PCV piping

Abstract

To provide a PCV pipeline capable of improving OBD detectability.SOLUTION: A PCV (Positive Crankcase Ventilation) pipeline connected to an internal combustion engine and an intake passage includes a first portion connected to the internal combustion engine, a second portion connected to the intake passage, and a third portion positioned between the first portion and the second portion. An inside diameter of the third portion is smaller than an inside diameter of the first portion and an inside diameter of the second portion.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to PCV piping. [Background technology]

[0002] A PCV (Positive Crankcase Ventilation) structure is known that draws unburned gas (blow-by gas) leaking from a combustion chamber of an internal combustion engine into an intake passage (see, for example, Patent Document 1). The blow-by gas is introduced into the combustion chamber together with air. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2018-119411 A Summary of the Invention [Problem to be solved by the invention]

[0004] A hose (PCV path) is used to supply blow-by gas from the crankcase to the intake passage. By measuring the pressure in the PCV path, a hole in the PCV path can be detected (OBD detection, On Board Diagnosis). Specifically, a hole is detected according to the difference between the pressure when there is no hole and the pressure when there is a hole. However, if the pressure difference is small, OBD detection can be difficult. Therefore, the objective of the present invention is to provide a PCV piping that can improve OBD detection. [Means for solving the problem]

[0005] The object of the present invention is to provide a compressor connected to an internal combustion engine and an intake passage, The system includes a first pipe, a second pipe, and a third pipe provided between the first pipe and the second pipe and connected to the first pipe and the second pipe, and the first pipe is A first portion connected to the internal combustion engine Includes , The second piping is A second portion connected to the intake passage Includes , The third piping is A third portion located between the first portion and the second portion. the first pipe is connected to a portion other than the first portion and the second pipe is connected to a portion other than the second portion, the first portion is connected to a union of the internal combustion engine, and the second portion is connected to a union of the intake passage,The inner diameter of the third portion is smaller than the inner diameter of the first portion and the inner diameter of the second portion. an inner diameter of the first pipe other than the first portion and an inner diameter of the second pipe other than the second portion are equal to an inner diameter of the third pipe This can be achieved by using PCV (Positive Crankcase Ventilation) piping.

[0006] The inner diameter of the third portion is 80% or less of the inner diameter of the first portion and the inner diameter of the second portion. Good too.

[0007] The system includes a first connection pipe and a second connection pipe, the first connection pipe connects the third pipe to a portion of the first pipe other than the first portion, and the second connection pipe connects the third pipe to a portion of the second pipe other than the second portion. This is also fine.

[0008] The inner diameter of the third portion may be equal to the inner diameter of the engine union and the inner diameter of the intake passage union. Effect of the Invention

[0009] It is possible to provide PCV piping that enables improved OBD detectability. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic diagram illustrating an engine system. [Diagram 2] FIG. 2 is an enlarged cross-sectional view of the PCV structure. [Diagram 3] FIG. 3 is an enlarged cross-sectional view of a PCV structure according to a comparative example. [Figure 4] 4(a) and 4(b) are cross-sectional views illustrating an example of a PCV piping. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The PCV structure of this embodiment will be described below with reference to the drawings. Fig. 1 is a schematic diagram illustrating an engine system 100. The engine system 100 has an internal combustion engine 10, an ECU (Electronic Control Unit) 25, and a PCV structure 30.

[0012] The internal combustion engine 10 is, for example, a gasoline engine. The internal combustion engine 10 includes a cylinder block 20, a cylinder head 21, a crankcase 27, a fuel injector 13, a piston 24, a crankshaft 22, an intake valve 17, and an exhaust valve 19.

[0013] A cylinder head 21 is attached on top of the cylinder block 20, and a crankcase 27 is attached below the cylinder block 20. A crankshaft 22 is housed inside the crankcase 27. One end of a connecting rod 23 is connected to a piston 24, and the other end is connected to the crankshaft 22. A combustion chamber 26 is defined by the cylinder block 20, the cylinder head 21, and the piston 24.

