JP2018048589A - Intake system for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an intake system for an internal combustion engine capable of reducing a difference between concentrations of evaporation fuel in intake air supplied from a surge tank to respective cylinders.SOLUTION: An intake system 10 for an internal combustion engine includes: a surge tank 20; a first intake pipe 30 and a second intake pipe 40 connected to the surge tank 20; and a purge passage 55 having a main passage 56 coupled to a canister 51 for collecting evaporation fuel generated in a fuel tank 200, a first branch passage 57 for connecting the main passage 56 with the first intake pipe 30, and a second branch passage 58 for connecting the main passage 56 with the second intake pipe 40. Check valves 61, 62 for allowing a flow of gas flowing out to the first intake pipe 30 or the second intake pipe 40 and blocking a flow of gas flowing in from the first intake pipe 30 or the second intake pipe 40 are provided in the first branch passage 57 and the second branch passage 58 in the purge passage 55, respectively.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an intake device for an internal combustion engine.

  The intake device for an internal combustion engine described in Patent Document 1 has a surge tank that is a member constituting an intake passage. Two intake pipes are connected to the surge tank, and intake air is introduced into the surge tank through each intake pipe. The surge tank communicates with each cylinder of the internal combustion engine. The intake air introduced from each intake pipe flows through the surge tank and is supplied to each cylinder.

Japanese Patent No. 2676996

  The above-described intake device for the internal combustion engine may be provided with a purge device that collects the evaporated fuel generated in the fuel tank and discharges it to each intake pipe. The purge device has a canister that collects the evaporated fuel generated in the fuel tank. A purge passage is connected to the canister. The purge passage has a main passage connected to the canister, and a first branch passage and a second branch passage branched from the main passage. The first branch passage is connected to one intake pipe, and the second branch passage is connected to the other intake pipe. The evaporated fuel collected in the canister flows through the main passage and each branch passage of the purge passage and flows out to each intake pipe.

  By the way, in an intake device of an internal combustion engine, a difference may occur in the pressure in each intake pipe due to a difference in pressure loss. When such a pressure difference becomes correspondingly large, the intake air may flow from one intake pipe to the other intake pipe through each branch passage of the purge passage. In this case, the evaporated fuel discharged from the canister to the purge passage flows along only the other intake pipe without flowing into one intake pipe along the flow of intake air. In the surge tank, it is desirable to supply intake air to each cylinder after mixing the intake air introduced from each intake pipe to make the concentration of the evaporated fuel uniform. However, if there is a large difference in the concentration of evaporated fuel in the intake air introduced from each intake pipe, the concentration of the evaporated fuel may not be sufficiently equalized, and intake air may be supplied from the surge tank to each cylinder.

  An intake device for an internal combustion engine for solving the above problems includes a surge tank communicating with each cylinder of the internal combustion engine, a plurality of intake pipes connected to the surge tank and introducing intake air to the surge tank, and a fuel A purge passage including a main passage connected to a canister for collecting evaporated fuel generated in the tank, and a plurality of branch passages connecting the main passage to each of the plurality of intake pipes; Each of the branch passages is provided with a check valve that blocks the flow of gas flowing in from the intake pipe while allowing the flow of gas flowing out to the intake pipe.

  In the above configuration, a check valve is provided in each branch passage of the purge passage, and the check valve blocks the flow of gas flowing from the intake pipe into the purge passage. Therefore, even if a pressure difference occurs in the plurality of intake pipes, the flow of intake air from the intake pipe to the other intake pipe through the branch passage of the purge passage is suppressed. Further, the check valve allows the flow of gas flowing out from the purge passage to the intake pipe. Therefore, the evaporated fuel discharged from the canister to the purge passage flows out to each intake pipe. That is, even if pressure differences occur in the plurality of intake pipes, the evaporated fuel flows into the plurality of intake pipes through the purge passages. Therefore, the concentration difference of the evaporated fuel in the intake air flowing through each intake pipe becomes smaller than when the evaporated fuel flows into only some of the intake pipes. Accordingly, when the intake air merges in the surge tank, the concentration of the evaporated fuel is easily made uniform, and the concentration difference of the evaporated fuel can be reduced in the intake air supplied from the surge tank to each cylinder.

