JP2010007620A - Lubricating device for double link type piston crank mechanism in internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lubricating device for a double link type piston crank mechanism in an internal combustion engine suitable for improving lubricity of a connecting part of an upper pin and an upper link. <P>SOLUTION: This lubricating device for the double link type piston crank mechanism in the internal combustion engine is provided with an oil jet 30 jetting lubricating oil from a lower side toward a boss part 5 of another end of the upper link 5 in a down stroke from a top dead center of a piston 3. An oil hole 21 as an introduction passage introducing lubricating oil jet from the oil jet 30 to a bearing fitting part with the upper pin 6 is formed at the boss part 5A of another end of the upper link 5. Lubricating oil jet from the oil jet 30 is introduced to the bearing fitting part with the upper pin 6 via the introduction passage provided at the boss part 5A of the upper link 5 in the down stroke of the piston 3. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a lubrication device for a multi-link type piston crank mechanism in which a piston and a crankshaft of an internal combustion engine are coupled by a multi-link. The present invention relates to a lubrication device for a link type piston crank mechanism.

  Conventionally, a multi-link type piston crank mechanism that connects a piston and a crankshaft of an internal combustion engine by a multi-link has been proposed (see Patent Documents 1 and 2).

The upper link connected to the piston pin of the piston, the lower link connecting the upper link and the crank pin of the crankshaft, one end of which is swingably supported on the engine body side, and the other end is the lower link A control link coupled to the link. The upper link and the lower link are rotatably connected to each other via an upper pin, and the control link and the lower link are rotatably connected to each other via a control pin. The lower link in such a multi-link type piston crank mechanism receives the combustion pressure received by the piston from the upper pin via the upper link, and transmits the force to the crank pin by a swinging operation with the control pin as a fulcrum.
JP 2001-227367 A JP 2002-61501 A

  By the way, the maximum combustion gas pressure received by the piston is input to the lower link as described above from the upper pin bearing portion via the piston pin and the upper link. At the same time, a load is also generated in the crank pin bearing portion and the control pin bearing portion so that the load and the inertial force are balanced. Accordingly, the surface pressure of each bearing portion is stricter than that of a general single link type reciprocating engine, and it is required to maintain a sufficient lubrication state in order to prevent wear and seizure.

  However, in the above conventional configuration, both ends of the upper pin are press-fitted into the end portion of the lower link that is bifurcated so as to support both ends of the upper pin, and the lower end of the upper link is supported by the bearing by the intermediate region of the upper pin sandwiched between the press-fit portions. In addition, the boss width of the upper link is made as large as possible so as to suppress the bearing surface pressure. For this reason, the clearance between the boss portion of the upper link and the lower link disposed on both sides thereof tends to be small, and cooling due to the supply of lubricating oil to the bearing portion via the clearance cannot be sufficiently performed. was there.

  Therefore, the present invention has been made in view of the above problems, and an object thereof is to provide a lubrication device for a multi-link type piston crank mechanism in an internal combustion engine suitable for improving the lubricity of a connecting portion between an upper pin and an upper link. To do.

  The present invention is a lubricating device of a multi-link type piston crank mechanism in an internal combustion engine, and an oil jet that injects lubricating oil from below toward the boss portion at the other end of the upper link in the downward stroke from the top dead center of the piston. And an introduction passage for introducing the lubricating oil injected from the oil jet into the bearing fitting portion with the upper pin is formed in the boss portion at the other end of the upper link, and in the downward stroke of the piston, The lubricating oil injected from the oil jet is introduced into the bearing fitting portion with the upper pin through the introduction passage provided in the boss portion.

  Therefore, in the present invention, an oil jet for injecting lubricating oil from below is provided toward the boss portion at the other end of the upper link in the downward stroke from the top dead center of the piston, and the boss portion at the other end of the upper link. Forming an introduction passage for introducing the lubricating oil injected from the oil jet into the bearing fitting portion with the upper pin, and the oil is passed through the introduction passage provided in the boss portion of the upper link in the downward stroke of the piston. Since the lubricating oil injected from the jet is introduced into the bearing fitting portion with the upper pin, the lubricating oil jetted upward from the oil jet hits the boss portion of the upper link that moves downward and passes through the introduction passage. Thus, it can be reliably supplied to the bearing fitting portion with the upper pin. At that time, since the bearing fitting portion is in a negative pressure state in the region where the introduction passage is formed, the lubricating oil is reliably introduced into the bearing fitting portion. For this reason, the lubricity of the connection part of an upper pin and an upper link can be improved.

