overall configuration of an engine according to an embodiment of the present invention will be described with reference to FIGS. 1 to 3. As shown in FIG. 1, the engine 1 has a cylinder block 2 at the top of the main body and a crankcase 5 at the bottom. The cylinder block 2 forms a cylinder 2a in the vertical direction in the center of the inside, and houses the piston 4. A chamber surrounded by the cylinder 2 a, the piston 4 and the cylinder head 6 is a combustion chamber 40. A communication passage 41 of the present invention is provided in a side portion of the cylinder 2a in parallel with the axis of the cylinder 2a, and communicates the inside of the crankcase 5 with the combustion chamber 40 in the cylinder 2a. The upper end of the communication passage 41 is provided with an opening 41 a on the side surface above the upper end at the lowest point of the piston 4 toward the combustion chamber 40. The lower end opens toward the upper part of the crankcase 5. Thus, the opening is provided at the time of engine exhaust, expansion, and end of intake. A crankshaft 3 is supported on the crankcase 5, and the piston 4 and the crankshaft 3 are connected by a connecting rod 17. The upper part of the cylinder block 2 is covered with a cylinder head 6, and the upper part of the cylinder head 6 is covered with a bonnet 7 to constitute a valve arm chamber. A muffler 8 is disposed on one side of the bonnet 7 (left side in FIG. 1), and a fuel tank 9 is disposed on the other side (right side in FIG. 1).

  A governor 11 is disposed on the side of the crankcase 5 below the cylinder block 2 and interlocked with the governor lever, and a fuel injection pump 12 is disposed above the governor lever. The gear 50 that is externally fitted to the crankshaft 3 and the cam gear 51 that is externally fitted to the camshaft 13 mesh with each other. The pump drive cam 14 formed in the middle portion of the cam shaft 13 is in contact with a roller 80 that is a rolling element provided at one end of the plunger 84 of the fuel injection pump 12. Therefore, when the crankshaft 3 rotates, the camshaft 13 also rotates, and the plunger 84 of the fuel injection pump 12 slides to suck in fuel stored in the fuel tank 9, and at the same time, the fuel injection nozzle via the high-pressure pipe 19. A predetermined amount of fuel is supplied to 30 at a predetermined timing. The fuel supply amount of the fuel injection pump 12 is configured to be adjustable by rotating the control lever 34. The control lever 34 is interlocked and connected to the governor 11, and the governor 11 operates when power is transmitted to the governor gear 53 meshed with the cam gear 51. The rotating shaft of the governor gear 53 also has a function of driving a pump for circulating the lubricating oil in the crankcase 5.

  An intake cam 21 and an exhaust cam 22 are formed on the cam shaft 13 with the pump drive cam 14 interposed therebetween. The lower end of the intake push rod 23 and the exhaust push rod 24 are connected to the intake cam 21 and the exhaust cam 22. Are in contact with the lower end of each. A push rod chamber 60 for accommodating the intake push rod 23 and the exhaust push rod 24 is formed across the cylinder block 2, the cylinder head 6 and the bonnet 7.

  The upper ends of the intake push rod 23 and the exhaust push rod 24 are brought into contact with the lower ends on one side of the intake valve arm 25 and the exhaust valve arm 26, respectively, and the intake valves 27 are respectively connected to the lower ends on the other side of the intake valve arm 25 and the exhaust valve arm 26. And the upper end of the exhaust valve 28 are in contact with each other. Middle portions of the intake valve arm 25 and the exhaust valve arm 26 are rotatably supported by support members 31 and 31 fixed on the cylinder head 6. The support members 31 are disposed on both front and rear sides with the fuel injection nozzle 30 in between.

  As shown in FIGS. 2 and 3, the intake valve 27 and the exhaust valve 28 are disposed above the piston 4. The intake valve 27 (exhaust valve 28) includes a valve head 27a (28a) at the lower end and a valve rod 27b (28b) at the body. The valve rod 27b (28b) protrudes toward the bonnet 7 through the cylinder block 6 so as to be slidable. The valve head 27a (28a) is configured to be able to be seated and separated with respect to a valve seat formed on the lower surface of the cylinder head 6 by the sliding of the intake valve 27 and the exhaust valve 28 in the axial direction. The cylinder 2 a formed in the cylinder block 2 and the intake port 6 a (exhaust port 6 b) formed in the cylinder head 6 can be communicated and blocked. In the bonnet 7, a spring 32 (32) is fitted on the valve rod 27 b (28 b) to urge the intake valve 27 (exhaust valve 28) to slide upward, and the intake valve 27 (exhaust valve 28). ) Is closed. The intake port 6 a communicates with the air cleaner 70 via the intake manifold 71, and the exhaust port 6 b communicates with the muffler 8 via the exhaust manifold 72.