The schematic diagram which shows schematic structure of the intake device of an internal combustion engine. The front view which shows typically the structure of a surge tank and an engine main body. The schematic diagram which shows the flow of the evaporative fuel from a fuel tank to a canister in the intake device of an internal combustion engine. The schematic diagram which shows the flow of the evaporative fuel from a canister to a surge tank in the intake device of an internal combustion engine.

An embodiment of an intake device for an internal combustion engine will be described with reference to FIGS. In the present embodiment, an example in which a V-type 6-cylinder internal combustion engine is employed as the internal combustion engine is shown.
As shown in FIG. 1, an intake device 10 for an internal combustion engine has a surge tank 20 that is a member constituting an intake passage. The surge tank 20 is disposed at a position close to the engine body 100 of the internal combustion engine. The surge tank 20 has a merging portion 21 disposed in the central portion thereof. The first introduction part 22 is connected to one end (the left end in FIG. 1) of the joining part 21. The merge part 21 and the first introduction part 22 communicate with each other. Further, the second introduction part 23 is connected to the other end (right end in FIG. 1) of the joining part 21. The merge part 21 and the second introduction part 23 communicate with each other.

  A first intake pipe 30 is connected to the first introduction part 22 of the surge tank 20. Intake air is introduced into the surge tank 20 through the first intake pipe 30. A first throttle valve 31 is disposed in the first intake pipe 30. The amount of intake air flowing through the first intake pipe 30 is adjusted by the first throttle valve 31.

  A second intake pipe 40 is connected to the second introduction portion 23 of the surge tank 20. Intake air is also introduced into the surge tank 20 through the second intake pipe 40. A second throttle valve 41 is disposed in the second intake pipe 40. The amount of intake air flowing through the second intake pipe 40 is adjusted by the second throttle valve 41.

  As shown in FIG. 2, the engine body 100 of the internal combustion engine has a cylinder block 101. The cylinder block 101 includes a main body portion 101A constituting a lower end portion thereof, and a first block portion 101B and a second block portion 101C which branch from the main body portion 101A and extend upward so as to form a V shape. It consists of.

  The engine body 100 of the internal combustion engine also has a cylinder head 102. The cylinder head 102 includes a first cylinder head 102A connected to the upper end of the first block portion 101B, and a second cylinder head 102B connected to the upper end of the second block portion 101C.

  The engine main body 100 includes a first bank 103 that includes a first block portion 101B and a first cylinder head 102A. A cylinder 103 </ b> A is formed inside the first bank 103. In the present embodiment, three cylinders 103 </ b> A are arranged in parallel in the first bank 103. A plurality of intake ports 1020A communicating with each cylinder 103A are formed in the first cylinder head 102A. FIG. 2 shows only one cylinder 103A and one intake port 1020A.

  The engine body 100 also includes a second bank 104 that is configured by the second block portion 101C and the second cylinder head 102B. A cylinder 104 </ b> A is formed inside the second bank 104. In the present embodiment, three cylinders 104 </ b> A are arranged in parallel in the second bank 104. The second cylinder head 102B is formed with a plurality of intake ports 1020B communicating with each cylinder 104A. FIG. 2 shows only one cylinder 104A and one intake port 1020B.

  A crankcase 105 is connected to the lower end of the main body 101 </ b> A of the cylinder block 101. A crankshaft 106 is supported by the lower end portion of the cylinder block 101 and the crankcase 105.

