JP2012154195A - Structure of return path - Google Patents

Abstract

PROBLEM TO BE SOLVED: To preferably guide oil flowing down from a supercharger, in an internal combustion engine provided with a balance shaft.SOLUTION: A flow down path 81 communicating with an oil pan is formed by using a clearance between the outer wall of a balance shaft housing 62 housing a balance weight 612 provided at an intermediate part of the balance shaft 61, and a balance shaft gear 611 provided at the end of the balance shaft 61. The leading end of an outlet pipe guiding oil flowing down from the supercharger is disposed near an introducing part of the flow down path 81.

Description

  The present invention relates to an internal combustion engine associated with an exhaust turbocharger, and more particularly to a configuration of an oil return passage for lubricating a bearing of the turbocharger.

  The oil that lubricates the bearings of the exhaust turbocharger is the same as the oil that lubricates each component of the internal combustion engine such as the crankshaft, camshaft, piston, and timing chain. Conventionally, oil flowing down from a supercharger is returned to an oil pan in a crankcase below a cylinder block via an oil outlet pipe (see, for example, Patent Document 1 below).

  In an internal combustion engine provided with a balance shaft that rotates following a crankshaft, a balance shaft housing is formed in a crankcase, and the balance shaft is disposed substantially parallel to the crankshaft. Due to the presence of the balance shaft housing, the outer casing of the crankcase bulges out and interferes with the oil outlet pipe. Therefore, as before, it is difficult to connect the oil outlet pipe directly to the vicinity of the oil pan.

  It is also a proposal to join oil from the supercharger to an oil dropping passage (for example, see Patent Document 2 below) in the cylinder block. However, the oil that lubricates the bearings of the turbocharger is very hot. Oil flowing through the oil drop passage is used to lubricate the bearings of the balance shaft. By applying high-temperature oil to a member that rotates at high speed, oil mist is generated and the oil is taken away. Increases and causes a reduction in fuel consumption.

JP 2007-198271 A JP 2009-270507 A

  An object of the present invention is to make it possible to favorably guide oil flowing down from a supercharger in an internal combustion engine having a balance shaft.

  In the present invention, the oil pan is communicated by utilizing the gap between the outer wall of the balance shaft housing that accommodates the balance weight provided at the intermediate portion of the balance shaft and the balance shaft gear provided at the shaft end of the balance shaft. The outlet pipe leading the oil flowing down from the supercharger is communicated with the downstream path.

  According to the present invention, in an internal combustion engine including a balance shaft, oil flowing down from the supercharger can be suitably guided.

The figure which shows the whole structure of the internal combustion engine in one Embodiment of this invention. The sectional side view which expands and shows the crankcase, crankshaft, balance shaft, and balance shaft housing of the internal combustion engine in the same embodiment. FIG. 3 is an enlarged plan sectional view showing a balance shaft, a balance shaft housing, a balance shaft gear, and a flow passage of the internal combustion engine in the same embodiment. The side view which shows the positional relationship of the crankshaft of the internal combustion engine in the same embodiment, a balance shaft, a supercharger, and an outlet pipe.

  An embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows an outline of a vehicle internal combustion engine 0 to which the present invention is applied. The internal combustion engine 0 in this embodiment includes a plurality of cylinders 1 (one of which is shown in FIG. 1), an injector 11 that injects fuel into each cylinder 1, and intake air to each cylinder 1. An intake passage 3 for exhausting the exhaust gas, an exhaust passage 4 for discharging exhaust gas from each cylinder 1, an exhaust turbocharger 5 for supercharging intake air flowing through the intake passage 3, and an exhaust passage 4 to the intake passage 3. And an external EGR passage 2 for refluxing the EGR gas.

  The internal combustion engine 0 in this embodiment is a two-cylinder four-cycle engine, and there is a phase difference of 360 ° CA (crank angle) between the stroke of the first cylinder 1 and the stroke of the second cylinder 1. In other words, the piston 12 of the first cylinder 1 and the piston 12 of the second cylinder 1 are simultaneously raised and simultaneously lowered. Therefore, the volume of the crankcase 7 in the crankcase of the internal combustion engine 0 is greatly expanded / reduced compared to a multi-cylinder engine having three or more cylinders.

