JP6492825B2 - engine - Google Patents

Description

  The present invention relates to an engine including a cooling circuit for cooling a water-cooled intercooler provided in an intake passage.

  2. Description of the Related Art Conventionally, an engine having a cooling circuit that cools a water-cooled intercooler (hereinafter referred to as an intercooler) provided in an intake passage of the engine is known separately from a cooling circuit that cools the engine. In other words, the engine is provided with an intercooler cooling circuit, which is different from the engine cooling circuit including the water jacket formed in the engine body. In addition to the intercooler, an electric pump or a radiator is interposed in such an intercooler cooling circuit, and the cooling water cooled by the radiator is pumped by the electric pump. In addition, a technique has been proposed in which heat exchange is performed between the engine cooling circuit and the intercooler cooling circuit to promote engine warm-up (see, for example, Patent Document 1).

JP 2014-118910 A

  By the way, it is known that when the intake air is cooled by the intercooler, water vapor contained in the intake air is condensed to generate water (hereinafter referred to as condensed water). If the generated condensed water adheres to the surface of the intercooler, the heat exchange rate may decrease and the intake air cooling performance may deteriorate. In addition, when the supercharging pressure rises while condensate is accumulated in the intercooler, the condensate is introduced into the cylinder together with the intake air, leading to problems such as a decrease in combustion stability and a decrease in engine durability and reliability. there is a possibility. In addition, since the amount of this condensed water generated increases as the temperature in the intercooler decreases, it is desirable that the temperature in the intercooler does not decrease.

  This case has been devised in view of such a problem, and relates to an engine having an intercooler cooling circuit, and one of the purposes is to effectively suppress the generation of condensed water by heating the intercooler. . The present invention is not limited to this purpose, and is a function and effect derived from each configuration shown in the embodiments for carrying out the invention described later, and other effects of the present invention are to obtain a function and effect that cannot be obtained by conventional techniques. Can be positioned.

(1) The engine disclosed herein includes an electric pump that can switch between forward rotation and reverse rotation, an intercooler cooling circuit in which cooling water pumped by the electric pump circulates, and an intake passage of the engine A water-cooled intercooler that is disposed on the intercooler cooling circuit and is located on the downstream side of the electric pump when the electric pump is rotating forward, and is interposed on the intercooler cooling circuit and is operated in the forward rotation. Sometimes located on the downstream side of the water-cooled intercooler and located on the upstream side of the electric pump at the time of forward rotation with a turbocharger that supercharges intake air flowing through the intake passage and the intercooler cooling circuit And a radiator. Further, when the intake air temperature of the intake air flowing into the water-cooled intercooler is higher than a predetermined value, the engine rotates the electric pump at a higher speed as the intake air temperature is higher, and the intake air temperature is higher than the predetermined value. In the case where the temperature is less than 1, the controller includes a controller that reverses the electric pump at a higher speed as the intake air temperature is lower. Further, the control device prohibits reverse rotation of the electric pump when the temperature of the lubricating oil supplied to the bearing portion of the turbocharger is equal to or higher than a predetermined oil temperature.

(2 ) It is preferable that the control device controls the rotation speed of the electric pump to be equal to or higher than a preset minimum rotation speed when the oil temperature is equal to or higher than the predetermined oil temperature.
( 3 ) It is preferable that the said control apparatus makes the rotation speed of the said electric pump high, so that the said oil temperature is high.

( 4 ) The engine cools the EGR passage that communicates the exhaust passage and the intake passage upstream of the turbocharger, and the recirculated gas that is provided on the EGR passage and flows through the EGR passage. It is preferable to include an EGR cooler interposed on the intercooler cooling circuit and positioned on the downstream side of the turbocharger during the forward rotation. In this case, it is preferable that the control device increases the rotational speed of the electric pump relative to the intake air temperature if the electric pump is reversed when the flow rate of the reflux gas is equal to or greater than a predetermined amount.

( 5 ) In the above case, the control device may reduce the rotational speed with respect to the intake air temperature if the electric pump is normally rotated when the flow rate of the reflux gas is equal to or greater than the predetermined amount. preferable.
( 6 ) It is preferable that the predetermined value is set to a higher value as the humidity of the intake air introduced into the water-cooled intercooler is higher.

According to the disclosed engine, when the intake air temperature is higher than a predetermined value, the higher the intake air temperature is, the higher the rotation speed of the electric pump is rotated. Therefore, when the intake air temperature is high, the cooling water cooled by the radiator is It can be sent to a cooler to cool the intake air. Thereby, the charging efficiency can be increased, and the turbocharger provided on the downstream side of the water-cooled intercooler can also be cooled. On the other hand, when the intake air temperature is less than a predetermined value, the lower the intake air temperature, the higher the rotation speed of the electric pump is reversed. Therefore, the water-cooled intercooler can be heated using the exhaust heat of the turbocharger. Thereby, the production | generation of condensed water can be suppressed effectively. Further, according to the disclosed engine, when the oil temperature of the lubricating oil supplied to the bearing portion of the turbocharger is equal to or higher than a predetermined oil temperature, the reverse rotation of the electric pump is prohibited. That is, when the oil temperature of the lubricating oil is equal to or higher than the predetermined oil temperature, cooling of the turbocharger is prioritized, so that the turbocharger can be appropriately protected.

It is a mimetic diagram showing the engine concerning a first embodiment, and shows the time of forward rotation of an electric pump. It is an example of the map used with the control apparatus of FIG. It is an example of the flowchart which shows the control procedure by the control apparatus of FIG. It is a schematic diagram which shows the engine which concerns on 2nd embodiment, and shows the time of normal rotation of an electric pump. It is an example of the map used with the control apparatus of FIG. It is an example of a flowchart which shows the control procedure by the control apparatus of FIG. It is a schematic diagram which shows the engine which concerns on the modification of 2nd embodiment, and shows the time of normal rotation of an electric pump.

