JP2019065760A - Engine warm-up system - Google Patents

Abstract

To more efficiently warm up an engine.SOLUTION: An engine warm-up system 100 includes: an intake flow passage 18; an electric supercharger 22; an exhaust flow passage 20; an EGR flow passage 33; an exhaust control valve 32 for opening/closing the exhaust flow passage; an EGR valve 35 for opening/closing the EGR flow passage; an intake valve 12 and an exhaust valve 13 for an engine 1; an intake/exhaust valve control section 114 for performing opening control of the intake valve and the exhaust valve when the engine is stopped; an electric supercharger control section 128 for driving the electric supercharger when a predetermined engine warming-up execution condition is satisfied; and valve control sections 120, 122 for controlling the exhaust control valve and the EGR valve. The valve control sections close the exhaust control valve and the EGR valve when the engine warming-up execution condition is satisfied, and controls the EGR valve so as to drive the electric supercharger in a predetermined driving region when a predetermined engine warming-up circulation condition is satisfied.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an engine warm-up system for warming up an engine.

  An engine equipped with an electric supercharger for compressing intake air is known. As a technology using this electric supercharger, for example, there is known a technology of warming up a catalyst by driving the electric supercharger while the engine is stopped and circulating gas through the EGR path (for example, , Patent Document 1).

JP 2008-255940 A

  When warming up using an electric supercharger like the technique described in the said patent document 1, it is desirable to use the electric supercharger which is a heat source more efficiently.

  Then, an object of the present invention is to provide an engine warm-up system capable of warming up an engine more efficiently.

  In order to solve the above problems, the engine warm-up system of the present invention is connected to the engine, is provided in an intake flow passage through which intake flows, and in the middle of the intake flow passage. A feeder, an exhaust flow path connected to the engine and discharging exhaust gas, and an EGR flow path for recirculating the exhaust gas discharged to the exhaust flow path upstream of the electric supercharger in the intake flow path An exhaust control valve provided on the downstream side of a branch position of the exhaust flow passage with the EGR flow passage and opening and closing the exhaust flow passage, an EGR valve provided in the EGR flow passage and opening and closing the EGR flow passage, and An intake valve for opening and closing the intake port and the combustion chamber of the engine, an exhaust valve for opening and closing the exhaust port of the engine and the combustion chamber of the engine, and an intake valve and An intake / exhaust valve control unit for opening control of the air valve, an electric supercharger control unit for driving the electric supercharger when a predetermined engine warm-up execution condition is satisfied when the engine is stopped, an exhaust control valve and an EGR valve The valve control unit closes the exhaust control valve and the EGR valve when the engine warm-up execution condition is satisfied, and the electric supercharging when the predetermined engine warm-up circulation condition is satisfied. The EGR valve is controlled to drive the machine in a predetermined drive range.

  Further, an intake control valve, which is provided on the upstream side of the joining position with the EGR passage in the intake passage and opens and closes the intake passage, and a pressure for measuring the pressure downstream of the electric turbocharger in the intake passage. The valve control unit may perform control to close the intake control valve when an engine warm-up circulation condition based on the pressure measured by the pressure sensor is established.

  The valve control unit may perform control to open the exhaust control valve when the pressure measured by the pressure sensor is equal to or higher than a predetermined pressure after the engine warm-up execution condition is satisfied.

  In addition, a pressure sensor for measuring the pressure downstream of the electric turbocharger in the intake passage is provided, and the valve control unit adjusts the opening degree of the EGR valve based on the pressure measured by the pressure sensor. Good.

  In addition, a pressure sensor for measuring the pressure downstream of the electric supercharger in the intake air passage is provided, and the drive region is more electrically over than in the case where the electric supercharger is driven at the best efficiency point according to the intake flow rate. The pressure ratio, which is the ratio of the pressure of the air flowing through the feeder to the pressure of the air compressed by the electric turbocharger, is high, and the flow rate of the air flowing through the electric turbocharger is small. Good.

  Further, the valve control unit is provided with a pressure sensor for measuring the pressure downstream of the electric turbocharger in the intake passage, and the valve control unit is configured to set a predetermined engine warm-up high-pressure condition based on the pressure measured by the pressure sensor Control may be performed to open the exhaust control valve.

  According to the present invention, the engine can be warmed up more efficiently.

It is a schematic diagram explaining an engine warm-up system in this embodiment. It is explanatory drawing which shows the flow of the air in warming up. It is explanatory drawing which shows the flow of the air in warming up. It is a figure which shows the map of the efficiency at the time of a motor-driven supercharger driving. It is a flowchart explaining engine warm-up processing at the time of engine stop. It is a flow chart explaining engine warm-up processing at the time of engine starting. It is a figure which shows the modification in this embodiment.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The dimensions, materials, and other specific numerical values and the like shown in this embodiment are merely examples for facilitating the understanding of the invention, and do not limit the present invention unless otherwise specified. In the specification and the drawings, elements having substantially the same functions and configurations will be denoted by the same reference numerals to omit repeated description, and elements not directly related to the present invention will not be illustrated. Do.

  FIG. 1 is a schematic view illustrating an engine warm-up system 100 in the present embodiment. In FIG. 1, the flow of the signal is indicated by a broken arrow.

  As shown in FIG. 1, the engine warm-up system 100 is provided with an engine 1. The engine 1 is a horizontally opposed four-cylinder engine in which cylinder bores 3a respectively formed in two cylinder blocks 3 sandwiching a crankshaft 2 are opposed to each other.

