JP2013096229A - Blowby gas recirculation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a blowby gas recirculation device adaptive to blowby gas having large pulsation.SOLUTION: A plurality of reed valves having different opening/closing characteristics are disposed in series along a flowing direction of blowby gas on an upstream side of a labyrinth structure 601 for separating lubricating oil contained in flowing blowby gas from blowby gas. A valve element 603 of the reed valve acts as the labyrinth structure 601 and removes the lubricating oil from blowby gas. Further, the reed valves of a plurality of stages repress pulsation of blowby gas flowing in the labyrinth structure 601.

Description

  The present invention relates to a blow-by gas recirculation device for an internal combustion engine.

  Generally, a crank chamber of an internal combustion engine is isolated from a combustion chamber by a cylinder and a piston. However, this isolation is not perfect, and unburned gas leaks in the compression stroke of the internal combustion engine, and combustion gas leaks into the crank chamber through the gap between the cylinder and the piston in the expansion stroke. The leaked blow-by gas may cause deterioration of lubricating oil stored in the crank chamber and corrosion of the internal combustion engine body.

  For this reason, conventionally, it is common to implement a mechanism for ventilating blow-by gas accumulated in the crank chamber. At present, the crank chamber and the surge tank communicate with each other through the PCV passage, and the cam chamber and the upstream of the compressor communicate with each other through the blow-by passage, and fresh air is taken into the cam chamber and the crank chamber through the blow-by passage. Blow-by gas is sent out toward the surge tank via the PCV passage (see, for example, Patent Document 1 below).

  Lubricating oil is present in the blow-by gas as fine particles, that is, oil mist. If this is sent directly to the surge tank, the lubricating oil gradually decreases. Therefore, an oil separator having a labyrinth structure is used to separate the lubricating oil contained in the blow-by gas from the blow-by gas and return it to the crank chamber (see, for example, Patent Document 2 below).

  In an internal combustion engine such as a two-cylinder engine in which the volume of the crank chamber is greatly expanded and contracted, the pulsation of blow-by gas also increases. Since the flow rate of blow-by gas fluctuates greatly, it is necessary to design a labyrinth structure of an oil separator that is suitable not only for a low-speed flow but also for a high-speed flow, but this is difficult. In addition, the volume of the oil separator has to be increased for the purpose of removing the lubricating oil from the gas having a high flow rate.

JP 2011-202591 A JP 2011-174406 A

  The present invention has been made by paying attention to the above-mentioned problem for the first time, and an object of the present invention is to provide a blow-by gas recirculation device adapted to blow-by gas having a large pulsation.

  According to the present invention, in a blow-by gas recirculation device applied to an internal combustion engine, a plurality of reed valves having different opening and closing characteristics are provided in an oil separator that separates lubricating oil contained in the circulating blow-by gas from the blow-by gas. Arranged in series along the direction of flow.

  ADVANTAGE OF THE INVENTION According to this invention, the blowby gas recirculation apparatus adapted to blowby gas with a large pulsation is realizable.

The figure which shows the structure of the internal combustion engine and blow-by gas recirculation apparatus in one Embodiment of this invention. The principal part plane sectional view which shows the oil separator of the blowby gas recirculation apparatus in the embodiment. The figure which illustrates the pattern of the pulsation of the gas part of blowby gas, the pulsation of an oil mist, or an oil drop.

  An embodiment of the present invention will be described with reference to the drawings. In FIG. 1, the outline | summary of the internal combustion engine 0 for vehicles to which the blowby gas recirculation apparatus 6 of this embodiment is applied is shown. 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 crank chamber 7 in the crankcase of the internal combustion engine 0 is greatly expanded / reduced compared to the multi-cylinder engine.

  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.

  The blow-by gas recirculation device 6 is for sending blow-by gas generated in the inner chambers 7 and 8 of the internal combustion engine 0 to the intake passage 3 and ventilating the blow-by gas. The cam chamber 8 communicates with the crank chamber 7. The blow-by gas recirculation device 6 includes a PCV passage 63, a PCV valve 64, a blow-by passage 65, and oil separators 61 and 62.

  One end of the PCV passage 63 is connected to the outer peripheral wall of the crank chamber 7, and the other end is connected to the surge tank 34 of the intake passage 3, so that the crank chamber 7 communicates with the intake passage 3.

  The PCV valve 64 increases or decreases the flow rate of blow-by gas flowing through the PCV passage 63. The PCV valve 64 is a mechanical type in which the valve body that is elastically biased and pressed against the valve seat is displaced in a direction away from the valve seat (against the elastic biasing force) by the pressure of blow-by gas. This is a differential pressure type valve. The PCV valve 64 is closed when the intake pressure in the surge tank 34 is equal to or higher than the atmospheric pressure, and the opening degree increases as the intake pressure in the surge tank 34 decreases (as the negative pressure with respect to atmospheric pressure). However, when the intake pressure in the surge tank 34 is significantly reduced, the opening degree is conversely reduced.

  An oil separator 61 is interposed between the crank chamber 7 and the PCV valve 64. The oil separators 61 and 62 have a labyrinth structure and perform a gas-liquid separation action for separating the lubricating oil contained in the flowing gas from the gas, and prevent the lubricating oil from being lost from the crank chamber 7.

  One end of the blow-by passage 65 is connected to the cam chamber 8 in the cylinder head cover of the internal combustion engine 0, and the other end is connected to the upstream side of the compressor 51 in the intake passage 3, and the cam chamber 8 communicates with the intake passage 3. Let me. An oil separator 62 is also provided at a location where the blow-by passage 65 is connected to the cam chamber 8.

