JP2018168710A - Internal combustion engine - Google Patents

Abstract

To prevent the eccentric wear of a crankshaft and a metal bearing caused by a start of the crankshaft in a non-lubrication state by a simple structure.SOLUTION: An oil sump space 13 is formed in a region at a lower part of a crankshaft 1 out of a crank cap 5, and an oil flow-in/flow-out passage 18 which is opened toward the crankshaft 1 and a ventilation passage 19 opened toward a crank chamber are formed in the oil sump space 13. An oil sump space 10 is filled with oil at an operation of an engine. At a start of the engine, the oil is scooped up to the oil flow-in/flow-out passage 18 from the oil sump space 13 by a negative pressure action, and made to circulate in a state before the oil is pressure-send by an oil pump. By this constitution, the wear (particularly, eccentric wear) of the crankshaft 1 and a metal bearing 3 can be prevented.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an internal combustion engine characterized by crankshaft lubrication.

  A crankshaft of an internal combustion engine is generally rotatably supported by an upper bearing portion and a crank cap (lower bearing) formed on a cylinder block (crankcase) via a metal bearing. Lubricating oil is supplied to the sliding surface from an oil passage formed in the cylinder block.

  The oil passage has a main gallery having a portion extending in parallel with the crankshaft, and a branch passage branched from the location of the main gallery to each upper bearing portion. Lubricating oil is directly or indirectly on the crankshaft. The oil pump is driven to the main gallery by an oil pump, and is sent to each sliding portion from each branch passage. Such a lubrication structure is disclosed in Patent Document 1, for example.

JP 2013-64373 A

  Lubricating oil is pumped by an oil pump, but when a certain amount of time has passed since the engine stopped, the oil falls off the sliding surface. At the start, the crankshaft starts to rotate immediately by cranking by the starter motor, but there is a slight (several seconds) lag for the lubricating oil to actually reach the sliding part after the oil pump is driven. For this reason, the crankshaft may rotate in an unlubricated state in the initial stage of starting.

  If the rotation in a non-lubricated state is repeated, the metal bearing and the journal part are reduced (deviation wear), the roundness of the metal bearing and the journal part is lowered, the resistance is increased, and the fuel consumption is deteriorated. There is a problem that the life of the internal combustion engine is reduced. In particular, when the engine is frequently stopped after being stopped for a certain period of time, such as an internal combustion engine mounted on a luggage delivery vehicle, the above-mentioned problem is likely to appear remarkably.

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

The present invention is
The journal part of the crankshaft is rotatably held by the bearing part, and the lubricating oil is supplied to the sliding surface between the bearing part and the journal part,
An oil reservoir space is formed in a portion of the bearing portion located below the journal portion, and an oil access passage that opens in a sliding surface with the journal portion is formed in the oil reservoir space, and the crank chamber opens. An air vent passage is formed.

  In this case, the bearing part may consist of an upper bearing part formed in the shilling block and a crank cap as the lower bearing part. Usually, however, a split metal is provided between the upper and lower bearing parts. In many cases, a bearing is interposed. Accordingly, the “bearing portion” recited in the claims includes a case where a bearing is present. In the case where a metal bearing is disposed, the oil access passage also penetrates the metal bearing.

  The oil reservoir space is arranged below the journal part, and the lubricating oil is pumped to the sliding part by the oil pump, so that the lubricating oil flows down from the oil access passage into the oil reservoir space during operation of the internal combustion engine. Even after the engine is stopped, the oil sump space is filled with lubricating oil.

  When the crankshaft starts to rotate due to start by the starter motor, a negative pressure effect is generated in the sliding portion. This negative pressure causes the action of sucking the lubricating oil from the oil pool space, and the presence of the air vent passage. Since no negative pressure is generated in the oil reservoir space, the lubricating oil is sucked up from the oil reservoir space into the oil access passage without resistance.

  Therefore, in the present invention, the journal portion and the bearing portion can be lubricated almost simultaneously with the start of cranking. As a result, the wear (especially uneven wear) of the journal and bearings (especially metal bearings) is prevented or significantly suppressed, and the journal and bearings are maintained at a high roundness to prevent an increase in resistance and fuel consumption. It is possible to prevent the deterioration of the internal combustion engine and the durability of the internal combustion engine.

