JP2014211088A - Closed breather system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a closed breather system capable of preventing oil mist remaining in blow-by gas without being eliminated in a ventilator from flowing into an intake air pipe.SOLUTION: The present invention relates to a closed breather system for separating and recovering oil mist from a blow-by gas 1 extracted from an engine 3 via a ventilator 2 and returning the oil mist to an intake pipe 7. A part of a gas return pipe 6 introducing the blow-by gas 1 from the ventilator 2 to the intake pipe 7 is brought into contact with an exhaust pipe 17 to constitute a heating part 22 receiving heat from the exhaust pipe 17. Oxidation catalyst 23 for the blow-by gas 1 oxidizing the oil mist is provided in the heating part 22.

Description

  The present invention relates to a closed breather system.

  The blow-by gas that leaks into the crankcase through the gap between the piston rings during the compression stroke and explosion stroke of the engine fills the crankcase and the cylinder head cover that communicates with the crankcase. The crankshaft and connecting rod are moving at high speed in the crankcase, and the rocker arm and valve are operating in the cylinder head cover communicating with the crankcase. The inside is filled with oil mist.

  For this reason, if the blow-by gas is released as it is, the oil mist mixed with the blow-by gas may be discharged to the outside. Therefore, the oil mist in the blow-by gas 1 as shown in FIG. A ventilator 2 (CCV: Closed Crankcase Ventilator) with a built-in filter net or labyrinth structure for separating and recovering gas is provided, and the blow-by gas 1 extracted from the cylinder head cover 4 of the engine 3 via the gas extraction pipe 5 is provided in the ventilator 2. The oil mist is separated and recovered by passing it through and then returned to the intake pipe 7 via the gas return pipe 6, and the oil 8 recovered by the ventilator 2 is returned to the oil pan (not shown) via the oil recovery pipe 9. Yes.

  In FIG. 5, 10 is an air cleaner, 11 is a turbocharger, 11a is a compressor, 11b is a turbine, 12 is an intercooler, 13 is intake air, 14 is exhaust gas, 15 is an intake manifold, 16 is an exhaust manifold, and 17 is exhaust. A pipe, 18 is a muffler containing an oxidation catalyst 19, 20 is an EGR cooler, and 21 is an EGR valve.

  Generally, a system for processing the blow-by gas 1 as described above in a closed circuit is called a closed breather system. As prior art document information related to this type of closed breather system, the following patent document 1 and the like are disclosed. is there.

JP 2003-278523 A

  However, in such a conventional closed breather system, although the oil mist contained in the blow-by gas 1 is separated and recovered by the ventilator 2, it is difficult to completely remove the oil mist by the ventilator 2. A small amount of oil mist that has not entered the compressor 11a of the turbocharger 11 is exposed to a temperature increase caused by the pressure increase of the intake air 13 and the thermosetting component in the oil mist is cured, and the blade portion of the compressor 11a There is a possibility that coking will be caused by such as to cause malfunction of the turbocharger 11.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a closed breather system capable of preventing the oil mist remaining in blow-by gas remaining in the blow-by gas without being removed by the ventilator from flowing into the intake pipe.

  The present invention relates to a closed breather system in which blow-by gas extracted from the engine side is separated and recovered via an air ventilator and returned to the intake pipe, and a part of the gas return pipe that guides the blow-by gas from the ventilator to the intake pipe is provided. A heating unit that contacts the exhaust pipe and receives heat from the exhaust pipe side is configured, and an oxidation catalyst for blow-by gas that oxidizes oil mist is provided in the heating unit.

  Thus, in this way, the heat on the exhaust pipe side through which the high-temperature exhaust gas flows is transmitted to the heating part of the gas return pipe, and the oxidation catalyst for blow-by gas in the heating part is heated to a high activity state. Therefore, when the blow-by gas passes through this highly active oxidation catalyst, a small amount of oil mist that could not be removed by the ventilator was efficiently oxidized, thereby removing the oil mist. Only gas will be returned to the intake pipe.

  Further, in the present invention, an exhaust gas oxidation catalyst that oxidizes unburned hydrocarbon components in the exhaust gas is interposed in the middle of the exhaust pipe, and the gas return pipe side is disposed along the interposed position. It is preferable that the heating unit is configured. In this way, not only the heat of the exhaust gas but also the reaction heat due to the oxidation treatment of the unburned hydrocarbon component with the oxidation catalyst for the exhaust gas is caused on the gas return pipe side. It is transmitted to the heating part, and it becomes possible to raise the temperature of the oxidation catalyst for blow-by gas to a higher temperature for further activation.

  In addition, even if the exhaust gas flow rate and temperature fluctuate greatly depending on the operating condition on the engine side, the exhaust gas oxidation catalyst functions as a heat accumulator, which can cause large heat fluctuations in the heating part on the gas return pipe side. Therefore, there is an advantage that the oxidation catalyst for blow-by gas is stably maintained in a high activity state.

  According to the above-described closed breather system of the present invention, various excellent effects as described below can be obtained.

  (I) According to the invention described in claim 1 of the present invention, the oil mist remaining in the blowby gas without being removed by the ventilator can be efficiently oxidized with the oxidation catalyst for blowby gas. As a result, the oil mist can be reliably prevented from flowing into the intake pipe, so that the occurrence of coking in the wings of the compressor of the turbocharger can be avoided in advance, thereby preventing malfunction of the turbocharger and the turbocharger. The charger can be operated soundly over a long period of time.

  (II) According to the invention described in claim 2 of the present invention, not only the heat of the exhaust gas but also the heat of reaction caused by the oxidation treatment of the unburned hydrocarbon component in the oxidation catalyst for the exhaust gas is added. Since it can be transmitted to the heating part on the gas return pipe side, the oxidation catalyst for blow-by gas can be heated to a higher temperature for further activation, and the oxidation catalyst for exhaust gas can be used as a heat storage body. As a result, the oxidation catalyst for blow-by gas can be stably maintained in a highly active state.

