JP2016109081A - Temperature control device for intercooler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To smoothly raise a boost pressure during acceleration of a vehicle when an intercooler has two circuits through which refrigerants at different temperatures flow.SOLUTION: A temperature control device for an intercooler includes a supercharger provided in an intake passage 1 of an engine E, an intercooler 6 disposed on the downstream side of the supercharger in the intake passage 1, a cooler 6a provided in the intercooler 6 and having a refrigerant passage, a low temperature circuit 30 for supplying a low temperature refrigerant to the refrigerant passage, a high temperature circuit 20 for supplying a high temperature refrigerant to the refrigerant passage, and refrigerant supply switch means for switching supply of the refrigerant to the refrigerant passage between the low temperature circuit 30 and the high temperature circuit 20. The refrigerant supply switch means normally performs feedback control for switching between the low temperature circuit 30 and the high temperature circuit 20 based on a temperature of intake air and a target intake temperature, and supplies the refrigerant to the refrigerant passage from the low temperature circuit 30 after an exhaust pressure rising rate in an exhaust passage 2 of the engine E is equal to or higher than a target exhaust pressure rising rate or a rotation speed rising rate of the supercharger is equal to or higher than a target value during acceleration.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a temperature control device that controls the temperature of air flowing out from an intercooler.

  Engines with superchargers that increase the intake pressure and increase the output by turbochargers such as turbochargers and superchargers are widely used. In an engine with a supercharger, an intercooler is provided on the downstream side of the supercharger in an intake passage to suppress an increase in intake air temperature due to an increase in intake pressure.

  In addition to the so-called air-cooled type, the intercooler includes a type that cools intake air by supplying a coolant such as water into a core that functions as a heat exchanger.

  Further, for example, Patent Document 1 includes a low-temperature circuit that supplies a low-temperature refrigerant to the intercooler, a high-temperature circuit that supplies a high-temperature cooling medium, and a circuit switching unit that switches between the low-temperature circuit and the high-temperature circuit. Technology is disclosed.

  In this technique, the temperature of the intake air flowing out from the intercooler is adjusted according to the scene by controlling the circuit switching means. That is, the control for lowering the intake air temperature is performed by using a low-temperature circuit, or the control for increasing the intake air temperature is performed by using a high-temperature circuit as necessary.

JP 2007-255262 A

  As described above, in an intercooler including a low-temperature circuit and a high-temperature circuit, the intercooler heats or cools the intake air depending on the temperature difference between the intake air and the refrigerant.

  The refrigerant passage of the high temperature circuit is branched from an engine cooling system circuit constituted by engine cooling water piping or the like. The refrigerant in the engine cooling system circuit receives heat from the engine and dissipates heat by the radiator. The refrigerant passage in the low-temperature circuit is provided independently of the engine cooling system circuit. The refrigerant in the low-temperature circuit mainly cools the intake air and dissipates heat received by the cooling by a dedicated radiator provided in a part of the low-temperature circuit.

  By properly using the two circuits, for example, when the engine is under a heavy load, the intake air that has been supercharged can be cooled using a low-temperature circuit to increase the intake air density, and the output performance can be improved by suppressing knocking. . In addition, when the engine is under a low load, the fuel efficiency can be improved by reducing the pumping loss of intake and exhaust by introducing the exhaust gas recirculation gas. Can be improved.

  However, when the vehicle accelerates, if the intake air is cooled with the refrigerant in the low-temperature circuit in order to increase the intake air density, the combustion may deteriorate and the exhaust energy may decrease. In such a case, a smooth increase in supercharging pressure by the supercharger may not be obtained.

  Accordingly, an object of the present invention is to smoothly increase the supercharging pressure when the vehicle accelerates when the intercooler includes two circuits having different refrigerant temperatures.

  In order to solve the above problems, the present invention provides a supercharger provided in an intake passage of an engine, an intercooler provided on the downstream side of the supercharger in the intake passage, and a refrigerant provided in the intercooler. A cooler having a passage; a low-temperature circuit that supplies a relatively low-temperature refrigerant to the refrigerant passage; a high-temperature circuit that supplies a refrigerant having a temperature higher than that flowing through the low-temperature circuit to the refrigerant passage; Refrigerant supply switching means for switching the supply of refrigerant to the low temperature circuit and the high temperature circuit, the refrigerant supply switching means, when accelerating, the exhaust pressure increase rate in the exhaust passage of the engine is equal to or higher than the target exhaust pressure increase rate, Or the temperature control apparatus of the intercooler which supplies a refrigerant | coolant from the said low-temperature circuit to the said refrigerant | coolant passage after the rotation speed increase rate of the said supercharger became more than target value was employ | adopted.

