JP4941538B2 - Engine waste heat control device - Google Patents

Description

  The present invention relates to an engine waste heat control device that controls the amount of waste heat of an engine based on a heat utilization request.

  In the in-vehicle engine, the combustion energy generated by the combustion of the fuel contains a lot of heat energy in addition to the kinetic energy used for running the vehicle. The heat energy is used to heat the vehicle interior and warm up the engine. Etc. are done. For example, a configuration is known in which engine waste heat contained in engine cooling water is recovered and heating is performed using the recovered waste heat.

  Also, when there is a heat utilization request such as an engine warm-up request or a heating request during engine operation, the engine waste heat amount is increased by controlling the ignition timing and the valve opening / closing timing of the intake / exhaust valves. Various techniques have been proposed for promoting the machine and satisfying the heating requirement in the passenger compartment (see, for example, Patent Document 1 and Patent Document 2).

Japanese Utility Model Publication No. 61-186766 Japanese Patent Laid-Open No. 11-324746

  When increasing the amount of engine waste heat in response to a heat utilization request, the amount of fuel consumed to increase the engine waste heat by a desired amount may vary depending on the engine operating state at the time when the heat utilization request is made. . However, in Patent Document 1 and Patent Document 2, engine waste heat control is performed by ignition timing control, valve timing control, or the like regardless of the engine operating state at the time when a heat utilization request is made. Therefore, depending on the engine operating state at the time of heat utilization request, there is a concern that the fuel consumption required to satisfy the heat utilization request increases and fuel consumption deterioration is promoted.

  The present invention has been made to solve the above-described problem, and provides an engine waste heat control apparatus capable of performing engine waste heat control in accordance with a heat utilization request while suppressing deterioration in fuel consumption as much as possible. Is the main purpose.

  The present invention employs the following means in order to solve the above problems.

  When increasing the amount of engine waste heat in response to a request for heat utilization, it is desirable to suppress as much as possible the increase in fuel consumption (deterioration of fuel consumption) due to the increase in waste heat. The present inventor found that the fuel increase amount with respect to the generated heat amount when increasing the engine waste heat differs depending on the engine operating state when starting the increase in waste heat, and the fuel consumption accompanying the increase in waste heat due to the difference. We focused on the change in the degree of deterioration. And it came to complete this invention in order to suppress the fuel consumption deterioration accompanying the increase in waste heat.

In other words, the first configuration is applied to a waste heat reuse system that recovers and reuses engine waste heat, and controls the amount of waste heat of the engine based on the amount of heat required for the heat utilization request. The present invention relates to a control device. In addition, when the heat utilization request is made, an increase rate calculating means for calculating a fuel increase rate indicating an amount of fuel increase with respect to the amount of heat generated when engine waste heat is increased based on the request, and an engine accompanying the heat utilization request Determination value setting means for setting an increase rate determination value for determining whether to perform waste heat increase control for increasing the amount of waste heat based on the fuel increase rate, and fuel increase calculated by the increase rate calculation means Waste heat control means for switching whether or not to implement the waste heat increase control according to the heat utilization request, based on a comparison result between the rate and the increase rate determination value set by the determination value setting means, It is characterized by providing.

  In the above configuration, when there is a heat utilization request, the content of waste heat control is switched between implementation / restriction of increase in waste heat based on the fuel increase rate when waste heat increase is performed based on the request. In other words, even if there is a heat utilization request, it is determined whether or not to implement according to the fuel increase rate every time, instead of immediately increasing the waste heat accordingly. For example, when the amount of fuel increase relative to the amount of generated heat is small and engine waste heat can be generated efficiently, waste heat increase is positively performed; otherwise, waste heat increase is not performed. In this way, the increase in waste heat when there is a demand for heat utilization is carried out with sharpness. Thereby, the fuel increase amount accompanying the increase in waste heat can be reduced on average while satisfying the required heat amount on average.

  Here, specifically, the fuel increase rate is, for example, the fuel increase amount per unit amount of the heat amount (additional heat amount) of the increase due to the waste heat control. Or it is set as the additional heat amount per unit fuel increase amount.

When the engine waste heat amount is increased in response to a heat use request, specifically, as in the second configuration , the increase rate calculating means increases the fuel with respect to the generated heat amount with respect to the engine operating state when starting the increase of waste heat. In the fuel increase rate characteristic calculated by the increase rate calculating means when the waste heat control means performs the waste heat increase control according to the heat utilization request, the fuel increase rate characteristic indicating the relationship of the rate is calculated. The waste heat increase control may be performed based on the generated heat amount corresponding to the fuel increase rate on the side where the fuel increase amount decreases with respect to the increase rate determination value. By so doing, waste heat can be increased within a range that is allowed as a fuel increase amount with respect to the generated heat amount, and deterioration of fuel consumption can be suitably suppressed.

