JP5655711B2 - Internal combustion engine - Google Patents

Description

  The present invention relates to an internal combustion engine.

  In order to cancel the vibration generated in the internal combustion engine, a technique for installing a balancer below the crankshaft in the crankcase is known (for example, see Patent Document 1).

  By the way, since the volume in the crankcase fluctuates due to the reciprocation of the piston, pressure pulsation occurs in the crankcase. For this reason, the pressure in a crankcase may become atmospheric pressure or more, and it may become difficult to introduce fresh air into a crankcase. Further, if the pressure in the crankcase is lower than the pressure in the intake passage, it may be difficult to suck the blowby gas from the crankcase.

JP 2006-144616 A International Publication No. 2009/122616 JP 2005-240792 A

  An object of this invention is to suppress the pulsation of the pressure in a crankcase.

In order to achieve the above object, an internal combustion engine according to the present invention provides:
In an internal combustion engine having a balancer shaft that rotates in conjunction with a crankshaft provided in a crankcase chamber of the internal combustion engine,
A balancer weight provided eccentrically on the balancer shaft;
A partition wall that encloses the rotation path of the balancer weight and seals the balancer weight;
An opening that communicates with the space that is inside the partition and in which the balancer weight is not present, and the crankcase chamber outside the partition; and
With
When the volume in the crankcase chamber is greater than or equal to a predetermined value, the balancer weight closes the opening to block communication between the space and the crankcase chamber, and the volume in the crankcase chamber is less than the predetermined value. Sometimes, the balancer weight opens the opening to communicate the space with the crankcase chamber.

  The balancer weight rotates inside the partition wall. Since the balancer weight is provided eccentrically with respect to the balancer shaft, the balancer weight is surrounded by a partition wall so as to be rotatable, so that the space where no balancer weight exists is filled with gas. The balancer weight is at least in contact with the partition wall around the opening. At this time, the balancer weight covers the opening to close the opening. At this time, no gas enters and exits inside the crankcase chamber and inside the partition wall. On the other hand, when the balancer weight is separated from the opening, the opening is opened and the space and the crankcase chamber communicate with each other. For this reason, gas flows from the higher pressure to the lower pressure in the space and the crankcase chamber. In this way, the balancer weight rotates to open and close the opening.

  Here, when the opening is open, gas can flow from the crankcase chamber to the space. For this reason, the volume in the crankcase chamber is apparently large by the amount corresponding to the space portion. By the way, when the volume in the crankcase chamber changes due to the reciprocation of the piston, there is a possibility that pressure pulsation occurs. On the other hand, by opening the opening when the volume in the crankcase chamber is less than the predetermined value, it is possible to suppress an increase in pressure, and thus it is possible to suppress the occurrence of pressure pulsation. That is, the predetermined value can be a volume in the crankcase chamber where pressure pulsation can occur in the crankcase chamber. In this way, the opening and closing of the opening according to the volume in the crankcase chamber can suppress the occurrence of pressure pulsation.

  In the present invention, the balancer weight opens the opening when the piston of the internal combustion engine is at the bottom dead center side relative to the middle between the top dead center and the bottom dead center, and when the balancer weight is on the top dead center side. The opening can be closed.

  That is, the predetermined value is the volume in the crankcase chamber when the piston is positioned between the top dead center and the bottom dead center. When the piston is positioned between the top dead center and the bottom dead center, the pressure in the crankcase chamber is close to the average value of the pressures. And this average value is substantially equal to atmospheric pressure. That is, the pressure in the crankcase chamber is negative when the piston is at the top dead center side than when the piston is positioned in the middle, and is positive when the piston is at the bottom dead center side. And it can suppress that the pressure in a crankcase chamber becomes too high by opening an opening part when the pressure in a crankcase chamber becomes a positive pressure.

In the present invention, provided with a blow-by gas discharge passage communicating the space portion and the intake passage of the internal combustion engine,
The balancer weight opens the discharge passage when the piston of the internal combustion engine is at the bottom dead center side from the middle between the top dead center and the bottom dead center, and opens the discharge passage when the piston is at the top dead center side. Can be closed.

  The blowby gas is discharged from the crankcase chamber to the intake passage through the blowby gas discharge passage when the pressure in the crankcase chamber is higher than the pressure in the intake passage. However, if the blow-by gas discharge passage is open when the pressure in the crankcase chamber is lower than the pressure in the intake passage, the blow-by gas flows backward. On the other hand, when the piston of the internal combustion engine is on the top dead center side with respect to the middle between the top dead center and the bottom dead center, the balancer weight closes the discharge passage, thereby suppressing the backflow of blow-by gas.