  Here, the refrigerant supply switching means is provided on the upstream side of the refrigerant passage, a three-way switching valve for switching the communication to the refrigerant passage between the low temperature circuit and the high temperature circuit, and provided in the low temperature circuit on the refrigerant passage side A low-temperature circuit pump for sending refrigerant to the high-temperature circuit, and a high-temperature circuit pump for feeding refrigerant to the refrigerant passage side when supplying the refrigerant from the low-temperature circuit to the refrigerant passage. The means may employ a configuration in which the three-way switching valve is communicated with the low-temperature circuit and the low-temperature circuit pump is operated.

  In each of these configurations, at the time of acceleration, the refrigerant supply switching means is configured so that the exhaust pressure increase rate in the engine exhaust passage is equal to or higher than the target exhaust pressure increase rate, or the rotation speed increase rate of the supercharger is equal to or higher than the target value. After that, if the temperature of the intake air flowing out from the intercooler is equal to or higher than the target intake air temperature, the refrigerant is supplied from the low temperature circuit to the refrigerant passage, and if the temperature of the intake air flowing out from the intercooler is less than a predetermined temperature, the A configuration in which supply of the refrigerant from the low-temperature circuit to the refrigerant passage is blocked can be employed.

  The refrigerant supply switching means further includes a high-pressure exhaust gas recirculation passage communicating the downstream side of the exhaust port of the engine exhaust passage and the upstream side of the intake port of the intake passage, If the temperature of the intake air flowing out from the cooler is lower than the target intake air temperature, the refrigerant is supplied from the high-temperature circuit to the refrigerant passage, the high-pressure exhaust gas recirculation gas is introduced into the intake air from the high-pressure exhaust gas recirculation passage, and flows out from the intercooler If the temperature of the intake air is equal to or higher than the target intake air temperature, a configuration in which the refrigerant is supplied from the low temperature circuit to the refrigerant passage can be employed.

  In each of these configurations, the refrigerant supply switching means further includes an exhaust pipe located downstream of the exhaust purification unit in the exhaust passage of the engine, and a low-pressure exhaust recirculation passage communicating with the upstream side of the supercharger of the intake passage. If the temperature of the intake air flowing out from the intercooler is lower than the target intake air temperature in the high load high speed range, the refrigerant is supplied from the high temperature circuit to the refrigerant passage, and the temperature of the intake air flowing out from the intercooler is the target intake air temperature. If the temperature is higher than the temperature, it is possible to adopt a configuration in which the refrigerant is supplied from the low-temperature circuit to the refrigerant passage and the low-pressure exhaust gas recirculation gas is introduced from the low-pressure exhaust gas recirculation passage.

  Further, the refrigerant supply switching means feedback-controls switching between supply of the refrigerant from the low temperature circuit and supply of the refrigerant from the high temperature circuit based on the temperature of the intake air flowing out from the intercooler and the target intake air temperature in a steady state. And adopting a configuration for controlling the switching period and switching cycle of the low-temperature circuit and the high-temperature circuit based on the rate of change of the temperature of the intake air for each predetermined period after switching between the low-temperature circuit and the high-temperature circuit. can do.

  In the present invention, during acceleration, after the exhaust pressure increase rate in the engine exhaust passage exceeds the target exhaust pressure increase rate or the turbocharger rotational speed increase rate exceeds the target value, the low temperature is reduced to the refrigerant passage of the intercooler. Since the refrigerant is supplied from the circuit, normal combustion and sufficient exhaust energy are ensured by normal intake air cooling in the early stage of acceleration, and after the normal boost pressure rise is confirmed, By increasing the intake air density, the intake air density can be increased and higher exhaust energy can be obtained. Therefore, the boost pressure can be increased smoothly when the vehicle accelerates.

1 is an overall view of an engine and an intercooler temperature control device according to an embodiment of the present invention. It is a graph which shows an example of the map used for control of this invention. It is a flowchart which shows the example of control of this invention. It is a flowchart which shows the example of control of this invention.

  Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is an overall view showing the configuration of an intercooler temperature control device and an engine equipped with the temperature control device of the present invention. In the figure, the members related to the present invention are mainly shown, and the others are not shown.

  The engine E is an automobile engine, and as shown in FIG. 1, an intake passage 1 leading to an intake port for sending intake air into a cylinder containing a piston, an exhaust passage 2 drawn from the exhaust port, and other necessary fuels A fuel injection device or the like for injection is provided. In the intake port and the exhaust port, the opening to the combustion chamber is opened and closed by a valve. Further, the intake passage 1 is provided with a throttle valve or the like for adjusting the flow passage area at an appropriate location.

