JP2010190046A - Exhaust heat recovery control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance engine output by utilizing an exhaust heat recovery device for an engine. <P>SOLUTION: When a target engine output is in a high output side area, an electric water pump 15 is controlled to increase the quantity of exhaust heat recovery of the exhaust heat recovery device 19. As the temperature of exhaust gas lowers and the volume flow rate of the exhaust gas lowers, and the exhaust gas pressure loss decreases and exhaustion efficiency improves accordingly, the engine output improves. When the target engine output is in a low output side area, the electric water pump 15 is controlled to decrease the quantity of exhaust heat recovery of the exhaust heat recovery device 19. Although the temperature of the exhaust gas rises and the volume flow rate of the exhaust gas rises, and the exhaust gas pressure loss increases and exhaustion efficiency lowers accordingly, as a combustion state can be improved by lowering the exhaust efficiency appropriately and increasing the inner EGR quantity (exhaust gas remaining quantity) of the engine 11 in the low output side area, it is possible to improve the engine output. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an exhaust heat recovery control device for an internal combustion engine that includes an exhaust heat recovery device that recovers exhaust heat by exchanging heat between exhaust gas and cooling water of the internal combustion engine.

  As described in Patent Document 1 (Japanese Patent Laid-Open No. 2008-190437), an exhaust heat recovery device is provided that recovers exhaust heat by exchanging heat between exhaust gas and cooling water of an internal combustion engine. Some exhaust heat recovered by an exhaust heat recovery device is used for early warm-up of an internal combustion engine. In the technique of this Patent Document 1, when the internal combustion engine is started and before the catalyst is warmed up, the flow rate of the cooling water circulated to the exhaust heat recovery device is set to a predetermined amount or less to reduce the exhaust heat recovery amount. Thus, warming up of the catalyst by exhaust heat is promoted.

JP 2008-190437 A (second page, etc.)

  However, the above conventional technology simply uses the exhaust heat recovery device for promoting warm-up of the internal combustion engine and the catalyst, so that the range of use of the exhaust heat recovery device is narrow and the merit of providing the exhaust heat recovery device (added value) )Less is.

  Therefore, the problem to be solved by the present invention is to provide an exhaust heat recovery control device for an internal combustion engine that can utilize the exhaust heat recovery device for output control of the internal combustion engine in addition to promoting warm-up of the internal combustion engine and the catalyst. It is to provide.

  When the amount of exhaust heat recovered by the exhaust heat recovery unit changes, the temperature of the exhaust gas changes and the volume flow rate of the exhaust gas changes, and the exhaust pressure loss in the catalyst, muffler (silencer), etc. changes accordingly and the exhaust gas changes. Efficiency changes. This means that the exhaust efficiency can be changed by changing the exhaust heat recovery amount of the exhaust heat recovery device.

  Focusing on such characteristics, the invention according to claim 1 is an exhaust gas of an internal combustion engine provided with an exhaust heat recovery device that recovers exhaust heat by exchanging heat between exhaust gas of the internal combustion engine and cooling water. In the heat recovery control device, the exhaust heat recovery amount adjusting means for adjusting the exhaust heat recovery amount by the exhaust heat recovery device and the output of the internal combustion engine or information related thereto (hereinafter referred to as “engine output information”) And an exhaust heat recovery control means for controlling the exhaust heat recovery amount adjusting means so as to change the exhaust heat recovery amount according to the above. In this configuration, since the exhaust heat recovery amount can be changed according to the engine output information, it becomes possible to appropriately change the exhaust efficiency according to the output of the internal combustion engine and improve the output of the internal combustion engine. In addition to promoting warm-up of internal combustion engines and catalysts, exhaust heat recovery devices can also be used to control the output of internal combustion engines, and the range of use of exhaust heat recovery devices can be expanded. Value added).

  Specifically, as in claim 2, when the engine output information is in a predetermined high output side region, the exhaust heat recovery amount adjusting means is controlled to increase the exhaust heat recovery amount, and the engine output information is predetermined. It is preferable to control the exhaust heat recovery amount adjusting means so as to reduce the exhaust heat recovery amount in the low output side region. In this way, when the engine output information is in the high output side region, increasing the exhaust heat recovery amount reduces the exhaust gas temperature and decreases the volume flow rate of the exhaust gas. Since the exhaust efficiency decreases and the exhaust efficiency increases, the output of the internal combustion engine can be improved (output can be generated efficiently).

  On the other hand, when the engine output information is in the low output region, the exhaust heat recovery amount is reduced, so that the exhaust gas temperature rises and the exhaust gas volume flow rate increases, and the exhaust pressure loss increases accordingly. Although the efficiency is reduced, in the low output side region, the internal combustion engine can be improved by increasing the internal EGR amount (exhaust gas residual amount) of the internal combustion engine by appropriately reducing the exhaust efficiency. Output can be improved (output can be generated efficiently).

  According to a third aspect of the present invention, at least one of the target output of the internal combustion engine, the target fuel injection amount, and the accelerator opening may be used as the engine output information. Since the target output of the internal combustion engine changes according to the accelerator opening, and the target fuel injection amount changes accordingly and the output of the internal combustion engine changes, the target output, the target fuel injection amount, and the accelerator opening are all The information reflects the output of the internal combustion engine.

  Alternatively, as in claim 4, at least one of the exhaust gas temperature, the exhaust gas volume flow rate, and the catalyst temperature of the internal combustion engine may be used as the engine output information. Since the exhaust gas temperature and the exhaust gas volume flow rate change according to the output of the internal combustion engine, and the catalyst temperature changes accordingly, the exhaust gas temperature, the exhaust gas volume flow rate, and the catalyst temperature all reflect the output of the internal combustion engine. Information.