  According to the present invention, pulsation of pressure in the crankcase can be suppressed.

It is a figure which shows schematic structure of the internal combustion engine which concerns on an Example. It is the figure which showed the relationship between a weight, an opening part, and a discharge part. It is the figure which showed the relationship between a weight, an opening part, and a discharge part. It is the figure which showed the relationship between a weight, an opening part, and a discharge part. It is the figure which showed the relationship between a weight, an opening part, and a discharge part. It is the figure which showed the relationship between a weight, an opening part, and a discharge part. It is the figure which showed the relationship between a weight, an opening part, and a discharge part. It is the figure which showed the relationship between a weight, an opening part, and a discharge part. It is the figure which showed the relationship between a weight, an opening part, and a discharge part. It is the figure which showed transition of the pressure in a crankcase chamber with respect to a crank angle.

  Hereinafter, specific embodiments of the internal combustion engine according to the present invention will be described with reference to the drawings.

<Example 1>
FIG. 1 is a diagram illustrating a schematic configuration of an internal combustion engine according to the present embodiment. The internal combustion engine 1 shown in FIG. 1 is a four-stroke engine having two cylinders. The present embodiment can be similarly applied to a diesel engine or a gasoline engine.

  Each cylinder of the internal combustion engine 1 is provided with a piston 2 that reciprocates. The piston 2 is connected to the crankshaft 4 by a connecting rod 3.

  The crankshaft 4 is provided in the crankcase chamber 11. Further, a balancer 5 for suppressing vibration is provided in the crankcase chamber 11. The balancer 5 includes a shaft 51 serving as a center of rotation, a weight 52 eccentric from the shaft 51, a partition wall 53 surrounding the weight 52, an opening 54 communicating the inside and outside of the partition wall 53, and gas inside the partition wall 53. A discharge portion 55 serving as an outlet when discharging to the outside of the crankcase chamber 11 is provided. Further, in the partition wall 53, a space portion 56 filled with gas is formed at a location where the shaft portion 51 and the weight 52 do not exist.

  The shaft portion 51 is arranged so that the central axis thereof is parallel to the central axis of the crankshaft 4. The shaft portion 51 rotates in the direction opposite to the crankshaft 4 in conjunction with the crankshaft 4. In FIG. 1, while the crankshaft 4 makes one round by right rotation, the shaft portion 51 makes one round by left rotation. In this embodiment, the shaft portion 51 corresponds to the balancer shaft in the present invention.

  The weight 52 rotates integrally with the shaft portion 51 around the central axis of the shaft portion 51. The inner wall of the partition wall 53 is formed so as to be in contact with the outer peripheral surface along the outer peripheral surface of the rotation locus of the weight 52. Note that the weight 52 and the partition wall 53 may be in contact with each other at least around the opening 54 and around the discharge portion 55.

  As the weight 52 rotates, the space portion 56 also rotates around the central axis of the shaft portion 51. In this embodiment, the weight 52 corresponds to the balancer weight in the present invention.

  The opening 54 is provided at a position where the outer peripheral surface of the rotation locus of the weight 52 contacts the partition wall 53. As the shaft portion 51 rotates, the weights 52 and the space portions 56 are alternately in contact with the openings 54. And when the weight 52 covers the opening part 54, the opening part 54 is closed and the distribution | circulation of the gas through this opening part is interrupted | blocked. On the other hand, when the weight 52 is separated from the opening 54, the opening 54 is opened, and the space 56 and the crankcase chamber 11 are communicated with each other, so that gas can be circulated through the opening 54. In this way, the opening 54 is opened and closed as the weight 52 rotates. That is, the weight 52 serves as a valve that opens and closes the opening 54.

  The discharge part 55 is connected to the intake passage 7 of the internal combustion engine 1 through the PCV passage 6. The PCV passage 6 is a passage for blow-by gas when the blow-by gas in the crankcase chamber 11 is discharged to the intake passage. The PCV passage 6 is connected to the downstream side of the throttle 71 provided in the intake passage 7. The discharge part 55 is opened and closed by the weight 52 in the same manner as the opening part 54. In this embodiment, the PCV passage 6 corresponds to the blow-by gas discharge passage in the present invention.

  Further, a fresh air supply passage 72 that connects the intake passage 7 upstream of the throttle 71 and the inside of the cylinder head chamber 12 of the internal combustion engine 1 is provided. The fresh air supplied into the cylinder head chamber 12 through the fresh air supply passage 72 flows through the internal combustion engine 1 and reaches the crankcase chamber 11.