  In the intake passage 1, an intake air cooling device 6 (hereinafter referred to as “intercooler 6”) that cools intake air flowing through the intake passage 1 from the intake port toward the upstream side, a turbocharger arranged as a supercharger An air cleaner case or the like that houses an air cleaner is provided on the upstream side of the compressor 5. In this embodiment, the intercooler 6 is provided in the intake manifold constituting the intake passage 1.

  The exhaust passage 2 includes a turbocharger turbine, an exhaust purification unit 8 equipped with a catalyst for removing nitrogen oxide (NOx) and the like in the exhaust, and an exhaust pipe (muffler) from the exhaust port toward the downstream side. Provided.

  The downstream side of the exhaust port of the exhaust passage 2 and the upstream side of the intake port of the intake passage 1 are communicated with each other by a high-pressure exhaust gas recirculation passage 3 a constituting the high-pressure exhaust gas recirculation device 3. A high-pressure exhaust gas recirculation valve 4 is provided in the high-pressure exhaust gas recirculation passage 3a. Depending on the opening and closing of the high pressure exhaust recirculation valve 4 and the pressure state in the intake passage 1 associated with the opening and closing of the throttle valve provided on the upstream side of the junction between the high pressure exhaust recirculation passage 3a and the intake passage 1, the high pressure exhaust recirculation passage Through 3a, a part of the exhaust gas discharged from the engine E returns to the intake passage 1 as high-pressure recirculation gas.

  Further, the exhaust pipe located downstream of the exhaust purification unit 8 in the exhaust passage 2 and the upstream side of the compressor 5 in the intake passage 1 are communicated with each other by a low pressure exhaust gas recirculation passage 13 a constituting the low pressure exhaust gas recirculation device 13. ing. A low pressure exhaust gas recirculation valve 14 is provided in the low pressure exhaust gas recirculation passage 13a. Depending on the opening and closing of the low pressure exhaust recirculation valve 14 and the pressure state in the intake passage 1 associated with the opening and closing of the throttle valve provided on the upstream side of the junction of the low pressure exhaust recirculation passage 13a and the intake passage 1, the low pressure exhaust recirculation passage A part of the exhaust gas discharged from the engine E returns to the upstream side of the supercharger in the intake passage 1 as a low-pressure recirculation gas through 13a.

  The turbocharger is composed of a compressor 5 for applying a boost pressure in the intake passage 1 of the engine, and a turbine provided in the exhaust passage 2 of the engine. The turbine is rotated by the exhaust gas discharged through the exhaust passage 2, and the rotation of the turbine is transmitted to the compressor 5. The intake air taken in from the air cleaner is compressed by the rotation of the compressor 5 and supplied to the combustion chamber of the engine E through the intake passage 1 in a supercharged state.

  The temperature of the intake air flowing out from the intercooler 6 and the intake air flow rate are acquired by the intake air temperature / intake pressure sensor 7. The exhaust pressure sensor 9 provided in the exhaust passage 2 is used for the exhaust pressure, and the rotational speed sensor 10 provided adjacent to the crankshaft 11 is used for the engine E. The temperature of the cooling water is acquired by a water temperature sensor 12 provided in a part of the pipe.

  The information obtained from each of these devices is sent to an electronic control unit (Electronic Control Unit) 40 provided in a vehicle on which the engine E is mounted, and is used to control the engine E, the temperature control device of the intercooler 6, and other devices. The

  The intercooler 6 is provided with a cooler 6a having a refrigerant passage through which a refrigerant (cooling medium) passes. The refrigerant can be selectively supplied to the refrigerant passage of the cooler 6a from the low-temperature circuit 30 for supplying the low-temperature refrigerant and the high-temperature circuit 20 for supplying the high-temperature refrigerant by the control by the refrigerant supply switching means. .

  In this embodiment, the refrigerant supply switching means for switching the supply of the refrigerant to the refrigerant passage of the cooler 6a between the low-temperature circuit 30 and the high-temperature circuit 20 is provided on the upstream side of the refrigerant passage of the cooler 6a. A three-way selector valve 32 that switches the communication between the low-temperature circuit 30 and the high-temperature circuit 20, a low-temperature circuit pump 35 that is provided in the low-temperature circuit 30 and sends refrigerant to the refrigerant passage side of the cooler 6a, and a cooler 6a that is provided in the high-temperature circuit 20 And a high-temperature circuit pump 25 for feeding the refrigerant to the refrigerant passage side.