  A crankcase 4 is integrally formed with the cylinder block 3, and a cylinder head 5 is fixed to the side opposite to the crankcase 4. The crankshaft 2 is rotatably supported in a crank chamber 6 formed by two crankcases 4.

  A piston 8 connected to the crankshaft 2 via a connecting rod 7 is slidably accommodated in the cylinder bore 3a. In the engine 1, a space surrounded by the cylinder bore 3 a, the cylinder head 5, and the crown surface of the piston 8 is formed as a combustion chamber 9.

  An intake port 10 and an exhaust port 11 are formed in the cylinder head 5 so as to communicate with the combustion chamber 9. The tip of the intake valve 12 is located between the intake port 10 and the combustion chamber 9, and the tip of the exhaust valve 13 is located between the exhaust port 11 and the combustion chamber 9.

  Further, in the engine 1, an intake valve cam 15 and an exhaust valve cam 16 are provided in a cam chamber surrounded by the cylinder head 5 and the head cover 14. The intake valve cam 15 is in contact with the other end of the intake valve 12 and moves the intake valve 12 in the axial direction by rotating. Thereby, the intake valve 12 opens and closes between the intake port 10 and the combustion chamber 9. The exhaust valve cam 16 is in contact with the other end of the exhaust valve 13 and moves the exhaust valve 13 in the axial direction by rotating. Thereby, the exhaust valve 13 opens and closes between the exhaust port 11 and the combustion chamber 9.

  An intake passage 18 including an intake manifold 17 is in communication with the upstream side of the intake port 10. Further, an exhaust flow passage 20 including an exhaust manifold 19 is in communication with the downstream side of the exhaust port 11. Exhaust gas discharged from the combustion chamber 9 is collected by the exhaust manifold 19 through the exhaust port 11 and is led to the exhaust flow passage 20.

  In the intake passage 18, an air cleaner 21, an intake control valve 25, a compressor impeller 22c of an electric supercharger 22 described later, an intercooler 23, a throttle valve 24, and an intake manifold 17 are provided in this order from the upstream side. Here, in the intake passage 18, the upstream side of the compressor impeller 22c is referred to as the upstream intake passage 18a, and the downstream side of the compressor impeller 22c is referred to as the downstream intake passage 18b.

  The electric supercharger 22 includes a motor 22a, a shaft 22b, and a compressor impeller 22c. The motor 22a is driven by the supply of power. The shaft 22b is connected to the motor 22a and is rotated by driving of the motor 22a. The compressor impeller 22c is connected to the shaft 22b and integrally rotates with the shaft 22b.

  Further, the compressor impeller 22c is rotated by driving of the motor 22a to compress air (intake air) from which impurities such as dust and dirt have been removed by the air cleaner 21 and supply the compressed air to the downstream side intake flow passage 18b.

  The intercooler 23 cools the intake air compressed and heated by the compressor impeller 22c. The cooled air is led to the combustion chamber 9 through the throttle valve 24, the intake manifold 17 and the intake port 10.

  The throttle valve 24 changes the flow rate of the intake air supplied to the combustion chamber 9 by adjusting the opening degree by an actuator (not shown).

  The intake control valve 25 is in an open state during operation of the engine 1 and passes downstream without adjusting the flow rate of air sucked from the outside through the air cleaner 21. Further, the intake control valve 25 adjusts the flow rate of air (intake air) sucked from the outside by adjusting the opening degree during engine warm-up described later in detail.

  Further, an air bypass passage 26 is provided in the intake passage 18 for bypassing the compressor impeller 22c. The air bypass passage 26 is connected between the intake control valve 25 and the compressor impeller 22c in the upstream side intake passage 18a. Further, the air bypass flow passage 26 is connected between the intercooler 23 and the throttle valve 24 in the downstream side intake flow passage 18 b. An air bypass valve 27 is interposed in the air bypass flow path 26. The air bypass valve 27 is opened when the driver releases the accelerator and the throttle valve 24 is closed, and prevents the pressure in the downstream side intake passage 18 b from becoming excessive.

  Further, the downstream side intake flow passage 18 b is provided with a first bypass flow passage 28 which bypasses the intercooler 23. A first flow passage switching valve 29 is provided at a point where the upstream side of the first bypass flow passage 28 and the downstream side intake flow passage 18 b are connected. The first flow passage switching valve 29 switches the flow passage so that the intake air flows through either the intercooler 23 or the first bypass flow passage 28.

  In the engine 1, a mixture of intake air introduced to the combustion chamber 9 and fuel injected from an injector (not shown) is ignited at a predetermined timing by an ignition plug (not shown) provided on the cylinder head 5 and burnt. Be done. By this combustion, the piston 8 reciprocates in the cylinder bore 3 a, and the reciprocation is converted to the rotational motion of the crankshaft 2 through the connecting rod 7.

  Further, the exhaust gas generated by the combustion is discharged to the outside of the vehicle through the exhaust port 11 and the exhaust flow passage 20. The exhaust flow path 20 is provided with an upstream catalyst (catalyst) 30 and a downstream catalyst 31. The upstream catalyst 30 and the downstream catalyst 31 purify the exhaust gas flowing through the exhaust flow passage 20. The upstream catalyst 30 and the downstream catalyst 31 may be filter devices with a catalytic function.