By the way, when switching the content of engine waste heat control according to the fuel increase rate in the engine operating state when starting the waste heat increase, it is conceivable that the opportunity for increasing the waste heat is limited. In view of that point, in the third configuration , when the waste heat increase control is performed in accordance with the heat use request, the fuel increase rate characteristic calculated by the increase rate calculating means is configured to generate a fuel with respect to the increase rate determination value. The maximum heat amount among the generated heat amounts corresponding to the fuel increase rate on the side where the increase amount decreases is set as a heat amount command value to be increased by the waste heat increase control, and the waste heat increase control is performed based on the set command value. carry out. That is, when engine waste heat cannot be generated so efficiently in the engine operating state at the start of increase in waste heat, the increase in waste heat is not performed, thereby suppressing deterioration in fuel consumption due to increase in waste heat. On the other hand, if engine waste heat can be generated efficiently, heat energy is concentratedly generated from the engine by increasing the amount of waste heat of the engine as much as possible without increasing waste heat otherwise. In this way, by strengthening the sharpness of the implementation and restriction of waste heat control, the effect of reducing the fuel consumption accompanying the increase in waste heat on average while satisfying the required heat amount on average is preferable. Can get to.

When switching between implementation of waste heat increase and its implementation restriction at the time of heat utilization request, the frequency of heat increase accompanying heat utilization request decreases, and as a result, the required heat amount cannot be satisfied when the required heat amount is relatively large Is concerned. In view of this point, the increase rate determination value may be variably set based on the required heat amount as in the fourth configuration . By doing so, it is possible to switch between the increase of waste heat and the restriction on its implementation when a heat utilization request is made, and it is possible to generate engine waste heat commensurate with the required heat amount. At this time, it is preferable to set the increase rate determination value on the side where the fuel increase amount with respect to the generated heat amount increases as the required heat amount increases.

  For example, when the engine coolant temperature is low, such as when the engine is started, it is possible that the engine cannot be sufficiently warmed up and the combustion of the engine is not stable. In such a case, the emission may be deteriorated or the driver may feel uncomfortable due to torque fluctuation. In addition, when the engine coolant temperature is low, it may be considered that the heating requirement cannot be satisfied.

In view of this point, in the fifth configuration , the increase rate determination value is variably set based on the engine coolant temperature. By doing so, it is possible to switch between the implementation of the increase of waste heat and the implementation restriction according to the engine cooling water temperature at the time of heat utilization request.

More specifically, with regard to the configuration ( fifth configuration ) in which the increase rate determination value is variably set according to the engine coolant temperature, as in the sixth configuration , the temperature detection means for detecting the engine coolant temperature, and the heat and a target temperature setting means for setting a target temperature of the engine coolant when the use request is generated, the difference between the engine cooling water temperature detected by the target temperature set by the target temperature setting means and the temperature detecting means The increase rate determination value may be variably set based on the above. If the difference between the current value of the engine coolant temperature and the target value is large, it can be considered that the period until the required amount of heat can be satisfied is prolonged. In that respect, by adopting the above-described configuration, it is possible to ensure immediate warming, and as a result, it is possible to quickly satisfy the heat utilization request. At this time, the increase rate determination value may be set on the side where the fuel increase amount with respect to the generated heat amount increases as the difference between the current value of the engine coolant temperature and the target value increases.

  It is conceivable that the lower the outside air temperature, the easier the recovered heat energy escapes to the outside air, making it impossible to quickly satisfy the heat utilization request. Specifically, when recovering engine waste heat using engine cooling water as a medium, the lower the outside air temperature, the easier the recovered heat escapes from the engine cooling water, and as a result, the recovered heat from the engine is the same amount. However, it is conceivable that the engine coolant temperature rises more slowly as the outside air temperature is lower.

In view of this point, in the seventh configuration , the increase rate determination value is variably set based on the outside air temperature. Thereby, even if it is a case where external temperature is low, a heat utilization request | requirement can be satisfied quickly.

The block diagram which shows the outline | summary of an engine waste heat control system. A map showing the relationship between the engine operating state and the fuel consumption rate. The figure which shows the relationship between an engine driving | running state and additional heat amount. Explanatory drawing about the fuel consumption at the time of the additional heat generation | occurrence | production with a heat utilization request | requirement. The heat cost characteristic figure which shows the relationship of the heat cost (eta) with respect to additional heat quantity (DELTA) Q. The functional block diagram for calculating a request | requirement calorie | heat amount and target engine water temperature. The functional block diagram for calculating a standard heat cost. The functional block diagram for calculating command heat quantity. The figure which shows an example of a target water temperature map. The figure which shows an example of a request | requirement calorie | heat amount reference | standard calculation map. The figure which shows an example of a temperature reference | standard calculation map. The figure for demonstrating the calculation method of instruction | command additional calorie | heat amount. The flowchart which shows the calculation procedure of instruction | command calorie | heat amount.

  Hereinafter, an embodiment in which the present invention is embodied in a vehicle equipped with a spark ignition type multi-cylinder gasoline engine will be described with reference to the drawings. FIG. 1 is a configuration diagram showing an outline of a waste heat control system (waste heat reuse system) of the present embodiment.