  Next, a configuration for supplying fuel to the fuel injection pump 12 will be described. A fuel tank 9 is disposed at the upper part of the main body of the engine 1, and a fuel outlet 9 a is provided at the lower part of the fuel tank 9. One end of a hose 73 is connected to the fuel outlet 9a, and the other end is connected to a suction portion 89 of the fuel injection pump 12. The fuel filter 16 is provided in the fuel tank 9, and the fuel that has passed through the fuel filter 16 is sent from the fuel outlet 9a to the fuel injection pump 12 through the hose 73. The discharge part 90 of the fuel injection pump 12 is communicated with the fuel injection nozzle 30 via the high-pressure pipe 19.

  Next, an EGR apparatus that is Embodiment 1 of the present invention will be described. As described above, the communication passage 41 is provided in the vertical direction on the side of the cylinder 2a of the cylinder block 2 so that the inside of the crankcase 5 and the combustion chamber 40 are connected in the exhaust stroke, the expansion stroke, and the late stage of the intake stroke in the combustion cycle. An opening 41a provided at the upper end of the communication path 41 is formed on the side surface of the vertically middle part of the cylinder 2a so as to communicate with each other. That is, the combustion stroke will be described with reference to FIG. 4. FIG. 4A is a transition period from a compression stroke to an expansion stroke, FIG. 4B is an initial stage of an exhaust stroke, FIG. 4C is a transition period from an exhaust stroke to an intake stroke, and FIG. It is the latter period. In the compression stroke, the piston 4 rises with both the intake valve 27 and the exhaust valve 28 closed, the air in the cylinder 2a is compressed, and the temperature rises rapidly above the fuel ignition point. When the piston 4 rises to the state shown in FIG. 4A, fuel is injected from the fuel injection nozzle 30, the fuel burns, and the pressure in the cylinder 2a increases rapidly. In the expansion stroke, the piston 4 is pushed down by the increase in the internal pressure of the cylinder 2a. When the piston 4 is lowered to the state shown in FIG. 4B, the exhaust valve 28 is opened by the exhaust stroke, and the exhaust gas whose pressure is greater than the atmospheric pressure is discharged to the exhaust manifold 72 (path a). In the later stage of the expansion stroke and the early stage of the exhaust stroke, the piston 4 descends to open the opening 41a at the upper end of the communication passage 41 connecting the inside of the crankcase 5 and the combustion chamber 40, and a part of the exhaust gas passes through the communication passage 41 (path b). It is discharged into the crankcase. When the piston 4 rises and the opening 41a is closed and rises to the state shown in FIG. 4C, the exhaust gas discharge is finished, and the intake valve 27 is opened as an intake stroke. Thereafter, the pressure in the cylinder 2a becomes equal to or lower than the atmospheric pressure due to the lowering of the piston, and air is sucked from the intake manifold 71 (path c). In the latter half of the intake stroke, the opening 41a at the top of the communication passage 41 is opened by the lowering of the piston 4, and the exhaust gas in the crankcase 5 can be supplied to the combustion chamber from the communication passage 41 (path d). Since the exhaust gas is an inert gas (with a small amount of oxygen), mixing with the intake air from the path c makes it possible to lower the combustion temperature in the combustion chamber and to reduce NOx. be able to.

  As described above, the EGR device has a simple structure, and a part of the exhaust gas is discharged from the combustion chamber 40 into the crankcase 5 during the exhaust stroke, and the exhaust gas is discharged from the crankcase 5 into the combustion chamber during the intake stroke. 40 can be supplied. Further, the communication passage 41 can be manufactured at the same time when the cylinder block 2 is created, and an EGR device can be configured at a low cost without adding new parts, and the EGR device can be formed without changing the layout outside the engine 1. Therefore, there is no problem when the engine 1 is installed. Furthermore, since the breather can be recirculated from the crankcase 5 to the combustion chamber together with the exhaust gas, the cost for the breather can be reduced by reducing the number of breather parts. The exhaust gas to be recirculated becomes a part of the latter part of the exhaust stroke and has a temperature lower than that of the conventional one, so that it does not need to be cooled and efficiency is improved.