  Further, an exhaust control valve 32 is provided in the exhaust flow passage 20. The exhaust control valve 32 is provided downstream of a point where the EGR (Exhaust Gas Recirculation) passage 33 is connected in the exhaust passage 20 and on the upstream side of the downstream catalyst 31. The exhaust control valve 32 is in an open state during operation of the engine 1, and does not adjust the flow rate of air flowing from the upstream side of the exhaust control valve 32 in the exhaust flow passage 20, but downstream of the exhaust control valve 32. Pass it to the side. Further, the exhaust control valve 32 adjusts the flow rate of the air discharged to the outside through the exhaust flow passage 20 by adjusting the opening degree during engine warm-up described later in detail.

  In addition, an EGR flow path 33 that causes part of exhaust gas to flow back to the intake flow path 18 is connected to the exhaust flow path 20. The EGR passage 33 is connected between the upstream catalyst 30 and the exhaust control valve 32 in the exhaust passage 20, and between the intake control valve 25 and the compressor impeller 22c in the upstream intake passage 18a. In the following, the exhaust gas (air) recirculated in the EGR passage 33 is referred to as "EGR gas".

  In the EGR passage 33, an EGR cooler 34 and an EGR valve 35 are sequentially provided from the upstream side. The EGR cooler 34 cools the EGR gas. The EGR valve 35 adjusts the opening degree to adjust the flow rate of the EGR gas flowing through the EGR passage 33. The detailed control of the EGR valve 35 will be described later.

  Further, in the EGR passage 33, a second bypass passage 36 for bypassing the EGR cooler 34 is provided. A second flow path switching valve 37 is provided at a point where the upstream side of the second bypass flow path 36 and the EGR flow path 33 are connected. The second flow path switching valve 37 switches the flow path so as to flow the EGR gas (air) to either the EGR cooler 34 or the second bypass flow path 36.

  Further, the engine warm-up system 100 is provided with a control device 110. A first pressure sensor (pressure sensor) 50, a second pressure sensor 52, a first temperature sensor 54, a second temperature sensor 56, a third temperature sensor 58, and an engine start switch sensor 60 are connected to the control device 110.

  The first pressure sensor 50 is provided between the intercooler 23 and the throttle valve 24 in the downstream side intake flow passage 18b, and measures the pressure in the downstream side intake flow passage 18b. In addition, the first pressure sensor 50 transmits, to the control device 110, a detection signal corresponding to the pressure (pressure P1) in the downstream intake flow passage 18b.

  The second pressure sensor 52 is provided downstream of the connection point of the EGR flow path 33 in the upstream side intake flow path 18a, and measures the pressure in the upstream side intake flow path 18a. Further, the second pressure sensor 52 transmits a detection signal corresponding to the pressure (pressure P2) in the upstream intake flow passage 18a to the control device 110.

  The first temperature sensor 54 is provided in the cylinder block 3 and measures the temperature of the cooling water flowing in the engine 1. Further, the first temperature sensor 54 transmits a detection signal according to the temperature (temperature T1) in the engine 1 to the control device 110.

  The second temperature sensor 56 is provided on the upstream side of the intake control valve 25 in the upstream side intake flow passage 18a, and measures the temperature of the air (intake air) taken in. The second temperature sensor 56 also transmits a detection signal to the control device 110 according to the temperature (temperature T2) of the intake air (outside air).

  The third temperature sensor 58 is provided in the intake manifold 17 and measures the temperature of the air flowing in the intake manifold 17. Further, the third temperature sensor 58 transmits a detection signal corresponding to the temperature (temperature T3) in the intake manifold 17 to the control device 110.

  When the engine start switch (not shown) is turned on, the engine start switch sensor 60 transmits an engine start switch on signal indicating that the engine start switch is turned on to the control device 110. In addition, when the engine start switch is turned off, the engine start switch sensor 60 transmits to the control device 110 an engine start switch off signal indicating that the engine start switch has been turned off.

  The control device 110 is, for example, an ECU (Engine Control Unit), and is constituted by a semiconductor integrated circuit including a central processing unit (CPU), a ROM storing programs and the like, and a RAM as a work area. Control. Further, the control device 110 controls the operation of the entire vehicle including the engine 1 and further includes a drive control unit 112, an intake and exhaust valve control unit 114, a throttle valve control unit 116, and an intake control valve control unit (valve control unit) 118, Exhaust control valve control unit (valve control unit) 120, EGR valve control unit (valve control unit) 122, first flow passage switching valve control unit 124, second flow passage switching valve control unit 126, and electric turbocharger control unit 128 It also works as Hereinafter, specific operations of the engine warm-up system 100 will be described.

  2 and 3 are explanatory views showing the flow of air during warm-up. FIG. 2 shows the flow of warm air when drawing in fresh air. FIG. 3 shows the flow of warm air as the air circulates. Also, in FIG. 2 and FIG. 3, the solid arrows indicate the flow of air.

  Here, when the engine start switch is turned on (the engine start switch on signal is received), the drive control unit 112 starts the engine 1, but when the engine 1 is at a low temperature, the viscosity of the engine oil Is high, and the startability of the engine 1 is reduced. Therefore, in the engine warm-up system 100, when the engine warm-up execution condition is satisfied when the engine start switch is turned on, the engine warm-up is executed. The engine warm-up execution condition is that the temperature (temperature T1) in the engine 1 is lower than a predetermined temperature at which the temperature is preset. The warm-up by the engine warm-up system 100 is performed by warming up the combustion chamber 9 of the engine 1 as a first object to stabilize the combustion at the start even when the outside air temperature is low.