[0014] An intake valve 17, an exhaust valve 19, and a fuel injection valve 13 are provided in a cylinder head 21. The fuel injection valve 13 performs in-cylinder injection. The fuel injection valve 13 is provided in an intake passage 12, and may perform port injection.

[0015] The intake passage 12 and the exhaust passage 14 are connected to a cylinder head 21. In the intake passage 12, an air cleaner 15, an air flow meter 16, and a throttle valve 18 are provided in this order from the upstream side. The air cleaner 15 removes dust and other particles from the air in the intake passage 12 to purify the air. The air flow meter 16 detects the flow rate of air in the intake passage 12. The throttle valve 18 adjusts the flow rate of air. The larger the opening of the throttle valve 18, the greater the flow rate of air. The smaller the opening of the throttle valve 18, the smaller the flow rate of air. The exhaust passage 14 is provided with a catalyst and the like (not shown).

[0016] Air in the intake passage 12 is introduced into the combustion chamber 26 in response to the opening of the intake valve 17. The fuel injector 13 injects fuel into the combustion chamber 26. A mixture of fuel and air is generated in the combustion chamber 26. The mixture is burned by, for example, ignition by a spark plug (not shown). The combustion of the mixture moves the piston 24 downward. Power is transmitted from the piston 24 to the crankshaft 22, causing the crankshaft 22 to rotate. The piston 24 reciprocates up and down. When the exhaust valve 19 opens, the exhaust gas after combustion is discharged into the exhaust passage 14.

[0017] Unburned gas (blow-by gas) may leak from the combustion chamber 26 into the crankcase 27. The PCV structure 30 is a device for returning the blow-by gas from the crankcase 27 to the intake passage 12. The PCV structure 30 has a pressure sensor 31, a PCV passage 32, and a PCV piping 34. The PCV passage 32 is provided inside the cylinder block 20 and the cylinder head 21, and extends to the crankcase 27.

[0018] The PCV piping 34 is provided outside the internal combustion engine 10 and extends from the internal combustion engine 10 to the intake passage 12. One end of the PCV piping 34 is connected to the cylinder head 21 of the internal combustion engine 10 and communicates with the PCV passage 32. The other end of the PCV piping 34 is connected to the intake passage 12 upstream of the throttle valve 18. Blow-by gas flows through the PCV passage 32 and the PCV piping 34, and is supplied from the crankcase 27 to the intake passage 12. The blow-by gas is introduced into the combustion chamber 26 together with air and is combusted. The pressure sensor 31 detects the pressure in the PCV piping 34.

[0019] The ECU 25 is a control device that includes a calculation device such as a CPU (Central Processing Unit) and storage devices such as a flash memory, a ROM (Read Only Memory) and a RAM (Random Access Memory). The ECU 25 acquires the air flow rate detected by the air flow meter 16. The ECU 25 controls the amount and timing of fuel injection from the fuel injection valve 13. The ECU 25 controls the opening of the throttle valve 18. The ECU 25 acquires the internal pressure of the PCV piping 34 measured by the pressure sensor 31, and detects whether there is a hole in the PCV piping 34 based on the internal pressure (OBD detection).

[0020] Because the PCV piping 34 is connected to the intake passage 12, the internal pressure is lower than atmospheric pressure (negative pressure) like the intake passage 12. When a hole penetrating the wall surface of the PCV piping 34 occurs, air flows into the inside of the PCV piping 34. This causes the internal pressure of the PCV piping 34 to rise above the normal pressure. The ECU 25 calculates the difference between the pressure when there is no hole in the PCV piping 34 and the internal pressure of the PCV piping 34. The ECU 25 detects that there is a hole in the PCV piping 34 when, for example, the difference becomes equal to or exceeds a predetermined value.

[0021] 2 is an enlarged cross-sectional view of the PCV structure 30. The PCV piping 34 has a hose 40 (first piping), a hose 42 (second piping), and a pipe 44 (third piping, third portion). The hoses 40 and 42 and the pipe 44 are cylindrical and made of, for example, resin or metal. The hose 40 is connected to a union 46 of the internal combustion engine 10. The hose 42 is connected to a union 48 of the intake passage 12. The pipe 44 is connected to the hose 40 and the hose 42.

