JP6135886B2 - EGR gas condensate treatment equipment - Google Patents

Description

  The present invention relates to an EGR gas condensate treatment apparatus for returning condensed water generated when EGR gas is cooled by a heat exchanger to an engine.

A diesel engine mounted on a vehicle is supercharged by a turbocharger (supercharger). In many of the supercharged diesel engines, an intercooler (heat exchanger) is provided in an intake passage that guides intake air to an intake manifold (intake side) of the engine in order to increase charging efficiency.
Even in a supercharged diesel engine, an exhaust gas recirculation device is mounted in order to reduce NOx in the exhaust gas, as in other engines. The exhaust gas recirculation device returns a part of the exhaust gas discharged from the engine as EGR gas (inert gas) to the intake side of the engine to lower the combustion temperature. Recently, diesel engines that use both high-pressure EGR and low-pressure EGR or use only low-pressure EGR have been developed so that effective EGR gas recirculation can be performed. The high-pressure EGR is a part of exhaust gas that has just been exhausted from the engine, that is, a part of the exhaust gas in the exhaust path upstream of the turbocharger turbine as EGR gas, and the intake path downstream of the turbocharger compressor The low-pressure EGR uses a part of the exhaust gas in the exhaust passage downstream of the turbocharger turbine as EGR gas, and the intake passage upstream of the compressor of the turbocharger, which is the intake passage before supercharging. This is a reflux structure for refluxing.

  Although the low pressure EGR has an advantage that the EGR gas can be recirculated irrespective of the magnitude of the supercharging pressure, the exhaust gas downstream of the supercharger has a high water content (for example, about 10%). When the recirculation is performed and the intake air containing a large amount of the EGR gas is compressed by the supercharger and then cooled by the intercooler, the vapor (moisture) contained in the EGR gas is condensed. That is, condensed water (condensation) is generated, and the condensed water is accumulated in the tank part (cavity part) on the outlet side of the intercooler.

In particular, the condensed water is concentrated by repeating evaporation and deposition at the same site, so that it becomes extremely acidic water, which may cause corrosion of the intercooler and parts downstream of the intercooler.
As a countermeasure, it is conceivable to boil the condensed water, but in this case, a sulfur content contained in the condensed water that does not evaporate remains, and satisfactory treatment cannot be performed.

  Therefore, as disclosed in Patent Document 1, the condensed water generated in the EGR cooler (heat exchanger) is stored in the tank, and the ejector operating with the flow of EGR gas is used to suck the condensed water in the tank, A processing technique has been proposed in which the ejector effect and the perforated plate attached to the ejector are atomized and returned to the intake side of the engine.

JP 2011-140922 A

When this processing technique is applied to an intercooler, the components contained in the condensed water are surely refined together with the condensed water, and processed by the combustion of the engine, the catalyst of the exhaust gas purifying device thereafter, or the like.
However, since the ejector operates depending on the EGR gas, it is affected by the operation of the engine. In other words, the ejector effect cannot be exhibited when the engine is started or when the engine speed is low when the flow rate or flow rate of the exhaust gas decreases.

  Therefore, an object of the present invention is to provide an EGR gas condensate treatment apparatus that can return the condensed water generated in the heat exchanger to the intake side of the engine in any engine operation.

The processing apparatus according to claim 1 includes a return path for returning condensed water generated in the heat exchanger from the heat exchanger to the downstream flow path, and the return path is a flow path sandwiching the heat exchanger. A passage that connects the upstream side and the downstream side, and an introduction path that connects the heat exchanger and the passage are provided .

In the processing apparatus according to the second aspect , the heat exchanger includes a tank portion that stores condensed water, and the introduction path extends from the bottom surface of the tank portion.
The processing apparatus according to claim 3 includes a tank for storing condensed water generated in the heat exchanger, and an atomizing structure for atomizing and atomizing the condensed water stored in the tank.
In the processing apparatus according to the fourth aspect , the atomizing structure section vibrates the condensed water to atomize the condensed water and atomize the condensed water.

ADVANTAGE OF THE INVENTION According to this invention, the condensed water produced | generated with the heat exchanger from the return path can be returned to the intake side of an engine using the upstream and downstream differential pressure | voltage of a heat exchanger.
Therefore, the condensed water generated by the cooling of the EGR gas can be satisfactorily processed by the combustion of the engine, the exhaust gas purification device, and the like together with the components contained in the condensed water in any engine operation. In addition, a separate structure that does not use a blower and reduces costs is sufficient.