  An engine as an embodiment will be described with reference to the drawings. Each embodiment shown below is only an example, and there is no intention of excluding various modifications and application of technology that are not clearly shown in each of the following embodiments.

[1. First embodiment]
[1-1. Device configuration]
In the present embodiment, a gasoline engine 2 (hereinafter referred to as engine 2) mounted on a vehicle is exemplified. Although FIG. 1 shows one of a plurality of cylinders 3 provided in the multi-cylinder engine 2, the other cylinders 3 have the same configuration. A piston 4 is slidably mounted in the cylinder 3, and the reciprocating motion of the piston 4 is converted into the rotational motion of the crankshaft 5 through a connecting rod.

  An intake port 12 and an exhaust port 13 are provided on the top surface of the cylinder 3. An intake valve 14 is provided at the opening of the intake port 12, and an exhaust valve 15 is provided at the opening of the exhaust port 13. A spark plug 8 is provided between the intake port 12 and the exhaust port 13 with its tip projecting toward the combustion chamber. In the engine 2, as an injector for supplying fuel to the cylinder 3, an in-cylinder injection valve (direct injection injector) 6 that directly injects fuel into the cylinder 3 and a port injection that injects fuel into the intake port 12. A valve (port injection injector) 7 is provided.

  The in-cylinder injection valve 6 is connected to the high pressure pump 11A via the high pressure fuel supply path 10A. On the other hand, the port injection valve 7 is connected to the low-pressure pump 11B via the low-pressure fuel supply path 10B. The cylinder injection valve 6 is supplied with fuel having a pressure higher than that of the port injection valve 7. Both the high-pressure pump 11A and the low-pressure pump 11B are mechanical flow rate variable pumps for pumping fuel. The high-pressure pump 11A and the low-pressure pump 11B operate by receiving driving force from the engine 2 or an electric motor. It discharges to supply path 10A, 10B.

  Around the cylinder 3, a water jacket 16 through which engine coolant flows is provided. The engine cooling water is a refrigerant for cooling the engine 2 and circulates in the engine cooling circuit 20 that connects the water jacket 16 and the main radiator 21 in an annular shape. In FIG. 1, the engine cooling circuit 20 is indicated by a thick arrow. On the engine cooling circuit 20, a water pump 22 driven by the rotation of the engine 2 is interposed. The engine cooling circuit 20 also has a function of heating the throttle valve 29 by way of a throttle body having a throttle valve 29 described later.

  An intake manifold 23 (hereinafter referred to as an intake manifold 23) is provided on the upstream side of the intake port 12. The intake manifold 23 is provided with a surge tank 24 for temporarily storing the air flowing toward the intake port 12 side. An intake passage 25 is connected to the upstream end of the intake manifold 23. An air filter 26 is provided on the most upstream side of the intake passage 25, and fresh air filtered by the air filter 26 is introduced into the intake passage 25.

  On the other hand, an exhaust manifold 30 (hereinafter referred to as an exhaust manifold 30) is provided on the downstream side of the exhaust port 13. An exhaust passage 31 is connected to the downstream end of the exhaust manifold 30, and an exhaust purification device 32 is interposed in the exhaust passage 31. The exhaust purification device 32 is configured to incorporate, for example, a three-way catalyst.

  The intake / exhaust system of the engine 2 is provided with a turbocharger 27 that supercharges intake air into the cylinder 3 using exhaust pressure. The turbocharger 27 is a supercharger that is disposed across both the intake passage 25 upstream of the intercooler 28 and the exhaust passage 31 upstream of the exhaust purification device 32. The turbocharger 27 rotates the turbine with the exhaust pressure in the exhaust passage 31 and uses the rotational force to drive the compressor, thereby compressing the intake air on the intake passage 25 side and supercharging the engine 2. . Lubricating oil is supplied to bearing portions (both not shown) that rotatably support a shaft connecting the turbine of the turbocharger 27 and the compressor.

  An intercooler 28 for cooling the intake air is provided in the intake passage 25 on the downstream side of the compressor of the turbocharger 27. The intercooler 28 is a water-cooled heat exchanger (water-cooled intercooler), and is interposed on an intercooler cooling circuit 40 indicated by a white arrow in the figure. The intercooler cooling circuit 40 is a cooling water circulation path provided as a separate system from the engine cooling circuit 20, and connects the intercooler 28 and the radiator 41 in a ring shape. On the intercooler cooling circuit 40, an electric water pump 42 (hereinafter referred to as an electric pump 42) is interposed.

  The electric pump 42 is a pump capable of switching between forward rotation and reverse rotation. During normal rotation of the electric pump 42, as indicated by the white arrow in the figure, the cooling water pumped from the electric pump 42 flows in the order of the intercooler 28, the turbocharger 27, and the radiator 41, and returns to the electric pump 42. . That is, on the intercooler cooling circuit 40, when the electric pump 42 is rotating forward, the radiator 41 is positioned upstream of the electric pump 42, the intercooler 28 is positioned downstream of the electric pump 42, and further downstream A turbocharger 27 is located on the side.

At the time of reverse rotation of the electric pump 42, the cooling water pumped from the electric pump 42 flows in the opposite direction to that at the time of normal rotation. That is, the cooling water pumped from the electric pump 42 flows in the order of the radiator 41, the turbocharger 27, and the intercooler 28, and returns to the electric pump 42. Switching between forward rotation and reverse rotation of the electric pump 42 and its rotation speed (hereinafter referred to as pump rotation speed Np) are controlled by the control device 1 described later.
A throttle valve 29 that throttles intake air is interposed downstream of the intercooler 28 in the intake passage 25.