  When receiving the engine start switch off signal sent from the engine start switch sensor 60, the drive control unit 112 stops the engine 1. At this time, the intake / exhaust valve control unit 114 opens both the intake valve 12 and the exhaust valve 13 regardless of whether or not the engine warm-up is performed at the start of the engine 1 as a step prior to the engine warm-up. The engine 1 is controlled to stop so as to be in the (overlap state). Thereby, in the engine 1, the state where the intake port 10 and the combustion chamber 9 are in communication is maintained. Further, in the engine 1, the state in which the exhaust port 11 and the combustion chamber 9 are in communication is maintained.

  After that, when the engine start switch is turned on (the engine start switch on signal is received), the drive control unit 112 determines whether the engine warm-up execution condition is satisfied. Then, when it is determined that the engine warm-up execution condition is satisfied, the drive control unit 112 causes each part of the control device 110 to perform engine warm-up without starting the engine 1.

  When the engine warm-up is started, the throttle valve control unit 116 opens the throttle valve 24. Further, the intake control valve control unit 118 opens the intake control valve 25, the exhaust control valve control unit 120 closes the exhaust control valve 32, and the EGR valve control unit 122 closes the EGR valve 35.

  Further, the first flow path switching valve control unit 124 controls the first flow path switching valve 29 so that the air flows through the first bypass flow path 28. Furthermore, the second flow path switching valve control unit 126 controls the second flow path switching valve 37 so that the air flows through the second bypass flow path 36.

  Then, the electric supercharger control unit 128 drives the electric supercharger 22 with a predetermined constant power. At this time, as shown in FIG. 2, when the electric supercharger 22 is driven by opening the intake control valve 25, the compressor impeller 22c sucks in air (fresh air) from the outside.

  Here, since the intake control valve 25 is opened and the exhaust control valve 32 and the EGR valve 35 are closed, the electric supercharger 22 is driven to suck in air from the outside by suction. The amount of air in the flow passage 18, the engine 1, the exhaust flow passage 20 and the EGR flow passage 33 is increased. As a result, the pressure in the intake flow passage 18, the engine 1, the exhaust flow passage 20 and the EGR flow passage 33 also increases, and as a result, the intake flow passage 18, the engine 1, the exhaust flow passage 20 and the EGR flow passage 33 By raising the internal temperature, it is possible to warm up the engine 1 early.

  Thereafter, when it is determined that the engine warm-up circulation condition is established, the intake control valve control unit 118 closes the intake control valve 25. Further, the EGR valve control unit 122 controls the EGR valve 35 so that the electric supercharger 22 is driven in a predetermined area. The engine warm-up circulation condition is that the pressure (pressure P1) in the downstream side intake passage 18b has reached a predetermined pressure higher than the preset atmospheric pressure. Further, detailed control of the intake control valve 25 and the EGR valve 35 will be described later.

  As a result, as shown by the solid arrows in FIG. 3, the air compressed by the electric turbocharger 22 (compressor impeller 22c) bypasses the intercooler 23 when flowing through the downstream intake flow passage 18b. It flows through the first bypass channel 28. Thereafter, the air flowing in the downstream side intake flow passage 18 b flows in the combustion chamber 9 of the engine 1 and then flows in the exhaust flow passage 20. Then, the air flowing through the exhaust flow passage 20 is guided to the EGR flow passage 33 by closing the exhaust control valve 32. The air led to the EGR passage 33 bypasses the EGR cooler 34 and is led to the upstream intake passage 18 a when flowing through the EGR passage 33.

  As described above, in the engine warm-up system 100, a circulation flow path through which air is circulated is formed in the intake flow path 18, the engine 1, the exhaust flow path 20, and the EGR flow path 33. Then, the heat of the air compressed by the electric turbocharger 22 warms up the engine 1 and the catalyst 30 on the upstream side. At this time, since the intake control valve 25 and the exhaust control valve 32 are closed and the circulation flow path is sealed, the air that has been warmed can be used again for warming up without being cooled by the outside air. As a result, in the engine warm-up system 100, it is possible to warm up the engine 1 earlier.

  Then, the electric turbocharger control unit 128 warms up the engine 1 until the temperature (temperature T3) in the intake manifold 17 becomes equal to or higher than the threshold T based on the temperature of the outside air (temperature T2). The threshold T is a value higher than the temperature of the outside air (temperature T2) and different depending on the temperature of the outside air (temperature T2), and the threshold T when the temperature of the outside air (temperature T2) is low Is relatively lower than that when the outside air temperature (temperature T2) is high.

  At this time, the temperature of the air in the circulation flow path gradually increases in order to continue being compressed by the electric supercharger 22, and in accordance therewith, the pressure in the circulation flow path also gradually rises. In the circulation flow path, for example, a large number of parts which can not withstand high pressure (for example, 1.5 atmospheric pressure or more) such as the intake flow path 18 are provided. When the pressure in the circulation passage is high, components such as the intake passage 18 may be destroyed by the high pressure. Therefore, in the engine warm-up system 100, when the engine warm-up high pressure condition is satisfied, the air in the circulation flow path is discharged. The engine warm-up high-pressure condition is that the pressure (pressure P1) in the downstream side intake passage 18b is higher than a predetermined high pressure.

  The exhaust control valve control unit 120 temporarily opens the exhaust control valve 32 when it is determined that the engine warm-up high pressure condition is satisfied. As a result, the pressure in the circulation flow path is reduced, and parts that can not withstand high pressure (for example, 1.5 atm) such as the intake flow path 18 provided in the engine warm-up system 100 are destroyed by the high pressure You can prevent. The detailed control of the exhaust control valve 32 will be described later.