  As shown in FIGS. 1 and 2, the surge tank 20 is also provided with a plurality of branch branches 24 having one ends connected to the junction 21. The branch branch portion 24 is formed in a tubular shape. In the present embodiment, as the branch branches 24, three first branch branches 24A arranged in parallel on the first bank 103 side (left side in FIG. 1) and in parallel on the second bank 104 side (right side in FIG. 1). It has three second branch branches 24B provided. As shown in FIG. 2, the first branch branches 24A are each connected to the first cylinder head 102A. The first branch branch 24A communicates with the cylinder 103A of the first bank 103 through an intake port 1020A formed in the first cylinder head 102A. Further, each of the second branch branches 24B is connected to the second cylinder head 102B. The second branch 24B communicates with the cylinder 104A of the second bank 104 through an intake port 1020B formed in the second cylinder head 102B. That is, the surge tank 20 communicates with each cylinder 103A, 104A of the internal combustion engine. As indicated by arrows in FIG. 2, the intake air that flows from the first intake pipe 30 to the first introduction part 22 flows into the merge part 21 of the surge tank 20 with the intake air that flows from the second intake pipe 40 to the second introduction part 23. Join. The intake air merged at the merge unit 21 is supplied to the cylinders 103A and 104A of the engine body 100 through the branch branches 24.

  As shown in FIG. 1, the intake device 10 of the internal combustion engine also has a purge device 50 that collects the evaporated fuel generated in the fuel tank 200 and discharges it to the first intake pipe 30 and the second intake pipe 40. The purge device 50 includes a canister 51 and a purge passage 55 having one end connected to the canister 51 and the other end connected to the first intake pipe 30 and the second intake pipe 40. The canister 51 has a box-shaped case 52. An adsorbent 53 made of, for example, activated carbon is accommodated inside the case 52. The case 52 is formed with a first opening 52A, a second opening 52B, and a third opening 52C that allow the inside and the outside of the case 52 to communicate with each other. One end of the communication path 59 is connected to the first opening 52A. The other end of the communication path 59 is connected to the upper end portion of the fuel tank 200.

  One end of the main passage 56 in the purge passage 55 is connected to the second opening 52B. The main passage 56 is provided with a flow control valve 60 on its path. The flow rate control valve 60 is an electromagnetic valve and controls the flow of gas flowing through the main passage 56. One end of the first branch passage 57 and one end of the second branch passage 58 of the purge passage 55 are connected to the other end of the main passage 56. That is, the purge passage 55 has one end portion constituted by the main passage 56 as one passage, and the other end portion constituted by the branch passages 57 and 58 is a passage branched into two branches. Yes.

  The other end of the first branch passage 57 is connected to the intake downstream side of the first intake pipe 30 with respect to the first throttle valve 31. Thereby, the main channel | path 56 and the 1st intake pipe 30 are connected. The first branch passage 57 is provided with a first check valve 61 on its path. The first check valve 61 is a pressure-sensitive check valve. That is, the first check valve 61 is opened when the pressure on the one end side (main passage 56 side) of the first branch passage 57 is higher than the pressure on the other end side (first intake pipe 30 side). The flow of gas flowing out from the first branch passage 57 to the first intake pipe 30 is allowed. On the other hand, when the pressure on the one end side of the first branch passage 57 is equal to or lower than the pressure on the other end side, the valve is closed to block the flow of gas flowing from the first intake pipe 30 into the first branch passage 57.

  The other end of the second branch passage 58 is connected to the intake downstream side of the second intake valve 40 with respect to the second throttle valve 41. Thereby, the main channel | path 56 and the 2nd intake pipe 40 are connected. The second branch passage 58 is provided with a second check valve 62 on its path. The second check valve 62 is a pressure-sensitive check valve. That is, the second check valve 62 is opened when the pressure on the one end side (main passage 56 side) of the second branch passage 58 is higher than the pressure on the other end side (second intake pipe 40 side). The flow of gas flowing out from the second branch passage 58 to the second intake pipe 40 is allowed. On the other hand, when the pressure on the one end side of the second branch passage 58 is equal to or lower than the pressure on the other end side, the valve is closed to block the flow of gas flowing from the second intake pipe 40 into the second branch passage 58.