1 is a cross-sectional view showing an engine system to which a processing apparatus according to a first embodiment of the present invention is applied. Sectional drawing which expands and shows the A section in FIG. 1 used as the structure of the principal part of the processing apparatus. Sectional drawing which shows the structure of the processing apparatus used as the principal part of the 2nd Embodiment of this invention.

Hereinafter, the present invention will be described based on the first embodiment shown in FIG. 1 and FIG.
FIG. 1 shows a system of an engine to which the present invention is applied, for example, a supercharged diesel engine with an intercooler. Referring to the system, reference numeral 1 in the figure denotes a diesel engine, and 10 denotes a turbocharger (supercharger).
The diesel engine 1 includes, for example, a cylinder 2 in which a piston 3 can be reciprocated, suction / exhaust ports 4 and 5 that open to the head of the cylinder 2, and intake / exhaust ports that open and close the suction / exhaust ports 4 and 5. The engine body 1a includes valves 4a and 5a, intake / exhaust manifolds 4b and 5b connected to the intake / exhaust ports 4 and 5, an injector (not shown) for injecting fuel into the head of the cylinder 2, and the like. An A / F sensor 7 is provided in the surge tank portion 4c of the intake manifold 4b.

  The turbocharger 10 includes a turbine unit 11 and a compressor unit 12 that is coaxially connected to the turbine unit 11. Among these, the inlet 11a of the turbine part 11 is connected to the exhaust manifold 5b, and rotates the rotor (not shown) of the turbine part 11 with exhaust heat energy discharged from the diesel engine 1, and the rotational force of the compressor part 12 A rotor (not shown) is rotated. An exhaust gas purification device, for example, a filter unit 17 containing an oxidation catalyst 15 or a DPF 16 (diesel particulate filter) is connected to the outlet 11 b of the turbine unit 11 via an exhaust passage 13, and the exhaust gas that has passed through the turbine unit 11. PM (particulate matter) in the gas is collected and oxidation of CO and the like contained in the exhaust gas can be performed.

  Further, an upstream intake passage 18 a that leads to an air cleaner (not shown) is connected to the inlet 12 a of the compressor unit 12. An intake manifold 4b is connected to an outlet 12b of the compressor unit 12 via a downstream intake passage 18b (which constitutes an intake passage together with the upstream intake passage 18a), and the compressor unit 12 driven by exhaust heat energy is connected to the outlet 12b. With the rotation of the rotor, the intake air taken in from the intake passage 18a is compressed and supercharged to the engine body 1a. The downstream intake passage 18b is provided with an intercooler (equivalent to the heat exchanger of the present application) for cooling the intake air that has passed through the turbocharger 10, for example, an air-cooled intercooler 19 in order to increase the charging efficiency. Yes. The intercooler 19 includes, for example, an inlet side tank portion 21 connected to the compressor portion 12 and an intake manifold 4b at an end portion of a cooler core portion 20 having a flow path capable of exchanging heat with outside air as shown in FIG. It is configured by forming a tank part 22 (formed by any hollow part) on the outlet side to be connected. That is, the intake air whose temperature has increased due to the compression of the compressor unit 12 is cooled by the cooler core unit 20 (by heat exchange with the outside air) and then sent to the intake manifold 4b.

  The diesel engine 1 is provided with an exhaust gas recirculation device 25 in order to reduce NOx in the exhaust gas. The exhaust gas recirculation device 25 returns a part of the exhaust gas discharged from the engine main body 1 to the intake side of the engine main body 1 as EGR gas (inert gas) to lower the combustion temperature. Here, a structure using both high pressure EGR and low pressure EGR is used.

  Among these, the high pressure EGR is connected, for example, between the exhaust manifold 5b and the intake passage portion downstream of the intercooler 19 by a high pressure EGR passage 27, and an EGR valve 27a is provided in the high pressure EGR passage 27. It is constituted by a structure in which an intake throttle 27b (new air amount control) is provided in the part. Thus, a part of the exhaust gas (exhaust gas that has just been exhausted from the engine) upstream of the turbine section 11 is recirculated to the intake passage downstream of the intercooler 19 of the turbocharger 10 as EGR gas. The Here, an EGR catalyst 28 is provided in the high-pressure EGR passage 27. Incidentally, when the EGR catalyst 28 is not provided, an EGR cooler (including a case where there is a bypass and a case where there is no bypass: not shown) may be provided instead.