  Then, drive control unit 112 determines the end of engine warm-up based on the temperature (temperature T3) in intake manifold 17 and threshold value T, and drives engine 1 (starts up). At this time, after taking into consideration the heat capacity of the combustion chamber 9 and after the temperature (temperature T3) in the intake manifold 17 reaches the threshold value T and after a predetermined time set as the drive start time set in advance, the engine 1 is Drive (start).

  By the way, when the electric supercharger 22 rotates the compressor impeller 22c, useless energy (heat generation) occurs. Therefore, during normal engine driving, the electric turbocharger 22 is controlled to minimize heat generation (to improve efficiency) when compressing intake air (adiabatic compression is performed).

  On the other hand, when warm-up is performed using the electric supercharger 22, if the electric supercharger 22 is driven as in normal engine driving, heat generation of the electric supercharger 22 is minimized and the warm-up efficiency is lowered. Do. Therefore, in the engine warm-up system 100 in the present embodiment, the electric supercharger 22 is controlled by a drive different from normal to warm up the engine 1.

  FIG. 4 is a diagram showing a map of the efficiency when the electric supercharger 22 is driven. In FIG. 4, the vertical axis indicates the pressure ratio, and the horizontal axis indicates the flow rate. The pressure ratio is a ratio of the pressure of the air flowing to the electric turbocharger 22 to the pressure of the air compressed by the electric turbocharger 22. The flow rate is the mass flow rate of the air compressed by the electric supercharger 22. Control of the EGR valve 35 will be described with reference to FIG. Further, in FIG. 4, a broken line indicates the efficiency (power efficiency) of the electric turbocharger 22. The respective power efficiency lines a to d show equal power efficiency. Further, in FIG. 4, an alternate long and short dash line indicates the power input to the electric supercharger 22. Power lines shown by respective one-dotted lines indicate equal power.

  As shown in FIG. 4, the power efficiency of the electric turbocharger 22 becomes higher toward the center in the figure. For example, in the inner area surrounded by the power efficiency line a, the electric supercharger 22 is driven at an efficiency of 85% or more. In addition, the electric supercharger 22 is motive power with an efficiency of 80% to 85% in the inner area surrounded by the power efficiency line b and an efficiency of 75% to 80% in the inner area surrounded by the power efficiency line c. In the inner region surrounded by the efficiency line d, driving is performed with an efficiency of 70% to 75%.

  An inner area A surrounded by the power efficiency line a indicates the power efficiency when the electric supercharger 22 is driven normally. As described above, in the inner region surrounded by the power efficiency line a, the electric turbocharger 22 is driven at an efficiency of 85% or more. At this time, the heat generated by driving the electric turbocharger 22 is about 10%. Therefore, the electric supercharger 22 can efficiently compress air by driving in the region A.

  On the other hand, as the power efficiency line b, the power efficiency line c, and the power efficiency line d become farther from the power efficiency line a in this order, the amount of heat generated by the drive of the electric supercharger 22 increases. Although the power efficiency of the electric supercharger 22 deteriorates with the rise of the calorific value, the energy due to the heat generation is transmitted to the air flowing through the intake flow passage 18, and the temperature of the air rises.

  Here, the area surrounded by the solid line indicated by low in FIG. 4 is inefficient (low) with respect to the area surrounded by the solid line indicated by high (when the electric turbocharger 22 is driven normally). Efficiency) area. In FIG. 4, the area on the left side is referred to as area B, and the area on the right side is referred to as area C. However, in the region B and the region C, the efficiencies of the electric turbocharger 22 are approximately equal.

  In the area B and the area C, the calorific value generated from the electric supercharger 22 is substantially the same. However, if the electric power supplied to the electric turbocharger 22 is the same, air is compressed more in area B than in area A, and the flow rate decreases. On the other hand, in the region C, air is not compressed as compared with the region A, and the flow rate increases. Therefore, driving the electric supercharger 22 in the area B can make the temperature of the air higher by the temperature increase due to compression than in the case where the electric supercharger 22 is driven in the area C.

  Therefore, in the engine warm-up system 100 of the present embodiment, the electric supercharger 22 adjusts the opening degree of the EGR valve 35 so as to drive in the region B, and warms up the engine 1.

  Specifically, when the engine warm-up execution condition is satisfied, first, the intake control valve 25 is opened, and the exhaust control valve 32 and the EGR valve 35 are closed to drive the electric supercharger 22, as shown in FIG. As indicated by the solid black arrows (1), the mass flow rate (air amount) flowing through the electric turbocharger 22 increases. At this time, since the inside of the circulation flow path is sealed, if the electric supercharger 22 is kept driven as it is, the circulation flow is continued by continuing to take in fresh air as shown by the solid arrow (2) in FIG. The air in the road is compressed, the compression ratio of the electric turbocharger 22 increases, and the mass flow rate (air amount) decreases.

  Then, when the drive efficiency of the electric turbocharger 22 reaches the region B (the pressure (pressure P1 in the downstream intake passage 18b reaches a predetermined value set in advance)), that is, the engine warm-up circulation condition When the following condition is established, the intake control valve control unit 118 closes the intake control valve 25 and stops the intake of air (fresh air) from the outside. Then, the EGR valve control unit 122 derives a pressure ratio based on the pressure P1 and the pressure P2 measured by the first pressure sensor 50 and the second pressure sensor 52. Then, the EGR valve control unit 122 controls the opening degree of the EGR valve 35 so that the electric supercharger 22 is driven in the region B using the map of FIG. 4. Here, for example, when the pressure ratio decreases, the opening degree of the EGR valve 35 is decreased so as to increase the pressure ratio, and when the pressure ratio increases, the pressure ratio decreases so as to decrease. The electric supercharger 22 is driven in the region B by increasing the opening degree of the motor. That is, in the engine warm-up system 100, the compression ratio of the electric supercharger 22 is adjusted by controlling the opening degree of the EGR valve 35.

