JP2005248745A - Blow-by gas returning structure of multcylinder engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To uniformalize abrasion and exhaust gas performance in respective cylinders by eliminating variations of intake amount of blow-by gas in accordance with cylinders, and accelerate uniform distribution of the blow-by gas to respective cylinders by utilizing a structure in which EGR gas is returned to an intake passage. <P>SOLUTION: In the blow-by gas returning structure of a multicylinder engine, a reducing passage 52 of blow-by gas and a returning passage W of EGR gas are both connected to a single pipe part 13a before branching out into respective cylinders 21 in an intake passage K. In addition, the reducing passage 52 and the returning passage W are arranged so as to be faced to each other in the single pipe part 13a. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a blow-by gas return structure for a multi-cylinder engine such as a 4-cylinder diesel engine.

  In general, in an engine, there is a phenomenon that the mixed gas in the combustion chamber is blown out from the combustion chamber to the crank chamber due to the compression pressure. In order to avoid the possibility of oil leaking out from the oil seal portions, a processing device for preventing blow-by gas from accumulating in the crankcase is provided.

  There are two types of blow-by gas processing devices: a configuration in which the outlet of the breather chamber is opened to the atmosphere by a breather pipe (open breather method) and a configuration in which the air is returned to the intake passage of the engine (closed breather method). Has the latter configuration. That is, blow-by gas blown out from the combustion chamber to the crank chamber contains a large amount of hydrocarbons (HC) and causes air pollution, so after separating the oil with a breather device, it is introduced into the intake passage and again in the combustion chamber. It burns. As such a blow-by gas processing apparatus, the one disclosed in Patent Document 1 is known.

Conventionally, as a structure for returning blow-by gas to the intake passage in a multi-cylinder engine E such as a four-cylinder in-line diesel engine, a return passage (return pipe) 62 for blow-by gas taken out from the cylinder head cover 63 is provided as shown in FIG. , Connected to the branching portion 61 a in the intake manifold 61.
JP 2001-263037 A

  As shown in FIG. 13, in the structure in which the return passage 62 is connected to the branching portion 61 a of the intake manifold 61, the first and second ports P <b> 1 and P <b> 2 that are close to the return port 62 a among the plurality of intake ports P. The blow-by gas flows in a large amount, and the blow-by gas does not flow so much in the third and fourth intake ports P3 and P4 located far from the return port 62a. There was a variation in the inflow of gas. For this reason, inconveniences such as noticeable wear and deterioration around the valve due to blow-by gas in a specific cylinder, and influence on exhaust gas performance have occurred.

  An object of the present invention is to eliminate the variation in the intake amount of blow-by gas between cylinders, and to make the wear and exhaust gas performance in each cylinder uniform. Further, since an EGR device is attached depending on the type and specification of the engine, it is also intended to promote uniform distribution of blow-by gas to each cylinder by using a structure for returning the EGR gas to the intake passage. And

  In the blow-by gas return structure of the multi-cylinder engine, the structure of claim 1 is a single pipe portion (front tube) that branches the blow-by gas reduction passage (52) into each cylinder (21) in the intake passage (K). 13a), and the extension line of the passage center (X) at the connection side end of the reduction passage (52) to the single tube portion (13a) is the tube center of the single tube portion (13a). (Z) is configured so as not to pass through.

  According to the second aspect of the present invention, in the blow-by gas return structure of the multi-cylinder engine, a blow-by gas reduction passage (52) and an EGR gas return passage (W) are both provided to each cylinder (21) in the intake passage (K). It is connected to the single pipe portion (13a) before branching, and the reduction passage (52) and the return passage (W) are arranged and configured to face each other in the single pipe portion (13a). It is characterized by being.

  According to a third aspect of the present invention, in the blow-by gas return structure of the multi-cylinder engine according to the second aspect, the return passage (W) is a two-position switching type on-off valve (which can be intermittently connected to the return passage (W)). 46).