  Hereinafter, a lubrication device for a multi-link piston crank mechanism in an internal combustion engine of the present invention will be described based on each embodiment.

(First embodiment)
1 to 7 show a first embodiment of a lubrication device for a multi-link piston crank mechanism in an internal combustion engine to which the present invention is applied, FIG. 1 is a schematic configuration diagram of the multi-link piston crank mechanism, and FIG. 2 is a lower link 3 is a longitudinal sectional view and a transverse sectional view of an upper pin bearing portion, FIG. 4 is a side view of a multi-link type piston crank mechanism, FIG. 5 is a detailed view of an oil jet for injecting lubricating oil, and FIG. FIG. 7 is an explanatory view showing a lubricating oil supply path, and is a schematic configuration diagram of a multi-link piston crank mechanism including the device.

  First, an outline will be described based on a configuration example in which a multi-link piston crank mechanism is configured as a variable compression ratio mechanism with reference to FIG. This multi-link type piston crank mechanism includes an upper link 5 connected via a piston pin 4 to a piston 3 disposed in a plurality of cylinders 2 formed along a cylinder row of the cylinder block 1 so as to be movable up and down. One end of the upper link 5 is connected to the other end of the upper link 5 via the upper pin 6, and the center portion is swingably supported by the crankpin 11 A of the crankshaft 11, and the other end of the lower link 7 is controlled. And a control link 9 connected via a pin 8. The other end of the control link 9 is swingably supported by the eccentric shaft 10A of the control shaft 10. The upper pin 6 that rotatably connects the upper link 5 and the lower link 7 constitutes an upper pin bearing portion 6A. The control pin 8 that rotatably connects the lower link 7 and the control link 9 constitutes a control pin bearing portion 8A.

  The crankshaft 11 includes a plurality of journal portions (not shown) and a crank pin 11 </ b> A, and the journal portion is rotatably supported by a main bearing (not shown) configured by the cylinder block 1 and the ladder frame 12. The crank pin 11A is eccentric by a predetermined amount from the journal portion, and a lower link 7 is rotatably connected thereto.

  As shown in FIG. 2, the lower link 7 is formed by joining two members, a portion connected to the upper pin bearing portion 6A and a portion connected to the control pin bearing portion 8A. A crank pin bearing portion 7A is formed on the crank pin 11A. The connecting positions of the crank pin 11A, the upper pin 6, and the control pin 8 that are connected to the lower link 7 are not on the same straight line but are arranged in a substantially triangular shape.

  Returning to FIG. 1, the control shaft 10 is rotatably supported by a bearing portion (not shown) formed by a ladder frame 12 and a bearing cap 13. The eccentric shaft 10 </ b> A of the control shaft 10 can variably control its support position by controlling the rotational angle position of the control shaft 10. Although not shown, a worm wheel is coupled to the shaft end of the control shaft 10, and the rotational angle position of the control shaft 10 is controlled by rotationally driving a worm gear meshing with the worm wheel by an actuator motor. Reference numeral 14 denotes an oil pan.

  In this variable compression ratio mechanism using a multi-link type piston crank mechanism, the rotational position of the control shaft 10 is controlled by an actuator motor, and the top dead center position of the piston 3 is lowest when the eccentric shaft 10A is eccentric upward. While the lowest compression ratio can be achieved, as the eccentric shaft 10A is gradually displaced downward by rotating the control shaft 10, the top dead center position of the piston 3 is raised and shifted to the high compression ratio side. When 10A is eccentric to the lowermost position, the top dead center position of the piston 3 can be highest, and the highest compression ratio can be obtained. The piston motion by this mechanism has a characteristic close to simple vibration, and has a characteristic that the moving amount of the piston 3 near the top dead center is small.

  The engine controller (not shown) receives various signals such as engine speed, engine load, intake negative pressure, exhaust temperature, cooling water temperature from the water temperature sensor, intake air temperature, and knock signal from the knock sensor. The engine controller determines the operating state of the engine based on these input signals, calculates the target compression ratio of the engine according to the operating state, and the rotational angle position to the actuator motor so as to obtain the target compression ratio obtained by the calculation Outputs a command. The rotational angle position of the actuator motor is detected by a built-in motor encoder (not shown) and fed back to the engine controller.

  The variable compression ratio mechanism operates an actuator motor and a multi-link type piston crank mechanism by an engine controller in an engine low load low rotation range (internal EGR range in the EGR stratified combustion mode (first combustion mode)). Thus, the top dead center position of the piston 3 is raised and the high compression ratio is set. As the engine load or engine speed rises, the top dead center position of the piston 3 is lowered, the compression ratio is lowered ("internal + external" EGR region), and the high load high rotation region (homogeneous combustion mode (second combustion mode) )) Is set to be a low compression ratio. As a result, fuel efficiency is improved in the low load and low rotation region, and output is improved by avoiding knocking in the high load and high rotation region.