  In FIG. 1, an intake pipe 11 and an exhaust pipe 12 are connected to the engine 10, and the intake pipe 11 is provided with a throttle valve 13 for adjusting the amount of intake air into the cylinder. The throttle valve 13 is an air amount adjusting means that is electrically opened and closed by a throttle actuator 14 made of a motor or the like. The throttle actuator 14 has a built-in throttle sensor for detecting the opening of the throttle valve 13 (throttle opening).

  The engine 10 includes an injector 15 as fuel injection means for injecting and supplying fuel to each cylinder of the engine 10, and an igniter (ignition device) 17 as ignition means for generating an ignition spark in a spark plug 16 provided for each cylinder. And an intake side valve drive mechanism 18 and an exhaust side valve drive mechanism 19 as valve timing adjusting means for adjusting the opening and closing timings of the intake and exhaust valves. In the present embodiment, an intake port injection type engine is adopted, and the injector 15 is provided in the vicinity of the intake port. Instead, a direct injection type engine is adopted, and the injector 15 is provided for each cylinder. It is good also as a structure provided in a cylinder head etc.

  The valve drive mechanisms 18 and 19 on the intake side and the exhaust side adjust the advance amounts of the cam shafts on the intake side and the exhaust side with respect to the crankshaft of the engine 10. According to the intake side valve drive mechanism 18, the opening / closing timing of the intake valve is changed to the advance side or the retard side, and according to the exhaust side valve drive mechanism 19, the opening / closing timing of the exhaust valve is set to the advance side or the retard side. Changed to That is, according to the valve drive mechanisms 18 and 19, the valve overlap amount when the valve opening period of the intake valve and the valve opening period of the exhaust valve overlap is changed. In the present embodiment, both the intake side valve drive mechanism 18 and the exhaust side valve drive mechanism 19 are provided. However, a valve drive mechanism is provided on the side that changes the valve opening timing when the overlap amount is changed. If it is, the structure provided only with either one may be sufficient.

  The exhaust pipe 12 is provided with an oxygen concentration sensor 21 that detects the oxygen concentration in the exhaust. A catalyst 22 as an exhaust purification device is provided on the downstream side of the oxygen concentration sensor 21. The catalyst 22 is, for example, a three-way catalyst, and purifies harmful components and the like in the exhaust when the exhaust passes.

  This system is provided with an EGR device (exhaust gas recirculation device) that introduces a part of the exhaust gas into the intake system as EGR gas. That is, between the intake pipe 11 and the exhaust pipe 12, one end is connected to the throttle valve downstream side of the intake pipe 11, and the other end is connected to the catalyst downstream side (or upstream side) of the exhaust pipe 12. A pipe 25 is provided. An electromagnetic EGR valve 26 is provided in the middle of the EGR pipe 25. In this case, the amount of EGR gas is adjusted to increase or decrease by adjusting the opening of the EGR valve 26.

  Next, the configuration of the cooling system of the engine 10 will be described.

  A water jacket 31 is formed in the cylinder block and cylinder head of the engine 10, and cooling water is circulated and supplied to the water jacket 31 so that the engine 10 is cooled. The temperature (cooling water temperature) of the cooling water in the water jacket 31 is detected by the water temperature sensor 32. A circulation path 33 composed of cooling water piping or the like is connected to the water jacket 31, and the circulation path 33 is provided with a water pump 34 for circulating the cooling water. The water pump 34 may be, for example, a mechanical pump that is driven as the engine 10 rotates, or may be an electric pump. Moreover, the structure which can adjust the amount of cooling water with the water pump 34 may be sufficient.

  The circulation path 33 extends toward the heater core 35 on the outlet side of the engine 10 (water jacket 31), and is provided so as to return to the engine 10 again via the heater core 35. Air conditioning air is sent to the heater core 35 from a blower fan (not shown). When the air conditioning air passes through the heater core 35 or the vicinity thereof, the air conditioning air is heated by heat received from the heater core 35, and the hot air is Supplied in the passenger compartment.

  The circulation path 33 is branched in two on the downstream side of the heater core 35, and a radiator 36 as an atmospheric heat radiating portion is provided in one of the circulation paths 33A. Further, a thermostat 37 that changes the flow path of the cooling water by operating according to the cooling water temperature is provided at a branch portion of the circulation path 33. When the cooling water is at a low temperature (below the thermostat operating temperature), the thermostat 37 prevents the cooling water from flowing into the radiator 36, and the cooling water circulates in the circulation path 33 without being dissipated by the radiator 36. To do. For example, before the engine 10 is warmed up (during warm-up operation), cooling of the cooling water (radiation) in the radiator 36 is suppressed. Further, when the cooling water reaches a high temperature (above the thermostat operating temperature), the cooling water is allowed to flow into the radiator 36 by the thermostat 37, and the cooling water circulates in the circulation path 33 while being radiated by the radiator 36. Thereby, the cooling water is maintained at an appropriate temperature (for example, about 80 ° C.) under the engine operating condition.