  According to a fourth aspect of the present invention, in the blow-by gas return structure of the multi-cylinder engine according to the third aspect, load detecting means (55) for detecting the magnitude of the load acting on the engine (E) is provided, and the detected load is large. Control means (56) for linking the load detection means (55) and the on-off valve (46) so that the on-off valve (46) is sometimes closed and the on-off valve (46) is opened when the detected load is small. It is equipped with.

  According to the configuration of claim 1, since the blow-by gas is returned to the intake passage of the single pipe portion before branching, it becomes possible to evenly distribute the blow-by gas to each cylinder. It is avoided that the amount of blow-by gas varies from cylinder to cylinder. In addition, the blow-by gas discharged from the reduction passage to the single pipe portion is displaced while the axis is shifted, so that the single pipe portion is discharged while generating a vortex flow, and the stirring action with the intake gas is promoted. Is done. This eliminates noticeable wear and deterioration around the valve in a specific cylinder, extends the life of the valve operating system as a whole, improves durability, stabilizes exhaust gas performance, and improves blow-by gas. There is an advantage that the intake gas is mixed well and the homogenization of the mixed gas is further promoted.

  According to the configuration of claim 2, since the reduction passage and the return passage are opposed to each other in the single pipe portion, the blow-by gas and the EGR gas collide with each other in the single pipe portion, and the stirring action with the intake gas is enhanced. This has the effect of promoting the homogenization of the mixed gas. Also, when the amount of EGR gas is large, such as when the load or rotational speed is high, the amount of blowby gas is large. When the amount of EGR gas is small, such as when the load or rotational speed is low, the amount of blowby gas is small, so Regardless of the fluctuation of the number, the above-mentioned collision between the gases is performed in a well-balanced manner, so that there is an advantage that uniform gas mixture due to the collision can be effectively obtained.

  According to the third aspect of the present invention, it is possible to switch between the state in which the EGR gas is discharged to the single pipe portion and the state in which the EGR gas is not discharged by the on-off valve. It is possible to selectively use a state where the reduction effect should be exhibited and a state where the reduction effect should not be exhibited. In addition, when the open / close valve is opened to discharge the EGR gas to the single pipe portion, there is an advantage that the uniformization of the mixed gas due to the collision with the blow-by gas described above is promoted.

  According to the fourth aspect of the present invention, when the engine load is large (when the exhaust gas temperature is high), the injection amount is large and air shortage tends to occur. This makes it possible to prevent PM deterioration. On the other hand, when the engine load is small (when the exhaust temperature is low), the injection amount is small and the air is abundant. Therefore, in such a state, the open / close valve is opened to return the EGR gas to the intake gas. A NOx reduction effect can be obtained. Therefore, the effect by the configuration of claim 3 can be further enhanced.

  Hereinafter, a case where the embodiment of the present invention is applied to a vertical overhead valve type multi-cylinder diesel engine will be described with reference to the drawings. 1 to 6 are partial views showing the structure of each part of the engine, FIG. 7 is a plan view of the whole engine, and FIGS. 8 and 9 are schematic views showing the main part of the blow-by gas return structure according to the first embodiment. FIG. 10 is a schematic diagram showing a main part of the blow-by gas return structure according to the second embodiment, and FIGS. 11 and 12 are quick reference tables showing combinations of EGR valve opening / closing control. FIG. 13 is a schematic view showing a main part of a conventional blow-by gas return structure.

  As shown in FIGS. 1 and 7, the engine E is configured by assembling a cylinder head 1 on an upper part of a cylinder block 49 and assembling a head cover 15 on the upper part thereof. A fuel injection nozzle 2 and a glow plug 3 are attached to the cylinder head 1. As shown in FIG. 1, the fuel injection nozzle 2 and the glow plug 3 are attached so that the front end of the fuel injection nozzle 2 faces the center 4 of the cylinder, and the intake port wall between the fuel injection nozzle 2 and the intake port 5. The glow plug 3 is passed through the portion 6, and the glow plug 3 is inclined by a predetermined angle θ 1 with respect to the fuel injection nozzle 2, and the tip thereof is inserted into the cylinder central portion 4.