  Next, an EGR apparatus that is Embodiment 2 of the present invention will be described with reference to FIG. A to D in FIG. 5 are the same steps as in FIG. In the EGR device of the second embodiment, the communication path 41 is arranged on the side of the cylinder 2a as in the first embodiment. As a difference from the above, the camshaft 13 is disposed in the middle of the communication path 41. A cam chamber 42 is formed in the middle of the communication passage 41, and a valve body 43 is provided on the cam shaft 13 in the cam chamber 42. The valve body 43 is rotated by the rotation of the camshaft 13 to open and close the communication path 41. That is, as in the first embodiment, the exhaust gas discharged to the communication passage 41 at the later stage of the expansion stroke and the early stage of the exhaust stroke is sent to the cam chamber 42 provided between the combustion chamber 40 and the crankcase 5. The cam chamber 42 is provided with a valve body 43 provided on the cam shaft 13 that is rotationally driven by the crankshaft 3, and the valve body 43 is provided with a concave groove 44. The groove 44 is formed in a crescent shape so that the inlet side and the outlet side of the communication path 41 can communicate with each other at the shortest distance, and at least one of the communication paths 41 is closed at other rotational positions of the cam shaft 13. . Further, as shown in FIG. 5D, a breather path 45 that communicates the inside of the crankcase 5 and the intake manifold 71 is provided. However, the breather path 45 can also be used as the push rod chamber 60. Since the camshaft 13 is configured to rotate once while the crankshaft 3 rotates twice, the groove range of the groove 44 of the valve body 43 is set to be less than 180 ° from the shaft center and is opened only during the exhaust stroke. It is configured as follows. Therefore, a part of the exhaust gas sent from the combustion chamber 40 in the exhaust stroke passes through the communication passage 41 and the groove 44 (path b) and is sent into the crankcase 5. Further, it passes through a breather path 45 (path d) communicating from the crankcase 5 to the intake side, is mixed with intake air from the intake manifold 71 (path c), and is sucked into the combustion chamber 40 again in the intake stroke. In the present embodiment, since the groove portion 44 is opened only in the exhaust stroke, exhaust gas does not flow back through the communication passage 41 in the intake stroke or the compression stroke, but the groove range of the groove portion 44 is 180 ° or more. As a result, the groove 44 can also be used for intake and exhaust.

  As described above, the EGR device is configured with a simple structure, and a part of the exhaust gas is discharged from the combustion chamber 40 into the crankcase 5 during the exhaust stroke, and the exhaust gas is discharged through the breather path 45 during the intake stroke. Thus, it can be supplied to the combustion chamber 40 from the intake side. Further, the amount of exhaust gas to be recirculated can be adjusted by the shape of the valve body 43.

  Next, an EGR apparatus that is Embodiment 3 of the present invention will be described with reference to FIG. A to D in FIG. 6 are the same steps as in FIG. In the EGR device of the third embodiment, the communication passage 41 and the cam chamber 42 are configured in substantially the same manner as in the second embodiment, but the notch position of the groove portion 44 of the valve body 43 is different, and the valve body 43 is only in the intake stroke. Configured to open. Further, an exhaust passage 46 is provided between the exhaust manifold 72 and the crankcase 5 so as to communicate therewith, and exhaust gas can be drawn into the crankcase 5 from the exhaust manifold 72 via the exhaust passage 46. That is, a part of the exhaust gas discharged from the combustion chamber 40 in the exhaust stroke is sent from the exhaust manifold 72 into the crankcase 5 through the exhaust passage 46 (path a). Then, the air is again sucked into the combustion chamber 40 from the communication passage 41 and the groove 44 (path b) opened in the intake stroke.

  As described above, the EGR device has a simple structure, and a part of the exhaust gas is discharged from the combustion chamber 40 into the crankcase 5 using the exhaust passage 46 in the exhaust stroke, and the exhaust is discharged in the intake stroke. The communication passage 41 can be used to supply the combustion chamber 40. Further, the amount of exhaust gas to be recirculated can be adjusted by the shape of the valve body 43. In addition, breather parts can be eliminated.