  As shown in FIGS. 2 and 3, the member connected to the upper pin bearing portion 6A of the lower link 7 is formed by a bifurcated member 20, and the upper pin 6 is press-fitted into a through hole 20A formed by penetrating the bifurcated member 20. By doing so, both ends of the upper pin 6 are supported. The boss portion 5A of the upper link 5 has both side surfaces in contact with the bifurcated member 20 of the lower link 7, and the bearing hole 5B is fitted in the central region of the upper pin 6 sandwiched between the press-fitted regions of the upper pin 6 into the lower link 7. Arranged together.

  The boss portion 5A bearing-fitted with the upper pin 6 of the upper link 5 is passed through the extension of the line connecting the centers of the upper and lower pin connecting portions of the upper link 5 so as to communicate the inside and outside of the boss portion 5A. An oil hole 21 is formed. The oil hole 21 is oriented along the center line of the line connecting the centers of the upper and lower pin connecting portions of the upper link 5 and the inner diameter and position thereof are set so as to include the oil hole 21. The outer diameter side of the boss portion 5A of the oil hole 21 may be increased in a tapered shape. Further, as shown in FIG. 3A, the oil hole 21 is arranged offset to the piston pin 4 side. Lubricating oil injected from an oil jet, which will be described later, is supplied to the oil hole 21, and the supplied lubricating oil flows into the boss portion 5 </ b> A through the oil hole 21, and the boss portion 5 </ b> A inner surface and the upper pin 6 Operates to lubricate sliding surfaces.

  Further, as shown in FIGS. 4 and 5, a bearing cap 13 that forms a bearing portion 10 </ b> B that rotatably supports the control shaft 10 with the ladder frame 12 is projected from the side surface of the bearing cap 13. And an oil jet 30 that injects lubricating oil upward. As shown in FIG. 5, the oil jet 30 injects lubricating oil toward the boss portion 5A located at the lower end of the upper link 5, but does not inject vertically upward, but during the piston lowering process. The injection direction when viewed from the axial direction of the crankshaft is slightly tilted so that the spray sprayed away from the cylinder axis so that the oil jet reaches the oil hole in most of (see A) It is configured to inject obliquely upward. In the downward stroke compared to the piston upward stroke, the upper link descends in a state of being substantially upright from the top dead center, and therefore the oil hole position moves less in the left-right direction of the engine. Can be reached. By injecting obliquely upward in this way, the lubricant that is injected upward and the falling lubricant flow are made different from each other, and the injection of the lubricant injected by collision between the two is reached. It is possible to prevent the distance from being shortened and the supply amount from becoming insufficient.

  As shown in FIGS. 6 and 7, the oil jet 30 is configured to be introduced through an oil passage 31 provided in the bearing cap 13. The oil passage 31 is opened in a bearing hole 32 that supports the bearing portion 10 </ b> B of the control shaft 10. The control shaft 10 is formed in a hollow shape so that lubricating oil is supplied from an oil gallery, and the supplied lubricating oil is provided in a bearing portion 10B through an oil supply hole 33 that penetrates the control shaft 10 in the radial direction. Further, it is supplied to the bearing surface of the eccentric shaft 10A to lubricate each bearing portion 10B and to lubricate the connecting portion between the eccentric shaft 10A and the control link 9.

  As described above, the rotational position of the control shaft 10 is changed by controlling the rotational angle by an actuator motor (not shown). Accordingly, the opening angle position of each oil supply hole 33 provided in the control shaft 10 is also changed. When the opening angle position of the oil supply hole 33 formed in the bearing portion 10B is set to a high compression ratio that becomes a low load low rotation region of the engine, the opening is positioned above (shown by a solid line), and the engine load Alternatively, the opening moves to the side (broken line) as the engine speed rises, and the opening is rotated downward (broken line) when the compression ratio is set to a high load and high rotation region. Thus, the oil passage 31 is in communication.

  A rotary valve 34 that rotates in conjunction with the crankshaft 11 and opens and closes according to the rotational position is disposed in the oil passage 31. The oil passage 31 is opened during the downward stroke of the piston 3. The oil passage 31 is configured to be shut off. Instead of the rotary valve 34, an electromagnetic valve that opens in the lowering stroke of the piston 3 and closes in the other strokes may be used.