  The control system includes an engine ECU (electronic control unit) 40 that forms the center of engine control, and the engine ECU 40 performs various controls related to the operation of the engine 10. That is, the engine ECU 40 is configured mainly with a microcomputer including a CPU, a ROM, a RAM, and the like as is well known, and executes various control programs stored in the ROM, so that various types of the engine 10 can be set according to the engine operating state. Implement control. In this system, as an operation state detection means for detecting an engine operation state, a rotation speed sensor 41 that detects an engine rotation speed, a load sensor 42 that detects an engine load such as an intake air amount and intake pipe negative pressure, and the like are provided. The detection signals from the sensors 41 and 42, the oxygen concentration sensor 21 and the water temperature sensor 32 described above, and the like are appropriately input to the engine ECU 40.

  The engine ECU 40 receives detection signals from the various sensors described above, and based on the various detection signals, the fuel injection control by the injector 15, the ignition timing control by the igniter 17, the valve timing control by the valve drive mechanisms 18 and 19, the throttle The air amount is controlled by the valve 13 (throttle actuator 14). Basically, the above various controls are adapted so that the maximum efficiency (maximum fuel consumption) of the engine 10 can be obtained in each engine operation state in consideration of the fact that the engine shaft efficiency (fuel consumption) varies depending on the engine operation state. Implement based on data. FIG. 2 shows an example of a map representing the relationship between the engine operating state and the fuel consumption rate. FIG. 2 shows the engine rotation speed and the engine torque as the engine operating state.

  In the present control system, among the fuel combustion energy generated by the combustion of fuel in the engine 10, heat energy is recovered and reused using the engine coolant as a medium, thereby improving the fuel efficiency of the entire system.

  Specifically, as shown in FIG. 1, the present system is provided with an air conditioner ECU 50 that performs air conditioning control in the passenger compartment, and a heat management ECU 60 that commands the engine ECU 40 to execute waste heat control. . As well known, the air conditioner ECU 50 and the heat management ECU 60 are mainly composed of a microcomputer including a CPU, a ROM, a RAM, and the like, and execute various control programs stored in the ROM to respond to various signals input each time. Each control is implemented.

  Specifically, the air conditioner ECU 50 includes an A / C switch 51 for switching on / off of the air conditioner, a temperature setting switch 52 for the driver to set a target value (target temperature) of the vehicle interior temperature, the vehicle interior A vehicle interior temperature sensor 53 that detects the temperature, an outside air temperature sensor 54 that detects the outside air temperature, and a blower that detects the temperature of the conditioned air sent from the heater core 35 or its vicinity to the vehicle interior via the air conditioner outlet (outlet temperature). Various signals are input from the outlet temperature sensor 55 and the like, various control signals and data from the engine ECU 40 are input, and the required heat quantity Qrq is calculated based on the input various signals and the like. Further, the calculated required heat amount Qrq is output to the heat management ECU 60. The heat management ECU 60 calculates a command heat quantity Qod as a heat quantity to be created by the engine 10 based on the required heat quantity Qrq, and outputs the calculated command heat quantity Qod to the engine ECU 40. And engine ECU40 controls the driving | running state of the engine 10 based on the input instruction | command calorie | heat amount Qod. Thereby, waste heat corresponding to the required heat quantity Qrq is generated in the engine 10.

  In this system, when the amount of generated waste heat (heat generation amount), which is thermal energy of the engine 10, is increased, control for increasing the amount of generated heat while minimizing the amount of fuel increase associated with the increase in waste heat (heat generation) Control). Specifically, the heat generation control includes a plurality of waste heat amount adjusting means for increasing the amount of generated heat. Then, when a heat utilization request such as a heating request is generated, a means capable of minimizing a reduction in fuel consumption is selected from the plurality of waste heat amount adjusting means, and the engine waste heat amount is increased by the selected waste heat amount adjusting means. .

The heat generation control will be described in more detail. In this control system, for example,
・ Delaying the ignition timing increases the amount of waste heat. ・ Changing the intake valve opening timing to the advanced side (by making the intake valve open quickly) increases the waste heat amount. ・ Delaying the exhaust valve opening timing. The engine waste heat amount is increased by using one or a plurality of factors such as an increase in waste heat amount when changing to the corner side (when exhaust exhaust is slowly opened). Further, in the present embodiment as the waste heat amount adjusting means, for example,
(1) Means for performing ignition retard and exhaust valve slow opening (2) Means for performing ignition retard and rapid opening of intake valve (3) Means for performing ignition retard. Then, the engine ECU 40 selects from the above (1) to (3) the waste heat amount adjusting means that can satisfy the command heat amount Qod input from the heat management ECU 60 and can minimize the fuel increase amount accompanying the increase in waste heat at that time. The waste heat amount of the engine 10 is increased by the selected waste heat amount adjusting means.

  The waste heat control of the engine 10 is required for the amount of heat generated at the fuel efficiency best point when, for example, there is a heat utilization request during engine operation at the fuel efficiency best point and the required heat amount Qrq increases with the heat utilization request. When the heat quantity Qrq cannot be satisfied, the heat quantity shortage is compensated. In this case, in order to satisfy the required heat quantity Qrq, for example, as shown in FIG. 3, the operating point of the engine 10 is shifted from the fuel efficiency best point A to a different point A ′ to thereby reduce the engine waste heat quantity to the fuel. The amount of heat generated at the best point A (additional heat amount = 0) needs to be increased by a heat amount ΔQ. Due to the transition of the engine operating point of A → A ′, the operating point of the engine 10 is shifted to the fuel increase side (fuel efficiency deterioration side) from the fuel efficiency best point, and the generated heat amount (base heat amount) at the fuel best point A is As a result, an increased amount of heat (additional heat amount ΔQ) is generated.