  Further, in a system having an exhaust turbine supercharger (so-called turbocharger) that rotationally drives an exhaust turbine with kinetic energy of exhaust gas of an internal combustion engine to supercharge intake air, the exhaust heat When the amount of exhaust heat recovered by the recovery device changes, the temperature of the exhaust gas changes and the volume flow rate of the exhaust gas changes, and the rotational speed of the exhaust turbine changes accordingly and the actual supercharging pressure changes. This means that the actual supercharging pressure can be changed by changing the exhaust heat recovery amount of the exhaust heat recovery device.

  By paying attention to such characteristics, an exhaust heat recovery device that recovers exhaust heat by exchanging heat between the exhaust gas of the internal combustion engine and the cooling water, and an exhaust gas of the internal combustion engine as in claim 5 In an exhaust heat recovery control device for an internal combustion engine having an exhaust turbine supercharger that rotationally drives an exhaust turbine to supercharge intake air by rotating the compressor, the amount of exhaust heat recovered by the exhaust heat recovery device is reduced. An exhaust heat recovery amount adjusting means for adjusting, and an exhaust heat recovery control means for controlling the exhaust heat recovery amount adjustment means so as to change the exhaust heat recovery amount in accordance with the target boost pressure and the actual boost pressure of the internal combustion engine. It is good also as a structure provided. In this configuration, since the exhaust heat recovery amount can be changed according to the target boost pressure and the actual boost pressure, the actual boost pressure is changed according to the relationship between the target boost pressure and the actual boost pressure. Thus, the actual boost pressure can be quickly controlled to the target boost pressure, and the controllability of the output of the internal combustion engine can be improved.

  Specifically, as in claim 6, when the actual supercharging pressure is lower than the target supercharging pressure, the exhaust heat recovery amount adjusting means is controlled so as to decrease the exhaust heat recovery amount, and the actual supercharging pressure is reduced. The exhaust heat recovery amount adjusting means may be controlled so as to increase the exhaust heat recovery amount when it is higher than the target boost pressure. In this way, when the actual supercharging pressure is lower than the target supercharging pressure, the exhaust heat recovery amount is decreased to increase the exhaust gas temperature and increase the volume flow rate of the exhaust gas. Since the rotational speed of the turbine is increased and the actual supercharging pressure is increased, the actual supercharging pressure can be quickly raised to the target supercharging pressure.

  On the other hand, when the actual supercharging pressure is higher than the target supercharging pressure, increasing the exhaust heat recovery amount reduces the exhaust gas temperature and decreases the volume flow rate of the exhaust gas, and accordingly the rotational speed of the exhaust turbine. Decreases and the actual supercharging pressure decreases, so that the actual supercharging pressure can be quickly lowered to the target supercharging pressure.

  Further, as in claim 7, when the target output of the internal combustion engine is less than a predetermined value, the control of the exhaust heat recovery amount according to the target boost pressure and the actual boost pressure is stopped, and the exhaust heat according to other requirements. You may make it perform control of collection | recovery amount. In this way, when the target output of the internal combustion engine is less than or equal to the predetermined value, it is determined that the exhaust turbine supercharger does not function sufficiently because the kinetic energy of the exhaust gas is small. The control of the exhaust heat recovery amount according to the supply pressure is stopped, and the exhaust heat recovery amount control according to other requirements (for example, control of the exhaust heat recovery amount according to the target output of the internal combustion engine) is performed. it can.

  An exhaust heat recovery control device for an internal combustion engine comprising an exhaust heat recovery device for recovering exhaust heat by exchanging heat between exhaust gas and cooling water of an internal combustion engine mounted on a vehicle as in claim 8 The exhaust heat recovery amount adjusting means for adjusting the exhaust heat recovery amount by the exhaust heat recovery device, the operation means operated by the driver of the vehicle, and the exhaust heat recovery amount is changed according to the operating state of the operation means. The exhaust heat recovery control means for controlling the exhaust heat recovery amount adjustment means may be provided. In this way, the exhaust efficiency can be appropriately changed by changing the exhaust heat recovery amount according to the operation of the driver.

  Further, as in the ninth aspect, as the exhaust heat recovery amount adjusting means, means for adjusting the flow rate of the cooling water circulated in the exhaust heat recovery device may be used. In this way, the exhaust heat recovery amount by the exhaust heat recovery device can be adjusted by adjusting the flow rate of the cooling water circulated to the exhaust heat recovery device by the exhaust heat recovery amount adjustment means (for example, an electric water pump or a flow rate adjustment valve). Can be adjusted.

  The exhaust heat recovery amount adjusting means is not limited to means for adjusting the flow rate of the cooling water to be circulated through the exhaust heat recovery device. For example, the heat exchange medium for exchanging heat between the exhaust gas and the cooling water. In the case of an exhaust heat recovery device provided with an on-off valve in the heat exchange medium circulation path enclosing the heat exchanger, the on-off valve is used as an exhaust heat recovery amount adjusting means, and the circulation amount of the heat exchange medium is adjusted by the on-off valve. The exhaust heat recovery amount by the exhaust heat recovery device may be adjusted.