  The intercooler 28 includes an intake air temperature sensor 36 that detects the temperature of the intake air flowing into the intercooler 28 (hereinafter referred to as intake air temperature Ti), and a humidity sensor 37 that detects the humidity H of the intake air flowing into the intercooler 28. Provided. Further, an oil temperature sensor 38 that detects an oil temperature Tt of the lubricating oil at the turbine outlet (turbine outlet oil temperature) is provided in the bearing portion of the turbocharger 27. The engine 2 is also provided with a pressure sensor that detects the pressure of intake air, an air flow sensor that detects the flow rate of intake air, an air-fuel ratio sensor that detects the air-fuel ratio of intake air and exhaust gas, and the like (none of which are shown). Information detected by these sensors 36 to 38 and the like is transmitted to the control device 1.

  The vehicle is provided with, for example, a control device 1 (Engine Electronic Control Unit) configured as an LSI device or an embedded electronic device in which a microprocessor, ROM, RAM, and the like are integrated. The control device 1 is an electronic control device that controls a wide range of systems such as an ignition system, a fuel system, and an intake / exhaust system related to the engine 2. Specific control objects of the control device 1 include the timing of ignition at the spark plug 8, the amount and timing of each fuel injected from the in-cylinder injection valve 6 and the port injection valve 7, the opening of the throttle valve 29, the electric drive The operation | movement of the pump 42 etc. are mentioned.

[1-2. Control configuration]
In the present embodiment, the operation of the electric pump 42 is controlled in order to suppress the generation of condensed water in the intercooler 28. Hereinafter, this control is referred to as pump control. When the intake air is cooled in the intercooler 28, the water vapor contained in the intake air is condensed and water (condensed water) is generated. Since this condensed water is generated more as the temperature in the intercooler 28 is lower, the engine 2 uses the exhaust heat of the turbocharger 27 to heat the intercooler 28 by performing pump control. This pump control is performed by the control device 1.

  In the pump control, the forward rotation and the reverse rotation of the electric pump 42 are switched according to the intake air temperature Ti, and the pump rotation speed Np is controlled. During forward rotation of the electric pump 42 (during normal operation), the cooling water cooled by the radiator 41 is supplied to the intercooler 28 to cool the intake air. At this time, if the pump rotational speed Np is increased, the flow rate of the cooling water flowing through the intercooler cooling circuit 40 is increased, so that the intake air can be further cooled (the cooling amount is increased). Conversely, if the pump rotation speed Np is decreased, the cooling amount is reduced.

  On the other hand, when the rotation direction of the electric pump 42 is reversed, the cooling water cooled by the radiator 41 is supplied to the turbocharger 27, and the temperature rises due to the exhaust heat of the turbocharger 27 and then supplied to the intercooler 28. Is done. That is, at the time of reverse rotation of the electric pump 42, the cooling water whose temperature has been increased is supplied to the intercooler 28, and the intercooler 28 is heated. If the pump rotational speed Np is increased at this time, the flow rate of the cooling water flowing through the intercooler cooling circuit 40 increases, so that the intercooler 28 can be further heated (the amount of heating increases). On the other hand, if the pump speed Np is decreased, the heating amount is reduced.

When the intake air temperature Ti detected by the intake air temperature sensor 36 is higher than the predetermined value Ti ₀ , the control device 1 causes the electric pump 42 to rotate forward at a higher speed as the intake air temperature Ti is higher, and the intake air temperature Ti is the predetermined air temperature Ti. When the value is lower than the value Ti ₀ , the electric pump 42 is reversely rotated at a higher speed as the intake air temperature Ti is lower. That is, the control device 1 switches the rotation direction of the electric pump 42 according to the magnitude relationship between the intake air temperature Ti and the predetermined value Ti _0, and sets the pump rotational speed Np to the absolute value of the difference between the intake air temperature Ti and the predetermined value Ti _0. The higher the value, the higher. Note that the control device 1 stops the electric pump 42 (the pump rotation speed Np is set to zero) when the intake air temperature Ti is equal to the predetermined value Ti ₀ . Hereinafter, this control is also referred to as basic pump control.

The predetermined value Ti ₀ is a switching temperature for switching the rotation direction of the electric pump 42. That is, the predetermined value Ti ₀ can be said to be a heating start temperature at which the cooling of the intercooler 28 is stopped and heating is started, and a cooling start temperature at which the heating of the intercooler 28 is stopped and cooling is started. The predetermined value Ti ₀ of this embodiment is set according to the humidity H of the intake air. Since the temperature at which condensed water begins to be generated increases as the humidity H increases (the amount of water vapor contained in the intake air increases), the predetermined value Ti ₀ of this embodiment is set to a higher value as the humidity H increases. That is, as the humidity H is higher, the rotation direction of the electric pump 42 is switched at a higher intake air temperature Ti.

In the pump control of the present embodiment, when the oil temperature Tt is equal to or higher than the predetermined oil temperature Tt ₀ , the reverse rotation of the electric pump 42 is prohibited and the pump rotation speed Np is controlled according to the intake air temperature Ti. The predetermined oil temperature Tt ₀ is a temperature at which the bearing portion of the turbocharger 27 should be positively cooled, and is set in advance. That is, when the oil temperature Tt is equal to or higher than the predetermined oil temperature Tt ₀ , the turbocharger 27 is driven at a high speed, so that the reverse rotation of the electric pump 42 is prohibited and the turbocharger 27 is more heated than the intercooler 28 is heated. Prioritize cooling. Note that when the oil temperature Tt is lower than the predetermined oil temperature Tt ₀ , the basic pump control according to only the intake air temperature Ti is performed as described above. Hereinafter, the pump control performed when Tt ≧ Tt ₀ is also referred to as first pump control.