  Next, an EGR device according to Embodiment 4 of the present invention will be described with reference to FIG. A to D in FIG. 7 are the same steps as in FIG. The EGR device of the fourth embodiment is provided with a cooler 47 for cooling the exhaust gas to be recirculated, and a communication passage 48 that communicates the cooler 47 and the combustion chamber 40. The opening on the combustion chamber 40 side at one end of the communication passage 48 is disposed at a position that opens at the later stage of the exhaust stroke, the expansion stroke, and the intake end stroke in the combustion cycle, and the cam chamber 42 is placed in the middle of the communication passage 48. A valve body 43 that is formed and opened only in the exhaust stroke is housed in the cam chamber 42 with a groove 44 formed in the same manner as described above. One end of the cooler 47 communicates with the cam chamber 42, and the other end communicates with an exhaust passage 49 communicating with the intake manifold 71. The cooler 47 is cooled by cooling water from a radiator or air cooling, and may be configured integrally with the cylinder block 2 or may be disposed separately from the cylinder block 2. In the exhaust stroke, the exhaust gas is sent from the combustion chamber 40 to the cooler 47 through the communication passage 48 and the groove 44 (path b), and after being cooled, the exhaust gas passes through the exhaust passage 49 and the intake manifold 71 (path c) and is taken into the intake air. In the stroke, it is sucked again into the combustion chamber 40.

  As described above, the EGR device is configured with a simple structure, and a part of the exhaust gas is discharged from the combustion chamber into the cooler 47 in the exhaust stroke to cool the exhaust gas. In the intake stroke, exhaust can be supplied from the cooler 47 to the intake manifold 71. Therefore, the EGR device can be configured by adding a small number of members, and the cost can be reduced. Further, the exhaust gas to be recirculated becomes a part of the latter part of the exhaust stroke and has a lower temperature than that of the conventional one, so that it does not need to be cooled and efficiency is improved. Furthermore, since the exhaust gas is cooled by the cooler 47, the intake side does not become hot, and safety can be further improved.

  Next, an EGR device according to Embodiment 5 of the present invention will be described with reference to FIG. A to D in FIG. 8 are the same steps as in FIG. The EGR device according to the fifth embodiment has substantially the same configuration as that of the fourth embodiment except that the notch position of the groove portion 44 of the valve body 43 is different, the valve body 43 is configured to open only during the intake stroke, and further, the exhaust manifold An exhaust passage 54 for drawing exhaust gas from 72 to the other end of the cooler 47 is communicated. Thus, a part of the exhaust gas discharged from the combustion chamber 40 in the exhaust stroke is sent from the exhaust manifold 72 to the cooler 47 through the exhaust passage 54 (path b). Then, the air is again sucked into the combustion chamber 40 from the communication passage 48 and the groove 44 (path d) opened in the intake stroke.

  As described above, the EGR device has a simple structure, and a part of the exhaust gas is discharged from the exhaust manifold 72 into the cooler 47 in the exhaust stroke, and the exhaust gas is supplied from the cooler 47 to the combustion chamber 40 in the intake stroke. It becomes possible to do. Therefore, the EGR device can be configured by adding a small number of members, and the cost can be reduced. Further, the exhaust gas to be recirculated becomes a part of the latter part of the exhaust stroke and has a lower temperature than that of the conventional one, so that it does not need to be cooled and efficiency is improved. Furthermore, since the exhaust gas is cooled by the cooler 47, the intake side does not become hot, and safety can be further improved.

  Next, an EGR apparatus according to Embodiment 6 of the present invention will be described with reference to FIG. A to D in FIG. 9 are the same steps as in FIG. In the EGR device according to the sixth embodiment, the communication path 48 does not pass through the cam shaft 13 but passes through the upper part thereof and is in communication with the cooler 47. A valve body 55 driven by the camshaft 13 that is rotationally driven by the crankshaft 3 is disposed in the middle of the communication path 48, and the communication path 48 is opened and closed by being driven up and down. It is composed. The valve body 55 is urged in the closing direction by a spring interposed in the upper portion, and is configured to be pushed up and opened by the camshaft 13 only in the exhaust stroke. Further, an exhaust passage 49 communicating with the intake manifold 71 is provided at the other end of the cooler 47. The exhaust gas is sent from the combustion chamber 40 to the cooler 47 through the communication passage 48 and the valve body 55 (path b) in the exhaust stroke, and then from the exhaust passage 49 through the intake manifold 71 to the exhaust passage 49 (path) in the intake stroke. from c) to the combustion chamber 40 again.