  In this embodiment, the weight 52, the opening 54, and the discharge portion 55 are formed so as to have the following relationship with respect to the rotation angle of the crankshaft 4.

  Here, FIG. 2-9 is a diagram illustrating the relationship between the weight 52, the opening 54, and the discharge portion 55. 2 shows when the piston 2 is located at the top dead center, FIG. 3 shows when the rotation angle of the crankshaft 4 is 45 degrees after the top dead center of the piston 2, and FIG. 4 shows the rotation angle of the crankshaft 4 FIG. 5 shows a case where the rotation angle of the crankshaft 4 is 135 degrees after the top dead center of the piston 2, and FIG. 6 shows a case where the rotation angle of the crankshaft 4 is 135 degrees after the top dead center of the piston 2. FIG. 7 shows the case where the rotation angle of the crankshaft 4 is 215 degrees after the top dead center of the piston 2, and FIG. FIG. 9 shows a case where the rotation angle is 270 degrees after the top dead center of the piston 2, and FIG. 9 shows a case where the rotation angle of the crankshaft 4 is 315 degrees after the top dead center of the piston 2.

  The volume in the crankcase chamber 11 can change by the stroke volume of the piston and the volume in the space 56.

  As shown in FIG. 2, when the piston 2 is at the top dead center, the volume in the crankcase chamber 11 is large. Here, as the piston 2 rises, the pressure in the crankcase chamber 11 becomes negative. At this time, the opening portion 54 and the discharge portion 55 are closed by the weight 52. By doing in this way, it can control that blow-by gas in partition 53 and PCV passage 6 flows backward.

  As shown in FIG. 3, when the piston 2 starts to descend, the volume in the crankcase chamber 11 is reduced, so that the gas in the crankcase chamber 11 is compressed. As a result, the pressure in the crankcase chamber 11 begins to rise, but is still in a negative pressure state. Also at this time, the opening 54 and the discharge portion 55 are closed by the weight 52. By doing in this way, it can control that blow-by gas in partition 53 and PCV passage 6 flows backward.

  As shown in FIG. 4, when the piston 2 moves to an intermediate position between the top dead center and the bottom dead center, the volume in the crankcase chamber 11 is further reduced, so that the pressure in the crankcase chamber 11 is further increased. To do. For this reason, the pressure in the crankcase chamber 11 becomes substantially equal to the atmospheric pressure. The opening 54 is opened when the pressure in the crankcase chamber 11 becomes substantially equal to the atmospheric pressure. As a result, the space 56 and the crankcase chamber 11 communicate with each other, so that the volume in the crankcase chamber 11 is apparently increased by the space 56.

As shown in FIG. 5, when the piston 2 descends further to the bottom dead center side than the intermediate position between the top dead center and the bottom dead center, the crankcase chamber is maintained even when the opening 54 is open. 11 starts to become higher than atmospheric pressure. Thus, when the pressure in the crankcase chamber 11 becomes higher than the atmospheric pressure, the discharge part 55 is opened. Here, since the pressure in the intake passage 7 on the downstream side of the throttle 71 is lower than the atmospheric pressure, the pressure on the crankcase chamber 11 side of the PCV passage 6 is higher when the discharge portion 55 is opened. It is higher than the pressure on the passage 7 side. For this reason, in the PCV passage 6, blow-by gas flows from the crankcase chamber 11 side toward the intake passage 7 side. In addition, when the supercharger is provided, the pressure in the intake passage 7 can be higher than the pressure in the crankcase chamber 11. In this case, the pressure in the intake passage 7 becomes lower than the pressure in the crankcase chamber 11 by connecting the PCV passage 6 to the intake passage 7 upstream of the supercharger.

  As shown in FIG. 6, when the piston 2 reaches bottom dead center and then the piston 2 starts to rise as shown in FIG. 7, the volume in the crankcase chamber 11 starts to increase. As a result, the pressure in the crankcase chamber 11 starts to drop, but at this time, the pressure is still positive. At this time, since the opening portion 54 and the discharge portion 55 are opened, blow-by gas is continuously discharged to the intake passage 7 through the PCV passage 6.

  As shown in FIG. 8, when the piston 2 rises to an intermediate position between the top dead center and the bottom dead center, the pressure in the crankcase chamber 11 further falls and becomes substantially equal to the atmospheric pressure. Thus, the opening 54 is closed when the pressure in the crankcase chamber 11 becomes substantially equal to the atmospheric pressure. Thereby, it is possible to suppress the gas in the space 56 from flowing back into the crankcase chamber 11. At this time, if the discharge part 55 is opened, gas flows from the space part 56 to the intake passage 7, and the pressure in the space part 56 becomes negative.