Controller 1, when the detected oil temperature Tt at an oil temperature sensor 38 is Tt ₀ or greater than the predetermined oil temperature prohibits the reverse rotation of the electric pump 42. That is, if the oil temperature Tt is equal to or higher than the predetermined oil temperature Tt ₀ , the normal rotation is maintained without rotating the electric pump 42 even if the intake air temperature Ti is lower than the predetermined value Ti ₀ . In this case (when Tt ≧ Tt ₀ and Ti <Ti ₀ ), the control device 1 controls the pump rotational speed Np to the minimum rotational speed Npmin.

Further, when the oil temperature Tt is equal to or higher than the predetermined oil temperature Tt ₀ and the intake air temperature Ti is equal to or higher than the predetermined value Ti ₀ , the control device 1 controls the pump rotational speed Np to be equal to or higher than the minimum rotational speed Npmin and As the temperature Ti is higher, the electric pump 42 is rotated forward at higher speed. The minimum rotation speed Npmin is a value larger than zero, and is set in advance in consideration of, for example, the water flow resistance of the intercooler cooling circuit 40, the cooling performance of the turbocharger 27, and the like. Further, the rate of change of the pump rotation speed Np with respect to the intake air temperature Ti is set to be the same as that at the time of basic pump control, for example. Therefore, in this case (when Tt ≧ Tt ₀ and Ti ≧ Ti ₀ ), the control device 1 sets the pump rotational speed Np to a higher rotational speed than the pump rotational speed Np in the basic pump control at the same intake air temperature Ti. Control.

  The control apparatus 1 of this embodiment implements pump control using a map as shown in FIG. In the map of FIG. 2, the horizontal axis represents the intake air temperature Ti and the vertical axis represents the pump rotation speed Np, and the pump rotation speed Np with respect to the intake air temperature Ti is set. The horizontal axis means that the pump rotation speed Np is controlled to zero, the area above the horizontal axis means that the electric pump 42 is rotated forward, and the area below the horizontal axis is that where the electric pump 42 is operated. It means to reverse.

In the map of FIG. 2, a basic graph (solid line) corresponding to the basic pump control and a first graph (dashed line) corresponding to the first pump control are set. The basic graph is set as a linear function with the pump rotational speed Np being zero when the intake air temperature Ti is a predetermined value Ti ₀ and having a predetermined positive slope. On the other hand, the first graph shows that the pump rotational speed Np is set to the minimum rotational speed Npmin when the intake air temperature Ti is equal to or lower than the predetermined value Ti ₀ , and the pump rotational speed Np is set to be higher when the intake air temperature Ti is higher than the predetermined value Ti _0. It is set as a linear function with the same slope as the basic graph.

The control device 1 has a map (basic graph and first graph) as shown in FIG. In other words, the control device 1 stores a plurality of maps set for each humidity H in advance. Multiple maps, as humidity H is higher the higher the predetermined value Ti _0, so as humidity H is low predetermined value Ti ₀ becomes lower, base graph and a first graph is set by moving in parallel. The control device 1 selects a map corresponding to the humidity H from a plurality of maps, and selects the first graph if the oil temperature Tt detected by the oil temperature sensor 38 is equal to or higher than the predetermined oil temperature Tt _0. If the temperature Tt is lower than the predetermined oil temperature Tt ₀ , the basic graph is selected.

For example, assume that the control device 1 selects the map shown in FIG. In this case, when the oil temperature Tt is lower than the predetermined oil temperature Tt ₀ , the control device 1 selects the basic graph, and if the intake air temperature Ti is a temperature Ti ₁ higher than the predetermined value Ti _{0, the} electric pump 42 is pumped. Rotate forward at rotation speed Np ₁ . On the other hand, if the intake air temperature Ti is a temperature Ti ₂ lower than the predetermined value Ti ₀ , the control device 1 acquires a negative pump rotational speed Np ₂ (−Np ₂ ). Reverse with Np ₂ .

When the oil temperature Tt is equal to or higher than the predetermined oil temperature Tt ₀ , the control device 1 selects the first graph, and if the intake air temperature Ti is a temperature Ti ₁ higher than the predetermined value Ti _{0, the} electric pump 42 is pump-rotated. Rotate forward with the number Np ₁ ′. On the contrary, if the intake air temperature Ti is a temperature Ti ₂ lower than the predetermined value Ti ₀ , the control device 1 causes the electric pump 42 to rotate forward at the pump rotation speed Npmin.

[1-3. flowchart]
FIG. 3 is a flowchart illustrating a pump control procedure. The flow in FIG. 3 is repeatedly executed at a predetermined calculation cycle in the control device 1 when the main power supply of the vehicle is turned on, for example.
In the control device 1, each information (sensor value) detected by each of the sensors 36 to 38 is acquired (step S1), and a map corresponding to the humidity H is selected from a plurality of maps (step S2). When the oil temperature Tt is equal to or higher than the predetermined oil temperature Tt ₀ (step S3), the first graph is selected from the selected map (step S4).

Then, the intake air temperature Ti is applied to the first graph of the map, the pump rotation speed Np is acquired (step S5), and the electric pump 42 is controlled with the acquired pump rotation speed Np (step S6). That is, when the oil temperature Tt is equal to or higher than the predetermined oil temperature Tt ₀ , the first pump control is performed by selecting the first graph from the map.