  As a result, the engine warm-up system 100 can drive the electric supercharger 22 in the region B where the temperature of the air is the highest, without the outside air (cold air) entering the engine 1. You can warm up early.

  Further, as described above, when the electric supercharger 22 is continuously driven in a state where the circulation flow channel is sealed (in a state where there is no air flow into and out of the outside), the pressure in the circulation flow channel is increased. Therefore, if the pressure P1 measured by the first pressure sensor 50 is higher than the predetermined high pressure set in advance, that is, if the engine warm-up high-pressure condition is satisfied, the exhaust control valve control unit 120 The exhaust control valve control unit 120 opens the exhaust control valve 32. Then, the exhaust control valve control unit 120 closes the exhaust control valve 32 again after the pressure P1 measured by the first pressure sensor 50 becomes lower than a predetermined high pressure.

  Thus, the engine warm-up system 100 can prevent the intake passage 18, the engine 1, the exhaust passage 20, and the EGR passage 33 forming the circulation passage from being destroyed by high pressure.

(Engine warm-up process)
Next, the flow of the engine warm-up process by the engine warm-up system 100 will be described. FIG. 5 is a flowchart for explaining an engine warm-up process when the engine is stopped.

  First, based on the signal transmitted from the engine start switch sensor 60, the drive control unit 112 determines whether the engine start switch is turned off (S10). Then, if it is determined that the engine start switch has been turned off (YES in step S10), the intake and exhaust valve control unit 114 controls the intake valve 12 and the exhaust valve 13 to the open state (overlap state) (S12). Thereafter, the drive control unit 112 stops the engine 1 (S14), and ends the engine warm-up process when the engine is stopped.

  On the other hand, when the drive control unit 112 determines that the engine start switch is not turned off (NO in step S10), the process of step S10 is repeated until it is determined that the engine start switch is turned off.

  FIG. 6 is a flow chart for explaining an engine warm-up process at the time of start of the engine. The engine warming-up process at the time of starting the engine is a process that is executed when the engine start switch is turned on.

  When the engine start switch is turned on, the drive control unit 112 determines whether the engine warm-up execution condition is satisfied, specifically, whether the temperature T1 is lower than a predetermined temperature (S20) ). The temperature T2 may be added to the determination as to whether the engine warm-up execution condition is satisfied. In this case, it is determined that the engine warm-up execution condition is satisfied when the temperature T1 and the temperature T2 are equal to or lower than the temperatures (threshold values) set for the respective temperatures.

  When it is determined that the engine warm-up execution condition is satisfied (YES in step S20), throttle valve control unit 116 opens throttle valve 24 and intake control valve control unit 118 controls intake control valve 25. The exhaust control valve control unit 120 closes the exhaust control valve 32, and the EGR valve control unit 122 closes the EGR valve 35 (S22). Further, the first flow path switching valve control unit 124 controls the first flow path switching valve 29 so that the air flows through the first bypass flow path 28. In addition, the second flow path switching valve control unit 126 controls the second flow path switching valve 37 so that the air flows through the second bypass flow path 36.

  And the electric supercharger control part 128 drives the electric supercharger 22 by predetermined electric power (S24). The intake control valve control unit 118 determines whether the engine warm-up circulation condition is satisfied (S26).

  Then, if it is determined that the engine warm-up circulation condition is established (YES in step S26), the intake control valve control unit 118 closes the intake control valve 25. In addition, the EGR valve control unit 122 controls the EGR valve 35 so that the electric supercharger 22 is driven in a predetermined area B (S28).

  On the other hand, if it is not determined that the engine warm-up circulation condition is established, that is, if it is determined that the engine warm-up circulation condition is not established (NO in step S26), a sufficient amount of air is taken. It will not be (or it has not risen to a sufficient pressure). Therefore, the process of step S26 is repeated.

  Thereafter, the exhaust control valve control unit 120 determines whether or not the engine warm-up high pressure condition is established (S30). Specifically, the exhaust control valve control unit 120 determines whether or not the pressure P1 in the downstream intake passage 18b measured by the first pressure sensor 50 is equal to or higher than a pressure set to a high pressure set in advance. judge. Then, if the exhaust control valve control unit 120 determines that the engine warm-up high pressure condition is satisfied (YES in step S30), the exhaust control valve 32 is opened (S32). Then, the exhaust control valve control unit 120 determines whether or not the engine warm-up high pressure condition has been canceled (S34).

  Then, if it is determined that the engine warm-up high pressure condition is released (YES in step S34), the exhaust control valve control unit 120 closes the exhaust control valve 32 (S36), and returns the process to step S28. On the other hand, if it is determined that the engine warm-up high pressure condition is not released (NO in step S34), the exhaust control valve 32 is kept open until it is determined that the engine warm-up high pressure condition is released.

  On the other hand, when it is not determined that the engine warm-up high pressure condition is satisfied, that is, when the pressure P1 in the downstream side intake passage 18b is less than the high pressure set in advance (NO in step S30), the electric turbocharger control The unit 128 determines whether the engine warm-up termination condition is satisfied based on the temperature T3 (S38).