  The high temperature circuit 20 is drawn out from a cooling passage formed in a cylinder block or the like in the engine E, and reaches a radiator 24 provided at the front of the vehicle, etc., and a feed passage 26 drawn out from the radiator 24. , 29 are provided. The feed passages 26, 29 connect the radiator 24 and the cooler 6 a of the intercooler 6, and an engine cooling passage 27 is directed from the branch portion provided in the middle of the feed passages 26, 29 to the cooling passage in the engine E. Has been pulled out. The radiator 24 is an air-cooling type cooling device and has a function of cooling the refrigerant. The high-temperature circuit pump 25 is provided on the downstream side of the radiator 24.

  Further, a radiator three-way switching valve 22 is provided in the middle of the radiator passage 21 connecting the engine E and the radiator 24. A short-circuit passage 23 that does not pass through the radiator 24 is connected to the three-way switching valve 22 for the radiator. The short-circuit passage 23 connects the radiator three-way switching valve 22 located on the upstream side of the radiator 24 and the downstream side of the radiator 24. Further, the high temperature return passage 28 drawn out from the refrigerant passage of the cooler 6 a is connected to the upstream side of the radiator 24.

  The radiator three-way switching valve 22 can switch the refrigerant of the high-temperature circuit 20 between a route passing through the radiator 24 and a route not passing through the radiator 24. This switching control is automatically performed by the thermostat according to the temperature of the refrigerant, but may be performed by the electronic control unit 40 according to the operating conditions.

  The low-temperature circuit 30 is drawn from the low-temperature circuit cooling radiator 34 and connected to the three-way switching valve 32 provided in the middle of the feed passages 26 and 29 of the high-temperature circuit 20 and the refrigerant passage of the cooler 6a. A low temperature return passage 31 is provided which is drawn out and connected to the low temperature circuit cooling radiator 34. The low-temperature circuit cooling radiator 34 is an air-cooled cooling device and has a function of cooling the refrigerant of the low-temperature circuit 30. The low-temperature circuit pump 35 is provided downstream of the low-temperature circuit cooling radiator 34.

  The three-way switching valve 32 allows the refrigerant passage of the cooler 6a of the intercooler 6 to communicate with the route of the feed passages 26 and 29 on the high temperature circuit 20 side, or to the route of the feed passages 33 and 29 on the low temperature circuit 30 side. You can switch between communicating. This switching control is similarly performed by the electronic control unit 40 in accordance with the refrigerant temperature and operating conditions.

  In this embodiment, both the high-temperature circuit 20 and the low-temperature circuit 30 employ water as a refrigerant, but a refrigerant composed of a fluid other than water may be employed.

  When supplying the refrigerant from the low temperature circuit 30 to the refrigerant passage of the cooler 6a of the intercooler 6, the control of the refrigerant supply switching means communicates the three-way switching valve 32 with the routes of the feed passages 33 and 29 on the low temperature circuit 30 side. The low temperature circuit pump 35 is operated. At this time, it is not necessary to stop the operation of the high-temperature circuit pump 25 as long as the cooling of the engine E is continued through the engine cooling passage 27.

  When supplying refrigerant from the high temperature circuit 20 to the refrigerant passage of the cooler 6a of the intercooler 6, the control of the refrigerant supply switching means communicates the three-way switching valve 32 with the routes of the feed passages 26 and 29 on the high temperature circuit 20 side. The high temperature circuit pump 25 is operated. At this time, the operation of the low-temperature circuit pump 35 is stopped.

  In the control of the engine E, the switching between the high temperature circuit 20 and the low temperature circuit 30 by the three-way switching valve 32 is a value of the intake air temperature flowing out from the intercooler 6 and a target intake air temperature value determined in advance according to the operating conditions. Based on this, feedback control is performed until the temperature of the intake air reaches the target intake air temperature. Corresponding to the switching of the three-way switching valve 32, the operation of the high-temperature circuit pump 25 and the low-temperature circuit pump 35 is appropriately controlled.

  Regarding the responsiveness of the feedback control, in order to speed up the convergence of the intake air temperature to the target intake air temperature, the actual intake air temperature (intake air flowing out from the intercooler 6) every predetermined period from the switching of the three-way switching valve 32. The change rate per unit time of the temperature can be measured from the temperature of the three-way switching valve 32 and the switching period and switching cycle of the three-way switching valve 32 can be controlled so as to stabilize quickly without overshooting from the target intake air temperature. .

  Specifically, if the rate of change in the intake air temperature per unit time is large, the change in the intake air temperature per unit time is large. Therefore, after switching the three-way switching valve 32 to one of the high temperature circuit 20 and the low temperature circuit 30, Reduce the time to switch to the other. Also, if the rate of change in the intake air temperature is small, the change in the intake air temperature per unit time is small. Therefore, after the three-way switching valve 32 is switched to one of the high-temperature circuit 20 and the low-temperature circuit 30, the time until switching to the other is set. Lengthen. At this time, based on the value of the rate of change, it is possible to calculate an appropriate time and period until switching by using a previously prepared calculation formula and other methods.