On the other hand, if the oil temperature Tt is lower than the predetermined oil temperature Tt ₀ , a basic graph is selected from the selected map (step S9). Then, the intake air temperature Ti is applied to the basic graph of the map, the pump rotation speed Np is acquired (step S5), and the electric pump 42 is controlled with the acquired pump rotation speed Np (step S6). That is, when the oil temperature Tt is lower than the predetermined oil temperature Tt ₀ , the basic pump control is performed by selecting the basic graph from the map.

[1-4. effect]
(1) In the engine 2 described above, when the intake air temperature Ti is higher than the predetermined value Ti ₀ , the higher the intake air temperature Ti, the faster the electric pump 42 rotates at a higher speed. The cooling water cooled in the above can be sent to the intercooler 28 to cool the intake air. Thereby, the charging efficiency can be increased, and the turbocharger 27 provided on the downstream side of the intercooler 28 can also be cooled. On the other hand, when the intake air temperature Ti is less than the predetermined value Ti ₀ , the lower the intake air temperature Ti, the higher the rotational speed of the electric pump 42 is reversed, so that the intercooler 28 is heated using the exhaust heat of the turbocharger 27. can do. Thereby, the production | generation of condensed water can be suppressed effectively.

(2) In the engine 2 described above, the reverse rotation of the electric pump 42 is prohibited when the oil temperature Ti is equal to or higher than the predetermined oil temperature Ti ₀ . That is, when the oil temperature Tt is equal to or higher than the predetermined oil temperature Tt _0, the reverse rotation of the electric pump 42 is prohibited and cooling of the turbocharger 27 is given priority, so that the turbocharger 27 can be appropriately protected.

(3) In the engine 2 described above, when the oil temperature Tt is equal to or higher than the predetermined oil temperature Tt ₀ , the pump speed Np is controlled to be equal to or higher than the minimum speed Npmin. Can be increased.
In particular, in the engine 2 of the present embodiment, when the oil temperature Tt is equal to or higher than the predetermined oil temperature Tt ₀ and the intake air temperature Ti is equal to or higher than the predetermined value Ti ₀ , the pump speed Np is controlled to be equal to or higher than the minimum speed Npmin. At the same time, the higher the intake air temperature Ti, the higher the rotational speed of the electric pump 42. As a result, the intake air can be appropriately cooled while improving the cooling performance of the turbocharger 27.

(4) In addition, the higher the humidity H of the intake air flowing into the intercooler 28, the more the amount of water vapor contained in the intake air. On the other hand, in the engine 2 described above, the predetermined value Ti ₀ that is the intake air temperature Ti when switching between normal rotation and reverse rotation of the electric pump 42 is set to a higher value as the humidity H is higher. Can be more effectively suppressed.

[2. Second embodiment]
[2-1. Constitution]
Next, the engine 2 ′ according to the second embodiment will be described with reference to FIGS. The engine 2 ′ of the present embodiment includes an EGR (Exhaust Gas Recirculation) passage 33 that recirculates exhaust gas that flows through the exhaust passage 31 to the intake passage 25, and exhaust gas that flows through the EGR passage 33 (hereinafter referred to as recirculation gas). It differs from the above-mentioned first embodiment in that the flow rate is considered for pump control. In addition, about the structure similar to 1st embodiment, the code | symbol same as 1st embodiment is attached | subjected and the overlapping description is abbreviate | omitted.

  As shown in FIG. 4, the EGR passage 33 communicates the exhaust passage 31 on the downstream side of the exhaust purification device 32 and the intake passage 25 on the upstream side of the compressor of the turbocharger 27. On the EGR passage 33, an EGR cooler 34 for cooling the recirculation gas and an EGR valve 35 for adjusting a flow rate of the recirculation gas introduced into the intake passage 25 (hereinafter referred to as an EGR amount Q) are provided. The EGR amount Q increases as the opening degree of the EGR valve 35 increases, and becomes zero when the opening degree is zero (closed valve). The opening degree of the EGR valve 35 is controlled by the control device 1.

The EGR cooler 34 is interposed on an intercooler cooling circuit 40 ′ indicated by a white arrow in the drawing, and is located downstream of the turbocharger 27 and upstream of the radiator 41 when the electric pump 42 rotates forward. . That is, when the electric pump 42 is rotating forward, the cooling water pumped from the electric pump 42 flows in the order of the intercooler 28, the turbocharger 27, the EGR cooler 34, and the radiator 41, and returns to the electric pump 42. On the contrary, when the electric pump 42 is reversely rotated, the cooling water pumped from the electric pump 42 flows in the order of the radiator 41, the EGR cooler 34, the turbocharger 27, and the intercooler 28, and returns to the electric pump 42.
The EGR passage 33 is provided with a differential pressure sensor 39 that detects a pressure difference ΔP upstream and downstream of the EGR valve 35, and information detected by the differential pressure sensor 39 is also transmitted to the control device 1.

  In the engine 2 ′ of the present embodiment, intake air (air mixture) in which the recirculated gas flowing from the EGR passage 33 and fresh air are mixed is introduced into the intake port 12. In this way, the recirculation gas is mixed in the intake air, so that excessive exhaust temperature rise and NOx emission are suppressed. On the other hand, since the recirculated gas contains water vapor generated by combustion, if the intake air containing the recirculated gas is cooled in the intercooler 28, the amount of condensed water generated can be increased.