[0022] The hose 40 and the pipe 44 are connected by a connecting pipe 41. The hose 40 is connected to one end of the connecting pipe 41. The pipe 44 is connected to the other end of the connecting pipe 41. The hose 40 and the pipe 44 are in contact with the outer circumferential surface of the connecting pipe 41. The hose 42 and the pipe 44 are connected by a connecting pipe 43.

[0023] Hose 40 has a portion 40a (first portion) and a portion 40b. Part 40a is connected to union 46. Part 40b is connected to pipe 44. Hose 42 has a portion 42a (second portion) and a portion 42b. Part 42a is connected to union 48. Part 42b is connected to pipe 44.

[0024] The inner diameter of the portion 40a is φ1, and the inner diameter of the portion 42a is φ2. The inner diameter of the portion 40b, the portion 42b, and the pipe 44 is φ3. The inner diameters φ1 and φ2 are equal. The inner diameters φ1 and φ2 are greater than the inner diameter φ3. The inner diameter φ4 of the union 46 and the inner diameter φ5 of the union 48 are, for example, equal to each other and equal to the inner diameter φ3 of the pipe 44.

[0025] 3 is an enlarged cross-sectional view of a PCV structure 30R according to a comparative example. The PCV structure 30R has a PCV pipe 34R. The PCV pipe 34R is a single hose, and is connected to a union 46 and a union 48. The inner diameter φ6 of the PCV pipe 34R is constant from one end to the other end, and is larger than the inner diameter φ4 of the union 46 and the inner diameter φ5 of the union 48, and is larger than the inner diameter φ3 of the pipe 44 in FIG. 2.

[0026] 4(a) and 4(b) are cross-sectional views illustrating an example of a PCV piping, showing a state in which a hole 50 is drilled in the PCV piping. Fig. 4(a) shows a PCV piping 34R of a comparative example. Fig. 4(b) shows a pipe 44 of the PCV piping 34 of the embodiment. The hole 50 penetrates the wall of the piping.

[0027] As shown in Figures 4(a) and 4(b), the inner diameter φ3 of the pipe 44 is smaller than the inner diameter φ6 of the PCV piping 34R. The cross-sectional area of ​​the pipe 44 is smaller than the cross-sectional area of ​​the PCV piping 34R. Therefore, the proportion of the cross-sectional area of ​​the pipe 44 that is occupied by the hole 50 is larger than the proportion of the cross-sectional area of ​​the PCV piping 34R. The larger the proportion of the hole 50, the greater the effect of the hole 50 on the internal pressure.

[0028] The effect of the hole 50 on the internal pressure of the PCV piping 34R is small. Therefore, the amount of change in the internal pressure of the PCV piping 34R is small. The smaller the pressure difference between the normal state (no hole) and the abnormal state (hole), the more difficult it becomes to detect the hole.

[0029] On the other hand, the hole 50 has a large effect on the internal pressure of the pipe 44. The amount of change in the internal pressure of the pipe 44 increases. The increase in the pressure difference between the normal state (no hole) and the abnormal state (a hole exists) makes it possible to detect the hole with high accuracy.

[0030] According to this embodiment, the portion 40a of the PCV piping 34 has an inner diameter φ1, and the portion 42a has an inner diameter φ2. The portions 40b, 42b, and the pipe 44 have an inner diameter φ3 that is smaller than the inner diameters φ1 and φ2. The effect of the hole on the internal pressure of the PCV piping 34 becomes greater. That is, the amount of change in the internal pressure between a state where there is no hole and a state where there is a hole becomes greater. Therefore, the occurrence of a hole can be detected based on the internal pressure, improving OBD detectability.

[0031] The PCV piping 34 includes hoses 40 and 42 and a pipe 44, which are connected together. The hose 40 includes a portion 40a. The hose 42 includes a portion 42a. The inner diameter φ3 of the pipe 44 is smaller than the inner diameter φ1 of the portion 40a and the inner diameter φ2 of the portion 42a. The amount of change in internal pressure between a state with no hole and a state with a hole increases. OBD detectability is improved.