  The intake passage 3 takes in air from the outside and guides it to the intake port of the cylinder 1. On the intake passage 3, an air cleaner 31, an intake throttle valve 35, a compressor 51 of the supercharger 5, an intercooler 32, a throttle valve 33, and a surge tank 34 are arranged in this order from the upstream.

  The exhaust passage 4 guides exhaust generated as a result of burning fuel in the cylinder 1 from the exhaust port of the cylinder 1 to the outside. A drive turbine 52 and a three-way catalyst 41 of the supercharger 5 are disposed on the exhaust passage 4.

  The exhaust turbocharger 5 is configured such that the drive turbine 52 and the compressor 51 are connected and linked in a coaxial manner. Then, the driving turbine 52 is rotationally driven by using the energy of the exhaust gas, and the compressor 51 is pumped by using the rotational force, whereby the intake air is pressurized and compressed (supercharged) and sent to the cylinder 1.

  The external EGR passage 2 realizes a so-called low pressure loop EGR. The pressure loss in the low-pressure loop EGR passage 2 is as small as several hundred Pa. The inlet of the external EGR passage 2 is connected to a predetermined location downstream of the three-way catalyst 41 in the exhaust passage 4. The outlet of the external EGR passage 2 is connected to a predetermined location in the intake passage 3 downstream of the intake throttle valve 35 and upstream of the compressor 51. An EGR cooler 21 and an EGR valve 22 are provided on the external EGR passage 2.

  In the low-pressure loop EGR, low-pressure exhaust gas close to atmospheric pressure is recirculated to the intake passage 3 through the EGR passage 2. For this purpose, the pressure around the outlet of the EGR passage 2 is reduced to a negative pressure by restricting the intake throttle valve 35 upstream of the outlet of the EGR passage 2.

  The ECU 9 that controls the operation of the internal combustion engine 0 is a microcomputer system having a processor, a memory, an input interface, an output interface, and the like. The input interface includes a vehicle speed signal a output from the vehicle speed sensor that detects the vehicle speed, a rotation speed signal b output from the rotation speed sensor that detects the engine rotation speed, and a throttle position sensor that detects the opening of the throttle valve 33. The output throttle opening signal c, the intake pressure signal d output from the pressure sensor for detecting the intake pressure (supercharging pressure) in the surge tank 34, the water temperature signal e output from the water temperature sensor for detecting the cooling water temperature, etc. Is entered. From the output interface, the fuel injection signal f for the injector 11, the ignition signal g for the ignition plug (ignition coil thereof), the opening operation signal h for the EGR valve 22, and the opening degree for the intake throttle valve 35. An operation signal i or the like is output.

  The processor of the ECU 9 controls the operation of the internal combustion engine 0 by interpreting and executing a program stored in the memory in advance. The ECU 9 acquires various information a, b, c, d, and e necessary for controlling the operation of the internal combustion engine 0 via the input interface, and based on them, the intake air amount, the required fuel injection amount, the ignition timing, the target EGR Calculate the rate, etc. Then, various control signals f, g, h, i corresponding to the calculation result are applied through the output interface.

  As already described, the internal combustion engine 0 in the present embodiment is a two-cylinder engine and tends to increase the vibration associated with the reciprocating motion of the piston 12. Therefore, the internal combustion engine 0 includes a balance shaft 61 for reducing the vertical vibration force.

  As shown in FIG. 2, the balance shaft 61 that suppresses this vibration is disposed substantially parallel to the crankshaft 71. The balance shaft 61 transmits the rotational driving force from the crankshaft 71 via a transmission mechanism by meshing between the balance shaft gear 611 provided at the shaft end portion thereof and the crankshaft gear 711 provided at the shaft end portion of the crankshaft 71. In response, it rotates counterclockwise in the figure. An intermediate portion of the balance shaft 61 is a balance weight 612 that is eccentric from the axis of the balance shaft 61. The balance weight 612 has a substantially semicircular shape when viewed from a side cross-section, in other words, viewed from the axial direction of the balance shaft 61.