FIG. 1 is a schematic configuration diagram of the entire engine cooling system in Embodiment 1 of the present invention. FIG. 2 is a block diagram illustrating exhaust heat recovery control according to the first embodiment. FIG. 3 is a flowchart for explaining the processing flow of the exhaust heat recovery control routine of the first embodiment. FIG. 4 is a time chart for explaining an execution example of the exhaust heat recovery control of the first embodiment. FIG. 5 is a block diagram illustrating exhaust heat recovery control according to the second embodiment. FIG. 6 is a flowchart for explaining the processing flow of the exhaust heat recovery control routine of the second embodiment. FIG. 7 is a time chart for explaining an execution example of the exhaust heat recovery control of the second embodiment. FIG. 8 is a schematic configuration diagram of the entire engine cooling system of the third embodiment. FIG. 9 is a block diagram illustrating the exhaust heat recovery control of the third embodiment. FIG. 10 is a flowchart for explaining the processing flow of the exhaust heat recovery control routine of the third embodiment. FIG. 11 is a time chart for explaining an execution example of the exhaust heat recovery control of the third embodiment. FIG. 12 is a schematic configuration diagram of an entire engine cooling system according to another embodiment.

  Hereinafter, some embodiments embodying the mode for carrying out the present invention will be described.

A first embodiment of the present invention will be described with reference to FIGS.
First, a schematic configuration of the entire engine cooling system will be described with reference to FIG.
A cooling water circulation passage 12 through which cooling water circulates is connected between an outlet and an inlet of a water jacket (cooling water passage) of an engine 11 that is an internal combustion engine. A radiator 13 is provided in the middle of the cooling water circulation passage 12. Is provided. A bypass flow path 14 that bypasses the radiator 13 is connected between the outlet of the water jacket of the engine 11 and the downstream side of the radiator 13 in the cooling water circulation flow path 12. Further, an electric water pump 15 for circulating the cooling water is provided in the middle of the cooling water circulation passage 12 (for example, downstream of the connection portion with the bypass passage 14).

  Further, a thermostat 16 that opens and closes according to the cooling water temperature is provided in the middle of the cooling water circulation channel 12 (for example, a connection portion with the bypass channel 14), and the cooling water temperature corresponds to a predetermined temperature (for example, completion of warm-up). In the non-warm-up water temperature region lower than (temperature), the thermostat 16 is closed and the circulation of the cooling water between the engine 11 and the radiator 13 is stopped. As a result, the cooling water temperature on the engine 11 side is quickly raised to promote warm-up of the engine 11. Thereafter, when the cooling water temperature becomes equal to or higher than the predetermined temperature, the thermostat 16 is opened to circulate the cooling water between the engine 11 and the radiator 13, and the cooling water temperature is appropriately warmed up by the heat radiation action of the radiator 13. The engine 11 is prevented from being overheated by adjusting it within the temperature range.

  On the other hand, the exhaust pipe 17 of the engine 11 is provided with a catalyst 18 such as a three-way catalyst for purifying exhaust gas, and an exhaust heat recovery device 19 is provided upstream (or downstream) of the catalyst 18. . The exhaust heat recovery device 19 is connected to the middle of the cooling water circulation passage 12 (for example, downstream of the electric water pump 15), and the exhaust gas flowing in the exhaust pipe 17 and the cooling water flowing in the cooling water circulation passage 12 are connected. Exhaust heat is recovered by exchanging heat with each other. Further, the amount of exhaust heat recovered by the exhaust heat recovery unit 19 is adjusted by adjusting the flow rate of the cooling water circulated to the exhaust heat recovery unit 19 by the electric water pump 15. In this case, the electric water pump 15 serves as exhaust heat recovery amount adjusting means.

  A crank angle sensor 20 that outputs a pulse signal every time the crankshaft rotates a predetermined crank angle is attached to the cylinder block of the engine 11, and the crank angle and the engine rotation speed are detected based on the output signal of the crank angle sensor 20. Is done. The air flow meter 21 detects the intake air amount, and the accelerator sensor 22 detects the accelerator opening (the amount of depression of the accelerator pedal).

  Outputs of these various sensors are input to an engine control circuit (hereinafter referred to as “ECU”) 23. The ECU 23 is mainly composed of a microcomputer, and executes various engine control programs stored in a built-in ROM (storage medium) to thereby control the fuel injection valve (not shown) according to the engine operating state. The fuel injection amount and the ignition timing of a spark plug (not shown) are controlled.

  Here, when the amount of exhaust heat recovery by the exhaust heat recovery unit 19 changes, the temperature of the exhaust gas changes and the volume flow rate of the exhaust gas changes, and the exhaust pressure loss in the catalyst 18, muffler (silencer) and the like accordingly. Changes and exhaust efficiency changes. This means that the exhaust efficiency can be changed by changing the exhaust heat recovery amount of the exhaust heat recovery unit 19.

  Focusing on such characteristics, in the first embodiment, the ECU 23 executes an exhaust heat recovery control routine of FIG. 3 to be described later, whereby the exhaust heat recovery amount of the exhaust heat recovery unit 19 is set according to the target engine output. Exhaust heat recovery control for controlling the electric water pump 15 so as to be changed is executed.

  Specifically, as shown in FIG. 2, the target exhaust heat recovery amount Qr corresponding to the target engine output Per is calculated with reference to the map of the target exhaust heat recovery amount Qr. This map of the target exhaust heat recovery amount Qr is set so that, for example, when the target engine output Per is in a region on the higher output side than a predetermined value, the target exhaust heat recovery amount Qr increases as the target engine output Per increases. When the target engine output Per is in a region on the output side lower than the predetermined value, the target exhaust heat recovery amount Qr is set to decrease as the target engine output Per decreases. Further, the upper limit value of the target exhaust heat recovery amount Qr is set to the allowable maximum exhaust heat recovery amount of the exhaust heat recovery device 19 or a value smaller than that by the margin.

  Thereafter, referring to the map of the target coolant flow rate Vw, the target coolant flow rate Vw corresponding to the target exhaust heat recovery amount Qr is calculated, and the electric water pump 15 is controlled according to the target coolant flow rate Vw. The exhaust heat recovery amount of the exhaust heat recovery device 19 is adjusted to the target exhaust heat recovery amount Qr by adjusting the flow rate of the cooling water circulated through the exhaust heat recovery device 19 to the target cooling water flow rate Vw.