  The operation of the lubrication device for the multi-link piston crank mechanism in the internal combustion engine having the above configuration will be described below. Lubricating oil is supplied to the inside of the control shaft 10 from the oil gallery, and lubricates each bearing portion 10B via an oil supply hole 33 opened to each bearing portion 10B, and a connecting portion between the eccentric shaft 10A and the control link 9 Lubricate. Further, the rotary valve 34 disposed in the oil passage 31 operates to communicate the oil passage 31 during the downward stroke of the piston 3.

  When the engine is set to a high compression ratio that is a low load and low rotation region of the engine, the lubricating oil supplied to the bearing portion of the control shaft 10 via the oil supply hole 33 depends on the rotation angle of the control shaft 10. The oil supply hole 33 opens upward and does not communicate with the oil passage 31, and no lubricating oil is supplied to the oil passage 31. In this low-load low-rotation region, the engine is operated at a low rotational speed, and the sliding speed at the upper pin bearing portion 6A formed by the boss portion 5A of the upper link 5 and the upper pin 6 can be kept low. For this reason, the lubricating oil film can be satisfactorily maintained without being actively supplied with the lubricating oil, while the decrease in hydraulic pressure in the oil gallery due to the constant oil supply at the time of low engine speed can be suppressed.

  As the engine load or engine rotation increases, the control shaft 10 is rotated by an actuator motor (not shown). When the compression ratio is set to be a high load and high rotation region, the opening position of the oil supply hole 33 is downward and is in communication with the oil passage 31. In the high load and high rotation region, the engine is operated at high load and high rotation, so that the supply of lubricating oil to the oil gallery is increased, and the oil temperature of the lubricating oil is also increased. For this reason, the lubricating oil supply to the lubrication site | part of each part of an engine is also increased.

  8A to 8H, the expansion stroke and the exhaust stroke are performed from the state of the crank angle (0 degree) located at the top dead center of the piston 3 that has finished the compression stroke by the rotation of the crankshaft 11. Crank angle every 45 degrees (0 ° (A), 45 ° (B), 90 ° (C), 135 ° (D), 180 ° (E), 225 ° (F), 270 ° (G), It shows the posture of each link at 315 ° (H). As the crankshaft 11 rotates, the piston 3 descends in the cylinder 2 through the crank pin 11A, the lower link 7, the upper link 5 and the piston pin 4 of the multi-link type piston crank mechanism, and then rises. The control link 9 connected to the link 7 swings with the swing axis Oc on the lower end side as a fulcrum.

  The upper link 5 starts to descend from a state where the piston 3 is located at the top dead center (crank angle 0 °), and descends in an upright state in which the rotation is suppressed from a state where the crank angle is 45 °. It is actuated to start clockwise rotation at a crank angle of around 135 ° approaching the dead center.

  When the crank angle exceeds 45 °, the rotary valve 34 disposed in the oil passage 31 is opened to connect the oil passage 31, and the lubricating oil introduced into the oil passage 31 is supplied to the oil jet 30 to Jetted from the jet 30. The injected lubricating oil flies toward the boss portion 5A of the upper link 5 that is lowered in an upright state with its rotation suppressed, and is provided on the lower surface of the boss portion 5A as shown in FIGS. The oil hole 21 is introduced into the gap between the inner surface of the boss portion 5A and the upper pin 6.

  In this case, since the upper link 5 is lowered in an upright state with the rotation being suppressed, the relative speed with the oil droplets of the lubricating oil injected from the oil jet 30 disposed below is large, and the oil droplets It effectively strikes the boss portion 5A of the upper link 5 and flows into the oil hole 21 that opens below the boss portion 5A.

  Further, in the expansion stroke, as indicated by a line P in FIG. 9, a load due to the combustion gas pressure acts on the upper link 5 from the piston 3, and the upper link 5 is operated to be pushed down toward the lower link 7. For this reason, as shown in FIG. 10, the boss portion 5A operates to push down the upper pin 6, and the upper pin 6 moves relatively upward from the floating state by the lubricating oil in the boss portion 5A. The upper pin 6 is brought into contact with the upper inner surface of the boss portion 5A to generate an oil film pressure therebetween, and the gap space between the lower inner surface of the boss portion 5A and the upper pin 6 is increased to create a negative pressure state. Become. For this reason, the lubricating oil scattered toward the oil hole 21 is sucked into the oil hole 21 and introduced into the gap space between the lower inner surface of the boss portion 5A and the upper pin 6 by the negative pressure. Is done. In the suction stroke in which the piston 3 descends, the above-described operation does not occur. However, since a large load is not applied to the upper pin 6 and the upper link 5, the lubricating oil between the inner surface of the boss portion 5A and the upper pin 6 is used. The floating state by is maintained well.