Therefore, when the EGR amount Q is large, the control device 1 of the present embodiment performs pump control that prevents the intake air from being overcooled, and suppresses the amount of condensed water generated. Specifically, the control device 1, EGR quantity Q if the electric pump 42 is rotated forward in the case of more than a predetermined amount Q _0, reducing the pump speed Np for intake air temperature Ti. On the contrary, if the electric pump 42 is reversed when the EGR amount Q is equal to or greater than the predetermined amount Q _{0, the} pump rotational speed Np with respect to the intake air temperature Ti is increased. Hereinafter, this pump control is also referred to as second pump control. That is, in the second pump control, the amount of cooling is reduced when the electric pump 42 is rotating forward, and the amount of heating is increased when the electric pump 42 is rotating reversely, so that the generation of condensed water is suppressed regardless of the rotation direction.

In the second pump control, similarly to the basic pump control, when the intake air temperature Ti is higher than the predetermined value Ti ₀ , the control device 1 causes the electric pump 42 to rotate forward at a higher speed as the intake air temperature Ti is higher. When the intake air temperature Ti is lower than the predetermined value Ti ₀ , the electric pump 42 is reversely rotated at a higher speed as the intake air temperature Ti is lower. Further, when the intake air temperature Ti is equal to the predetermined value Ti ₀ , the electric pump 42 is stopped (the pump rotation speed Np is set to zero). That is, also in the second pump control, the control device 1 switches the rotation direction of the electric pump 42 according to the magnitude relationship between the intake air temperature Ti and the predetermined value Ti _0, and changes the pump rotational speed Np to the intake air temperature Ti and the predetermined value Ti. _The higher the absolute value of the difference from ₀ , the higher. However, in the second pump control, the pump rotation speed Np is lowered during normal rotation and the pump rotation speed Np is increased during reverse rotation, compared with the pump rotation speed Np during basic pump control.

The second pump control can be performed except when the first pump control is performed. In other words, the second pump control is performed when the oil temperature Tt is lower than the predetermined oil temperature Tt ₀ and the EGR amount Q is equal to or greater than the predetermined amount Q ₀ . The first pump control oil temperature Tt is equal to the predetermined oil temperature Tt ₀ or more, is performed irrespective of the EGR amount. The basic pump control is performed when the oil temperature Tt is less than the predetermined oil temperature Tt ₀ and the EGR amount Q is less than the predetermined amount Q ₀ .

The control device 1 estimates the EGR amount Q using the opening degree of the EGR valve 35 and the pressure difference ΔP detected by the differential pressure sensor 39, and the estimated EGR amount Q is a predetermined amount Q ₀ or more. If the oil temperature Tt is lower than the predetermined oil temperature Tt ₀ , the electric pump 42 is controlled according to the intake air temperature Ti. The predetermined amount Q ₀ is preset based on the generated easiness of condensed water in the water content and the intercooler 28 that may be included in the recirculating gas.

The control apparatus 1 of this embodiment performs pump control using a map as shown in FIG. The map of FIG. 5 is obtained by adding a second graph (broken line) corresponding to the second pump control to the map of FIG. Second graph intake air temperature Ti is the pump speed Np is zero when a predetermined value Ti _0, and, as a linear function intake air temperature Ti is having a small positive slope than the basic chart with a predetermined value Ti ₀ or more In addition, when the intake air temperature Ti is less than the predetermined value Ti _0, it is set as a linear function having a positive slope larger than that of the basic graph.

As in the first embodiment, the control device 1 of the present embodiment has a map (basic graph, first graph, and second graph) as shown in FIG. The plurality of maps are set by moving the basic graph, the first graph, and the second graph so that the predetermined value Ti ₀ increases as the humidity H increases and the predetermined value Ti ₀ decreases as the humidity H decreases. ing. The control device 1, and the map is selected according to the humidity H from the plurality of maps, the detected oil temperature Tt at an oil temperature sensor 38 to select the first graph if predetermined oil temperature Tt ₀ or more. If the oil temperature Tt is less than the predetermined oil temperature Tt ₀ and the EGR amount Q is equal to or greater than the predetermined amount Q ₀ , the second graph is selected, and the oil temperature Tt is less than the predetermined oil temperature Tt ₀ and the EGR amount Q Is less than the predetermined amount Q ₀ , the basic graph is selected.

For example, assume that the control device 1 selects the map of FIG. In this case, when the oil temperature Tt is lower than the predetermined oil temperature Tt ₀ and the EGR amount Q is equal to or greater than the predetermined amount Q ₀ , the control device 1 selects the second graph. If the intake air temperature Ti is a temperature Ti ₁ higher than the predetermined value Ti _{0, the} electric pump 42 is rotated forward at the pump rotational speed Np ₁ ″. Conversely, the intake air temperature Ti is a temperature Ti lower than the predetermined value Ti _0. If it is ₂ , the control device 1 acquires the negative pump rotation speed Np ₂ ″ (−Np ₂ ″), and therefore reverses the electric pump 42 at the pump rotation speed Np ₂ ″.

[2-2. flowchart]
FIG. 6 is a flowchart illustrating a pump control procedure according to this embodiment. The flow in FIG. 6 is repeatedly executed at a predetermined calculation cycle in the control device 1 when, for example, the main power supply of the vehicle is on. This flow is obtained by adding steps S7 and S8 to the flow of FIG.

In the control device 1, each information (sensor value) detected by each sensor 36 to 39 is acquired (step S1), and a map corresponding to the humidity H is selected from a plurality of maps (step S2). When the oil temperature Tt is equal to or higher than the predetermined oil temperature Tt ₀ (step S3), the first graph is selected from the selected map (step S4). Then, the intake air temperature Ti is applied to the first graph of the map, the pump rotation speed Np is acquired (step S5), and the electric pump 42 is controlled with the acquired pump rotation speed Np (step S6). That is, when the oil temperature Tt is equal to or higher than the predetermined oil temperature Tt ₀ , the first pump control is performed by selecting the first graph from the map.