  By this exhaust heat recovery control, when the target engine output is in the high output region, the electric water pump 15 is controlled so as to increase the exhaust heat recovery amount of the exhaust heat recovery unit 19. If the exhaust heat recovery amount of the exhaust heat recovery unit 19 is increased, the exhaust gas temperature is decreased and the volume flow rate of the exhaust gas is decreased. Accordingly, the exhaust pressure loss is decreased and the exhaust efficiency is increased. improves.

  On the other hand, when the target engine output is in the low output region, the electric water pump 15 is controlled so as to reduce the exhaust heat recovery amount of the exhaust heat recovery device 19. When the exhaust heat recovery amount of the exhaust heat recovery device 19 is decreased, the exhaust gas temperature rises and the volume flow rate of the exhaust gas increases, the exhaust pressure loss increases accordingly, and the exhaust efficiency decreases, but the low output side In this region, it is possible to improve the combustion state by increasing the internal EGR amount (exhaust gas residual amount) of the engine 11 by appropriately reducing the exhaust efficiency, so that the engine output is improved.

The exhaust heat recovery control of the first embodiment described above is executed by the ECU 23 according to the exhaust heat recovery control routine of FIG. The processing contents of this routine will be described below.
The exhaust heat recovery control routine shown in FIG. 3 is repeatedly executed at a predetermined cycle while the ECU 23 is turned on, and serves as exhaust heat recovery control means in the claims. When this routine is started, first, in step 101, various information such as the accelerator opening, the intake air amount, and the engine rotational speed is read, and then the process proceeds to step 102 where the accelerator opening, the intake air amount, and the engine rotational speed are read. The target engine output Per is calculated by a map or a mathematical formula based on various information such as.

  Thereafter, the routine proceeds to step 103, where the target exhaust heat recovery amount Qr corresponding to the target engine output Per is calculated with reference to the map of the target exhaust heat recovery amount Qr. Here, the map (see FIG. 2) of the target exhaust heat recovery amount Qr is, for example, when the target engine output Per is in a region on the higher output side than a predetermined value, the target exhaust heat recovery amount Qr becomes higher as the target engine output Per becomes higher. When the target engine output Per is in a region where the target engine output Per is lower than the predetermined value, the target exhaust heat recovery amount Qr is set to decrease as the target engine output Per decreases.

  Thereafter, the process proceeds to step 104, the target coolant flow rate Vw corresponding to the target exhaust heat recovery amount Qr is calculated with reference to the map of the target coolant flow rate Vw, and then the process proceeds to step 105, where the target coolant flow rate Vw is set. Accordingly, the electric water pump 15 is controlled to adjust the flow rate of the cooling water circulated to the exhaust heat recovery unit 19 to the target cooling water flow rate Vw, so that the exhaust heat recovery amount of the exhaust heat recovery unit 19 is set to the target exhaust heat recovery rate. Adjust to quantity Qr.

  An execution example of the exhaust heat recovery of the first embodiment described above will be described with reference to the time chart of FIG. During the period A in which the target engine output is in the high output side region, the electric water pump 15 is controlled so as to increase the flow rate of the cooling water circulated to the exhaust heat recovery device 19, and the exhaust heat recovery of the exhaust heat recovery device 19. Increase the amount. As a result, the exhaust gas temperature decreases, the exhaust gas volume flow rate decreases, the exhaust pressure loss decreases accordingly, and the exhaust efficiency increases, thereby improving the engine output (generating the output efficiently). it can.

  On the other hand, during the period B in which the target engine output is in the low output side region, the electric water pump 15 is controlled so as to decrease the flow rate of the cooling water circulated to the exhaust heat recovery unit 19, Reduce heat recovery. As a result, the exhaust gas temperature rises and the volume flow rate of the exhaust gas increases, and accordingly, the exhaust pressure loss increases and the exhaust efficiency decreases.However, in the low output region, the exhaust efficiency should be lowered moderately. Thus, since the combustion state can be improved by increasing the internal EGR amount (exhaust gas residual amount) of the engine 11, the engine output can be improved (the output can be generated efficiently).

  Next, a second embodiment of the present invention will be described with reference to FIGS. However, description of substantially the same parts as those in the first embodiment will be omitted or simplified, and different parts from the first embodiment will be mainly described.

  In the first embodiment, the electric water pump 15 is controlled so as to change the exhaust heat recovery amount of the exhaust heat recovery unit 19 according to the target engine output, but the exhaust gas temperature and the exhaust gas volume flow rate are changed according to the engine output. Therefore, both the exhaust gas temperature and the exhaust gas volume flow rate are information reflecting the engine output.

  Thus, in the second embodiment, the exhaust heat recovery control routine of FIG. 6 described later is executed by the ECU 23, so that the exhaust heat recovery amount of the exhaust heat recovery unit 19 according to the exhaust gas temperature of the engine 11 and the exhaust gas volume flow rate. Exhaust heat recovery control is performed to control the electric water pump 15 so as to change the value.