  As shown in FIG. 9, when the piston 2 is further raised and the pressure in the crankcase chamber 11 is further lowered, the inside of the crankcase chamber 11 becomes negative pressure. At this time, since the opening portion 54 and the discharge portion 55 are closed, the blow-by gas does not flow back through the PCV passage 6 from the intake passage 7 side to the crankcase chamber 11 side.

  In this embodiment, the time when the opening 54 is opened, the time when the opening 54 is closed, the time when the discharge portion 55 is opened, the time when the discharge portion 55 is closed, and the shape of the weight 52 are set so as to obtain the above effect. That is, when the piston 2 is lowered, the opening 54 opens near the middle position between the top dead center and the bottom dead center, and when the piston 2 is raised, near the middle position between the top dead center and the bottom dead center. The opening 54 and the weight 52 are formed so that the opening 54 is closed. Similarly, when the piston 2 is lowered, the discharge portion 55 opens near the middle position between the top dead center and the bottom dead center, and when the piston 2 is raised, near the middle position between the top dead center and the bottom dead center. Thus, the discharge portion 55 and the weight 52 are formed so that the discharge portion 55 is closed.

  The opening 54 and the discharge part 55 may be set to open when the pressure in the crankcase chamber 11 is higher than the pressure in the intake passage 7. Further, these relationships may be obtained by experiments or the like.

  FIG. 10 is a diagram showing the transition of the pressure in the crankcase chamber 11 with respect to the crank angle. The solid line indicates the case of the internal combustion engine 1 according to the present embodiment, and the alternate long and short dash line indicates the case of the conventional internal combustion engine. The “average value” indicates an average value of the pressure in the crankcase chamber 11 in the case of the internal combustion engine 1 according to the present embodiment. Thus, in the internal combustion engine 1 according to the present embodiment, the pressure in the crankcase chamber 11 can be maintained lower than in the prior art. And the average value of the pressure in the crankcase chamber 11 can be made below atmospheric pressure. As a result, the blow-by gas in the crankcase chamber 11 can be efficiently discharged to the intake passage 7.

  As explained above, according to the present embodiment, the balancer 5 can be used to adjust the pressure in the crankcase chamber 11 and to discharge the blow-by gas. Thereby, the apparatus can be miniaturized. Further, since the balancer 5 is surrounded by the partition wall 53, it is possible to suppress the oil from being stirred by the balancer 5. Furthermore, a check valve for preventing the backflow of blow-by gas, which has been conventionally required, becomes unnecessary.

Further, even in an internal combustion engine such as a two-cylinder engine in which the pressure pulsation in the crankcase chamber 11 increases, it is possible to suppress the pressure pulsation, thereby promoting the discharge of blow-by gas. it can.

1 Internal combustion engine 2 Piston 3 Connecting rod 4 Crankshaft 5 Balancer 6 PCV passage 7 Intake passage 11 Crankcase chamber 12 Cylinder head chamber 51 Shaft portion 52 Weight 53 Partition wall 54 Opening portion 55 Discharge portion 56 Space portion 71 Throttle 72 Fresh air supply passage

Claims (2)

In an internal combustion engine having a balancer shaft that rotates in conjunction with a crankshaft provided in a crankcase chamber of an internal combustion engine in which the volume in the crankcase varies as the piston reciprocates ,
A balancer weight provided eccentrically on the balancer shaft;
A partition wall that encloses the rotation path of the balancer weight and seals the balancer weight;
An opening that communicates with the space that is inside the partition and in which the balancer weight is not present, and the crankcase chamber outside the partition; and
A blow-by gas discharge passage communicating the space and the intake passage of the internal combustion engine;
With
When the volume in the crankcase chamber is greater than or equal to a predetermined value, the balancer weight closes the opening to block communication between the space and the crankcase chamber, and the volume in the crankcase chamber is less than the predetermined value. the balancer weights to communicate between the crankcase chamber and the space portion by opening the opening when,
When the piston of the internal combustion engine is at the bottom dead center side with respect to the middle between the top dead center and the bottom dead center, the balancer weight passes through the discharge passage after the space portion communicates with the crankcase chamber. The balancer weight is opened when the piston of the internal combustion engine is on the top dead center side with respect to the middle between the top dead center and the bottom dead center, and after the communication between the space portion and the crankcase chamber is cut off. An internal combustion engine that closes the discharge passage .   The balancer weight opens the opening when the piston of the internal combustion engine is at the bottom dead center side from the middle between the top dead center and the bottom dead center, and opens the opening when the piston is at the top dead center side. The internal combustion engine according to claim 1.

Images