  The configuration of the intake port 5 uses a swirl intake port as the intake port 5 as shown in FIG. The inner wall surface 8 of the intake port wall portion 6 near the intake valve ports 10 a and 10 b is inclined so as to approach the cylinder center axis 7 as it approaches the cylinder 21, and this inner wall surface 8 is made to follow the inclination of the glow plug 3. The opposing wall surface 8a of the inner peripheral wall 8 is raised along a direction parallel to the cylinder center axis 7, and a wedge-shaped port portion 5a that becomes wider toward the intake valve ports 10a and 10b is formed between the wall surfaces 8 and 8a. Forming.

  2, the fuel injection nozzle 2 is inserted into a nozzle boss 6a bulged from the intake port wall portion 6, as shown in FIG. As shown in FIG. 1, the relationship between the glow plug 3 and the head jacket 43 is such that an inter-port transverse water channel 12 is formed between the intake port 5 and the exhaust port 11, and the glow plug 3 is placed in the inter-port transverse water channel 12. The port wall portion 6 penetrated through is faced. Further, the cooling water passing through the inter-port water passage 12 is directed from the intake distribution means (intake manifold) 13 side to the exhaust merge means (exhaust manifold) 14 side.

  As shown in FIG. 1, the relationship between the glow plug 3 and the head cover 15 is such that the end of the glow plug 3 passes through the outer wall 16 of the head cover 15 attached to the cylinder head 1 and the terminal of the glow plug 3 is outside the head cover 15. It is protruding. As shown in FIG. 5, the relationship between the glow plug 3 and the breather chamber 20 is such that the breather chamber 20 provided on the ceiling of the head cover 15 is directed to one side of the crankshaft center axis 17 when viewed in a direction parallel to the cylinder center axis 7. As shown in FIG. 6, two intake valve ports 10a and 10b are provided for each intake port 5, and the glow plug 3 is passed through the intake port wall portion 6 between the intake valve ports 10a and 10b. In doing so, it is as follows. That is, as shown in FIG. 6, when viewed in a direction parallel to the cylinder center axis 7, a virtual connection line 18 that connects the center points of the two intake valve ports 10 a and 10 b is orthogonal to the crankshaft center axis 17. From this posture, the glow plug 3 is shifted in the direction opposite to the biasing direction of the breather chamber 20 by rotating it by a predetermined angle θ2 about the cylinder center axis 7.

  As shown in FIGS. 2 to 4, the structure of the intake device is such that the intake distribution means 13 is arranged on the side surface 23 of the cylinder head 1, and the intake distribution means 13 is a longitudinal case structure along the side surface 23 of the cylinder head 1. The side surface of the intake air distribution means 13 facing the side surface 23 of the cylinder head 1 is fully opened, and the opening edge 24 is attached to the side surface 23 of the cylinder head 1. Further, a mounting edge 25 is provided on the side surface 23 of the cylinder head 1, and an opening edge 24 of the intake air distribution means 13 is mounted on the mounting edge 25, and a portion surrounded by the mounting edge 25 is mounted on the side surface 23 of the cylinder head 1. It is made to recede inside the head from the edge 25.

  Further, as shown in FIG. 2, a rounded portion 26 b is formed between the outward surface 27 located between the intake port inlets 26 of adjacent cylinders and the inner peripheral surface 26 a of each intake port inlet 26. For this reason, when intake air is introduced from the intake air distribution means 13 into the intake port 5, there is no possibility of turbulent flow occurring at the boundary portion 26b, and intake into each intake port 5 is performed smoothly. Further, when the mounting edge 25 is polished, a part of the radius is cut off and the defect that the edge is formed does not occur, and the smooth radius can be surely formed.

  As shown in FIG. 2, the component mounting structure to the cylinder head 1 is provided with an intake distributing means 13, an exhaust merging means 14, and a cooling water circulation thermostat case 31 in the cylinder head 1, and intake valve ports 10 a and 10 b and an exhaust gas. The intake port 5 and the exhaust port 11 are led out in opposite directions along the head width direction of the cylinder head 1 from the valve ports 32a and 32b, and the intake distribution means 13 is attached to one side surface 23 of the cylinder head 1 to The merging means 14 is attached to the other side surface 34.