  FIG. 4 is a diagram for explaining a fuel consumption amount when an additional heat amount is generated in accordance with a heat use request. In the figure, (a) shows the fuel consumption [g / h] when operating at the best fuel efficiency, and (b) shows the fuel when increasing the engine waste heat amount during operation at the best fuel efficiency. Consumption [g / h] is shown.

  In the best fuel economy, for example, about 25% of the fuel combustion energy of the engine 10 is converted into the shaft output of the engine 10 as kinetic energy, about 25% becomes a cooling loss, and the rest is an auxiliary machine loss, an exhaust loss, etc. Other loss. The heat energy corresponding to the cooling loss is recovered using the engine coolant as a medium, and the recovered heat is used for heating the vehicle interior or warming up the engine.

  If the required heat quantity Qrq increases with the demand for heat utilization and the required heat quantity Qrq cannot be satisfied only by the cooling loss at the fuel efficiency best point, the insufficient heat quantity is generated as additional heat quantity by engine waste heat control. . At this time, the amount of fuel consumption increases with the generation of additional heat, but from the viewpoint of suppressing fuel consumption deterioration, it is desirable that the amount of increase in fuel accompanying the generation of additional heat is as small as possible.

  Here, according to the knowledge of the present inventor, when a desired amount of engine waste heat is generated, the amount of fuel increase for the heat generation changes according to the engine operating point when starting the heat amount increase. For example, when the required heat quantity Qrq cannot be satisfied when the engine 10 is controlled at the best fuel efficiency, it is necessary to increase the generated heat quantity of the engine 10 to compensate for the shortage of the required heat quantity Qrq. At this time, when the engine operating point when starting the heat increase is the operating point X in FIG. 2 and the operating point Y different from the operating point X, the same amount of engine waste heat is increased. The amount of fuel increase required is different. That is, the fuel increase amount (fuel increase rate) with respect to the engine generated heat amount varies depending on the engine operating point at the start of the heat amount increase. In addition to the engine operating point, the fuel increase rate differs depending on parameters relating to the temperature such as the engine coolant temperature and the outside air temperature.

The fuel increase rate will be further described. The fuel increase rate is a parameter related to fuel consumption when increasing the amount of generated heat (waste heat) of the engine 10, and more specifically, the amount of heat generated by engine waste heat control (additional heat amount ΔQ) and , And the ratio of the increase in fuel injection amount due to the generation of the additional heat amount ΔQ (fuel increase amount Δqf). For example, the fuel increase rate is a fuel increase amount Δqf per unit amount of the additional heat amount ΔQ (hereinafter referred to as “heat cost”).
Heat cost η [g / kWh] = Fuel increase Δqf [g / h] / Additional heat ΔQ [kW]
FIG. 5 is a heat cost characteristic diagram showing the relationship of the heat cost η to the additional heat amount ΔQ at two different engine operating points X and Y (see FIG. 2). As shown in FIG. 5, the heat cost η varies depending on the additional heat quantity ΔQ. For example, the heat cost characteristics of the engine operating points X and Y have a minimum point within the set range of the additional heat quantity ΔQ. In addition, the relationship of the heat cost η with respect to the additional heat quantity ΔQ is different for each engine operating point. For example, when generating the additional heat quantity of a predetermined amount Q1, the heat cost η is smaller in Y than in X. Therefore, when the amount of heat generated by the engine 10 is increased by the predetermined amount Q1, when the engine operating point at the start of the increase in the amount of heat is X, the amount of increase in fuel is smaller than in the case of Y. In other words, when the amount of heat generated by the engine 10 is increased, there are cases where the heat energy of the engine 10 can be efficiently generated from the viewpoint of fuel efficiency and cases where it is not.

  In FIG. 5, the heat cost characteristic is represented by a curve having a minimum point within the setting range of the additional heat quantity ΔQ, but does not have a minimum point within the setting range of the additional heat quantity ΔQ, that is, the additional heat quantity ΔQ The heat cost η may increase or decrease with the increase.

  Therefore, in the present embodiment, when there is a heat utilization request, the fuel increase rate is calculated as a parameter indicating the fuel increase amount with respect to the generated heat amount when the waste heat increase is performed in accordance with the heat utilization request, and the calculated fuel increase The rate is compared with an increase rate determination value for determining whether to increase waste heat based on the fuel increase rate. Then, based on the comparison result between the fuel increase rate and the increase rate determination value, it is determined whether or not to increase the waste heat by the waste heat control (heat generation control) according to the heat use request.