  The low pressure EGR is, for example, an exhaust passage downstream of the turbine section 11, here an exhaust passage downstream of the filter unit 17 and an intake passage upstream of the compressor section 12 are connected by a low pressure EGR passage 30, and an EGR valve is connected to the low pressure EGR passage 30. 30a is provided, and an intake throttle 30b (new air amount control) is provided in the intake portion upstream of the outlet of the low pressure EGR passage 30. Thus, a part of the exhaust gas downstream of the turbine unit 11 is recirculated as EGR gas to the intake passage 18a before supercharging. The low pressure EGR passage 30 is provided with an EGR cooler 31 for cooling the EGR gas.

  Here, although the low pressure EGR can recirculate the EGR gas regardless of the magnitude of the supercharging pressure, the exhaust gas downstream of the turbocharger 10 used for the low pressure EGR has a high water content (for example, 10%). Place). Therefore, when the intake air containing a large amount of the EGR gas is compressed by the compressor unit 12 and then cooled by the intercooler 19, the vapor (moisture) contained in the EGR gas is condensed, that is, the condensed water α (Condensation) occurs and tends to accumulate in the tank portion 22 on the outlet side of the intercooler 19. Since the condensed water α is concentrated by repeatedly evaporating and accumulating at the same site, it is likely to be extremely acidic water, which may cause corrosion of the intercooler 19 and parts downstream of the intercooler.

As a countermeasure against this, a treatment device 35 for treating the condensed water α generated by cooling the intercooler 19 is provided. The structure of the processing apparatus 35 which is a main part of the present invention is shown in detail in FIG.
The processing device 35 stores, for example, the condensed water α generated in the intercooler 19 in a storage tank 36 installed near the intercooler 19, and atomizes the accumulated condensed water α by atomizing the ultrasonic water. From this, it has the function of returning to the intake air again. Therefore, the processing apparatus 35 has a structure in which a storage tank 36 that stores condensed water α is combined with an atomization structure 45 that atomizes the accumulated condensed water α, and a return path 50 that returns the atomized condensed water α to intake air. Is used.

  Each part will be described with reference to FIG. 2. The storage tank 36 is arranged at a lower position than the intercooler 19. A sealed tank 39 having a portion 38 is used. The tank 39 is disposed at a point below the intercooler 19. The tank 39 and the bottom surface of the tank portion 22 on the outlet side of the intercooler 19 are connected by an introduction path 40. Thus, the accumulated condensed water α is separated from the inside of the tank section 22 on the outlet side, led to the tank 39 through the introduction path 40, and stored at the bottom of the tank 39.

  The introduction path 40 is provided with an open / close valve, for example, an electromagnetic open / close valve 41, and a float switch 42 is provided at the bottom of the tank 39. The electromagnetic on-off valve 41 and the float switch 42 are connected to, for example, a control unit 43 (for example, composed of a microcomputer) disposed outside the tank 39. That is, the controller 43 controls the electromagnetic on-off valve 41 according to the detection signal from the float switch 42 so that the condensed water α is stored in the tank 39 so as to maintain a predetermined liquid level.

  The collector 37 is arranged in a vertical shape with the opening portion facing downward and the closing portion facing upward. A piezoelectric element 44 that generates, for example, ultrasonic vibrations is provided as an atomizing structure 45 on the bottom surface of the tank 39 that faces the open portion of the collector 37. The piezoelectric element 44 is arranged with the vibration surface facing upward, and applies ultrasonic vibration to the condensed water α stored in the tank 39. That is, the condensed water α stored in the tank 39 is atomized and atomized in the tank 39 by the applied ultrasonic vibration. The atomized condensed water α is collected in the collector 37. The piezoelectric element 44 is connected to the control unit 43, and the control unit 43 keeps operating as long as the condensed water α is present in the tank 39 during the operation of the diesel engine 1.