  As described above, the EGR device has a simple structure, and a part of the exhaust gas is discharged from the combustion chamber 40 into the cooler 47 in the exhaust stroke, and the exhaust gas is supplied from the cooler 47 to the intake manifold 71 in the intake stroke. It becomes possible to do. Therefore, the EGR device can be configured by adding a small number of members, and the cost can be reduced. Further, since the exhaust gas is cooled by the cooler 47, the intake side does not become hot, and safety can be further improved.

  Next, an EGR apparatus according to Embodiment 7 of the present invention will be described with reference to FIG. A to D in FIG. 10 are the same steps as in FIG. The EGR device of the seventh embodiment has substantially the same configuration as the EGR device of the sixth embodiment, and an exhaust passage 54 communicates with an exhaust manifold 72 instead of the exhaust passage 49. The valve body 55 is configured to open only during the intake stroke, and exhaust gas is drawn into the cooler 47 from the exhaust manifold 72 through the exhaust passage 54. A part of the exhaust gas discharged from the combustion chamber 40 in the exhaust stroke is sent from the exhaust manifold 72 to the cooler 47 through the exhaust passage 54 (path b). Then, the air is again drawn into the combustion chamber 40 from the communication passage 48 and the valve body 55 (path d) opened in the intake stroke.

  As described above, the EGR device is configured with a simple structure, and a part of the exhaust gas is discharged from the exhaust manifold 72 into the cooler 47 in the exhaust stroke, and the exhaust is supplied from the cooler 47 to the combustion chamber 40 in the intake stroke. Is possible. Therefore, the EGR device can be configured by adding a small number of members, and the cost can be reduced. Further, since the exhaust gas is not recirculated to the intake side, the intake side does not become hot, and safety can be further improved.

  Next, an EGR device according to an eighth embodiment of the present invention will be described with reference to FIG. A to D in FIG. 11 are the same steps as in FIG. The EGR device of the eighth embodiment is a modification of the fourth and fifth embodiments, and the configuration of the valve body 43 provided on the camshaft 13 is different, and the cooler 47 is not connected to the intake manifold 71 and the exhaust manifold 72. That is, the middle of the communication passage 48 that communicates between the cylinder 2a and the cooler 47 passes through the cam chamber 42, and the valve body 43 provided on the cam shaft 13 is disposed in the cam chamber 42. A communication hole 56 is provided. Thus, the recirculated exhaust gas is temporarily stored in the cooler 47 and cooled. The opening of the combustion chamber 40 that communicates with the communication passage 48 is disposed at a position that is opened at the later stage of the exhaust stroke, the expansion stroke, and the intake stroke in the combustion cycle. The communication hole 56 is provided so as to open only during the exhaust and intake strokes. The exhaust gas is sent from the combustion chamber 40 to the cooler 47 through the communication passage 48 and the communication hole 56 (path b) in the exhaust stroke. Thereafter, the air is sucked into the combustion chamber 40 again through the communication hole 56 and the communication path 48 (path d) in the intake stroke.

  As described above, the EGR device is configured with a simple structure, and a part of the exhaust gas is discharged from the combustion chamber 40 into the cooler 47 in the exhaust stroke, and the exhaust is supplied from the cooler 47 to the combustion chamber 40 in the intake stroke. Is possible. Therefore, there is no need to communicate the exhaust side and the intake side, so the number of parts can be reduced and the cost can be reduced. Further, since the exhaust gas is not recirculated to the intake side, the intake side does not become hot, and safety can be further improved.

  Next, an EGR apparatus according to Embodiment 9 of the present invention will be described with reference to FIG. In the EGR device according to the ninth embodiment, in the second, third, fourth, fifth, and eighth embodiments, there is a possibility that lubricating oil may accumulate in the cam chamber 42 that accommodates the valve body. An oil drain hole 57 is provided extending downward from the lower end of the cam chamber 42. A groove 57 a is provided at the upper end of the oil drain hole 57 on the front side in the rotation direction of the valve body 43. Thereby, excess lubricating oil can be efficiently scraped off from the valve body 43, and the flow of the exhaust gas in the groove part 44 can be made smooth.

