JP2008115727A - Dry sump engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress insufficient supply of oil in start, and also to suppress interference between a crankshaft or a counter weight and oil in a crank chamber, in a dry sump engine. <P>SOLUTION: In the dry sump engine, since an oil tank 3 has a housing chamber upper part 3a long in a vertical direction and is short in a vehicular lateral direction, the oil is stably supplied even if a gravity G in the lateral direction is received. The height of the oil level L4 in the crank chamber 11 during the stop is under the crankshaft 7 and the counter weight 8 to thereby suppress start resistance caused by interference (so-called oil hitting) between the crankshaft 7 or counter weight 8 and the oil. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a dry sump engine in which a crank chamber, an oil reservoir, and an oil tank are connected to move oil between them.

  Various dry sump engines have been proposed in which a crank chamber, an oil reservoir, and an oil tank are connected to move oil between them. For example, in the engine of Patent Document 1, an oil tank is disposed on the side portion of the crank chamber so as to reduce the size of the engine.

  On the other hand, as in the dry sump engine 301 of the prior art shown in FIG. 5, the oil outlet 303a from the oil tank 303 is disposed at the bottom of the oil tank 303, and the oil tank 303 is elongated in the vertical (vertical) direction. The structure to be known is known. This structure is advantageous in that the oil can be supplied stably even when subjected to the lateral G.

  However, in this structure, since the oil level in the oil tank 303 becomes high during operation of the engine (reference numeral L11), the oil in the oil tank 303 moves to the crank chamber 11 or flows backward while the engine is stopped. If the oil level in the oil tank 303 falls below a predetermined minimum level L13 due to this backflow, there is a risk of insufficient oil supply at the next start.

  Further, when the oil level in the crank chamber 11 becomes higher due to the reverse flow, the starting resistance increases due to interference between the crankshaft 7 or the counterweight 8 and the oil in the crank chamber 11 (so-called oil hitting). It can lead to defects. If the pressure control valve 340 is provided in the supply pipe 25 in order to suppress the back flow of the oil and the oil is allowed to pass only during the operation of the main pump 21, the load on the main pump 21 may increase.

  On the other hand, Patent Document 2 discloses a structure in which an oil tank is elongated in the traveling direction for a motorcycle.

JP-A-6-248927 Japanese Patent Laid-Open No. 4-265406

  However, the structure of Patent Document 2 is for a motorcycle, and the influence of the lateral G is not basically considered, and the height of the oil level in the crank chamber is not considered. Further, since the oil tank is arranged under the crank chamber, the installation height of the engine is high, and therefore the center of gravity of the vehicle is high.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a novel means capable of suppressing the shortage of oil supply at the start of a dry sump engine and suppressing the interference between the crankshaft or counterweight and the oil in the crank chamber.

  The present invention includes an oil reservoir disposed at a lower part of a crankcase, an oil tank disposed separately from the oil reservoir, a scavenge pump that transports oil from the oil reservoir to the oil tank, and the oil A dry sump engine having a main pump for transporting oil from the tank to the inside of the engine, wherein the oil tank has a storage chamber upper portion that is long in the vertical direction and a storage chamber lower portion that is long in the vehicle traveling direction, The oil level in the crank chamber when the engine is stopped is below the counterweight trajectory.

  Since the oil tank in the present invention has a short vehicle lateral direction, oil can be stably supplied even when the vehicle receives a lateral G. In addition, since the lower part of the oil tank storage chamber is long in the vehicle traveling direction, a large volume can be obtained, the height of the oil level in the oil tank can be suppressed, and the oil can be stabilized even when subjected to the lateral G. Can supply. Since the oil level in the crank chamber when the engine is stopped is below the counterweight trajectory, it is possible to suppress starting resistance due to interference between the counterweight and the oil in the crank chamber (so-called oil hitting).

  The main pump and scavenge pump in the present invention are preferably arranged at a position lower than the oil level in the crank chamber when the engine is stopped. In this case, the load and loss of the pump can be suppressed as compared with the case where the position of the pump is higher than the oil level in the crank chamber.

  Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, a dry sump engine 1 according to an embodiment of the present invention is a four-cycle gasoline engine, and includes an engine body 2 and an oil tank 3. The engine body 2 is a so-called vertical type, and includes four cylinders 4 arranged in series along the traveling direction, but FIG. 1 illustrates only one cylinder 4. A piston 5 is arranged in each cylinder 4 so as to be movable up and down, and the piston 5 is connected to a common crankshaft 7 via a connecting rod 6. A counterweight 8 is fixed to the crankshaft 7.

  The cylinder 4 is fixed on a crank upper case 9, a crank lower case 10 is fixed below the crank upper case 9, and a baffle plate 13 is installed as a partition between the crank upper case 9 and the crank lower case 10. . A crank chamber 11 is defined by the cylinder 4, the piston 5, the crank upper case 9 and the crank lower case 10. The bottom of the crank lower case 10 serves as an oil reservoir 12. The oil reservoir 12 is common to the four cylinders 4 and has a generally box-shaped internal shape whose longitudinal direction is parallel to the crankshaft 7. A baffle plate 13 is disposed outside the rotation locus of the crankshaft 7 and the counterweight 8 and between the oil reservoir. The baffle plate 13 allows the oil to be discharged due to the oil dropping through the numerous gaps, and suppresses the oil from jumping up from the oil reservoir 12.

  The oil tank 3 is disposed outside the crank chamber 11 and on the side of the crank chamber 11, and can store oil in a lower portion thereof. The oil tank 3 is connected to the main pump 21, and the oil collected in the oil tank 3 is transported by the main pump 21 to a predetermined lubrication point of the engine 1 through the cylinder block 20.

  The scavenge pipe 22 is arranged with an intake port 22 a, which is one end thereof, facing the bottom of the oil reservoir 12. The scavenge pipe 22 communicates between the crank chamber 11 and the upper end of the oil tank 3 via a scavenge pump 23 and an oil cooler 24.

  The positions of the main pump 21 and the scavenge pump 23 are set lower than the oil level height L4 in the crank chamber 11 when the engine 1 is stopped. More specifically, the highest point of the bottom of the rotor chamber in the pumps 21 and 23 and the bottom of any oil passage communicating with the rotor chamber is the oil level height in the crank chamber 11 when the engine 1 is stopped. The height is lower than L4.

  The main pump 21 and the scavenge pump 23 have a common rotor shaft (not shown), and the rotor shaft is driven by transmission of power from the crankshaft 7.

  As shown in FIG. 2, the oil tank 3 includes a storage chamber upper portion 3 a that is long in the vertical direction and a storage chamber lower portion 3 b that is long in the vehicle traveling direction. The lower storage chamber 3b extends longer in the traveling direction (arrow A direction) than the upper storage chamber 3a. A supply pipe 25 that allows the oil tank 3 and the main pump 21 to communicate with each other is connected to the vicinity of the bottom of the rear end portion of the storage chamber lower portion 3b.

  The operation of the present embodiment configured as described above will be described. During the operation of the engine 1, the main pump 21 is driven as the crankshaft 7 rotates, and the oil in the oil tank 3 is sucked from the supply pipe 25 and supplied to the engine body 2, whereby the crankshaft 7 Each portion of the engine body 2 including the bearing portion is lubricated. The oil that has lubricated the bearing portion of the crankshaft 7 falls to the oil storage portion 12 through the gap portion of the baffle plate 13.

  The oil in the oil reservoir 12 is sucked through the scavenge pipe 22 by the scavenge pump 23 and collected in the oil tank 3 through the oil cooler 24. As a result, the oil level in the oil tank 3 during operation of the engine 1 is maintained at a relatively high position L1.

  Since the operation of the scavenge pump 23 is stopped while the engine 1 is stopped, a part of the oil in the oil tank 3 flows back to the crank chamber 11 through the scavenge pipe 22 due to its own weight. For this reason, the oil level in the oil tank 3 is lowered to a relatively low position L2. Further, since the amount of oil in the crank chamber 11 increases with the backflow, the oil level in the crank chamber 11 rises to a relatively high position L4. That is, the oil level height L4 in the crank chamber 11 is equal to the oil level height L2 in the oil tank 3 when the engine 1 is stopped (that is, when a sufficient time has elapsed since the engine 1 was stopped).