  The return path 50 includes a passage 51 connecting the intake passage portion on the outlet side of the intercooler 19 and the upper wall portion of the collector 37, an intake passage portion on the inlet side of the intercooler 19, here, the tank portion 21 and the chamber on the inlet side. A structure in which a passage 52 connecting between the portions 38 and a through hole 53 formed in a boundary portion between the chamber portion 38 and the tank 39 is combined is used. Thus, a flow path 54 (passage) is formed in the tank 39, here through the collector 37, to connect the upstream side and the downstream side of the intake passage 18 b sandwiching the intercooler 19. As a result, the atomized condensed water α is sent out to the intake passage portion on the outlet side of the intercooler 19 by the flow of intake air generated by the differential pressure between the upstream side and the downstream side across the intercooler 19. In particular, the inflow side passage 52 is provided with a flow rate adjusting valve 55 for controlling the intake air amount in accordance with the operating state of the diesel engine 1 so that the condensed water α can be returned appropriately in accordance with the operating state of the engine. I have to.

Next, the operation of the condensate α treatment device 35 will be described together with the operation of the diesel engine 1.
In the diesel engine 1, when fuel is combusted in each cylinder 2, the combustion gas that has finished combustion is discharged to the exhaust manifold 5 b as exhaust gas. The exhaust gas passes through the turbine unit 11 of the turbocharger 10 and is guided to the filter unit 17 so that PM contained in the exhaust gas is removed or NOx is purified.

  At this time, the compressor unit 12 of the turbocharger 10 is driven by the turbine unit 11 rotated by the exhaust heat energy, and compresses intake air (intake air) taken from the intake passage 18a. The intake air is guided to the intercooler 19, cooled by the intercooler 19, and then pushed into each cylinder 2 of the engine body 1a (supercharging). As a result, the diesel engine is operated with increased filling efficiency.

  Here, the high pressure EGR is performed by opening the EGR valve 27a. As a result, a part of the exhaust gas flowing through the exhaust manifold 5b, that is, a part of the exhaust gas that has just been exhausted from the engine body 1a, is introduced into the intake passage 18b from the downstream of the intercooler 19 through the high-pressure EGR passage 27. At the same time, it is led to the intake side of the engine body 1 (recirculation), and the combustion temperature of the diesel engine 1 is lowered (for example, at the start).

  The low pressure EGR is also performed by opening the EGR valve 30a. As a result, part of the exhaust gas that has passed through the filter unit 17 is introduced from the upstream of the compressor unit 12 to the intake passage 18 a through the low-pressure EGR passage 30. The intake air containing the EGR gas is compressed by the compressor unit 12 and guided to the intercooler 19. After the intake air is cooled by the intercooler 19, it is similarly guided (refluxed) to the intake side of the engine body 1. (Most operating range).

During this low pressure EGR, the exhaust gas downstream of the turbocharger 10 has a high water content (for example, about 10%).
When the intake air containing a large amount of EGR gas is compressed by the compressor unit 12 and then cooled by the intercooler 19, the vapor (moisture) contained in the EGR gas is condensed (condensed), and condensed water α and And accumulates in the tank portion 22 on the outlet side of the intercooler 19. The amount of condensed water produced is, for example, 100 g / h or more when the vehicle traveling speed is 60 km / h or more and the EGR rate is 40% or more.

In this state, the condensed water α accumulated in the same portion may cause corrosion of the intercooler 19 and parts downstream of the intercooler 19, but this problem is caused by the treatment of the condensed water α performed in the processing device 35. Will disappear.
That is, as shown in FIG. 2, the condensed water α generated on the outlet side of the intercooler 19 is guided (separated) to the tank 39 through the introduction path 40 (electromagnetic switching valve 41: open), and the bottom of the tank 39 Accumulate. The piezoelectric element 44 starts to operate when the diesel engine 1 is started, and applies ultrasonic vibrations to the accumulated condensed water α from the upper vibration surface. As a result, as shown in FIG. 2, the condensed water α is subjected to ultrasonic vibrations and scatters upward, and is atomized and atomized. As a result, the condensed water α is atomized (particulates) together with components such as sulfur contained in the condensed water α. This mist of condensed water α is collected in the collector 37 directly above.