[0032] The inner diameter of the portion 40b of the hose 40 and the inner diameter of the portion 42b of the hose 42 are φ3, which is equal to the inner diameter of the pipe 44. In the PCV piping 34, the inner diameters of the portions 40b and 42b and the inner diameter of the pipe 44 are φ3. The amount of change in the internal pressure increases between a state where there is no hole and a state where there is a hole. OBD detectability is improved. The size of the inner diameter φ3 may be, for example, 80% or less of the inner diameters φ1 and φ2, 70% or less, or 50% or less.

[0033] It is difficult to manufacture a single hose with an inner diameter of φ1 at both ends and an inner diameter of φ3 in the middle. The PCV piping 34 of this embodiment is formed by hoses 40 and 42 and a pipe 44. The inner diameter of one end of the hose 40 is φ1, and the inner diameter of the other end is φ3. The inner diameter of one end of the hose 42 is φ2, and the inner diameter of the other end is φ3. A hose with a large inner diameter at one end and a small inner diameter at the other end can be easily manufactured. The inner diameter of the entire pipe 44 is φ3. A pipe with a constant inner diameter throughout can also be manufactured. The PCV piping 34 can be manufactured by manufacturing the hoses 40 and 42 and the pipe 44 and connecting them.

[0034] The portion 40a of the hose 40 is connected to a union 46. The portion 42a of the hose 42 is connected to a union 48. The inner diameter φ3 of the pipe 44 is equal to the inner diameter φ4 of the union 46 and the inner diameter φ5 of the union 48. The amount of change in the internal pressure between a state without a hole and a state with a hole increases. OBD detectability is improved.

[0035] Although a preferred embodiment of the present invention has been described in detail above, the present invention is not limited to such a specific embodiment, and various modifications and variations are possible within the scope of the gist of the present invention described in the claims. [Explanation of symbols]

[0036] 10 Internal combustion engine 12 Intake passage 13 Fuel injection valve 14 Exhaust passage 15 Air cleaner 16 Air flow meter 17 Intake valve 18 Throttle valve 19 Exhaust valve 25 ECU 20 Cylinder block 21 Cylinder head 22 Crankshaft 23 Connecting rod 24 Piston 26 Combustion chamber 30 PCV structure 31 Pressure Sensor 32 PCV passage 34, 34R PCV piping 40, 42 hose 44 Pipe 40a, 40b, 42a, 42b parts 41, 43 Connecting pipe 46, 48 Union 100 Engine System

Claims

1. connected to the internal combustion engine and to the intake passage, A first pipe; A second pipe; a third pipe provided between the first pipe and the second pipe and connected to the first pipe and the second pipe, the first pipe includes a first portion connected to the internal combustion engine, the second pipe includes a second portion connected to the intake passage, The third pipe constitutes a third portion located between the first portion and the second portion, is connected to a portion of the first pipe other than the first portion, and is connected to a portion of the second pipe other than the second portion, the first portion is connected to a union of the internal combustion engine; the second portion is connected to a union of the intake passage; an inner diameter of the third portion is smaller than an inner diameter of the first portion and an inner diameter of the second portion; A PCV (Positive Crankcase Ventilation) pipe, in which an inner diameter of the first pipe other than the first portion and an inner diameter of the second pipe other than the second portion are equal to an inner diameter of the third pipe.

2. The PCV piping as described in claim 1, wherein the inner diameter of the third portion is 80% or less of the inner diameter of the first portion and the inner diameter of the second portion.

3. A first connecting pipe; a second connecting pipe; The third pipe is connected to a portion of the first pipe other than the first portion by the first connection pipe, The PCV piping according to claim 1 or 2, wherein the third piping and a portion of the second piping other than the second portion are connected by the second connection pipe.

4. 4. The PCV piping according to claim 1, wherein an inner diameter of the third portion is equal to an inner diameter of a union of the internal combustion engine and an inner diameter of a union of the intake passage.

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