  When the crank angle advances to around 135 °, the upper link 5 starts to rotate in the clockwise direction as shown in FIG. In this case, as shown in FIG. 12, there is a slight deviation between the scattering direction of the oil droplets ejected from the oil jet 30 and the position of the oil hole 21 provided in the boss portion 5 </ b> A of the upper link 5. For this reason, the opening of the oil hole 21 provided in the boss portion 5A of the upper link 5 near the crank pin 11A is extended from a line connecting the centers of the upper and lower pin connecting portions of the upper link 5 to the crank pin 11A side. By offsetting or enlarging the opening itself, the supply end point can be delayed and the supply amount can be increased.

  Thereafter, the sliding speed of the upper pin bearing portion 6A between the boss portion 5A of the upper link 5 and the upper pin 6 is gradually increased to reach the maximum speed as shown by the line V in FIG. However, as described above, since sufficient lubricating oil is introduced into the upper pin bearing portion 6A between the inner surface of the boss portion 5A and the upper pin 6, it is sufficient to increase the sliding speed of the upper pin bearing portion 6A. A simple lubricating oil film can be maintained.

  In the present embodiment, the following effects can be achieved.

  (A) An upper link 5 having one end connected to the piston 3 via a piston pin 4 and an upper pin 6 that is bearing-fitted to a boss portion 5A at the other end of the upper link 5; A lower link 7 connected to the crank pin 11A, and a control link 9 having one end pivotably supported on the engine body side and the other end connected to the lower link 7 via a control pin 8. The lower link 7 press-fits both ends of a substantially central crank pin bearing portion 7A into which the crank pin 11A is fitted and upper pins 6 protruding from both side surfaces of the boss portion 5A of the upper link 5 at one end portion. A multi-link piston crank in an internal combustion engine comprising a bifurcated member 20 and a connecting portion connected to the control pin 8 at the other end An oil jet 30 for injecting lubricating oil from below is provided toward the boss portion 5A at the other end of the upper link 5 in the downward stroke from the top dead center of the piston 3, and the upper link 5 An oil hole 21 serving as an introduction passage for introducing the lubricating oil injected from the oil jet 30 into the bearing fitting portion with the upper pin 6 is formed in the boss portion 5A at the other end of the piston 3. Since the lubricating oil injected from the oil jet 30 is introduced into the bearing fitting portion with the upper pin 6 through the introduction passage provided in the boss portion 5A of the link 5, it is ejected upward from the oil jet 30. The lubricating oil hits the boss portion 5A of the upper link 5 that moves downward and is reliably supplied to the bearing fitting portion with the upper pin 6 through the introduction passage. Can. At that time, since the bearing fitting portion is in a negative pressure state in the region where the introduction passage is formed, the lubricating oil is reliably introduced into the bearing fitting portion. For this reason, the lubricity of the connection part of the upper pin 6 and the upper link 5 can be improved.

  (A) When viewed from the axial direction of the upper link 5 and the crankshaft, the introduction passage is oriented along a center line that connects the connecting portion center of the piston pin 4 and the connecting portion center of the upper pin 6 of the upper link 5. Since it is constituted by an oil hole 21 provided through the boss portion 5A of the upper link 5 so as to enclose this, it is injected from below to the upper link 5 that descends in a substantially upright state from the top dead center. The oil jet 30 thus made can be reliably supplied to the oil hole 21, and the supply amount of the lubricating oil can be increased to cope with the increase in the sliding speed near the bottom dead center. Further, the lubrication characteristic is better than providing the oil hole 21 for supplying the lubricant at the center of the upper pin 6 in the axial direction.

  (C) Since the introduction passage is arranged offset to the crankpin 11A side, the amount of oil supplied at the bottom dead center can be increased.

  (D) The oil jet 30 injects the lubricating oil obliquely upward toward the other end boss portion 5A of the upper link 5, thereby changing the paths of the injected lubricating oil and the falling lubricating oil. It is possible to suppress the reaching distance of the injected lubricating oil and the shortage of the supply amount from colliding with each other.

  (E) The oil jet 30 injects lubricating oil during high-speed operation of the engine, thereby making it possible to cope with a decrease in lubricity due to an increase in oil temperature and to suppress a decrease in oil pressure of the oil gallery during low-speed operation.

  (F) The oil jet 30 can improve lubricity in response to an increase in combustion pressure by injecting lubricating oil during low compression operation of the engine.