  As shown in FIG. 2, when the thermostat case 31 is disposed on the side surface 34 of the cylinder head 1 to which the exhaust gas merging means 14 is attached at one end in the longitudinal direction of the cylinder head 1, The exhaust valve ports 32a and 32b of each cylinder are disposed rearward of the intake valve ports 10a and 10b of the cylinders, with the one end portion of the cylinder head 1 having the cylinder 31 disposed at the front, and the exhaust merging means The thermostat case 31 is attached to the side surface 34 of the cylinder head 1 in front of the exhaust merging means 14.

  As shown in FIGS. 2 and 4, the valve actuator 35 of the EGR device 30 is disposed on the side surface 23 of the cylinder head 1 in front of the intake air distribution means 13. In this way, the large thermostat case 31 is disposed in the wide space in front of the exhaust merging means 14, and the small valve actuator 35 is disposed in the narrow space in front of the intake air distributing means 13. The cylinder head 1 can be compactly packed.

  As shown in FIG. 2, the relationship between the exhaust port 11 and the push rod 36 is that the push rod 36 of the valve operating device is disposed on the outlet side of the exhaust port 11 when viewed in a direction parallel to the cylinder center axis 7. A virtual transverse line 37 orthogonal to the crankshaft central axis 17 on the cylinder central axis 7 is assumed, and the intake valve ports 10a and 10b of the cylinder are located in front of the virtual transverse line 37 and the exhaust valve port 32a of the cylinder is located behind. , 32b are respectively arranged, and in the exhaust port 11, the intermediate portion 38 is deflected forward from the leading start end portion 39 along the head width direction, and the leading end portion 40 along the head width direction overlaps the virtual transverse line 37. Each of the pair of push rods 36 of the cylinder is distributed and arranged before and after the lead-out terminal portion 40.

  As shown in FIG. 2, the exhaust port 11 has a configuration in which a pair of exhaust valve ports 32 a and 32 b are arranged along the head width direction in the exhaust port 11, and the first exhaust valve port 32 a serves as a leading end of the exhaust port 11. When opening the second exhaust valve port 32b at the intermediate portion 38 of the exhaust port 11 while opening at the portion 39, the intermediate portion 38 is led forward from the lead-out starting end portion 39 along the head width direction of the exhaust port 11. The second exhaust valve port 32b is opened at the center of the curved arc of the intermediate portion 38, and the exhaust from the first exhaust valve port 32a is bypassed behind the second exhaust valve port 32b. A passage 41 is formed.

  As shown in FIG. 2, the relationship between the exhaust device and the EGR device 30 is that an EGR gas outlet passage (an example of a return passage W) 42 from an exhaust blow point guided by a curved intermediate portion 38 of the exhaust port 11. Is derived. Exhaust gas reduction can be performed using the pushing force of exhaust gas in addition to the supply / exhaust pressure difference, and a sufficient exhaust gas reduction amount can be ensured. Further, the EGR gas outlet passage 42 passes through the head jacket 43. For this reason, a dedicated EGR gas radiator is not necessary, and the component arrangement of the cylinder head 1 is facilitated. An EGR gas supply passage 44 following the EGR gas outlet passage (an example of the return passage W) 42 is formed in the meat wall of the intake air distribution means 13. For this reason, the EGR gas supply passage 44 does not protrude greatly from the cylinder head 1, and the arrangement of the components of the cylinder head 1 becomes easy.

  As shown in FIG. 2, the attachment structure of the valve actuator 35 of the EGR device 30 is such that the flange portion 45 is led out from the intake air distribution means 13 and the valve actuator 35 of the EGR device 30 is attached to the flange portion 45. Compared with the case where the valve actuator 35 is directly attached to the cylinder head 1, thermal deterioration of the valve actuator 35 is suppressed. In addition, a valve seat 47 of an EGR valve (an example of an on-off valve) 46 driven by the valve actuator 35 is formed on the side surface 23 of the cylinder head 1 to which the intake air distribution means 13 is attached. For this reason, the maintenance of the valve seat 47 can be easily performed.