  Specifically, as shown in FIG. 5, the target exhaust heat recovery amount Qr corresponding to the exhaust gas temperature Tg and the exhaust gas volume flow rate Vg is calculated with reference to the map of the target exhaust heat recovery amount Qr. The map of the target exhaust heat recovery amount Qr is, for example, a region where the exhaust gas temperature Tg and the exhaust gas volume flow rate Vg are higher than the predetermined line (the exhaust gas temperature Tg is higher than the predetermined line and the exhaust gas volume flow rate Vg. Is set such that the target exhaust heat recovery amount Qr increases as the exhaust gas temperature Tg increases and the exhaust gas volume flow rate Vg increases, so that the exhaust gas temperature Tg and the exhaust gas volume flow rate are increased. When Vg is a region on the lower output side than the predetermined line (region where the exhaust gas temperature Tg is lower than the predetermined line and the exhaust gas volume flow rate Vg is smaller than the predetermined line), the exhaust gas temperature Tg becomes lower and the exhaust gas volume. The target exhaust heat recovery amount Qr is set to decrease as the flow rate Vg decreases. Further, the upper limit value of the target exhaust heat recovery amount Qr is set to the allowable maximum exhaust heat recovery amount of the exhaust heat recovery device 19 or a value smaller than that by the margin.

  Thereafter, referring to the map of the target coolant flow rate Vw, the target coolant flow rate Vw corresponding to the target exhaust heat recovery amount Qr is calculated, and the electric water pump 15 is controlled according to the target coolant flow rate Vw. The amount of exhaust heat recovered by the exhaust heat recovery device 19 is adjusted to the target exhaust heat recovery amount Qr by adjusting the flow rate of the cooling water circulated through the exhaust heat recovery device 19 to the target cooling water flow rate Vw.

  By this exhaust heat recovery control, when the exhaust gas temperature and the exhaust gas volume flow rate are in the high output region, the electric water pump 15 is controlled to increase the exhaust heat recovery amount of the exhaust heat recovery unit 19, while When the gas temperature and the exhaust gas volume flow rate are in the low output region, the electric water pump 15 is controlled so as to reduce the exhaust heat recovery amount of the exhaust heat recovery device 19.

  Hereinafter, the processing contents of the exhaust heat recovery control routine of FIG. 6 executed by the ECU 23 in the second embodiment will be described. In this routine, first, in step 201, various information such as the intake air amount, the engine rotational speed, the intake air temperature, etc. are read, and then the process proceeds to step 202, on the basis of various information such as the intake air amount, the engine rotational speed, the intake air temperature. Then, the exhaust gas temperature Tg and the exhaust gas volume flow rate Vg are respectively calculated (estimated) by a map or a mathematical expression. The exhaust gas temperature Tg and the exhaust gas volume flow rate Vg may be detected by a sensor.

  Thereafter, the routine proceeds to step 203, where the target exhaust heat recovery amount Qr corresponding to the exhaust gas temperature Tg and the exhaust gas volume flow rate Vg is calculated with reference to the map of the target exhaust heat recovery amount Qr. Here, the map of the target exhaust heat recovery amount Qr (see FIG. 5) shows that the exhaust gas temperature Tg increases as the exhaust gas temperature Tg and the exhaust gas volume flow rate Vg are higher than the predetermined line, for example. The target exhaust heat recovery amount Qr is set so as to increase as the exhaust gas volume flow rate Vg increases. When the exhaust gas temperature Tg and the exhaust gas volume flow rate Vg are lower than the predetermined line, the exhaust gas temperature Tg is set. Is set so that the target exhaust heat recovery amount Qr decreases as the exhaust gas volume flow rate Vg decreases.

  Thereafter, referring to the map of the target coolant flow rate Vw, the target coolant flow rate Vw corresponding to the target exhaust heat recovery amount Qr is calculated, and the electric water pump 15 is controlled according to the target coolant flow rate Vw. The exhaust heat recovery amount of the exhaust heat recovery device 19 is adjusted to the target exhaust heat recovery amount Qr by adjusting the flow rate of the cooling water circulated to the exhaust heat recovery device 19 to the target cooling water flow rate Vw (steps 204 and 205). ).

  In the second embodiment described above, for example, as shown in the time chart of FIG. 7, the exhaust gas temperature Tg and the exhaust gas volume flow rate Vg are circulated to the exhaust heat recovery device 19 during the period A in which the exhaust gas temperature Tg and the exhaust gas volume flow rate Vg are in the high output region. The electric water pump 15 is controlled to increase the flow rate of the cooling water to be increased, and the exhaust heat recovery amount of the exhaust heat recovery unit 19 is increased. As a result, the exhaust gas temperature decreases and the volume flow rate of the exhaust gas decreases, the exhaust pressure loss decreases accordingly, and the exhaust efficiency increases, so that the engine output can be improved.

  On the other hand, during the period B in which the exhaust gas temperature Tg and the exhaust gas volume flow rate Vg are in the low output side region, the electric water pump 15 is controlled so as to decrease the flow rate of the cooling water circulated to the exhaust heat recovery device 19, The exhaust heat recovery amount of the exhaust heat recovery unit 19 is reduced. As a result, the exhaust gas temperature rises and the volume flow rate of the exhaust gas increases, and accordingly, the exhaust pressure loss increases and the exhaust efficiency decreases.However, in the low output region, the exhaust efficiency should be lowered moderately. Since the internal EGR amount (exhaust gas residual amount) of the engine 11 can be increased and the combustion state can be improved, the engine output can be improved.

  Next, Embodiment 3 of the present invention will be described with reference to FIGS. However, description of substantially the same parts as those in the first embodiment will be omitted or simplified, and different parts from the first embodiment will be mainly described.

  In the third embodiment, as shown in FIG. 8, an exhaust turbine supercharger 24 is provided on the downstream side of the exhaust heat recovery device 19 in the exhaust pipe 17 of the engine 11. The exhaust turbine supercharger 24 supercharges intake air by rotationally driving the compressor by rotationally driving the exhaust turbine with the kinetic energy of the exhaust gas. Further, a supercharging pressure sensor 25 that detects an actual supercharging pressure (for example, an actual intake pressure upstream of the throttle valve) is provided in an intake pipe (not shown) of the engine 11.