  More specifically, the fuel increase rate is the fuel increase amount Δqf (heat cost η) per unit amount of the additional heat amount ΔQ, and the waste heat increase is performed (the engine operating point is the fuel increase side (fuel consumption deterioration) The heat cost η in the case of shifting to the side) is compared with the reference heat cost ηth as the upper limit value of the allowable range of the heat cost η. And when heat cost (eta) at the time of performing waste heat increase is below standard heat cost (eta) th, waste heat increase by waste heat control is implemented with a heat utilization request | requirement. On the other hand, when the heat cost η is larger than the reference heat cost ηth, waste heat is not increased by waste heat control even if there is a heat utilization request. That is, in this control system, even if there is a heat utilization request, whether or not to increase the waste heat according to the fuel increase rate (heat cost η), rather than immediately increasing the waste heat according to the request. Judging.

  On the other hand, when switching whether or not to increase the waste heat based on the fuel increase rate, there is a possibility that the required amount of heat cannot be satisfied because the opportunity for increasing the waste heat is limited. Therefore, in the present embodiment, when increasing the engine waste heat, within the range allowed as the fuel increase rate, specifically, in the region where the heat cost η is equal to or less than the reference heat cost ηth, the additional heat amount is within the set range. The engine 10 is controlled so that the maximum amount of heat is generated by the engine 10.

  This waste heat control will be described in more detail. In this control, when there is a heat utilization request, the waste heat is not increased immediately, but first, the heat cost characteristic in the engine operating state when starting the heat increase is compared with the reference heat cost ηth. As a result, when there is no heat cost η that is equal to or lower than the reference heat cost ηth in the heat cost characteristics, that is, when the overall level of the heat cost η in the heat cost characteristics is relatively high, the increase in waste heat is not performed. In this case, the engine waste heat is not increased at the minimum value (minimum heat cost ηmin) of the heat cost η in the heat cost characteristics. On the other hand, when there is a heat cost η that is equal to or less than the reference heat cost ηth in the heat cost characteristic, that is, when the overall level of the heat cost η in the heat cost characteristic is relatively low, the heat that is equal to or less than the reference heat cost ηth. When the cost η does not exist, the increase in the waste heat of the engine 10 is intensively performed with the heat cost η larger than the minimum heat cost ηmin because the increase in the waste heat is not performed. In this way, by increasing the waste heat with sharpness based on the heat cost η, an average amount of heat corresponding to the required amount of heat Qrq is generated, and the amount of fuel increase associated with the generation of heat is minimized. ing.

  Of the generated engine waste heat, the excess heat energy with respect to the required heat amount is stored in the engine cooling water until it becomes necessary. In other words, the engine cooling water has a characteristic capable of storing thermal energy, and this control system uses this characteristic to concentrate heat energy from the engine 10 intensively when heat can be generated efficiently. generate. As a result, an amount of heat corresponding to the required amount of heat Qrq can be generated on average, and the amount of fuel increase accompanying the generation of heat is minimized.

  6 to 8 are functional block diagrams for calculating parameters relating to the amount of heat of the present waste heat control. Among these, FIG. 6 is an explanation for calculating the required heat quantity Qrq and the target value of the engine water temperature (target engine water temperature Twt), FIG. 7 is an explanation for calculating the reference heat cost ηth, and FIG. 8 is the command heat quantity. It is description about calculation of Qod. The required heat quantity Qrq and the target engine water temperature Twt in FIG. 6 are calculated by the air conditioner ECU 50, and the reference heat cost ηth in FIG. 7 and the command heat quantity Qod in FIG. 8 are calculated by the heat management ECU 60. Moreover, in FIGS. 6-8, the case where there exists a heating request | requirement as a heat utilization request | requirement is assumed. Hereinafter, it demonstrates in order.

  First, the required heat quantity Qrq and the target engine water temperature Twt will be described. In FIG. 6, first, the outlet temperature / air volume calculation unit M1 uses a map or the like to set the air conditioner set temperature Tse set by the temperature setting switch 52 and the vehicle interior temperature Tin detected by the vehicle interior temperature sensor 53. Then, the required value of the air-conditioner outlet temperature (required outlet temperature Trq) and the required value of the air-conditioner outlet air volume (required outlet air volume Vrq) are calculated using the outside air temperature Tou detected by the outside air temperature sensor 54 as parameters. The required heat amount calculation unit M2 uses a map or the like to calculate the required outlet temperature Trq and the required outlet air amount Vrq calculated by the outlet temperature / air volume calculation unit M1, and the outside air temperature Tou detected by the outside air temperature sensor 54. The required heat quantity Qrq is calculated as a parameter.

  In FIG. 6, the target water temperature calculation unit M3 uses the target water temperature map shown in FIG. 9 and uses the required outlet temperature Trq and the required outlet air amount Vrq calculated by the outlet temperature / air volume calculation unit M1 as parameters. A target engine water temperature Twt at the time of request is calculated. As shown in FIG. 9, in the target water temperature map, the target engine water temperature Twt is registered as a map value in association with the required air outlet temperature Trq and the required air flow rate Vrq. A target engine water temperature Twt is calculated based on the air volume Vrq. According to the map, a higher value is calculated as the target engine water temperature Twt as the required outlet temperature Trq is higher or as the required outlet air volume Vrq is higher.