(Second Embodiment)
FIGS. 13 to 15 show a second embodiment of a lubrication device for a multi-link piston crank mechanism in an internal combustion engine to which the present invention is applied. FIG. 13 is a side view and a bottom view of a boss portion of an upper link, and FIG. The longitudinal sectional view, the transverse sectional view and the bottom view of the upper pin bearing portion, and FIG. 15 are explanatory views showing the operating state of the lubricating device of the multi-link type piston crank mechanism. In the present embodiment, an oil groove provided on the side surface of the boss is added to the first embodiment in place of the oil hole 21 for introducing the lubricating oil to the upper pin bearing portion 6A. The same devices as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted or simplified.

  13 and 14, the lubrication device for the multi-link type piston crank mechanism of the present embodiment includes an oil groove 40A provided on the side surface of the boss portion 5A of the upper link 5, and a lower link facing the side surface of the boss portion 5A. The lubricating oil introduction hole 40 for introducing the injected lubricating oil into the bearing surface is constituted by the oil groove 40B provided on the side surface of the boss portion facing the seven bifurcated member 20.

  That is, as shown in FIG. 13, the boss portion 5A of the upper link 5 communicates the inside and outside of the boss portion 5A with both side surfaces on the extension of the line connecting the centers of the upper and lower pin connecting portions of the upper link 5. Thus, the oil groove 40A is formed. The oil groove 40A is arranged offset to the piston pin 4 side.

  Further, the oil groove 40B provided in the facing surface portion of the bifurcated member 20 of the lower link 7 is in the vicinity of the bottom dead center of the multi-link type piston crank mechanism, for example, in the range of the crank angle around 90 ° to around 135 °. It arrange | positions in the position which faces 40 A of oil grooves provided in the side surface of the boss | hub part 5A of the said upper link 5. FIG.

  Further, in the present embodiment, the hollow upper pin 6 by the hollow hole 44 is used, and the thickness thereof is such that the central region 42 fitted to the boss portion 5A of the upper link 5 and the axially opposite side regions are thick. In the area where the bifurcated member 20 of the lower link 7 is press-fitted, the thickness is gradually reduced toward the thin portion 43 at the end. For this reason, the rigidity reduction of the region where the oil groove 40B provided in the bifurcated member 20 of the lower link 7 is formed can be reinforced by the thick portion of the upper pin 6 (the central portion 42 and both axial regions). Further, since the central region 42 fitted to the boss portion 5A of the upper pin 6 is formed thick, deformation of the central region 42 of the upper pin 6 when the lower link 7 is press-fitted into the bifurcated member 20 can be suppressed. Lubrication characteristics of the upper pin bearing portion 6A constituted by the boss portion 5A of the link 5 and the upper pin 6 are improved.

  The hollow upper pin 6 is formed so as to be thick on the piston pin 4 side because the hollow hole 44 is offset in a direction away from the piston pin 4 connected via the upper link 5. Thus, the bending rigidity and the shear rigidity are improved, and the reduction in rigidity due to the provision of the oil groove 40B is reduced. Other configurations are the same as those in the first embodiment.

  Also in this embodiment, when the piston 3 is lowered from the top dead center, when the crank angle exceeds 45 °, the rotary valve 34 disposed in the oil passage 31 is opened and the oil passage 31 is communicated. The lubricating oil introduced into the oil passage 31 is supplied to the oil jet 30 and injected from the oil jet 30. The injected lubricating oil flies toward the boss portion 5A of the upper link 5 which is lowered in a state where the rotation is suppressed and is provided on both side surfaces of the boss portion 5A as shown in FIG. The oil is introduced into the gap between the inner surface of the boss 5A and the upper pin 6 through the oil groove.

  In this case, since the upper link 5 is lowered in an upright state with the rotation being suppressed, the relative speed with the oil droplets of the lubricating oil injected from the oil jet 30 disposed below is large, and the oil droplets It effectively strikes the boss portion 5A of the upper link 5 and flows into the oil groove 40A that opens on both side surfaces of the boss portion 5A. The lubricating oil that has flowed into the oil groove 40A goes straight through the oil groove 40A and is supplied to the bearing surfaces of the upper pin 6 and the boss portion 5A, while also being diffused in the lateral direction (circumferential direction) of the oil groove 40A. Lubrication of the sliding surfaces of both side surfaces of the boss portion 5A and the bifurcated member 20 is also performed, so that the lubricity in the thrust direction is improved.

