JP5757709B2 - Internal combustion engine - Google Patents

Description

  The present invention relates to an internal combustion engine accompanied by an exhaust turbocharger.

  In an internal combustion engine with a turbocharger that uses exhaust gas to rotate the turbine and drive the compressor to supercharge intake air, a portion of the exhaust gas flows into the turbine to prevent supercharging. It is customary to provide a waste gate valve that bypasses without making it (see, for example, the following patent document). Through the opening and closing of the waste gate valve, it is possible to control the supercharging pressure to a required target supercharging pressure corresponding to the engine speed.

  The exhaust gas that bypasses the turbine is guided downstream of the turbine in the exhaust passage, and flows into the exhaust purification catalyst after being mixed with the exhaust gas that has passed through the turbine. At this time, the exhaust gas that bypasses the turbine remains at a high temperature because it has not undergone a temperature drop in the turbine. Therefore, the temperature of the exhaust gas flowing into the catalyst rises and the catalyst is overheated, which may cause deterioration.

  Therefore, when the waste gate valve is opened, the fuel supply amount is increased to suppress the combustion temperature, thereby protecting the catalyst. However, it cannot be denied that such a treatment is disadvantageous in terms of fuel consumption.

  In addition, since the waste gate valve is exposed to high-temperature exhaust gas, a valve having a high heat resistance (such as a butterfly valve) has to be employed even at the expense of supercharging pressure control performance.

JP 2009-180112 A

  An object of the present invention is to effectively cool the exhaust gas that bypasses the turbine and appropriately protect the catalyst when preventing supercharging by the exhaust turbocharger.

An internal combustion engine with an exhaust turbocharger according to the present invention branches from an upstream side of a turbine in an exhaust passage outside a cylinder head and passes through the vicinity of a flow path of engine cooling water inside the cylinder head. An exhaust bypass passage that merges downstream of the turbine and upstream of the catalyst in the passage, and the exhaust bypass passage provided in a region after passing through the vicinity of the flow path of the engine cooling water inside the cylinder head in the exhaust bypass passage. And a valve for opening and closing.

  The exhaust bypass passage passes through the vicinity of the engine coolant flow path inside the cylinder head. The exhaust gas that flows through the bypass passage and bypasses the turbine is cooled by engine cooling water. Thereby, overheating of the catalyst can be prevented.

  According to the present invention, the exhaust gas that bypasses the turbine can be effectively cooled to appropriately protect the catalyst.

The figure which shows the structure of the internal combustion engine in one Embodiment of this invention.

  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 of this embodiment is shown. The internal combustion engine 0 in the present embodiment includes a plurality of cylinders 1, an injector 2 that injects fuel into each cylinder 1, an intake passage 3 for supplying intake air to each cylinder 1, and exhaust from each cylinder 1. And an exhaust turbocharger 5 that supercharges intake air flowing through the intake passage 3, and an external EGR passage 6 that recirculates EGR gas from the exhaust passage 4 toward the intake passage 3. Yes.

  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 of the first cylinder 1 and the piston of the second cylinder 1 are simultaneously raised and simultaneously lowered.

  The intake passage 3 takes in air from the outside and guides it to an intake port formed in the cylinder head 7. On the intake passage 3, an air cleaner 31, a compressor 51 of the supercharger 5, an intercooler 32, a throttle valve 33, a surge tank 34, and an intake manifold 35 are arranged in this order from the upstream side.

  The exhaust passage 4 guides exhaust generated as a result of burning fuel in the cylinder 1 to the outside through an exhaust port formed in the cylinder head 7. An exhaust manifold 41, a drive turbine 52 of the supercharger 5, and a three-way catalyst 42 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.

  Therefore, in the present embodiment, the exhaust bypass passage 8 that bypasses the upstream side and the downstream side of the turbine 52 in the exhaust passage 4 is provided in order to prevent supercharging by the exhaust turbocharger 5. The exhaust bypass passage 8 branches off from the exhaust manifold 41 and passes through the inside of the cylinder head 7 on the way, and then joins a predetermined location downstream of the turbine 52 and upstream of the catalyst 42 in the exhaust passage 4.

  Further, a valve 82 for opening and closing the exhaust bypass passage 8 is provided in a region 81 of the exhaust bypass passage 8 after passing through the inside of the cylinder head 7. In the present embodiment, the valve 82 is a so-called poppet valve in which the valve element moves back and forth (approaches / separates from the valve seat) along the extending direction of the exhaust bypass passage 8. The poppet valve 82 is, for example, a motor-integrated type, and its opening degree can be increased or decreased by receiving a control signal input from an electronic control unit (ECU, not shown). The poppet valve 82 is disposed at a location where the exhaust bypass passage 8 protrudes from the inside of the cylinder head 7 to the outside, and it appears to be assembled to the side surface of the cylinder head 7 from the outside.

  The exhaust bypass passage 8 passes in the vicinity of the engine coolant flow path (water jacket) formed in the cylinder head 7 inside the cylinder head 7.

  According to this embodiment, the exhaust bypass passage 8 branches from the upstream side of the turbine 52 in the exhaust passage 4 and joins the downstream side of the turbine 52 via the inside of the cylinder head 7, and the cylinder head 7 in the exhaust bypass passage 8. Since the internal combustion engine 0 including the valve 82 that opens and closes the exhaust bypass passage 8 provided in the region 81 after passing through the inside is configured, the exhaust gas that flows through the bypass passage 8 and bypasses the turbine 52 is engine. It is suitably cooled by the cooling water, and the catalyst 42 can be appropriately protected by preventing overheating of the catalyst 42.

  Since it is not necessary to increase the fuel supply amount for the purpose of lowering the combustion temperature in the cylinder 1, fuel consumption can be saved and fuel efficiency can be improved.

  In addition, a valve 82 for opening and closing the exhaust bypass passage 8 is installed at a relatively low temperature (exhaust gas is already cooled by cooling water). It is allowed to adopt a poppet valve or the like that does not require heat resistance and is not resistant to heat. The poppet valve has better controllability than the butterfly valve type waste gate valve, has a high supercharging pressure control performance when the exhaust bypass passage 8 should be opened, and when the exhaust bypass passage 8 should be completely closed. Also has high sealing performance. In addition, improvement in low-speed torque can be expected.

  In addition, the two-cylinder engine as in the present embodiment tends to have larger exhaust pulsation than a multi-cylinder engine having three or more cylinders. However, by cooling and compressing a part of the exhaust gas in the exhaust bypass passage 8. This also leads to suppression of exhaust pulsation.

  The present invention is not limited to the embodiment described in detail above. The specific configuration 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 with a supercharger mounted on a vehicle or the like.

DESCRIPTION OF SYMBOLS 0 ... Internal combustion engine 4 ... Exhaust passage 5 ... Supercharger 52 ... Turbine 7 ... Cylinder head 8 ... Exhaust bypass passage

Claims (1)

An internal combustion engine with an exhaust turbocharger,
An exhaust bypass passage that branches from the upstream side of the turbine in the exhaust passage outside the cylinder head and joins the downstream of the turbine and the upstream of the catalyst in the exhaust passage via the vicinity of the flow path of the engine cooling water inside the cylinder head When,
An internal combustion engine comprising: a valve provided in a region after passing through the vicinity of the flow path of engine cooling water inside the cylinder head in the exhaust bypass passage and opening and closing the exhaust bypass passage.

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