On the other hand, when the oil temperature Tt is lower than the predetermined oil temperature Tt ₀ and the estimated EGR amount Q is not less than the predetermined amount Q ₀ (step S7), the second graph is selected from the selected map (step S7). S8). Then, the intake air temperature Ti is applied to the second graph of the map, the pump rotation speed Np is acquired (step S5), and the electric pump 42 is controlled with the acquired pump rotation speed Np (step S6). That is, when the oil temperature Tt is lower than the predetermined oil temperature Tt ₀ and the EGR amount Q is equal to or greater than the predetermined amount Q ₀ , the second pump control is performed by selecting the second graph from the map.

When the oil temperature Tt is less than the predetermined oil temperature Tt ₀ and the EGR amount Q is less than the predetermined amount Q ₀ , a basic graph is selected from the selected map (step S9). Then, the intake air temperature Ti is applied to the basic graph of the map, the pump rotation speed Np is acquired (step S5), and the electric pump 42 is controlled with the acquired pump rotation speed Np (step S6). That is, when the oil temperature Tt is lower than the predetermined oil temperature Tt ₀ and the EGR amount Q is lower than the predetermined amount Q ₀ , the basic pump control is performed by selecting the basic graph from the map.

[2-3. effect]
Therefore, also with the engine 2 'of the present embodiment, when the intake air temperature Ti is higher than the predetermined value Ti ₀ , the higher the intake air temperature Ti, the higher the rotation speed of the electric pump 42, so that the intake air temperature Ti is higher. Sometimes the cooling water cooled by the radiator 41 can be sent to the intercooler 28 to cool the intake air. Thereby, the charging efficiency can be increased, and the turbocharger 27 provided on the downstream side of the intercooler 28 can also be cooled. On the other hand, when the intake air temperature Ti is less than the predetermined value Ti ₀ , the lower the intake air temperature Ti, the higher the rotational speed of the electric pump 42 is reversed, so that the intercooler 28 is heated using the exhaust heat of the turbocharger 27. can do. Thereby, the production | generation of condensed water can be suppressed effectively.

Further, in the engine 2 ′ of the present embodiment, if the control device 1 reverses the electric pump 42 when the EGR amount Q is equal to or greater than the predetermined amount Q _{0, the} pump rotation speed Np with respect to the intake air temperature Ti is increased. Thereby, when the EGR amount Q is large and the intake air temperature Ti is low, the amount of warming of the intercooler 28 can be increased, so that the generation of condensed water can be effectively suppressed.

Furthermore, in the engine 2 'of the present embodiment, the control device 1, EGR quantity Q if the electric pump 42 is rotated forward in the case of more than a predetermined amount Q _0, reducing the pump speed Np for intake air temperature Ti. Thereby, when the EGR amount Q is large and the intake air temperature Ti is high, the cooling amount of the intercooler 28 can be reduced, so that the generation of condensed water can be effectively suppressed. That is, if it is engine 2 'of this embodiment, regardless of the rotation direction of electric pump 42, the cooling of intake air can be prevented and generation of condensed water can be effectively suppressed.
In addition, the same effect can be acquired from the structure similar to 1st embodiment.

[2-4. Modified example]
A modification of the engine 2 'of the second embodiment is shown in FIG. The engine 50 of this modification is a multi-cylinder diesel engine. That is, the cylinder head of the engine 50 is provided with an in-cylinder injection valve 6, and fuel pumped by a high-pressure pump (not shown) is directly injected from the in-cylinder injection valve 6 into the fuel chamber.

  Further, the exhaust purification device 32 'of the engine 50 is configured by incorporating a catalyst 32A and a filter 32B. The catalyst 32A has a function of purifying hydrocarbon (HC) components, carbon monoxide (CO), nitrogen oxides (NOx), etc. contained in the exhaust gas, and is, for example, an oxidation catalyst. On the other hand, the filter 32B is a porous filter that collects particulate matter contained in the exhaust gas. The engine 50 has the same configuration as the engine 2 'described above except for these configurations. Therefore, even with the engine 50 shown in FIG. 7, the same operations and effects as those of the engine 2 'can be obtained.

[3. Others]
Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention. Can be selected or combined as appropriate.
The control content of the first pump control described above is an example, and is not limited to the above. For example, when Tt ≧ Tt ₀ and Ti <Ti ₀ , instead of keeping the pump rotational speed Np constant at the minimum rotational speed Npmin, the rate of change is smaller than when the intake air temperature Ti is a predetermined value Ti ₀ or more. The pump rotational speed Np may be decreased.

Further, when Tt ≧ Tt ₀ and Ti ≧ Ti ₀ , in addition to increasing the pump rotational speed Np as the intake air temperature Ti is higher, the pump rotational speed Np is increased as the oil temperature Tt is higher. The control content may be used. That is, when Tt ≧ Tt ₀ , the control device 1 may prohibit the reverse rotation of the electric pump 42 and forwardly rotate the electric pump 42 at a higher speed as the oil temperature Tt is higher. In this case, the turbocharger 27 can be cooled more appropriately, and the protection of the turbocharger 27 can be improved.

Further, when Tt ≧ Tt ₀ and Ti ≧ Ti ₀ , the rate of change of the pump speed Np with respect to the intake air temperature Ti may not be the same as that in the basic pump control. Further, when Tt ≧ Tt _0, the rate of change of the pump rotation speed Np with respect to the intake air temperature Ti may be changed with a temperature Ti ₀ ′ (Ti ₀ ′ ≠ Ti ₀ ) other than the predetermined value Ti ₀ as a boundary. That is, the first pump control may be performed using a temperature different from the temperature (predetermined value Ti ₀ ) for switching between normal rotation and reverse rotation in the basic pump control. For example, when Tt ≧ Tt ₀ and Ti <Ti ₀ ′, the pump rotational speed Np may be constant at the minimum rotational speed Npmin, and when Ti <Ti ₀ ′ and when Ti ≧ Ti ₀ ′ You may change the rate of change. Further, when Tt ≧ Tt ₀ and Ti ≧ Ti ₀ ′, the pump rotational speed Np is controlled to be equal to or higher than the minimum rotational speed Npmin, and the electric pump 42 is rotated forward at higher speed as the intake air temperature Ti is higher. It may be.