It is a vertical side view of 1st Embodiment. (A) is II-II sectional view taken on the line of FIG. 1, (B) is the elements on larger scale of (A). FIG. 2A is a cross-sectional view taken along the line IIIA-IIIA in FIG. 2B, and FIG. It is a vertical front view of 2nd Embodiment. It is a vertical front view of 3rd Embodiment.

(1). First Embodiment Next, an embodiment of the present invention will be described with reference to the drawings. First, a first embodiment shown in FIGS. In the following, the front / rear / left / right language is used to specify the direction, but the crank axis direction is the front / rear direction, and the horizontal direction orthogonal to the crank axis (to be precise, the direction orthogonal to both the crank axis and the cylinder bore axis) The direction. The front view is the crank axis direction.

  The internal combustion engine of the present embodiment is a three-cylinder internal combustion engine for automobiles. For this reason, the crankshaft 1 has four journal portions 2 arranged so as to jump in the front-rear direction. Each of these journal portions 2 is divided into a semicircular upper bearing portion 5 formed in a cylinder block (crankcase) 4 and a crank as a lower bearing portion via an upper and lower split metal bearing 3. The cap 6 is rotatably held. Precisely, the metal bearing 3 also constitutes a bearing portion.

  Needless to say, a pair of crank arms 7 is disposed between adjacent journal portions 2, and a crank pin 8 is connected to the pair of crank arms 7. In addition, the code | symbol 9 shown in FIG. 2 is a head bolt.

  A main gallery 10 to which oil is pumped is formed on one longitudinal side of the cylinder block 4 so as to extend in parallel with the crankshaft 1. A branch oil passage 11 extending from the main gallery 10 in an inclined posture toward each upper bearing portion 5 is branched. The upper metal bearing 3 has an oil hole 12 communicating with the branch oil passage 11.

  Each crank cap 6 is fixed to the cylinder block 4 with a pair of left and right bolts 15. An oil reservoir space 13 that opens downward is formed in each crank cap 6 and is closed by a cover plate 14. 14 and the crank cap 6 are fastened together with a cap bolt 15. Therefore, the cover plate 14 does not fall off.

  The oil reservoir space 13 extends on both the left and right sides with the axis of the crankshaft 1 interposed therebetween. The axis of the crankshaft 1 is eccentric by a slight dimension e in the left-right direction with respect to the axis 17 of the cylinder bore 16. For this reason, the crankshaft 1 rotates in the direction of arrow A, but an upward oil entry / exit passage 18 is communicated with the oil reservoir space 13 on the front side in the rotational direction A of the crankshaft 1. The oil access passage 18 passes through the metal bearing 3 and faces the journal portion 2.

  An air vent passage 19 communicates with an end portion on the rear side in the rotation direction A of the crankshaft 1 in the oil pool space 13. The air vent passage 19 includes a standing portion 19 a that protrudes upward from the oil reservoir space 13, and a lateral portion 19 b that communicates with the upper end of the standing portion 19 a, and the lateral portion 19 b opens on the side surface of the crank cap 6. . Accordingly, the air vent passage 19 opens into the crank chamber.

  As shown in FIG. 3 (B), the air vent passage 19 can also be in the form of an inclined straight line such that the lower end communicates with the oil reservoir space 13 and the upper end opens on the side surface of the crank cap 6. It is. In this case, the upper end of the air vent passage 19 needs to be positioned above the upper end of the oil reservoir space 13. The lower end is preferably communicated with the lower part of the oil reservoir space 13 as much as possible.

  Further, a downward projection 20 that prevents air from moving along the upper surface of the oil reservoir space 13 is provided at the left and right intermediate portions of the oil reservoir space 13. Instead of providing the downward projection 20, the upper surface of the oil sump space 13 may be formed in a mountain shape with a downward projection in front view.

  In the above configuration, oil is pumped to the sliding surface between the crankshaft 1 and the metal bearing 3 during the operation of the engine, so that the oil flows into the oil reservoir space 13 from the oil entrance / exit passage 18. In this case, since the air vent passage 19 exists, no air pool is generated in the oil pool space 13 and the oil pool space 13 is filled with oil.