The third opening 52C formed in the case 52 of the canister 51 is open to the atmosphere.
As shown by an arrow in FIG. 3, in the intake device 10 of the internal combustion engine, the evaporated fuel generated in the fuel tank 200 flows to the canister 51. That is, when evaporative fuel is generated in the fuel tank 200, the pressure in the fuel tank 200 increases, so that the flowing gas containing the evaporated fuel and the air in the fuel tank 200 flows into the case 52 of the canister 51 through the communication path 59. To do. The flowing gas passes through the adsorbent 53 inside the case 52, whereby the evaporated fuel contained in the flowing gas is adsorbed by the adsorbent 53. The flowing gas from which the evaporated fuel is removed after passing through the adsorbent 53 is released to the atmosphere from the third opening 52C. As the flowing gas flows in this manner, the evaporated fuel generated in the fuel tank 200 is collected in the canister 51.

  Further, the evaporated fuel collected in the canister 51 flows out to the intake pipes 30 and 40 as follows. That is, when the engine body 100 is driven, negative pressure is generated in the intake passage constituted by the intake pipes 30 and 40 and the surge tank 20. Therefore, in the first branch passage 57, the pressure on the one end side (main passage 56 side) becomes higher than the pressure on the other end side (first intake pipe 30 side), and the first check valve 61 opens. . Also in the second branch passage 58, the pressure on the one end side (main passage 56 side) is higher than the pressure on the other end side (second intake pipe 40 side), and the second check valve 62 opens. To do. When the first check valve 61 and the second check valve 62 are opened, air flows from the first branch passage 57 to the first intake pipe 30, and air flows from the second branch passage 58 to the second intake pipe 40. To do. In a state in which the flow control valve 60 provided in the purge passage 55 is closed, negative pressure is applied to the other end side of the first branch passage 57, the second branch passage 58, and the main passage 56 from the flow control valve 60. Is supplied.

  By the way, in the 1st intake pipe 30 and the 2nd intake pipe 40, pressure loss may change with differences in those shapes, a flow path diameter, a flow path length, etc. In the present embodiment, the flow path diameter of the first intake pipe 30 is slightly larger than the flow path diameter of the second intake pipe, and the pressure loss of the first intake pipe 30 is larger than the pressure loss of the second intake pipe 40. small. For this reason, when negative pressure is generated in the first intake pipe 30 and the second intake pipe 40, the pressure in the first intake pipe 30 is lower than the pressure in the second intake pipe 40. In this case, the pressure on the one end side of the first branch passage 57, the one end side of the second branch passage 58, and the other end side of the main passage 56 are substantially equal to the pressure in the first intake pipe 30. In other words, the pressure at the one end side of the first branch passage 57, the one end side of the second branch passage 58, and the other end side of the main passage 56 is lower than the pressure of the second intake pipe 40. As a result, in the first branch passage 57, the pressure on one end side is the same as the pressure on the other end side, and in the second branch passage 58, the pressure on one end side is lower than the pressure on the other end side. Therefore, both the first check valve 61 and the second check valve 62 shift from the open state to the closed state.

  Thus, when the flow control valve 60 is closed in the intake device 10 of the internal combustion engine, the first check valve 61 and the second check valve 62 are once opened by the negative pressure of the intake pipes 30 and 40. However, the check valves 61 and 62 are closed after that, and the flow of gas through the first branch passage 57 and the second branch passage 58 is suppressed. The check valves 61 and 62 are driven in the same manner when the pressure loss of the first intake pipe 30 and the second intake pipe 40 is the same, or when the pressure loss of the first intake pipe 30 is the pressure loss of the second intake pipe 40. This is the same even if it is larger than the above.

  When the flow control valve 60 is opened, the canister 51 and the branch passages 57 and 58 communicate with each other through the main passage 56. Since the pressure of the canister 51 opened to the atmosphere is higher than the pressure in the intake pipes 30 and 40, the pressure on the one end side of the first branch passage 57 becomes higher than the pressure on the other end side, and the second The pressure on the one end side of the branch passage 58 is higher than the pressure on the other end side. Therefore, the first check valve 61 and the second check valve 62 are opened, and air flows from the canister 51 to the intake pipes 30 and 40 through the purge passage 55.