  Here, for example, during acceleration, the normal intake air temperature control, that is, the above feedback control is continued, and the fuel is increased in accordance with the accelerator opening. In the initial stage of acceleration, even if the fuel for acceleration is increased, the intake air temperature is maintained properly by feedback control. Therefore, sufficient exhaust energy is secured by maintaining good combustion, and the intake air by the turbocharger is secured. The supercharging pressure can be increased.

  After the exhaust pressure increase rate in the exhaust passage 2 becomes equal to or higher than the target exhaust pressure increase rate, or after the rotational speed increase rate of the compressor 5 of the supercharger becomes equal to or higher than the target value, the cooler of the intercooler 6 The refrigerant is supplied from the low-temperature circuit 30 to the refrigerant passage 6a.

  Thus, at the initial stage of acceleration, normal combustion and sufficient exhaust energy are ensured by cooling the normal intake air, and after the normal boost pressure rise is confirmed, the intake air is cooled by the low-temperature circuit 30 and the intake air is cooled. The density can be increased to obtain higher exhaust energy. Therefore, the boost pressure can be increased smoothly when the vehicle accelerates.

  In the control at the time of acceleration, the information from the exhaust pressure sensor 9 is used as the information on the increase rate of the exhaust pressure, and the electronic control unit 40 performs the control. In addition, when information on the number of rotations of the compressor 5 is used for the control, a device such as a rotation sensor is attached to the compressor 5 of the supercharger, and the information from those devices is used, and the electronic control unit 40 Control.

  Further, at the time of acceleration, after the exhaust pressure increase rate in the exhaust passage 2 becomes equal to or higher than the target exhaust pressure increase rate, or after the rotational speed increase rate of the compressor 5 of the supercharger becomes equal to or higher than the target value, it is uniform. If the temperature of the intake air flowing out from the intercooler 6 is equal to or higher than a predetermined temperature, the refrigerant is supplied from the low temperature circuit 30 to the refrigerant passage of the cooler 6a, and the intake air flowing out from the intercooler 6 If the temperature is lower than the predetermined temperature, the supply of the refrigerant from the low-temperature circuit 30 to the refrigerant passage of the cooler 6a may be shut off. An example of the predetermined temperature includes 0 ° C., and this may be set independently of the target intake air temperature.

When the supply of the refrigerant from the low temperature circuit 30 is interrupted, the refrigerant is supplied from the high temperature circuit 20 to the cooler 6a instead. The operation state of the high-temperature circuit pump 25 always continues while the engine is operating. However, if the high-temperature circuit pump 25 is stopped, the supply of the refrigerant from the high-temperature circuit 20 is also cut off to the cooler 6a.
On the contrary, when the supply of the refrigerant from the high temperature circuit 20 is interrupted, there may be a case where the refrigerant is supplied from the low temperature circuit 30, or the low temperature circuit pump 35 is stopped and the refrigerant supply from the low temperature circuit 30 is also performed. A scene that is blocked at the same time is also assumed.

  Further, in a low / medium load / low / medium speed range, if the temperature of the intake air flowing out from the intercooler 6 is lower than the target intake air temperature, the refrigerant is supplied from the high-temperature circuit 20 to the refrigerant passage of the cooler 6a to increase the intake air temperature. In addition, by introducing the high-pressure exhaust gas recirculation gas into the intake air through the high-pressure exhaust gas recirculation device 3, the temperature rise of the intake air can be assisted. Conversely, if the temperature of the intake air flowing out from the intercooler 6 is equal to or higher than the target intake air temperature, the refrigerant may be supplied from the low-temperature circuit 30 to the refrigerant passage of the cooler 6a to lower the intake air temperature. At this time, the high-pressure exhaust gas recirculation gas is not introduced.

  In the high-load high-speed region, if the temperature of the intake air flowing out from the intercooler 6 is lower than the target intake air temperature, the refrigerant is supplied from the high-temperature circuit 20 to the refrigerant passage of the cooler 6a to increase the temperature of the intake air. If the temperature of the intake air flowing out from the intercooler 6 is equal to or higher than the target intake air temperature, the refrigerant is supplied from the low-temperature circuit 30 to the refrigerant passage of the cooler 6a, and the low-pressure exhaust gas recirculation gas is supplied to the intake air through the low-pressure exhaust gas recirculation device 13. By introducing it, it is possible to assist the temperature drop of the intake air.