  In the system provided with the exhaust turbine supercharger 24, when the exhaust heat recovery amount by the exhaust heat recovery device 19 changes, the temperature of the exhaust gas changes and the volume flow rate of the exhaust gas changes, and the exhaust turbine's flow rate changes accordingly. The rotational speed changes and the actual supercharging pressure changes. That is, the actual supercharging pressure can be changed by changing the exhaust heat recovery amount of the exhaust heat recovery unit 19.

  Focusing on such characteristics, in the third embodiment, the exhaust heat recovery control routine of FIG. 10 described later is executed by the ECU 23, whereby the exhaust heat according to the target boost pressure and the actual boost pressure of the engine 11 is executed. Exhaust heat recovery control for controlling the electric water pump 15 so as to change the recovery amount is executed.

  Specifically, as shown in FIG. 9, the target corresponding to the difference ΔP (= Ptg−Ptc) between the target boost pressure Ptg and the actual boost pressure Ptc is referred to with reference to the map of the target exhaust heat recovery amount Qr. The exhaust heat recovery amount Qr is calculated. The map of the target exhaust heat recovery amount Qr is, for example, a region where the difference ΔP between the target boost pressure Ptg and the actual boost pressure Ptc is a value greater than 0 (plus value), that is, the actual boost pressure Ptc is the target boost pressure. In a region lower than the supply pressure Ptg, the target exhaust heat recovery amount Qr is set to decrease as the difference ΔP between the target boost pressure Ptg and the actual boost pressure Ptc increases, and the target boost pressure Ptg In a region where the difference ΔP from the supply pressure Ptc is a value smaller than 0 (negative value), that is, in a region where the actual boost pressure Ptc is higher than the target boost pressure Ptg, the target boost pressure Ptg and the actual boost pressure Ptc. Is set so that the target exhaust heat recovery amount Qr increases as the difference ΔP decreases with (that is, as the absolute value of the difference ΔP increases). Further, the upper limit value of the target exhaust heat recovery amount Qr is set to the allowable maximum exhaust heat recovery amount of the exhaust heat recovery device 19 or a value smaller than that by the margin.

  Thereafter, referring to the map of the target coolant flow rate Vw, the target coolant flow rate Vw corresponding to the target exhaust heat recovery amount Qr is calculated, and the electric water pump 15 is controlled according to the target coolant flow rate Vw. The amount of exhaust heat recovered by the exhaust heat recovery device 19 is adjusted to the target exhaust heat recovery amount Qr by adjusting the flow rate of the cooling water circulated through the exhaust heat recovery device 19 to the target cooling water flow rate Vw.

  By this exhaust heat recovery control, when the actual supercharging pressure is lower than the target supercharging pressure, the electric water pump 15 is controlled so as to reduce the exhaust heat recovery amount of the exhaust heat recovery device 19. When the exhaust heat recovery amount of the exhaust heat recovery device 19 is decreased, the exhaust gas temperature increases and the volume flow rate of the exhaust gas increases, and the rotational speed of the exhaust turbine increases accordingly and the actual supercharging pressure increases. Therefore, the actual supercharging pressure quickly increases to the target supercharging pressure.

  On the other hand, when the actual supercharging pressure is higher than the target supercharging pressure, the electric water pump 15 is controlled to increase the exhaust heat recovery amount of the exhaust heat recovery device 19. When the exhaust heat recovery amount of the exhaust heat recovery unit 19 is increased, the exhaust gas temperature is decreased and the volume flow rate of the exhaust gas is decreased, and the rotational speed of the exhaust turbine is accordingly decreased and the actual supercharging pressure is decreased. Therefore, the actual supercharging pressure quickly decreases to the target supercharging pressure.

  When the target engine output is less than or equal to a predetermined value, the exhaust gas kinetic energy is small, so it is determined that the exhaust turbine supercharger 24 does not function sufficiently, and the target supercharging pressure and the actual supercharging pressure are determined. The control of the exhaust heat recovery amount is stopped, and the exhaust heat recovery amount is controlled according to other requirements (for example, control of the exhaust heat recovery amount according to the target engine output).

  Hereinafter, the processing contents of the exhaust heat recovery control routine of FIG. 10 executed by the ECU 23 in the third embodiment will be described. In this routine, first, in step 301, various information such as the accelerator opening, the intake air amount, and the engine rotational speed is read, and then the process proceeds to step 302, where various information such as the accelerator opening, the intake air amount, and the engine rotational speed are obtained. Based on the above, the target engine output Per is calculated by a map or a mathematical expression.

  Thereafter, the process proceeds to step 303, where it is determined whether or not the target engine output Per is higher than a predetermined value, and when it is determined that the target engine output Per is higher than the predetermined value, the kinetic energy of the exhaust gas is large. Therefore, it is determined that the exhaust turbine supercharger 24 functions, and the control of the exhaust heat recovery amount according to the target supercharging pressure and the actual supercharging pressure is executed as follows.

  First, the process proceeds to step 304, where the target boost pressure Ptg is calculated based on the target engine output Per or the like by using a map or a mathematical formula. Then, the process proceeds to step 305 and the target excess heat recovery amount Qr is referred to by referring to the target exhaust heat recovery amount Qr. A target exhaust heat recovery amount Qr corresponding to a difference ΔP (= Ptg−Ptc) between the supply pressure Ptg and the actual supercharging pressure Ptc is calculated. Here, the map of the target exhaust heat recovery amount Qr (see FIG. 9) is, for example, a region where the difference ΔP between the target boost pressure Ptg and the actual boost pressure Ptc is a positive value (that is, the actual boost pressure Ptc is the target). In a region lower than the supercharging pressure Ptg), the target exhaust heat recovery amount Qr is set to decrease as the difference ΔP between the target supercharging pressure Ptg and the actual supercharging pressure Ptc increases, and the target supercharging pressure Ptg In a region where the difference ΔP from the actual boost pressure Ptc is a negative value (that is, a region where the actual boost pressure Ptc is higher than the target boost pressure Ptg), the difference between the target boost pressure Ptg and the actual boost pressure Ptc The target exhaust heat recovery amount Qr is set to increase as ΔP decreases (that is, as the absolute value of the difference ΔP increases).