  If the operation of the engine is stopped for a certain period of time, oil will fall off from the sliding surface between the crankshaft 1 and the metal bearing 3, but the oil pool space 13 is located below the metal bearing 3, Even when the engine is stopped, the oil reservoir space 13 is kept filled with oil.

  At the time of the next start, there is a slight time lag for the oil pump to be driven and the oil to reach the sliding surface of the crankshaft 1. In this embodiment, when the crankshaft 1 starts to rotate by the starter motor. Since the oil is sucked up from the oil reservoir space 13 to the sliding surface by the suction action by the negative pressure, the sliding surface between the crankshaft 1 and the metal bearing 3 can be lubricated almost simultaneously with the start. Therefore, even in an internal combustion engine that is frequently started, wear (particularly uneven wear) of the metal bearing 3 and the crankshaft 1 can be prevented.

  In this case, since there is the air vent passage 19, the inside of the oil reservoir space 13 does not become negative pressure, and the oil is surely sucked up from the oil in / out passage 18. In addition, when the downward projection 20 is provided as in the embodiment, there is an advantage that it is possible to prevent the phenomenon that only air is sucked and to assure the oil suction.

(2). Other Embodiments Next, another embodiment shown in FIGS. 4 and 5 will be described. In the second embodiment shown in FIG. 4, the oil sump space 13 is formed by making a drill hole 21 from the side in the crank cap 6 and then closing the drill hole 21 with a plug 22. Since the drill hole 21 penetrates the cap bolt insertion hole 23, the plug 22 is arranged outside the cap bolt insertion hole 23 to prevent the crank cap 6 from being lowered in strength.

  The oil entrance / exit passage 18 is generally formed in an inclined posture at the left and right intermediate portions, but may be raised upward from the end of the oil reservoir space 13 as in the first embodiment. As in the first embodiment, the air vent passage 19 is composed of an upright portion 19a penetrating vertically and a lateral portion 19b communicating with the upright portion 19a. The sideways portion 19b may be opened on one side of the front and rear surfaces of the crank cap 6 or may be opened on both the front and rear surfaces.

  An air stop similar to the downward projection 20 of the first embodiment can be provided in a portion of the oil reservoir space 13 between the oil access passage 18 and the air vent passage 19. As the air stopper, for example, a ring plate can be used and can be fitted by forced fitting.

  In the third embodiment shown in FIG. 5, the oil sump space 13 is formed in a circular arc shape at the left and right central portions of the crank cap 6, and the upper surface is closed by the lower metal bearing 3. The oil sump space 13 is formed by cutting with a milling cutter, and the upper end is located below the lower end of the crankshaft 1 (the lower end of the oil access passage 18 is lower than the lower end of the crankshaft 1). I hope it is located.)

  The air vent passage 19 includes a downward portion 19c that protrudes downward from the left and right intermediate portions of the oil sump space 13, and an inclined portion 19d that communicates with the lower end of the downward portion 19c and extends obliquely upward, and the inclined portion 19d. Is open to the front or rear surface of the crank cap 6. In this embodiment, the upper end of the inclined portion 19 d is disposed above the upper end of the oil access passage 18. Therefore, the oil level is at the upper end of the oil entrance / exit passage 18, and as a result, it can be said that the oil suction action by the rotation of the crankshaft 1 can be ensured.

  While the embodiments of the present invention have been described above, the present invention can be embodied in various ways. For example, the crankshaft has a plurality of journal portions, but the present invention may be applied to at least one place. It is also possible to provide an oil in / out passage substantially in the middle of the left and right, and arrange air vent passages at two locations on the left and right sides (and vice versa).

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

DESCRIPTION OF SYMBOLS 1 Crankshaft 2 Journal part 3 Metal bearing 4 Cylinder block 5 Upper bearing part 6 Crank cap which comprises a lower bearing part 13 Oil reservoir space 15 Lid plate 15 Cap bolt 18 Oil inlet / outlet path 19 Air vent path 20 Downward protrusion (air stop)

Claims (1)

The journal part of the crankshaft is rotatably held by the bearing part, and the lubricating oil is supplied to the sliding surface between the bearing part and the journal part,
An oil reservoir space is formed in a portion of the bearing portion located below the journal portion, and an oil access passage that opens in a sliding surface with the journal portion is formed in the oil reservoir space, and the crank chamber opens. An air vent passage is formed,
Internal combustion engine.

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