  In the conventional intercooler 6, since the temperature of the refrigerant in the high-temperature circuit 20 is always 90 ° C. or higher in normal operation, there is a problem that the cooling efficiency is inferior. Even if the intercooler 6 is provided with two coolers having different refrigerant temperatures, there is a limit to the temperature responsiveness to a sudden change in the engine operating state. However, if the intake air temperature control is assisted by introducing high-pressure exhaust gas recirculation gas or low-pressure exhaust gas recirculation gas as in the present invention, the temperature responsiveness can be further improved.

  Hereinafter, based on a flowchart, the intake air temperature control method by the intercooler temperature control apparatus of the present invention will be described.

  In a normal operation state, that is, when the partial load is steady, control for switching the three-way switching valve 32 by feedback control is performed so that the target intake air temperature has high combustion efficiency.

  In step S1 of the flowchart shown in FIG. 3, if the temperature of the refrigerant in the high-temperature circuit 20 is equal to or lower than a predetermined value (for example, a certain temperature set in the range of 60 to 80 ° C. according to the operation state), the friction is reduced. In order to stabilize combustion, the three-way switching valve 22 for the radiator is switched to set the refrigerant in the high-temperature circuit 20 to a route that does not pass through the radiator 24 to increase the temperature of the refrigerant. Here, since a thermostat is adopted as the radiator three-way switching valve 22, this state is a thermostat OFF state. Further, the three-way switching valve 32 communicates with the low temperature circuit 30 side, the high temperature circuit pump 25 is stopped, and the engine E main body is warmed up quickly (see steps S11 and S12).

  If the temperature of the refrigerant in the high-temperature circuit 20 is equal to or higher than a predetermined value (same as above), the warm-up has been completed, so the three-way switching valve 22 for the radiator is switched and the refrigerant in the high-temperature circuit 20 is routed through the radiator 24. The high-temperature circuit pump 25 is operated and the refrigerant is cooled by heat radiation. This state is a thermostat ON state (see step S2).

  In steps S3 and S4, an engine operating range is selected from the engine speed Ne and the intake pressure Pi. FIG. 2 shows an example of a map diagram for selecting the engine operating range. The engine load can be calculated from the intake pressure Pi, for example.

  If the engine operating range is the idle range, the radiator three-way switching valve 22 is set to a route passing through the radiator 24, and the temperature of the refrigerant decreases. This state is a thermostat ON state. The three-way switching valve 32 communicates with the high-temperature circuit 20 side, stops the low-temperature circuit pump 35, supplies the intercooler 6 with the refrigerant of the high-temperature circuit 20 after radiating heat with the radiator 24, and slightly superheats the intake air. To stabilize the combustion (see steps S21 and S22).

  Target intake air temperature experimentally determined so that the fuel consumption and exhaust gas are best when the engine operating range is low, medium speed, and low and medium load range (in this case, for example, 40 to 80 ° C. depending on the driving situation) If the temperature is lower than a certain temperature), the three-way switching valve 32 communicates with the high temperature circuit 20 side, stops the low temperature circuit pump 35, supplies the intercooler 6 with the refrigerant of the high temperature circuit 20, The fuel efficiency is improved by increasing the combustion efficiency by stabilizing the combustion (see steps S6 and S7). At this time, the control of whether or not the refrigerant of the high-temperature circuit 20 is caused to pass through the radiator 24 can be performed by switching the radiator three-way switching valve 22 based on the refrigerant temperature and the target intake air temperature.

  Then, the exhaust gas recirculation gas from the high-pressure exhaust gas recirculation device 3 that is high temperature and high pressure is introduced into the intake passage 1 to reduce nitrogen oxides contained in the exhaust gas (see step S8).

  If the intake air temperature is equal to or higher than the target intake air temperature (same as above), the three-way switching valve 32 communicates with the low-temperature circuit 30 side, operates the low-temperature circuit pump 35, and supplies the refrigerant of the low-temperature circuit 30 to the intercooler 6. Abnormal combustion and engine damage due to excessive temperature rise of the intake air are suppressed (see steps S6 and S10).

  Here, if the rotational fluctuation rate of the crankshaft 11 of the engine E exceeds a predetermined value that is determined in advance from the viewpoint of combustion stability, the process returns to step S6 and control is performed again in order to prevent deterioration of combustion. If the rotation fluctuation rate is equal to or less than a predetermined value, the control is terminated (see step S9). Information on the rotational fluctuation rate is acquired by the rotational speed sensor 10, and based on the information, the electronic control unit 40 calculates the rotational fluctuation rate and performs control.

  The target intake air temperature experimentally determined so that the fuel consumption and exhaust gas are best when the engine is at a high load or high speed range (in this case, for example, in the range of 20 to 40 ° C. depending on the driving situation) If the temperature is equal to or higher than a certain temperature, the three-way switching valve 32 communicates with the low temperature circuit 30 side and operates the low temperature circuit pump 35 to supply the refrigerant of the low temperature circuit 30 to the intercooler 6 (step S32, (See S33).