  Next, the reference heat cost ηth will be described. In FIG. 7, the first reference calculation unit M4 calculates the first reference heat cost ηt1 using the required heat amount Qrq calculated by the required heat amount calculation unit M2 as a parameter. The second reference calculation unit M5 uses the target engine water temperature Twt calculated by the target water temperature calculation unit M3, the current water temperature Tac detected by the water temperature sensor 32, and the outside air temperature Tou detected by the outside air temperature sensor 54 as parameters. The heat cost ηt2 is calculated. In the reference heat cost setting unit M6, the larger one of the first reference heat cost ηt1 calculated by the first reference calculation unit M4 and the second reference heat cost ηt2 calculated by the second reference calculation unit M5 is determined as the reference heat. Set as cost ηth.

  Here, details of the first reference calculation unit M4 and the second reference calculation unit M5 will be described. The first reference calculation unit M4 calculates the first reference heat cost ηt1 using the required heat quantity reference calculation map shown in FIG. 10 and the required heat quantity Qrq as a parameter. As shown in FIG. 10, in the required heat quantity reference calculation map, a first reference heat cost ηt1 is registered as a map value in association with the required heat quantity Qrq, and the first reference heat cost is calculated based on the required heat quantity Qrq at each time. ηt1 is calculated. According to the map, when the required heat quantity Qrq is equal to or less than the predetermined value α, zero is set as the first reference heat cost ηt1, and when the required heat quantity Qrq is larger than the predetermined value α, the required heat quantity Qrq is larger. A large value is set as the first reference heat cost ηt1. Here, the predetermined value α is set as an upper limit value of the required heat quantity Qrq that can satisfy the heat use request with the generated heat quantity (base heat quantity) at the fuel best point.

  The second reference calculation unit M5 uses the temperature reference calculation map shown in FIG. 11 to calculate the second reference heat cost ηt2 using the target engine water temperature Twt, the current water temperature Tac, and the outside air temperature Tou as parameters. As shown in FIG. 11, in the temperature reference calculation map, the second reference heat cost ηt2 is registered as a map value in association with the temperature difference ΔTw obtained by subtracting the current water temperature Tac from the target water temperature Twt and the outside air temperature Tou. Then, the second reference heat cost ηt2 is calculated based on the temperature difference ΔTw and the outside air temperature Tou. According to the map, a larger value is calculated as the second reference heat cost ηt2 as the temperature difference ΔTw is larger or the outside air temperature Tou is lower. In addition, an upper limit is provided for the second reference heat cost ηt2, and when the temperature difference ΔTw is equal to or higher than a predetermined temperature, the maximum value determined for each outside air temperature Tou is set as the second reference heat cost ηt2.

  Next, the command heat quantity Qod will be described. In FIG. 8, first, the base heat amount calculation unit M7 uses a map or the like, and uses the engine torque Tr, the engine rotation speed NE, and the engine water temperature Tac as parameters, and the amount of heat generated in the engine 10 in the current engine operating state. That is, the amount of heat generated at the fuel best point (base heat amount) Qbs is calculated.

  The heat cost characteristic calculation unit M8 uses the engine torque Tr, the engine rotation speed NE, and the engine water temperature Tac as parameters, for example, by using a map or the like, so that the current engine operation state (engine operation state at the start of the increase in waste heat). The heat cost characteristic corresponding to is calculated. Note that the outside air temperature Tou may be included as a parameter. Details of the configuration of the heat cost characteristic calculation unit M8 and the heat cost map will be described later.

  In the additional heat quantity calculation unit M9, the additional heat quantity ΔQ is based on the heat cost characteristic corresponding to the current engine operating state calculated by the heat cost characteristic calculation part M8 and the reference heat cost ηth set by the reference heat cost setting part M6. Command value (command additional heat quantity ΔQod) is calculated.

  The command heat amount calculation unit M10 calculates the command heat amount Qod by adding the base heat amount Qbs calculated by the base heat amount calculation unit M7 and the command additional heat amount ΔQod calculated by the additional heat amount calculation unit M9.

  Here, details of the heat cost characteristic calculation unit M8 and the additional heat amount calculation unit M9 will be described. The heat cost characteristic calculation unit M8 stores in advance a map that defines the relationship between the engine cost Tr, the engine rotation speed NE, and the engine water temperature Tac and the heat cost η as parameters. The heat cost characteristic calculation unit M8 uses a map corresponding to each engine torque Tr, engine speed NE, and engine water temperature Tac, so that the heat cost characteristic corresponding to each engine torque Tr and the like (heat cost for the additional heat amount ΔQ). η relationship) is calculated. In this heat cost characteristic, the heat cost when the heat amount is increased by the minimum value of the heat cost η for each additional heat amount ΔQ, that is, among the plurality of waste heat adjusting means for increasing the heat amount, with the means that minimizes the heat cost. Is registered in association with the additional heat quantity ΔQ.