  The balance shaft housing 62 is a chamber formed so as to bulge outward from the crankcase 7 and rotatably accommodates the weight 612 of the balance shaft 61.

  As shown in FIG. 3, the balance shaft 61 is rotatably supported by a ball bearing 63. The inner ring 631 of the ball bearing 63 is fixed to the balance shaft 61, and the outer ring 632 is fixed to the balance shaft housing 62. 3 and 4, the ball bearing 63 is assembled in a shaft hole surrounded by a substantially ring-shaped peripheral edge 621 protruding in the axial direction of the balance shaft 61 on the outer wall of the balance shaft housing 62. Further, a thrust plate 64 that holds and holds the ball bearing 63 is fixed to the end surface of the peripheral edge 621 of the shaft hole. The thrust plate 64 is fastened and fixed to the end surface of the peripheral edge 621 with a plurality of bolts 641 that are screwed into nut holes 622 that are intermittently formed at a plurality of locations on the peripheral edge 621.

  The shaft end of the balance shaft 61 protrudes from the outer surface of the thrust plate 64, and the balance shaft gear 611 is fixed to the shaft end surface. That is, the balance shaft gear 611 is outside the balance shaft housing 62. The inner ring 631 of the ball bearing 63 appears to be sandwiched between the flange 613 of the balance shaft 61 and the boss 614 of the balance shaft gear 611.

  Thus, in this embodiment, the flow-down path 81 that communicates with the oil pan in the crankcase 7 is formed using the gap between the outer wall of the balance shaft housing 62 and the balance shaft gear 611. As shown in FIG. 3, the introduction portion above the flow-down channel 81 is formed from the peripheral edge 621 of the axial hole of the outer wall of the balance shaft housing 62, the thrust plate 64, and the balance shaft 61 from the frontmost edge portion of the crankcase 7. It is surrounded by an end wall 72 protruding in the axial direction.

  As shown in FIG. 4, the front end portion or the lower end portion of the outlet pipe 82 that is connected to the exhaust turbocharger 5 and guides the oil flowing down from the exhaust turbocharger 5 is the introduction portion of the downflow path 81 described above. Place in the vicinity.

  According to the present embodiment, the oil flowing down from the supercharger 5 is caused to flow into the downflow path 81 configured using the gap between the outer wall of the balance shaft housing 62 and the balance shaft gear 611 and returned to the oil pan. Therefore, it is possible to prevent the heated oil from hitting the balance shaft 61 and the balance shaft gear 611 rotating at high speed, and it is possible to prevent the generation of oil mist and the increase in mechanical loss. As a result, problems such as oil removal and fuel consumption reduction can be effectively avoided.

  The present invention is not limited to the embodiment described in detail above. The specific configuration of each part can be variously modified without departing from the spirit of the present invention.

  The present invention can be applied to an internal combustion engine mounted on a vehicle or the like.

DESCRIPTION OF SYMBOLS 0 ... Internal combustion engine 5 ... Supercharger 61 ... Balance shaft 611 ... Balance shaft gear 612 ... Balance shaft weight 62 ... Balance shaft housing 81 ... Downflow 82 ... Outlet pipe

Claims (1)

In an internal combustion engine attached with an exhaust turbocharger, a structure of a return passage that causes oil that lubricates a bearing of the turbocharger to flow down toward an oil pan,
A flow path that communicates with the oil pan using a gap between the outer wall of the balance shaft housing that accommodates the balance weight provided in the intermediate portion of the balance shaft and the balance shaft gear provided at the shaft end of the balance shaft. Forming,
A return passage structure characterized in that a leading end portion of an outlet pipe for guiding oil flowing down from a supercharger is communicated with the downflow passage.

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