  Thereafter, referring to the map of the target coolant flow rate Vw, the target coolant flow rate Vw corresponding to the target exhaust heat recovery amount Qr is calculated, and the electric water pump 15 is controlled according to the target coolant flow rate Vw. The exhaust heat recovery amount by the exhaust heat recovery device 19 is adjusted to the target exhaust heat recovery amount Qr by adjusting the flow rate of the cooling water circulated to the exhaust heat recovery device 19 to the target cooling water flow rate Vw (steps 307 and 308). ).

  On the other hand, if it is determined in step 303 that the target engine output Per is less than or equal to the predetermined value, it is determined that the exhaust turbine supercharger 24 does not function sufficiently because the kinetic energy of the exhaust gas is small. , Stop the control of the exhaust heat recovery amount according to the target boost pressure and the actual boost pressure, and control the exhaust heat recovery amount according to other requirements (for example, control of the exhaust heat recovery amount according to the target engine output) ) Is executed as follows.

  First, in step 306, the target exhaust heat recovery amount Qr corresponding to the target engine output Per is calculated with reference to the map of the target exhaust heat recovery amount Qr. Thereafter, referring to the map of the target coolant flow rate Vw, the target coolant flow rate Vw corresponding to the target exhaust heat recovery amount Qr is calculated, and the electric water pump 15 is controlled according to the target coolant flow rate Vw. The exhaust heat recovery amount by the exhaust heat recovery device 19 is adjusted to the target exhaust heat recovery amount Qr by adjusting the flow rate of the cooling water circulated to the exhaust heat recovery device 19 to the target cooling water flow rate Vw (steps 307 and 308). ).

  In the third embodiment described above, for example, as shown in the time chart of FIG. 11, during the period A in which the actual supercharging pressure is lower than the target supercharging pressure, the flow rate of the cooling water circulated to the exhaust heat recovery device 19 is set. The electric water pump 15 is controlled so as to decrease the exhaust heat recovery amount of the exhaust heat recovery unit 19. As a result, the exhaust gas temperature rises and the volume flow rate of the exhaust gas increases, and the rotational speed of the exhaust turbine rises accordingly and the actual supercharging pressure rises. The pressure can be increased.

  On the other hand, during the period B in which the actual supercharging pressure is higher than the target supercharging pressure, the electric water pump 15 is controlled so as to increase the flow rate of the cooling water circulated to the exhaust heat recovery device 19. Increase exhaust heat recovery. As a result, the exhaust gas temperature decreases and the exhaust gas volume flow rate decreases, and the rotational speed of the exhaust turbine decreases accordingly and the actual supercharging pressure decreases. Can be reduced to pressure.

  In the first embodiment, the electric water pump 15 is controlled to change the exhaust heat recovery amount of the exhaust heat recovery unit 19 according to the target engine output. However, the target engine output changes according to the accelerator opening. Since the target fuel injection amount changes accordingly and the engine output changes, the accelerator opening and the target fuel injection amount are also information reflecting the engine output. Therefore, the electric water pump 15 is controlled so as to change the exhaust heat recovery amount of the exhaust heat recovery device 19 according to the accelerator opening, or the exhaust heat of the exhaust heat recovery device 19 according to the target fuel injection amount. The electric water pump 15 may be controlled so as to change the recovery amount.

  In the second embodiment, the electric water pump 15 is controlled so as to change the exhaust heat recovery amount of the exhaust heat recovery unit 19 according to the exhaust gas temperature and the exhaust gas volume flow rate, but the exhaust gas is controlled according to the engine output. Since the temperature and the exhaust gas volume flow rate change and the catalyst temperature changes accordingly, the catalyst temperature also becomes information reflecting the engine output. Therefore, the electric water pump 15 may be controlled so as to change the exhaust heat recovery amount of the exhaust heat recovery device 19 according to the catalyst temperature.

  In addition, electric power is used to change the exhaust heat recovery amount of the exhaust heat recovery device 19 according to various information related to the engine output (for example, throttle opening, intake air amount, ignition timing, engine rotation speed, etc.). The water pump 15 may be controlled.

  Further, an exhaust heat recovery operation switch (operation means) operated by a driver of the vehicle equipped with the engine 11 is provided, and the exhaust heat recovery amount of the exhaust heat recovery unit 19 is set according to the operation state of the exhaust heat recovery operation switch. The electric water pump 15 is controlled so as to change, or the electric water recovery amount of the exhaust heat recovery unit 19 is changed according to the operation position of the shift lever (operation means) of the transmission. The pump 15 may be controlled. In this way, the exhaust efficiency can be appropriately changed by changing the exhaust heat recovery amount according to the operation of the driver.

  In the first to third embodiments, the exhaust heat recovery amount by the exhaust heat recovery device 19 is adjusted by adjusting the flow rate of the cooling water circulated to the exhaust heat recovery device 19 by the electric water pump 15. However, the method of adjusting the exhaust heat recovery amount by the exhaust heat recovery device 19 may be changed as appropriate.