  The EGR valve 46 is configured as a two-position switching type on-off valve that switches the return passage W composed of the EGR gas outlet passage 42 and the EGR gas supply passage 44 between a communication state and a cutoff state, and is switched by the valve actuator 35. Driven. That is, the valve actuator 35 detachably mounted on the flange portion 45 and the EGR valve 46 constitute a two-position switching type electromagnetic valve that allows the return path W to be intermittently connected.

  Next, the blow-by gas return structure according to the first embodiment will be described. As shown in FIGS. 7, 8, and 9, the blow-by gas processing apparatus A includes a breather mechanism 51 provided in the head cover 15, and a reduction passage 52 that connects an outlet 51 a of the breather mechanism 51 and the intake air distribution means 13. Although not shown, the inlet of the breather mechanism 51 is communicated with the inside of the crankcase. The intake air distribution means 13 is composed of a branch pipe portion 13b that branches into each cylinder (cylinder) 21 and a single pipe portion 13a that is in front of the branch pipe portion 13b. It comprises an L-shaped bent passage 53 formed within the thickness of the case block forming the distribution means 13, and a breather hose 54 connecting the bent passage 53 and the outlet 51a. The bent passage 53 includes a horizontal tube portion 53a connected to the single tube portion 13a and a vertical tube portion 53b connected to the breather hose 54.

  As shown in FIGS. 1 and 6 to 9, the end of each of the bent passage 53 and the EGR gas supply passage 44 has a single end before branching to each cylinder (cylinder) 21 in the intake air distribution means 13. In addition to being connected to the tube portion 13a, the single tube portion 13a is arranged and configured so that the bent passage 53 and the EGR gas supply passage 44 face each other. The horizontal pipe portion 53a of the bent passage 53 can be integrally formed with the same diameter sharing the shaft center X with the EGR gas supply passage 44 by, for example, extending a drilling process for drilling the EGR gas supply passage 44. it can. Note that the lateral tube portion 53a and the EGR gas supply passage 44 are laterally offset from the center position of the single tube portion 13a so that the shaft center X does not pass through the tube axis Z of the single tube portion 13a. However, the axial centers X and Z may be configured to intersect each other.

  Thus, since the reduction passage 52 and the EGR gas supply passage 44 are opposed to each other in the single pipe portion 13a, the blow-by gas and the EGR gas collide with each other in the single pipe portion 13a, and the stirring action with the intake gas is performed. It is strengthened and has an effect of promoting the homogenization of the mixed gas. Also, when the engine load and engine speed are high and the EGR gas amount increases, the blow-by gas amount also increases. When the load and rotation number is low and the EGR gas amount decreases, the blow-by gas amount also decreases. In addition, there is an advantage that the mixed gas can be made uniform due to the collision of the gases, regardless of the fluctuation of the rotation speed.

  As shown in FIGS. 8 and 9, the EGR device 30 includes load detection means 55 that detects the magnitude of the load acting on the engine E, and rotation speed detection means 57 that detects the engine rotation speed per unit time. The load detection means 55, the rotation speed detection means 57, and the EGR valve 46 are linked so that the opening / closing control of the EGR valve 46 is performed in accordance with the magnitude of the detected load and the level of the rotation speed, that is, the operating state of the engine. Control means 56 is provided. The load detection means 55 can be constituted by, for example, a rack position sensor that detects the position of the fuel metering rack in the governor device, and the rotation speed detection means 57 uses an actual rotation speed sensor or the like in the electronic governor device. Is possible.

  Due to the function of the control means 56, for example, as shown in FIG. 11, the on-off valve V is closed only when the load is high and the rotational speed is medium or high speed. V is controlled to open. Further, the rotation speed detecting means 57 is omitted, and the control means 56 closes the EGR valve 46 when the detected load is large, and opens the EGR valve 46 when the detected load is small, so that the load detecting means 55 and the EGR valve 46 are opened. May be linked to each other (see FIG. 12).