  On the other hand, from the inlet side of the intercooler 19, a part of the intake air flows in order from the upstream side and downstream side of the intercooler 19 as shown by the arrows in FIG. The inside of the collector 37 and the passage 51 are sent out. As a result, the atomized condensed water α is led into the intake pipe 18b together with the intake air flowing through the tank 39 while being collected by the collector 37 and, more specifically, mixed with the intake air. The intake air mixed with the condensed water α is guided to the intake side of the engine body 1a through the intake manifold 4b (intake side of the engine), and the content components such as the condensed water α and the sulfur content contained in the condensed water α are low. It is discharged in a concentration state.

  Therefore, the condensed water α generated in the intercooler 19 is sent out to the intake passage 18b through the flow path 54 due to the differential pressure between the upstream side and the downstream side across the intercooler 19, so that in any engine operation, It is processed in the system of the diesel engine 1. Therefore, it is possible to prevent the occurrence of corrosion due to the condensed water α that is acidic water. This is particularly effective for the condensed water α generated in the intercooler 19. In addition, the structure for sending the condensed water α to the intake passage 18b by the differential pressure allows the condensed water α to be returned to the intake passage 18b with a simple structure without using a separate blower, and the cost burden can be reduced. . In addition, the condensed water α can be finely refined to promise stable return of the condensed water α, that is, treatment. In addition, since condensed water α (water droplets, etc.) of large particles can be prevented from colliding with a sensor installed downstream of the intercooler 19, a means for avoiding collision between the sensor and the large particles of condensed water α is also provided. It becomes unnecessary. This is effective for the A / F sensor 7 which is easily damaged.

In particular, since the piezoelectric element 44 is used for atomization of the condensed water α, a simple structure is sufficient.
FIG. 6 shows a second embodiment of the present invention.
In this embodiment, a structure in which condensed water is sent to an intake passage by a differential pressure between an upstream side and a downstream side across an intercooler is applied to an EGR cooler (corresponding to the heat exchanger of the present application) of low pressure EGR. is there.

That is, also in the EGR cooler 31 provided in the low-pressure EGR passage 30 (corresponding to the flow path of the present application), condensed water is generated by heat exchange and may similarly affect each part of the engine.
Therefore, as a countermeasure in such a case, as shown in FIG. 6, the EGR cooler 31 is provided with a treatment device 60 having the same structure as that of the first embodiment so as to treat the condensed water generated in the EGR cooler 31. It is a thing. However, in FIG. 6, the same parts as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  Note that the present invention is not limited to the above-described embodiment, and various modifications may be made without departing from the spirit of the present invention. For example, in the above-described embodiment, an example in which the present invention is applied to a heat exchanger such as an intercooler or a low-pressure EGR EGR cooler has been described. However, the present invention is not limited to this, and a diesel engine that does not use a turbocharger, Condensate water may be generated by EGR gas cooling in the EGR cooler, such as bypassing the EGR passage with an EGR cooler (heat exchanger) between the intake and exhaust passages of a diesel engine You may apply to the engine with.

1a Engine body 18a, 30 Intake passage, EGR passage (flow passage)
19, 31 Intercooler, EGR cooler (heat exchanger)
22 Tank part 35,60 EGR gas condensate treatment device 39 Tank 40 Introduction path 45 Atomization structure part 50 Return path 54 Channel (passage)

Claims (4)

An EGR gas condensate treatment apparatus that has an engine including a flow path through which EGR gas circulates and a heat exchanger provided in the flow path, and returns condensed water generated in the heat exchanger to an intake passage of the engine Because
Comprising a return path for returning the condensed water generated in the heat exchanger from the heat exchanger to the downstream flow path;
The return path includes a path that connects the upstream side and the downstream side of the flow path across the heat exchanger, and an introduction path that connects the heat exchanger and the path. EGR gas condensate treatment equipment. The heat exchanger includes a tank unit that stores the condensed water,
The apparatus for treating EGR gas condensed water according to claim 1 , wherein the introduction path extends from a bottom surface of the tank portion. The EGR gas condensate treatment device is:
A tank for storing condensed water generated in the heat exchanger;
EGR gas condensate processing apparatus according to claim 1 or claim 2, characterized in that it comprises a atomizing structure which atomized atomized condensed water stored in the tank. The treatment apparatus for EGR gas condensed water according to claim 3 , wherein the atomizing structure section vibrates the condensed water to atomize the condensed water and atomize the condensed water.

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