  Then, the exhaust gas recirculation gas from the low-pressure exhaust gas recirculation device 13 which is a low temperature and low pressure is introduced into the intake passage 1 to reduce nitrogen oxides contained in the exhaust gas and to suppress the deterioration of combustion due to the generation of condensed water, thereby improving the combustion efficiency. To improve fuel efficiency (see step S34).

  If the intake air temperature is less than the target intake air temperature (same as above), the three-way switching valve 32 communicates with the high temperature circuit 20 side, stops the low temperature circuit pump 35, and stops the supply of refrigerant from the low temperature circuit 30 to the intercooler 6. To stabilize combustion. At this time, if the high-temperature circuit pump 25 is operating, the refrigerant of the high-temperature circuit 20 is supplied to the intercooler 6 (see step S36).

  Here, if the rotational fluctuation rate of the crankshaft 11 of the engine E exceeds a predetermined value determined in advance from the viewpoint of combustion stability, the process returns to step S32 and control is performed again to prevent deterioration of combustion. If the rotation fluctuation rate is equal to or less than the predetermined value, the control is terminated (see step S35).

  By the way, at the time of acceleration, the refrigerant supply to the intercooler 6 is switched to the low temperature circuit 30 to increase the degree of cooling of the intake air to increase the volumetric efficiency, increase the boost pressure increase rate, and increase the acceleration performance as much as possible. I want to improve. However, if the temperature of the intake air suddenly decreases, combustion worsens and exhaust energy decreases, and conversely, the supercharging capability by the supercharger decreases.

  Therefore, in the initial stage of acceleration, maintaining the above feedback control state with optimized acceleration fuel increase and fuel injection timing, it is possible to secure exhaust energy by improving combustion and increase the supercharging capability by the supercharger. it can.

  FIG. 4 shows a flowchart of control during acceleration. In step S41, when the amount of change in accelerator opening is equal to or greater than a predetermined value set in advance, it is determined in step S42 that the engine operating range is during acceleration.

  Then, the accelerator opening is further increased to increase the amount of acceleration fuel. Alternatively, the fuel injection timing is optimized corresponding to the acceleration (see step S43). In the initial stage of acceleration, even if the amount of fuel for acceleration is increased, the temperature of the intake air is appropriately maintained by feedback control, so that good combustion is maintained.

  When the acceleration initial state is finished and the exhaust pressure increase rate is equal to or higher than the target exhaust pressure increase rate experimentally obtained from the accelerator opening change rate, it is determined that the boost pressure rise is normal (step) (See S44). Here, instead of the determination based on the exhaust pressure increase rate, it may be determined that the rise of the supercharging pressure is normal when the increase rate of the compressor rotation speed of the supercharger is equal to or higher than the target value.

  When it is determined that the rise of the supercharger is normal, the process proceeds to step S45. Here, if the temperature of the intake air is equal to or higher than a predetermined temperature (here, for example, a certain temperature set in a range of −10 to 0 ° C.), the three-way switching valve 32 is connected to the low temperature circuit 30 side. Then, the low-temperature circuit pump 35 is operated, the refrigerant of the low-temperature circuit 30 is supplied to the intercooler 6, the intake air density is increased by the intake air cooling and the supercharging pressure is increased, and the output is increased and the acceleration performance is improved (step) (See S46, S47, and S48).

  If the temperature of the intake air is less than a predetermined temperature (same as above), the three-way switching valve 32 communicates with the high temperature circuit 20 and stops the low temperature circuit pump 35. Such control is effective when the temperature is extremely low, such as in winter, (see step S49).

  Thus, in order to speed up the rise of the supercharging pressure, it is effective to improve the acceleration performance by first increasing the exhaust energy to speed up the rotation of the supercharger.

  The intercooler temperature control device according to the present invention can be applied to various engines including a diesel engine and a gasoline engine, and an intercooler that cools a supercharger and intake air. The supercharger may be a supercharger in addition to the turbocharger.