  As indicated by the one-dot chain line arrow in FIG. 4, when the flow control valve 60 is opened, air flows into the case 52 of the canister 51 through the third opening 52 </ b> C. The air flowing into the case 52 passes through the adsorbent 53 and is then discharged from the second opening 52B to the main passage 56 of the purge passage 55. When the air passes through the adsorbent 53, the evaporated fuel collected in the adsorbent 53 is separated and mixed into the air. Therefore, the gas discharged from the canister 51 to the purge passage 55 becomes a purge gas containing air and evaporated fuel. As indicated by solid arrows in FIG. 4, the purge gas flows from the main passage 56 to the first branch passage 57 or the second branch passage 58. The purge gas that has flowed into the first branch passage 57 passes through the first check valve 61, flows out into the first intake pipe 30, and flows into the surge tank 20 together with the intake air. The purge gas that has flowed into the second branch passage 58 flows out to the second intake pipe 40 through the second check valve 62 and flows into the surge tank 20 together with the intake air.

  In addition, as shown in FIG. 1, the control apparatus 70 is also provided in the intake device 10 of the internal combustion engine. For example, output signals from various sensors such as an accelerator sensor 71 that detects the depression amount of the accelerator pedal and a rotation speed sensor 72 that detects the rotation speed of the crankshaft 106 are input to the control device 70. The control device 70 controls the opening degrees of the first throttle valve 31 and the second throttle valve 41 based on signals input from various sensors. The control device 70 also controls the flow control valve 60 based on signals from various sensors. For example, the flow control valve 60 is opened when a predetermined condition such as the amount of evaporated fuel collected by the canister 51 being equal to or greater than a predetermined amount is satisfied. Thereby, the evaporated fuel collected by the canister 51 flows out to the intake pipes 30 and 40.

Next, the effect of this embodiment is demonstrated.
(1) In the present embodiment, the first check valve 61 is provided in the first branch passage 57 of the purge passage 55, and the second check valve 62 is provided in the second branch passage 58. The first check valve 61 blocks the flow of intake air flowing from the first intake pipe 30 into the purge passage 55. Further, the second check valve 62 blocks the flow of intake air flowing from the second intake pipe 40 into the purge passage 55. Therefore, even if a pressure difference occurs between the first intake pipe 30 and the second intake pipe 40 due to a difference in pressure loss, the first intake pipe is passed through the first branch passage 57 and the second branch passage 58 of the purge passage 55. The flow of intake air between the air intake 30 and the second intake pipe 40 is suppressed.

  On the other hand, the first check valve 61 allows the purge gas to flow out from the purge passage 55 to the first intake pipe 30, and the second check valve 62 allows the purge gas to flow out from the purge passage 55 to the second intake pipe 40. Allow flow. Therefore, the purge gas discharged from the canister 51 to the purge passage 55 flows out to the intake pipes 30 and 40. That is, even if there is a pressure difference between the first intake pipe 30 and the second intake pipe 40, purge gas, that is, evaporated fuel, flows into the first intake pipe 30 and the second intake pipe 40 through the purge passage 55, respectively. Can be made. Therefore, compared with the case where the evaporated fuel flows into only one of the first intake pipe 30 and the second intake pipe 40, the concentration difference of the evaporated fuel in the intake air flowing through the intake pipes 30 and 40 becomes smaller. .

  Accordingly, when the intake air introduced from the first intake pipe 30 and the intake air introduced from the second intake pipe 40 merge in the surge tank 20, the concentration of the evaporated fuel is easily made uniform, and the cylinders from the surge tank 20 to each cylinder In the intake air supplied to 103A and 104A, the concentration difference of the evaporated fuel can be reduced.