  In the above operation, in the present embodiment, the position and capacity of the oil tank 3 are set so that the oil level height L4 in the crank chamber 11 is below the locus of the counterweight 8 while the engine 1 is stopped. Therefore, the starting resistance due to the interference (so-called oil hitting) between the crankshaft 7 or the counterweight 8 and the oil in the crank chamber 11 can be suppressed.

  In the present embodiment, since the oil tank 3 is short in the lateral direction of the vehicle, the oil can be stably supplied even when subjected to gravity in the lateral G, that is, during the cornering (B1-B2 direction). Further, since the lower part 3b of the storage chamber of the oil tank 3 is long in the vehicle traveling direction, a large volume can be obtained, the height of the oil level in the oil tank 3 can be suppressed, and the oil can be supplied even when receiving a lateral G. It can be supplied stably.

  In the present embodiment, the positions of the main pump 21 and the scavenge pump 23 are lower than the oil level height L4 in the crank chamber 11 when the engine 1 is stopped. Compared with a case where the oil level is higher than the oil level, the load and loss of the pumps 21 and 23 can be suppressed.

  Further, in the engine of the above embodiment, the pressure control valve 340 as shown in the prior art (FIG. 5) is not included in the supply pipe 25 that is the oil transport path by the main pump 21, so that the manufacturing cost can be suppressed, The load of the main pump 21 resulting from the pressure control valve can be suppressed.

  In the above embodiment, the present invention has been described with a certain degree of concreteness, but various modifications and changes can be made to the present invention without departing from the spirit and scope of the invention described in the claims. It must be understood that. That is, the present invention includes modifications and changes that fall within the scope and spirit of the appended claims and their equivalents. For example, as shown in FIG. 3, the shape of the oil tank is such that the storage chamber lower portion 103b extends longer in the traveling direction (opposite to the traveling direction indicated by the arrow A) than the storage chamber upper portion 3a. As shown in FIG. 4, the storage chamber lower portion 203b is directed forward and backward in the traveling direction (forward and reverse directions with respect to the traveling direction indicated by the arrow A) as compared to the storage chamber upper portion 3a. It is good also as the shape extended long.

  In the above embodiment, the rotor shaft (not shown) of the main pump 21 and the scavenge pump 23 is common. However, the main pump 21 and the scavenge pump 23 do not have to have a common rotor shaft, and are electrically operated. Also good. In the above embodiment, the oil tank 3 is separated from the crankcase. However, the oil tank may be formed integrally with a part of the crankcase or other engine body, and such modifications also belong to the scope of the present invention. Is.

1 is a front view showing a schematic configuration of a dry sump engine according to an embodiment of the present invention. It is a side view which shows an example of an oil tank. It is a side view which shows the modification of an oil tank. It is a side view which shows another modification of an oil tank. It is a front view which shows schematic structure of the dry sump type engine before the improvement by this invention.

Explanation of symbols

1,301 Engine 2 Engine body 3,303 Oil tank 3a, 103a, 203a Upper chamber 3b, 103b, 203b Lower chamber 7 Crankshaft 8 Counterweight 11 Crank chamber 12 Oil reservoir 13 Baffle plate 21 Main pump 22 Scavenge pipe 23 Scavenge pump 24 Oil cooler 25 Supply pipe

Claims (2)

An oil reservoir disposed at a lower part of the crankcase; an oil tank disposed separately from the oil reservoir; a scavenge pump for transporting oil from the oil reservoir to the oil tank; and A dry sump engine equipped with a main pump for transporting oil to
The oil tank has a storage chamber upper portion that is long in the vertical direction and a storage chamber lower portion that is long in the vehicle traveling direction,
A dry sump engine characterized in that the oil level in the crank chamber when the engine is stopped is below the counterweight trajectory. The dry sump engine according to claim 1,
The dry sump type engine, wherein the main pump and the scavenge pump are disposed at a position lower than the oil level in the crank chamber when the engine is stopped.

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