  Then, if it is determined that the engine warm-up termination condition is satisfied (YES in step S38), drive control unit 112 ends the engine warm-up. Then, the intake control valve control unit 118 opens the intake control valve 25, the exhaust control valve control unit 120 opens the exhaust control valve 32, and the EGR valve control unit 122 closes the EGR valve 35. In addition, the first flow passage switching valve control unit 124 controls the first flow passage switching valve 29 so that the air flows through the intercooler 23, and the second flow passage switching valve control unit 126 controls the air as an EGR cooler. The second flow path switching valve 37 is controlled to flow through 34 (S40).

  Then, the drive control unit 112 drives (starts) the engine 1 (S42), and ends the engine warm-up process at the time of starting the engine.

  When it is determined that the engine warm-up termination condition is not satisfied (NO in step S38), the electric turbocharger control unit 128 returns the process to step S28. During warm-up by the engine warm-up system 100 before starting the engine, it is difficult to accurately grasp the temperature of the combustion chamber 9 based on the temperature T1 indicating the temperature (cooling water temperature) in the engine 1 . Therefore, in the present embodiment, the temperature T3 in the intake manifold 17, that is, the temperature of the air supplied to the combustion chamber 9 is used to determine the end of the engine warm-up. Further, in consideration of the heat capacity of the combustion chamber 9, the elapsed time after the temperature T3 reaches the threshold value T is confirmed. Note that the end of engine warm-up may be determined based on the temperature T3 and the flow rate history (the integrated value of the air flow rate since the start of engine warm-up).

  If it is determined that the engine warm-up execution condition is not satisfied (NO in step S20), drive control unit 112 starts engine 1 without performing engine warm-up (S42). End machine processing. The fact that the engine warm-up execution condition is not established means that the engine 1 is not in the cold state. Therefore, since it is not necessary to warm the inside of the engine 1, the drive control unit 112 ends the engine warm-up processing at the time of starting the engine without performing the engine warm-up.

  With this configuration, the engine warm-up system 100 drives the electric supercharger 22 first when the engine 1 is driven in a cold state, and the heat insulation efficiency of the electric supercharger 22 is normally controlled (area A shown in FIG. ) Controls the opening degree of the EGR valve 35 so as to be in an area different from the time (area B shown in FIG. 4). As a result, the air compressed (supercharged) and warmed by the electric supercharger 22 can be circulated in the engine 1. Thus, by controlling the opening degree of the EGR valve 35, the engine 1 can be efficiently warmed up early.

  FIG. 7 is a view showing a modification of the present embodiment. Description of the configuration substantially equivalent to that of the above-described engine warm-up system 100 will be omitted. As shown in FIG. 7, the engine 1 is provided with an engine warm-up system 200. Specifically, the engine warm-up system 200 is newly configured to include the heater 202 and the control device 210.

  The heater 202 is provided upstream of the upstream catalyst 30 in the exhaust flow passage 20. The heater 202 warms the air (exhaust gas) flowing through the exhaust flow passage 20.

  The controller 210 newly functions as the heater controller 212 in addition to the functions of the controller 110 described above.

  The heater control unit 212 heats the heater 202. The heater control unit 212 heats the heater 202 after it is determined that the engine warm-up execution condition is satisfied. The air compressed and heated by the electric supercharger 22 is lowered in temperature by passing through the inside of the engine 1. Therefore, the temperature of the air flowing through the exhaust flow passage 20 is lower than that of the air passing through the downstream intake flow passage 18b. Therefore, the heater 202 is provided in the exhaust flow path 20, and the temperature of the air to be recirculated is raised by warming the circulating air. By raising the temperature of the recirculating air, the air is compressed to a higher temperature when it is again compressed by the electric supercharger 22. Thus, the engine 1 can be warmed up more effectively (more aggressively) and earlier by warming and circulating the air to be recirculated.

  Further, by providing the heater 202 upstream of the upstream catalyst 30 in the exhaust flow passage 20, the upstream catalyst 30 can be warmed. The upstream catalyst 30 can be activated earlier by warming the upstream catalyst 30.

  Although the preferred embodiments of the present invention have been described above with reference to the accompanying drawings, it goes without saying that the present invention is not limited to such embodiments. It is obvious that those skilled in the art can conceive of various changes or modifications within the scope of the claims, and it is naturally understood that they are also within the technical scope of the present invention. Be done.

  For example, although the case where the engine warm-up process is performed when the engine 1 is in the cold state has been described in the above embodiment, the engine warm-up process may be performed even when the engine 1 is not in the cold state.

  Further, in the above embodiment, the case where the first bypass flow passage 28 bypassing the intercooler 23 is provided in the downstream side intake flow passage 18 b has been described. However, the first bypass channel 28 is not an essential component.

  Further, in the above embodiment, the case where the second bypass flow passage 36 for bypassing the EGR cooler 34 is provided in the EGR flow passage 33 has been described. However, the second bypass passage 36 is not an essential component.

  Further, in the above-described embodiment, the case where the engine warm-up system 100, 200 is provided with the first bypass passage 28 and the second bypass passage 36 has been described. However, both the first bypass passage 28 and the second bypass passage 36 may not be provided. At least one of the first bypass channel 28 and the second bypass channel 36 may be provided.