  When the crank angle advances from about 90 ° to 135 °, the oil groove 40A provided on both side surfaces of the boss portion 5A of the upper link 5 and the oil groove 40B provided on the bifurcated member 20 of the lower link 7 face each other. And since it becomes a large opening area as shown in FIG.14 (C), the injected lubricating oil can be effectively supplied to the bearing surface of the upper pin 6 and the boss | hub part 5A.

  Further, in the expansion stroke, a load due to the combustion gas pressure acts on the upper link 5 from the piston 3 and operates to push the upper link 5 down toward the lower link 7 (press the upper pin 6 down by the boss portion 5A). Moves relatively upward in the boss portion 5A from the floating state by the lubricating oil. The upper pin 6 is brought into contact with the upper inner surface of the boss portion 5A to generate an oil film pressure therebetween, and the gap space between the lower inner surface of the boss portion 5A and the upper pin 6 is increased to create a negative pressure state. Become. For this reason, the lubricating oil scattered toward the oil groove 40A is sucked into the oil groove 40A and introduced into the gap space between the lower inner surface of the boss portion 5A and the upper pin 6 by the negative pressure. Is done.

  Further, when the crank angle exceeds 135 °, the upper link 5 starts to rotate in the clockwise direction, the oil droplets sprayed from the oil jet 30 are scattered, and the oil groove 40A provided in the boss portion 5A of the upper link 5. , 40B is slightly shifted. However, the oil groove 40A and the oil groove 40B provided on both side surfaces of the boss portion 5A of the upper link 5 near the crank pin 11A are connected to the crank pin from the extension of the line connecting the centers of the upper and lower pin connecting portions of the upper link 5. Since the offset is made to the 11A side, the supply amount can be increased by delaying the supply end point of the scattered oil droplets of the lubricating oil.

  Thereafter, the sliding speed of the upper pin bearing portion 6A between the boss portion 5A of the upper link 5 and the upper pin 6 is gradually increased to reach the maximum speed. However, as described above, since sufficient lubricating oil is introduced into the upper pin bearing portion 6A between the inner surface of the boss portion 5A and the upper pin 6, it is sufficient to increase the sliding speed of the upper pin bearing portion 6A. A simple lubricating oil film can be maintained.

  In the present embodiment, in addition to the effects (a) and (c) to (f) in the first embodiment, the following effects can be achieved.

  (G) When the upper link 5 is viewed from the crankshaft axial direction, the introduction passage is oriented along a center line that connects the connecting portion center of the piston pin 4 and the connecting portion center of the upper pin 6 of the upper link 5. Since it is configured by oil grooves 40A provided on both side surfaces of the boss portion 5A of the upper link 5 so as to enclose this, the injected lubricating oil is formed at the corners between the boss portion 5A and the side surface of the bifurcated member 20 of the lower link 7. It is easy to accumulate and is easy to be introduced into the oil groove 40A opening at the corner. Further, the lubrication in the thrust direction of the upper link 5 and the lower link 7 can be improved.

  (H) The introduction passage is formed on the side surface of the boss portion 5A of the lower link 7 facing the both side surfaces of the other end boss portion 5A of the upper link 5, and in the downward stroke to the bottom dead center of the piston 3, 5 is provided with oil grooves 40B facing the oil grooves 40A formed on both side surfaces of the other end boss portion 5A, the opening area of the introduction passage in the vicinity of the bottom dead center can be increased, and the amount of supplied oil can be increased. it can.

  (K) The upper pin 6 is formed of a hollow member which is thick in the central region 42 and the both side regions thereof which are bearing-fitted to the boss portion 5A of the upper link 5 and has a thin wall 43 in the end portion. A decrease in rigidity due to the groove 40B can be reduced. Further, when the upper pin 6 is press-fitted, the pin deformation of the sliding portion with the boss portion 5A of the upper link 5 can be reduced, and the lubrication characteristics are improved.

  (E) Since the upper pin 6 is offset in the direction away from the piston pin 4 to which the hollow hole 44 is connected via the upper link 5, the upper pin 6 is thick on the piston pin 4 side, and its bending rigidity and shear rigidity are improved. The reduction in rigidity due to the provision of the oil groove 40B is reduced.