The control content of the second pump control described above is also an example, and is not limited to the above. For example, when Tt <Tt ₀ and Q ≧ Q ₀ and the electric pump 42 is rotating forward, the pump rotational speed Np during basic pump control is maintained without decreasing the pump rotational speed Np. Also good. Even in this case, when the intake air temperature Ti is low, the amount of heating can be increased by increasing the pump rotational speed Np, and the generation of condensed water in the intercooler 28 can be suppressed.

The first pump control and the second pump control may be omitted, and only basic pump control for controlling the electric pump 42 according to the intake air temperature Ti may be performed. Or it is good also as a structure which abbreviate | omits 1st pump control and performs basic pump control and 2nd pump control. In the latter case, the oil temperature sensor 38 can be omitted.
Further, in each of the above-described embodiments, the case where the control device 1 acquires the pump rotation speed Np using the maps as illustrated in FIGS. 2 and 5 and controls the electric pump 42 is illustrated, but the map is used. Instead, the rotation direction and the rotation speed Np of the electric pump 42 may be controlled. Alternatively, the predetermined value Ti ₀ may not be changed according to the humidity H.

  In each of the above-described embodiments, the intercooler 28 is provided with the intake air temperature sensor 36 and the humidity sensor 37, but the positions of these sensors 36 and 37 are not limited thereto. The intake air temperature sensor 36 may be at least a position downstream of the turbocharger 27 and capable of detecting the temperature Ti of the intake air flowing into the intercooler 28. Further, if the engine 2 ′ has the EGR passage 33, the humidity sensor 37 may be at a position downstream of the outlet of the EGR passage 33 and capable of detecting the humidity H of the intake air flowing into the intercooler 28. . The humidity H may be estimated from the EGR gas amount Q, and the humidity sensor 37 may be omitted.

  The configuration of the engines 2, 2 ', 50 is not limited to the above. For example, an engine provided with a so-called high pressure EGR passage in addition to the EGR passage 33 of the second embodiment may be used, or an engine without the throttle valve 29 may be used. The fuel injection mode is not particularly limited, and may be an engine that performs only port injection or an engine that performs only in-cylinder injection.

DESCRIPTION OF SYMBOLS 1 Control apparatus 2, 2 ', 50 Engine 25 Intake passage 27 Turbocharger 28 Intercooler (water-cooled intercooler)
31 Exhaust passage 33 EGR passage 34 EGR cooler 40, 40 'Intercooler cooling circuit 41 Radiator 42 Electric pump
Ti intake temperature
Ti ₀ predetermined value
Np Pump speed (speed of electric pump)
H Humidity
Tt Oil temperature
Tt ₀ Predetermined oil temperature
Q EGR amount (flow rate of reflux gas)
Q ₀ Predetermined amount

Claims (6)

An intercooler cooling circuit that interposes an electric pump capable of switching between normal rotation and reverse rotation, and in which cooling water pumped by the electric pump circulates;
A water-cooled intercooler provided on the intake passage of the engine and interposed on the intercooler cooling circuit and positioned on the downstream side of the electric pump during forward rotation of the electric pump;
A turbocharger that is interposed on the intercooler cooling circuit and is located on the downstream side of the water-cooled intercooler during the forward rotation, and supercharges intake air flowing through the intake passage;
A radiator interposed on the intercooler cooling circuit and positioned upstream of the electric pump during the forward rotation;
When the intake air temperature of the intake air flowing into the water-cooled intercooler is higher than a predetermined value, the electric pump is rotated forward at a higher speed as the intake air temperature is higher, and when the intake air temperature is lower than the predetermined value, A controller that reverses the electric pump at a higher speed as the intake air temperature is lower ,
The engine according to claim 1, wherein the controller prohibits reverse rotation of the electric pump when the temperature of lubricating oil supplied to the bearing portion of the turbocharger is equal to or higher than a predetermined oil temperature . Wherein the control device, when the oil temperature is the higher predetermined oil temperature, characterized in that said controlling a preset or minimum rotation speed of the rotation speed of the electric pump, engine according to Claim 1. Wherein the control device is characterized in that the higher the oil temperature to increase the rotation speed of the electric pump, according to claim 1 or 2 engine according. An EGR passage communicating the exhaust passage with the intake passage upstream of the turbocharger;
An EGR cooler that is provided on the EGR passage and cools the recirculation gas flowing through the EGR passage, and is interposed on the intercooler cooling circuit and is located downstream of the turbocharger during the forward rotation. Prepared,
The said control apparatus raises the rotation speed of the said electric pump with respect to the said intake temperature, if the said electric pump is reversely rotated when the flow volume of the said recirculation | reflux gas is more than predetermined amount, It is characterized by the above-mentioned. 4. The engine according to any one of 3 . Wherein the controller, if allowed to forward the electric pump when the flow rate of the recirculated gas is not less than the predetermined amount, and wherein the reducing the rotational speed with respect to the intake air temperature, according to claim 4, wherein engine. The engine according to any one of claims 1 to 5 , wherein the predetermined value is set to a higher value as the humidity of the intake air introduced into the water-cooled intercooler is higher.

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