  Hereinafter, the oil separators 61 and 62 will be described in detail. As shown in FIG. 2, in the oil separators 61 and 62 in the present embodiment, a plurality of reed valves are provided upstream of the labyrinth structure (downward in the figure), and the direction of gas flow including oil mist (from the lower side in the figure). (In the upper direction).

  The labyrinth structure includes a plurality of walls 601 extending in a direction intersecting with the flow direction of blow-by gas. The specific shape and arrangement of the labyrinth structure walls are not uniquely limited. The wall 601 is an obstacle to the gas flow. When the gas collides with the wall 601, a mist of lubricating oil contained in the gas adheres to the wall 601 and is separated from the gas. The lubricating oil separated from the gas is collected in an oil dropping hole 602 formed in the bottom walls of the oil separators 61 and 62 and flows down to the crank chamber 7 from there.

  The reed valve is a kind of one-way valve, and prevents the blow-by gas from flowing backward from the downstream side, that is, the intake passage 3 side, toward the upstream side, that is, the crank chamber 7 side.

  The valve body 603 of the reed valve is an elastically deformable thin plate body made of carbon, metal, or the like, and has a fixed end to which one end 603b is fixed, and a movable end that allows the other end 603a to perform a flap operation through elastic deformation. It has become. The valve body 603 abuts the valve seat 604 and closes the flow path through which gas passes (shown by a solid line in the figure).

  The EGR gas flowing from the crank chamber 7 side toward the intake passage 3 side hits the valve body 603, presses the valve body 603, elastically deforms it, and separates it from the valve seat 604 (shown by a chain line in the figure). As a result, the EGR passage 20 and the intake passage 3 communicate with each other, and EGR gas flows into the intake passage 3. The valve body 603 acts just like a leaf spring. When the differential pressure between the pressure upstream of the valve body 603 and the downstream pressure is small, or the latter exceeds the former, the valve body 603 is seated on the valve seat 604.

  The open / close characteristics of the reed valve, that is, how large the differential pressure between the pressure upstream of the valve body 603 and the downstream pressure is to separate the valve body 603 from the valve seat 604 (relation between the front-rear differential pressure and the valve opening) It differs depending on the material, size, shape, etc. of the body 603. In the present embodiment, a plurality of reed valves having different opening / closing characteristics are provided upstream of the labyrinth structure. Preferably, the reed valve located on the downstream side is more difficult to open than the reed valve located on the upstream side (it does not open unless the front-rear differential pressure is larger).

  Moreover, the positional relationship between the fixed end 603b and the movable end 603a of the valve body 603 is staggered between adjacent reed valves.

  In the oil separators 61 and 62 of the present embodiment, the valve body 603 of each reed valve acts like a labyrinth structure wall 601. Thereby, the lubricating oil contained in blow-by gas can be separated and removed from blow-by gas.

  Further, as shown in FIG. 3, fluctuations in the flow rate of the gas part of the blowby gas (shown by a solid line in the figure) and fluctuations in the flow rate of oil mist and oil droplets contained in the blowby gas (shown by the chain line in the figure). There is a time difference between The lead valve opens when the flow velocity of the blow-by gas flow is fast, and closes the lead valve when the flow velocity of the blow-by gas flow is slow, leading to oil mist and oil droplets that flow at a high flow velocity. Can be blocked by a valve.

  The opening / closing characteristics of multiple reed valves differ from each other, which means that the possibility of opening each reed valve at the same time is reduced. Blow-by gas is temporarily stored in the space area between the reed valves, resulting in a labyrinth. The pulsation of the gas flowing into the structure is reduced and the flow velocity of the gas is reduced. That is, the lubricating oil trapping effect in the labyrinth structure is improved.

  In this embodiment, in the blow-by gas recirculation device 6 applied to the internal combustion engine, a plurality of different opening / closing characteristics are provided upstream of the oil separators 61 and 62 that separate the lubricating oil contained in the circulating blow-by gas from the blow-by gas. The reed valves were arranged in series along the direction of blowby gas flow.

  According to the present embodiment, the lubricating oil can be removed by a plurality of reed valves, and the pulsation of blow-by gas flowing into the labyrinth structure can be suppressed. Therefore, it is possible to reduce the number of walls 601 that are the elements of the labyrinth structure, the labyrinth structure can be easily designed, and the oil separators 61 and 62 can be reduced in size and weight, and the manufacturing cost of the oil separators 61 and 62 can be reduced.

  The present invention is not limited to the embodiment described in detail above. For example, in the above embodiment, the plurality of reed valves are all arranged upstream of the labyrinth structure, but a part or all of the reed valves are arranged in the labyrinth structure or downstream of the labyrinth structure. I do not disturb. In short, it is not always necessary to provide a plurality of reed valves on the upstream side of the oil separators 61 and 62.

  Other specific configurations 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 6 ... Blow-by gas recirculation apparatus 61, 62 ... Oil separator 601 ... Wall of labyrinth structure 603 ... Valve body of reed valve

Claims (1)

In a blow-by gas recirculation device applied to an internal combustion engine,
A plurality of reed valves having different opening / closing characteristics are arranged in series along the flow direction of blow-by gas in an oil separator that separates lubricating oil contained in the blow-by gas from the blow-by gas. Blowby gas recirculation device.

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