  Further, in the above embodiment, the case where the engine warm-up system 100, 200 is provided with the first pressure sensor 50 and the second pressure sensor 52, and controls the opening degree of the EGR valve 35 based on the pressure ratio has been described. . However, instead of the first pressure sensor 50 and the second pressure sensor 52, a pressure may be derived using a dedicated pressure sensor to control the opening degree of the EGR valve 35. Alternatively, instead of the pressure sensor, the flow rate sensor may be used to derive the flow rate to control the opening degree of the EGR valve 35.

  Further, in the above embodiment, the case where the intake control valve control unit 118 once closes the intake control valve 25 during engine warm-up has been described until the engine warm-up process ends. However, during the engine warm-up process, the intake control valve control unit 118 may open the intake control valve 25 after closing it. When this process is performed, for example, the state of the outside air may change rapidly and the inside of the engine 1 may be cooled under the influence of the influence. In such a case, the intake control valve control unit 118 may open the intake control valve 25 again, and perform the engine warm-up process again from step S22 (see FIG. 6).

  In the above embodiment, when controlling the intake valve 12 and the exhaust valve 13 in the overlap state, the case where the engine 1 is stopped at a crank angle at which the intake valve 12 and the exhaust valve 13 overlap is described. However, for example, a variable valve timing system (VVT) may be used to move the intake valve 12 and the exhaust valve 13 to an overlap state when the engine 1 is stopped or after it is stopped. In that case, the engine warm-up termination condition is satisfied (step S38), and when performing control of each valve (step S40), the engine start switch of the intake valve 12 and the exhaust valve 13 is turned off Control to return to the valve opening according to the crank angle at the time of

  In the above embodiment, the exhaust control valve 32 is opened until the engine warm-up high pressure condition is released when the engine warm-up high pressure condition is satisfied (step S30) while the engine warm-up is being executed. However, the engine warm-up termination condition may be determined after the engine warm-up high pressure condition is established and until the engine warm-up high pressure condition is canceled. In this case, when it is determined that the engine warm-up termination condition is satisfied, the engine warm-up is terminated.

  The present invention is applicable to an engine warm-up system.

DESCRIPTION OF SYMBOLS 1 engine 10 intake port 11 exhaust port 12 intake valve 13 exhaust valve 18 intake flow path 20 exhaust flow path 22 electric supercharger 22a motor 25 intake control valve 30 upstream side catalyst (catalyst)
32 exhaust control valve 33 EGR passage 35 EGR valve 50 first pressure sensor (pressure sensor)
100 Engine warm-up system 114 intake / exhaust valve control unit 118 intake control valve control unit (valve control unit)
120 Exhaust control valve control unit (valve control unit)
122 EGR valve control unit (valve control unit)
128 Electric turbocharger control unit

Claims (6)

An intake flow path connected to the engine and through which intake air flows;
An electric supercharger provided in the middle of the intake flow path and compressing intake air by driving a motor;
An exhaust flow path connected to the engine and from which exhaust gas is discharged;
An EGR flow path for recirculating the exhaust gas discharged to the exhaust flow path upstream of the electric turbocharger in the intake flow path;
An exhaust control valve provided downstream of a branch position of the exhaust flow passage with the EGR flow passage and opening and closing the exhaust flow passage;
An EGR valve provided in the EGR passage for opening and closing the EGR passage;
An intake valve for opening and closing an intake port of the engine and a combustion chamber of the engine;
An exhaust valve for opening and closing an exhaust port of the engine and a combustion chamber of the engine;
An intake / exhaust valve control unit that performs opening control of the intake valve and the exhaust valve when the engine is stopped or is stopped;
An electric supercharger control unit configured to drive the electric supercharger when a predetermined engine warmup execution condition is satisfied at the time of stopping the engine;
A valve control unit that controls the exhaust control valve and the EGR valve;
Equipped with
The valve control unit
When the engine warm-up execution condition is satisfied, the exhaust control valve and the EGR valve are closed, and when a predetermined engine warm-up circulation condition is satisfied, the electric supercharger is driven in a predetermined drive region. Engine warm-up system that controls the EGR valve. An intake control valve provided on the upstream side of a joining position of the intake passage with the EGR passage and opening and closing the intake passage;
A pressure sensor that measures the pressure downstream of the electric turbocharger in the intake passage;
Equipped with
The valve control unit
The engine warm-up system according to claim 1, wherein when the engine warm-up circulation condition based on the pressure measured by the pressure sensor is established, control is performed to close the intake control valve. The valve control unit
The engine warm-up system according to claim 2, wherein after the engine warm-up execution condition is satisfied, control is performed to open the exhaust control valve when the pressure measured by the pressure sensor is equal to or higher than a predetermined pressure. A pressure sensor that measures a pressure downstream of the electric turbocharger in the intake passage;
The valve control unit
The engine warm-up system according to any one of claims 1 to 3, wherein the opening degree of the EGR valve is adjusted based on the pressure measured by the pressure sensor. A pressure sensor that measures a pressure downstream of the electric turbocharger in the intake passage;
The driving range is the pressure of the air circulated to the electric supercharger and the air compressed by the electric supercharger than the case where the electric supercharger is driven at the efficiency best point according to the intake flow rate The engine warm-up system according to any one of claims 1 to 4, which is a region in which the pressure ratio, which is the ratio of the pressure to the pressure, is high and the flow rate of the air flowing through the electric turbocharger is low. A pressure sensor that measures a pressure downstream of the electric turbocharger in the intake passage;
The valve control unit
The engine warm-up system according to any one of claims 1 to 5, wherein when the predetermined engine warm-up high-pressure condition based on the pressure measured by the pressure sensor is established, the exhaust control valve is controlled to open.

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