DESCRIPTION OF SYMBOLS 1 Intake passage 2 Exhaust passage 3 High pressure exhaust gas recirculation apparatus 3a High pressure exhaust recirculation passage 4 High pressure exhaust recirculation valve 5 Supercharger (compressor)
6 Intercooler 7 Intake air temperature / intake pressure sensor 8 Exhaust gas purification part (catalyst)
9 Exhaust pressure sensor 10 Speed sensor 11 Crankshaft 12 Water temperature sensor 13 Low pressure exhaust gas recirculation device 13a Low pressure exhaust gas recirculation passage 14 Low pressure exhaust gas recirculation valve 20 High temperature circuit (engine cooling system circuit)
21 Radiator passage 22 Radiator three-way switching valve 23 Short-circuit passage 24 Radiator 25 High-temperature circuit pump 26 Feed passage 27 Engine cooling passage 28 High-temperature return passage 29 Feed passage 30 Low-temperature circuit 31 Low-temperature return passage 32 Three-way switching valve 33 Feed passage 34 Low-temperature circuit cooling Radiator 35 for low temperature circuit pump 40 electronic control unit

Claims (6)

A turbocharger provided in the intake passage of the engine;
An intercooler provided downstream of the supercharger in the intake passage;
A cooler provided in the intercooler and provided with a refrigerant passage;
A low temperature circuit for supplying a relatively low temperature refrigerant to the refrigerant passage;
A high-temperature circuit for supplying a refrigerant having a temperature higher than that flowing through the low-temperature circuit to the refrigerant passage;
Refrigerant supply switching means for switching supply of the refrigerant to the refrigerant passage between the low temperature circuit and the high temperature circuit;
With
The refrigerant supply switching means is
During acceleration, after the exhaust pressure increase rate in the engine exhaust passage exceeds the target exhaust pressure increase rate or the turbocharger speed increase rate exceeds the target value, the refrigerant is supplied from the low-temperature circuit to the refrigerant passage. Intercooler temperature controller to be supplied. The refrigerant supply switching means is
A three-way switching valve that is provided on the upstream side of the refrigerant passage and switches the communication to the refrigerant passage between the low-temperature circuit and the high-temperature circuit;
A low-temperature circuit pump that is provided in the low-temperature circuit and sends the refrigerant to the refrigerant passage side;
A high-temperature circuit pump that is provided in the high-temperature circuit and sends the refrigerant to the refrigerant passage side;
With
2. The intercooler according to claim 1, wherein when supplying the refrigerant from the low-temperature circuit to the refrigerant passage, the refrigerant supply switching unit causes the three-way switching valve to communicate with the low-temperature circuit and operate the low-temperature circuit pump. Temperature control device. The refrigerant supply switching means is
During acceleration, after the exhaust pressure increase rate in the exhaust passage of the engine exceeds the target exhaust pressure increase rate, or the rotational speed increase rate of the turbocharger exceeds the target value, the temperature of the intake air flowing out from the intercooler becomes If the temperature of the intake air flowing out from the intercooler is lower than a predetermined temperature, the refrigerant is supplied from the low temperature circuit to the refrigerant passage if the temperature of the intake air flowing out from the intercooler is lower than a predetermined temperature. The temperature control apparatus of the intercooler of Claim 1 or 2 which interrupts | blocks. A high-pressure exhaust gas recirculation passage communicating the downstream side of the exhaust port of the exhaust passage of the engine and the upstream side of the intake port of the intake passage;
The refrigerant supply switching means is
If the temperature of the intake air flowing out of the intercooler is lower than the target intake air temperature in the low / medium load / low / medium speed range, the refrigerant is supplied from the high-temperature circuit to the refrigerant passage, and the high-pressure exhaust gas is recirculated from the high-pressure exhaust gas recirculation passage The intercooler according to any one of claims 1 to 3, wherein the refrigerant is supplied from the low-temperature circuit to the refrigerant passage when the temperature of the intake air that introduces gas and flows out of the intercooler is equal to or higher than a target intake air temperature. Temperature control device. An exhaust pipe located on the downstream side of the exhaust purification section in the exhaust passage of the engine, and a low-pressure exhaust gas recirculation passage communicating with the upstream side of the supercharger of the intake passage,
The refrigerant supply switching means is
In a high-load high-speed range, if the temperature of the intake air flowing out from the intercooler is lower than the target intake air temperature, the refrigerant is supplied from the high temperature circuit to the refrigerant passage, and the temperature of the intake air flowing out from the intercooler is equal to or higher than the target intake air temperature. 5. The intercooler temperature control device according to claim 1, wherein the refrigerant is supplied from the low-temperature circuit to the refrigerant passage and the low-pressure exhaust gas recirculation gas is introduced from the low-pressure exhaust gas recirculation passage. The refrigerant supply switching means is
In a steady state, feedback control of switching between supply of the refrigerant from the low temperature circuit and supply of the refrigerant from the high temperature circuit based on the temperature of the intake air flowing out from the intercooler and the target intake air temperature,
6. The switching period and switching cycle between the low temperature circuit and the high temperature circuit are controlled based on a rate of change in the temperature of the intake air for each predetermined period after switching between the low temperature circuit and the high temperature circuit. The temperature control device for an intercooler according to item 1.

Images