1 is a schematic configuration diagram of a multi-link piston crank mechanism in an internal combustion engine showing an embodiment of the present invention. The perspective view of a lower link similarly. The longitudinal cross-sectional view (A) and cross-sectional view (B) of an upper pin bearing part. The side view of a multiple link type piston crank mechanism. Detailed view of an oil jet for injecting lubricating oil. The schematic block diagram of a multi-link type piston crank mechanism including a lubricating device. Explanatory drawing which shows the supply path | route of lubricating oil. Every crank angle 45 degrees due to rotation of the crankshaft (0 ° (A), 45 ° (B), 90 ° (C), 135 ° (D), 180 ° (E), 225 ° (F), 270 ° ( G) Explanatory drawing which shows the attitude | position of each link of 315 degrees (H)). The characteristic view which shows the pressure change in a cylinder with respect to the change of a crank angle, and the sliding speed change of an upper pin bearing part. Explanatory drawing explaining the action | operation state of an upper pin bearing part. Explanatory drawing explaining the operation state in 90 degrees of crank angles. Explanatory drawing explaining the operation state in crank angle 135 degrees. The side view (A) and bottom view (B) of the boss | hub part of the upper link in the multilink type piston crank mechanism in the internal combustion engine which show 2nd Embodiment of this invention. The longitudinal cross-sectional view (A) of a upper pin bearing part, a cross-sectional view (B), and a bottom view (C). Explanatory drawing which shows the operation state of the lubrication apparatus of a multi-link type piston crank mechanism.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cylinder block 2 Cylinder 3 Piston 4 Piston pin 5 Upper link 5A Boss part 6 Upper pin 7 Lower link 8 Control pin 9 Control link 10 Control shaft 11 Crank shaft 11A Crank pin 21 Oil hole 30 as an introduction passage 30 Oil jet 31 Oil passage

Claims (9)

An upper link having one end connected to the piston via a piston pin, and a lower link connected to the boss at the other end of the upper link via an upper pin that is bearing-fitted and connected to the crank pin of the crankshaft A control link having one end pivotably supported on the engine body side and the other end connected to the lower link via a control pin, the lower link being substantially fitted with the crank pin. An internal combustion engine comprising: a central crankpin bearing portion; a bifurcated portion for press-fitting and holding both ends of the upper pin protruding from both ends of the boss portion of the upper link at one end portion; and a connecting portion coupled to the control pin at the other end portion A lubrication device for a multi-link piston crank mechanism in an engine,
An oil jet for injecting lubricating oil from below is provided toward the boss at the other end of the upper link in the downward stroke from the top dead center of the piston, and from the oil jet to the boss at the other end of the upper link. Forming an introduction passage for introducing the injected lubricating oil into the bearing fitting portion with the upper pin;
In an internal combustion engine characterized in that, in the downward stroke of the piston, the lubricating oil injected from the oil jet is introduced into a bearing fitting portion with an upper pin through an introduction passage provided in a boss portion of an upper link. A lubrication system for a multi-link piston crank mechanism.   The introduction passage is formed on the side surface of the boss portion of the upper link so as to include a center line connecting the center of the piston pin coupling portion of the upper link and the center of the upper pin when the upper link is viewed from the crankshaft axial direction. 2. The lubricating device for a multi-link piston crank mechanism in an internal combustion engine according to claim 1, wherein the lubricating device is constituted by an oil groove provided.   When the upper link is viewed from the crankshaft axial direction, the introduction passage penetrates the boss portion of the upper link so as to include a center line connecting the piston pin coupling portion center of the upper link and the upper pin coupling portion center. 2. The lubrication device for a multi-link piston crank mechanism in an internal combustion engine according to claim 1, wherein the lubricating device is constituted by an oil hole provided.   The introduction passage is formed on the side surface of the lower link boss portion opposite to the side surface of the other end boss portion of the upper link, and on the side surface of the other end boss portion of the upper link in the downward stroke to the bottom dead center of the piston. The lubricating device for a multi-link type piston crank mechanism in an internal combustion engine according to claim 2, further comprising an oil groove facing the formed oil groove.   5. The upper pin is formed by a hollow member which is thick in a region where the bearing is fitted to the boss portion of the upper link and both sides thereof, and which is thin at the end. A lubrication device for a multi-link piston crank mechanism in an internal combustion engine according to claim 1.   The lubrication device for a multi-link type piston crank mechanism in an internal combustion engine according to any one of claims 1 to 4, wherein the introduction passage is arranged offset to the crankpin side.   The multi-link type piston in an internal combustion engine according to any one of claims 1 to 6, wherein the oil jet injects lubricating oil obliquely upward toward the other end boss portion of the upper link. Crank mechanism lubrication device.   The lubrication device for a multi-link piston crank mechanism in an internal combustion engine according to any one of claims 1 to 7, wherein the oil jet injects lubricating oil during high-speed operation of the engine.   The lubrication device for a multi-link piston crank mechanism in an internal combustion engine according to any one of claims 1 to 8, wherein the oil jet injects lubricating oil during low-compression operation of the engine.

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