  By the way, the intake passage K is the intake distributing means 13, the intake port 5, and the intake valve ports 10a and 10b, and the communication passage W is a general term for the EGR gas outlet passage 42 and the EGR gas supply passage 44. . The EGR gas outlet passage 42 is a passage extending between the exhaust port 11 of the cylinder 21 located at the end of the four cylinders 21 and the flange portion 45, and the EGR gas supply passage 44 is a single pipe of the intake air distribution means 13. This is a passage extending between the portion 13a and the flange portion 45 (see FIGS. 2 and 7).

  In the blow-by gas return structure of the multi-cylinder engine according to the second embodiment, as shown in FIG. 10, the blow-by gas reduction passage 52 is connected to the single pipe portion 13 a before branching into each cylinder 21 in the intake passage K. In addition, the extension line of the passage center X at the connection side end portion of the reduction passage 52 to the single tube portion 13a is configured not to pass through the tube center Z of the single tube portion 13a.

  In this way, by shifting the tube center so that the axes X and Z do not intersect each other, the blow-by gas discharged from the reduction passage 52 becomes a vortex inside the single tube portion 13a and can be mixed well with the intake gas. Therefore, the intake gas 5 and the blow-by gas are mixed well in each of the four intake ports 5 (see FIG. 2 and the like) after branching, and the same for any intake port 5 (cylinder 21). The amount of blow-by gas is reduced, and a more uniform distribution state can be obtained.

Vertical side view around the front end of the cylinder head 1 is a cross-sectional plan view of the front end portion of the cylinder head of FIG. (A) is a sectional view taken along line III-III in FIG. 2, and (B) is a side view of the cylinder head in FIG. IV-IV sectional view of FIG. It is a figure explaining the head cover of FIG. 1, (A) is a top view, (B) is a side view. Top view with the head cover of FIG. 1 removed Overall plan view of multi-cylinder engine Schematic diagram of essential parts showing blow-by gas return structure (EGR valve closed) (Example 1) Schematic diagram of essential parts showing blow-by gas return structure (EGR valve opening) (Example 1) Schematic of the main part showing the blow-by gas return structure (Example 2) Combination table showing an example of EGR valve opening adjustment control Combination table showing other examples of opening adjustment control of EGR valve Plan view of the main part showing a conventional blow-by gas return structure

Explanation of symbols

13a Single pipe portion 21 Cylinder 46 On-off valve 52 Reduction passage 55 Load detection means 56 Control means E Engine K Intake passage W Return passage X Passage center X Pipe center

Claims (4)

  The blow-by gas reduction passage (52) is connected to the single pipe portion (13a) before branching into each cylinder (21) in the intake passage (K), and the single passage of the reduction passage (52). The blow-by of the multi-cylinder engine is configured such that the extension line of the passage center (X) at the connection side end to the pipe portion (13a) does not pass through the pipe center (Z) of the single pipe portion (13a). Gas return structure.   The blow-by gas reduction passage (52) and the EGR gas return passage (W) are both connected to the single pipe portion (13a) in front of the intake passage (K) that branches into each cylinder (21). A blow-by gas return structure for a multi-cylinder engine, wherein the reduction passage (52) and the return passage (W) are arranged to face each other in the single pipe portion (13a).   The blow-by gas return structure for a multi-cylinder engine according to claim 2, wherein the return passage (W) is equipped with a two-position switching type on-off valve (46) that can connect and disconnect the return passage (W). A load detecting means (55) for detecting the magnitude of the load acting on the engine (E) is provided. When the detected load is large, the on-off valve (46) is closed, and when the detected load is small, the on-off valve (46) is closed. The blow-by gas return structure for a multi-cylinder engine according to claim 3, further comprising a control means (56) for linking the load detection means (55) and the on-off valve (46) so as to open.

Images