  (2) Since the first branch portion 24A of the surge tank 20 is arranged on the first introduction portion 22 side in the junction portion 21, the intake air flowing from the first introduction portion 22 to the junction portion 21 is the first branch portion. It tends to flow into the branch 24A. On the other hand, since the second branch branch portion 24B of the surge tank 20 is disposed on the second introduction portion 23 side in the junction portion 21, the intake air flowing from the second introduction portion 23 to the junction portion 21 is second branched. It tends to flow into the branch 24B. In such a configuration, the intake air introduced from the first intake pipe 30 and the intake air introduced from the second intake pipe 40 may not be actively mixed in the merging portion 21. Thus, even if the intake air merged at the merge portion 21 is difficult to be mixed, the concentration difference of the evaporated fuel in the intake air flowing through the intake pipes 30 and 40 can be reduced. It is possible to reduce the concentration difference of the evaporated fuel in the intake air supplied to 104A.

The above embodiment can be implemented with the following modifications.
In the above embodiment, the first intake pipe 30 and the second intake pipe 40 are connected to the surge tank 20, but three or more intake pipes may be connected to the surge tank 20. In this case, the purge passage 55 is provided with the same number of branch passages as the intake pipes, and the main passage 56 and each of the plurality of intake pipes are connected by a plurality of branch passages, thereby providing the same configuration as that of the above embodiment. be able to.

-The structure of the surge tank 20 is not restricted to what was mentioned above. For example, the first introduction part 22 may be omitted and the first intake pipe 30 may be connected to the merging part 21.
Although the example in which the intake device 10 for an internal combustion engine is applied to a V-type 6-cylinder internal combustion engine has been shown, it can also be applied to other internal combustion engines having different numbers of cylinders, such as a V-type 8-cylinder. The number of banks provided in the engine main body 100 is not limited to two, that is, the first bank 103 and the second bank 104, and may be three or more. Also, the number of banks may be one. That is, it is possible to apply the same configuration as that of the above-described embodiment to an in-line internal combustion engine.

  DESCRIPTION OF SYMBOLS 10 ... Intake device of internal combustion engine, 20 ... Surge tank, 21 ... Confluence | merging part, 22 ... 1st introduction part, 23 ... 2nd introduction part, 24 ... Branch branch part, 24A ... 1st branch branch part, 24B ... 2nd Branch branch portion 30 ... first intake pipe 31 ... first throttle valve 40 ... second intake pipe 41 ... second throttle valve 50 ... purge device 51 ... canister 52 ... case 52A ... first opening Part, 52B ... second opening, 52C ... third opening, 53 ... adsorbent, 55 ... purge passage, 56 ... main passage, 57 ... first branch passage, 58 ... second branch passage, 59 ... communication passage, DESCRIPTION OF SYMBOLS 60 ... Flow control valve, 61 ... 1st check valve, 62 ... 2nd check valve, 70 ... Control apparatus, 71 ... Accelerator sensor, 72 ... Rotational speed sensor, 100 ... Engine main body, 101 ... Cylinder block, 101A ... Body part, 101B... First block part, 101 2nd block, 102 ... Cylinder head, 102A ... 1st cylinder head, 1020A ... Intake port, 102B ... 2nd cylinder head, 1020B ... Intake port, 103 ... 1st bank, 103A ... Cylinder, 104 ... 2nd bank , 104A ... cylinder, 105 ... crankcase, 106 ... crankshaft, 200 ... fuel tank.

Claims (1)

A surge tank communicating with each cylinder of the internal combustion engine;
A plurality of intake pipes connected to the surge tank and introducing intake air to the surge tank;
A main passage connected to a canister that collects evaporated fuel generated in the fuel tank, and a purge passage including a plurality of branch passages connecting the main passage and each of the plurality of intake pipes;
Each branch passage of the purge passage is provided with a check valve that allows the flow of gas flowing out to the intake pipe while blocking the flow of gas flowing in from the intake pipe. apparatus.

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