  For example, as shown in FIG. 12, a bypass flow path 26 that bypasses the exhaust heat recovery device 19 is connected between the upstream side and the downstream side of the exhaust heat recovery device 19 in the cooling water circulation flow channel 12, A flow rate adjusting valve 27 is provided at a branch (or junction) between the cooling water circulation channel 12 and the bypass channel 26. The flow rate adjusting valve 27 is configured by an electromagnetically driven valve that can adjust a flow rate ratio between the flow rate of the cooling water flowing through the exhaust heat recovery unit 19 and the flow rate of the cooling water flowing through the bypass passage 26. The amount of exhaust heat recovered by the exhaust heat recovery device 19 may be adjusted by adjusting the flow rate of the cooling water circulated through the exhaust heat recovery device 19. In this case, the flow rate adjusting valve 27 serves as exhaust heat recovery amount adjusting means.

  Further, the exhaust heat recovery amount adjusting means is not limited to means for adjusting the flow rate of the cooling water to be circulated through the exhaust heat recovery device. For example, the heat exchange medium for exchanging heat between the exhaust gas and the cooling water. In the case of an exhaust heat recovery device provided with an on-off valve in the heat exchange medium circulation path enclosing the heat exchanger, the on-off valve is used as an exhaust heat recovery amount adjusting means, and the circulation amount of the heat exchange medium is adjusted by the on-off valve. The exhaust heat recovery amount by the exhaust heat recovery device may be adjusted.

  In addition, the present invention can be implemented with various changes without departing from the gist, such as appropriately changing the configuration of the engine cooling system.

  DESCRIPTION OF SYMBOLS 11 ... Engine (internal combustion engine), 12 ... Cooling water circulation flow path, 13 ... Radiator, 15 ... Electric water pump (exhaust heat recovery amount adjusting means), 16 ... Thermostat, 17 ... Exhaust pipe, 19 ... Exhaust heat recovery device, 23 ... ECU (exhaust heat recovery control means), 24 ... exhaust turbine supercharger, 27 ... flow rate adjustment valve (exhaust heat recovery amount adjustment means)

Claims (9)

In an exhaust heat recovery control device for an internal combustion engine equipped with an exhaust heat recovery device that recovers exhaust heat by exchanging heat between exhaust gas and cooling water of the internal combustion engine,
Exhaust heat recovery amount adjusting means for adjusting the exhaust heat recovery amount by the exhaust heat recovery device;
Exhaust heat for controlling the exhaust heat recovery amount adjusting means so as to change the exhaust heat recovery amount in accordance with the output of the internal combustion engine or information related thereto (hereinafter collectively referred to as “engine output information”) An exhaust heat recovery control device for an internal combustion engine, comprising: a recovery control means.   The exhaust heat recovery control means controls the exhaust heat recovery amount adjusting means so as to increase the exhaust heat recovery amount when the engine output information is in a predetermined high output side region, and the engine output information is predetermined. 2. The exhaust heat recovery control for an internal combustion engine according to claim 1, further comprising means for controlling the exhaust heat recovery amount adjusting means so as to reduce the exhaust heat recovery amount in the low output side region. apparatus.   The internal combustion engine according to claim 1 or 2, wherein the exhaust heat recovery control means uses at least one of a target output, a target fuel injection amount, and an accelerator opening of the internal combustion engine as the engine output information. Engine exhaust heat recovery control device.   The internal combustion engine according to claim 1 or 2, wherein the exhaust heat recovery control means uses at least one of an exhaust gas temperature, an exhaust gas volume flow rate, and a catalyst temperature of the internal combustion engine as the engine output information. Engine exhaust heat recovery control device. Exhaust heat recovery unit that recovers exhaust heat by exchanging heat between exhaust gas and cooling water of the internal combustion engine, and rotationally driving the compressor by rotating the exhaust turbine with the exhaust gas of the internal combustion engine to intake air In an exhaust heat recovery control device for an internal combustion engine comprising an exhaust turbine supercharger for supercharging
Exhaust heat recovery amount adjusting means for adjusting the exhaust heat recovery amount by the exhaust heat recovery device;
Exhaust heat recovery control means for controlling the exhaust heat recovery amount adjusting means so as to change the exhaust heat recovery amount in accordance with a target boost pressure and an actual boost pressure of the internal combustion engine. An exhaust heat recovery control device for an internal combustion engine.   The exhaust heat recovery control means controls the exhaust heat recovery amount adjusting means so as to decrease the exhaust heat recovery amount when the actual supercharging pressure is lower than the target supercharging pressure, and the actual supercharging pressure 6. The exhaust heat of the internal combustion engine according to claim 5, further comprising means for controlling the exhaust heat recovery amount adjusting means so as to increase the exhaust heat recovery amount when the pressure is higher than the target boost pressure. Collection control device.   The exhaust heat recovery control means stops the control of the exhaust heat recovery amount according to the target boost pressure and the actual boost pressure when the target output of the internal combustion engine is equal to or less than a predetermined value, and performs exhaust according to other requirements. The exhaust heat recovery control device for an internal combustion engine according to claim 5 or 6, further comprising means for controlling a heat recovery amount. In an exhaust heat recovery control device for an internal combustion engine comprising an exhaust heat recovery device that recovers exhaust heat by exchanging heat between exhaust gas and cooling water of an internal combustion engine mounted on a vehicle,
Exhaust heat recovery amount adjusting means for adjusting the exhaust heat recovery amount by the exhaust heat recovery device;
Operating means operated by a driver of the vehicle;
Exhaust heat recovery control means for controlling the exhaust heat recovery amount adjustment means so as to change the exhaust heat recovery amount in accordance with the operating state of the operation means. Control device.   The exhaust heat recovery control of an internal combustion engine according to any one of claims 1 to 8, wherein the exhaust heat recovery amount adjusting means is means for adjusting a flow rate of cooling water to be circulated through the exhaust heat recovery unit. apparatus.

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