  Next, the structure of the EGR device in Embodiment 10 of the present invention will be described with reference to FIG. In the EGR device of the tenth embodiment, the opening on the combustion chamber 40 side communicating with the communication passage 41 or 48 in the second, third, fourth, fifth, and eighth embodiments is vertically arranged on the contact surface with the piston 4 of the cylinder block 2. The groove 58 is formed. Thereby, by forming the groove portion 58 in the cylinder block 2 in advance, it is possible to eliminate the hole processing, reduce the processing steps, and reduce the cost.

  Next, an EGR apparatus according to Embodiment 11 of the present invention will be described with reference to FIG. In the EGR device according to the eleventh embodiment, a cylindrical member 59 in which a communication hole 61 is opened in a portion of the groove portion 58 is disposed in a portion of the groove portion 58 that contacts the piston 4. That is, a sleeve is fitted as a cylindrical member 59 in the cylinder 2a, and the communication hole 61 is opened at a position that opens in the later stage of the exhaust stroke, the expansion stroke, and the intake stroke in the combustion cycle. The communication path is formed by the sleeve. Thereby, the gas leak from the ring of the piston 4 surface etc. can be prevented.

1 is a front sectional view showing a diesel engine that is an embodiment of the present invention. 1 is a side cross-sectional view showing a diesel engine according to an embodiment of the present invention. The other side surface sectional view showing the diesel engine which is one embodiment of the present invention. Schematic which showed the operation process of the diesel engine which concerns on the present Example 1. FIG. A is the transition period from the compression stroke to the expansion stroke, B is the initial stage of the exhaust stroke, C is the transition period from the exhaust stroke to the intake stroke, and D is the late stage of the intake stroke. Schematic which showed the operation process of the diesel engine which concerns on the present Example 2. FIG. Schematic which showed the operation process of the diesel engine which concerns on the present Example 3. FIG. Schematic which showed the operation process of the diesel engine which concerns on the present Example 4. FIG. Schematic which showed the operation process of the diesel engine which concerns on the present Example 5. FIG. Schematic which showed the operation process of the diesel engine which concerns on the present Example 6. FIG. FIG. 10 is a schematic diagram illustrating an operation stroke of a diesel engine according to the seventh embodiment. Schematic which showed the operation process of the diesel engine which concerns on the present Example 8. FIG. Schematic which showed the structure of the diesel engine which concerns on the present Example 9. FIG. Schematic which showed the structure of the diesel engine which concerns on the present Example 10. FIG. Schematic which showed the structure of the diesel engine which concerns on the present Example 11. FIG.

DESCRIPTION OF SYMBOLS 1 Engine 2a Cylinder 3 Crankshaft 4 Piston 5 Crankcase 13 Camshaft 27 Intake valve 28 Exhaust valve 40 Combustion chamber 41 Communication path 42 Cam chamber 43 Valve body 44 Communication hole 47 Cooler

Claims (6)

  A communication passage that connects the inside of the crankcase and the combustion chamber is provided, and the opening of the combustion chamber that communicates with the communication passage is provided at a position that opens at the later stage of the exhaust stroke, the expansion stroke, and the intake stroke in the combustion cycle. An exhaust gas recirculation device for a four-cycle engine.   A cam chamber is provided in the middle of the communication path, a valve body is disposed on the cam shaft that is rotationally driven by a crankshaft in the cam chamber, and the communication path is opened only by an exhaust stroke by the valve body. The exhaust gas recirculation device for a four-stroke engine according to claim 1, further comprising a breather path that communicates the inside of the crankcase with the intake side.   A cam chamber is provided in the middle of the communication path, a valve body is disposed on the cam shaft that is rotationally driven by the crankshaft in the cam chamber, and the communication path is opened only by the valve body during the intake stroke. The exhaust gas recirculation device for a four-cycle engine according to claim 1, further comprising an exhaust passage communicating with the exhaust manifold in the crankcase. An oil drain hole communicating with the cam chamber and the inside of the crankcase is provided to extend downward, and a groove is formed on the cam chamber side of the oil drain hole on the front side in the rotation direction of the valve body. 4. An exhaust gas recirculation device for a 4-cycle engine according to 3 . The exhaust gas recirculation device for a four-cycle engine according to claim 2 or 3, wherein the communication path is configured by a piston and a groove formed in a contact surface between the piston of the cylinder block . The exhaust gas recirculation device for a four-stroke engine according to claim 5, wherein a cylindrical member is disposed in a portion of the groove portion that contacts the piston .