It is the schematic which shows an example of the form which implements this invention. It is the schematic which expands and shows the heating part of FIG. It is sectional drawing of the III-III arrow of FIG. It is sectional drawing which shows another structural example of the heating part of FIG. It is the schematic which shows a prior art example.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 shows an example of an embodiment for carrying out the present invention, and the same reference numerals as those in FIG. 5 denote the same components.

  As shown in FIG. 1, in this embodiment, as in the case of FIG. 5, the oil mist is removed by passing the blow-by gas 1 extracted from the cylinder head cover 4 of the engine 3 through the gas extraction pipe 5 through the ventilator 2. After separation and recovery, the gas 8 is returned to the intake pipe 7 via the gas return pipe 6, and the oil 8 recovered by the ventilator 2 is returned to the oil pan (not shown) via the oil recovery pipe 9. 6 is configured to contact the exhaust pipe 17 to form a heating section 22 that receives heat from the exhaust pipe 17 side. The heating section 22 is provided with an oxidation catalyst 23 for blow-by gas 1 that oxidizes oil mist. However, it is characterized.

  Here, particularly in the case of the present embodiment, the heating unit 22 is configured by bringing a part of the gas return pipe 6 into contact with the muffler 18 that forms part of the exhaust pipe 17. Further, as shown in FIG. 2 in an enlarged manner, an oxidation catalyst 19 for the exhaust gas 14 for oxidizing the unburned hydrocarbon component is accommodated in the muffler 18. It arrange | positions so that it may rank with the oxidation catalyst 23 of the heating part 22 in parallel.

  Further, as shown in FIG. 3, the muffler 18 and the heating unit 22 are in contact with each other in a rectangular cross section within a range where they are in contact with each other, and the contact area can be secured as much as possible. For example, as shown in FIG. 4, it is also possible to arrange a part of the gas return pipe 6 so as to penetrate the muffler 18 to form the heating unit 22. It becomes possible to warm up.

  Thus, if the closed breather system is configured in this manner, the heat on the exhaust pipe 17 side through which the high-temperature exhaust gas 14 flows is transferred to the heating section 22 of the gas return pipe 6, and the oxidation catalyst 23 of the heating section 22 rises. Since it is heated and kept in a highly active state, a small amount of oil mist that cannot be removed by the ventilator 2 is efficiently oxidized when the blowby gas 1 passes through the oxidation catalyst 23 in the highly active state. Thus, only the blow-by gas 1 from which the oil mist has been removed is returned to the intake pipe 7.

  Particularly in this embodiment, not only the heat of the exhaust gas 14 but also the reaction heat due to the oxidation treatment of the unburned hydrocarbon component by the oxidation catalyst 19 is transmitted to the heating unit 22 on the gas return pipe 6 side, The oxidation catalyst 23 of the heating unit 22 is heated to a higher temperature, and further activation is achieved.

  Moreover, even if the flow rate and temperature of the exhaust gas 14 fluctuate greatly depending on the operating state on the engine 3 side, the oxidation catalyst 19 functions as a heat accumulator, thereby giving a large heat fluctuation to the heating part 22 on the gas return pipe 6 side. Therefore, there is also an advantage that the oxidation catalyst 23 for the blow-by gas 1 is stably maintained in a highly active state.

  Therefore, according to the above embodiment, the oil mist remaining in the blow-by gas 1 without being removed by the ventilator 2 can be efficiently oxidized by the oxidation catalyst 23 for the blow-by gas 1, thereby Since the inflow into the intake pipe 7 can be reliably prevented, the occurrence of coking in the wings of the compressor 11a of the turbocharger 11 can be avoided in advance, thereby preventing malfunction of the turbocharger 11 and The turbocharger 11 can be operated soundly over a long period of time.

  Further, not only the heat of the exhaust gas 14 but also the reaction heat caused by the oxidation treatment of the unburned hydrocarbon components in the oxidation catalyst 19 can be added and transmitted to the heating unit 22 on the gas return pipe 6 side, so that blow-by Further activation can be achieved by raising the temperature of the oxidation catalyst 23 for the gas 1 to a higher temperature, and the oxidation catalyst 19 for the exhaust gas 14 functions as a heat storage body to oxidize the blowby gas 1. The catalyst 23 can be stably maintained in a highly active state.

  The closed breather system of the present invention is not limited to the above-described embodiment. In the illustrated example, a part of the gas return pipe is arranged along a muffler (a part of the exhaust pipe) in the middle of the exhaust pipe. However, it should be understood that various modifications may be made without departing from the spirit of the present invention. is there.

DESCRIPTION OF SYMBOLS 1 Blow-by gas 2 Ventilator 3 Engine 6 Gas return pipe 7 Intake pipe 14 Exhaust gas 17 Exhaust pipe 18 Muffler 19 Oxidation catalyst for exhaust gas 22 Heating part 23 Oxidation catalyst for blow-by gas

Claims (2)

  In a closed breather system in which blow-by gas extracted from the engine side is separated and recovered via an air ventilator and returned to the intake pipe, a part of the gas return pipe that guides the blow-by gas from the ventilator to the intake pipe contacts the exhaust pipe. A closed breather system characterized in that a heating unit that receives heat from the exhaust pipe side is configured, and an oxidation catalyst for blow-by gas that oxidizes oil mist is provided in the heating unit.   An exhaust gas oxidation catalyst that oxidizes unburned hydrocarbon components in the exhaust gas is interposed in the middle of the exhaust pipe, and the heating part on the gas return pipe side is configured along the position of the catalyst. The closed breather system according to claim 1.

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