  In the additional heat quantity calculation unit M9, first, the heat cost characteristic calculated by the heat cost characteristic calculation unit M8 is compared with the reference heat cost ηth set by the reference heat cost setting unit M6. When there is a heat cost η that is equal to or less than the reference heat cost ηth in the heat cost characteristic, the maximum value of the additional heat amount ΔQ in that region is set as the command additional heat amount ΔQod. On the other hand, when there is no heat cost η that is equal to or lower than the reference heat cost ηth in the heat cost characteristics, zero is set as the command additional heat amount ΔQod.

  FIG. 12 is a diagram for explaining a method of calculating the command additional heat amount ΔQod in the additional heat amount calculation unit M9. In FIG. 12, (a) shows a case where there is a heat cost η that is equal to or less than the reference heat cost ηth, and (b) shows a case where there is no heat cost η that is equal to or less than the reference heat cost ηth. FIG. 12 illustrates the case where the heat cost characteristic is represented by a curve having a minimum point.

  In FIG. 12, when there is a heat cost η that is equal to or lower than the reference heat cost ηth in the heat cost characteristics, as shown in (a), a line L1 indicating the heat cost characteristics, and a straight line L2 indicating the reference heat cost ηth, Intersect at points A and B. In this case, the maximum value ΔQb among the additional heat amounts corresponding to between A and B is set as the command additional heat amount ΔQod.

  On the other hand, when there is no heat cost η that is equal to or lower than the reference heat cost ηth in the heat cost characteristics, as shown in (b), the line L1 indicating the heat cost characteristics intersects with the straight line L2 indicating the reference heat cost ηth. do not do. In this case, zero is set as the command additional heat quantity ΔQod.

  In addition, when the maximum value ΔQb of the additional heat quantity is set as the command additional heat quantity ΔQod with the generation of the heat use request, the engine waste heat quantity increases due to the heat quantity corresponding to the command additional heat quantity ΔQod being generated in the engine 10. . At this time, the engine cooling water temperature rises as the waste heat increases and the vehicle interior temperature Tin rises, so the required heat quantity Qrq falls. Therefore, after the maximum value ΔQb is set as the command additional heat amount ΔQod, a gradually smaller value is set as the reference heat cost ηth as the waste heat increase control proceeds. As a result, the command additional heat amount ΔQod is gradually reduced, and the increase in waste heat is stopped by the fact that the line L1 indicating the heat cost characteristic and the straight line L2 indicating the reference heat cost ηth do not intersect with each other. In other words, in this system, when waste heat can be efficiently increased, waste heat is increased so that the maximum amount of heat allowed based on the heat cost is generated, and then the heat utilization request is satisfied. Heat increase is stopped.

  Next, a procedure for calculating the command heat quantity Qod in the engine waste heat control will be described. FIG. 13 is a flowchart showing a procedure for calculating the command heat quantity Qod in the present system. This process is executed at predetermined intervals by the microcomputer of the heat management ECU 60.

  In FIG. 13, first, in step S101, current values of parameters relating to the engine operating state such as the engine speed, engine torque, and engine water temperature are read. In step S102, the base heat quantity Qbs is set using the engine torque, engine speed, and engine water temperature as parameters. Is calculated. In step S103, heat cost characteristics are calculated based on the current engine speed, engine torque, and engine water temperature.

  In the following step S104, the required heat quantity Qrq calculated by the air conditioner ECU 50 using the air conditioner set temperature, the passenger compartment temperature and the outside air temperature as parameters is read. In step S105, it is determined whether or not the read required heat quantity Qrq is zero. If the required heat amount Qrq is zero, the process proceeds to step S106, where zero is set as the command additional heat amount ΔQod.

  On the other hand, if the required heat quantity Qrq is not zero, the process proceeds to step S107, and the target engine water temperature Twt calculated using the required outlet temperature Trq and the required blown air quantity Vrq as parameters by using the target water temperature map in the air conditioner ECU 50 is read. In Step S108, when the target engine water temperature Twt is lower than a predetermined lower limit temperature (for example, 40 ° C.) defined in advance as the minimum temperature required for engine warm-up, the target engine water temperature Twt is set to the lower limit temperature. Reset to.

  In step S109, a reference heat cost ηth is calculated. Specifically, the reference heat amount reference calculation map (FIG. 10) is referred to, and the first reference heat cost ηt1 is calculated using the required heat amount Qrq as a parameter. Further, with reference to the temperature reference calculation map (FIG. 11), the second reference heat cost ηt2 is calculated using the target engine water temperature Twt, the current water temperature Tac, and the outside air temperature Tou as parameters. The larger one of the first reference heat cost ηt1 and the second reference heat cost ηt2 is set as the reference heat cost ηth.

  Thereafter, in steps S110 to S112, a command additional heat quantity ΔQod is calculated. That is, in step S110, the calculated heat cost characteristic is compared with the reference heat cost ηth. If there is a heat cost η that is equal to or less than the reference heat cost ηth in the heat cost characteristics, the process proceeds to step S111, and the maximum value of the additional heat amount ΔQ corresponding to the heat cost η that is equal to or less than the reference heat cost ηth is set as the command additional heat amount ΔQod Set as. On the other hand, when there is no heat cost η that is equal to or lower than the reference heat cost ηth in the heat cost characteristics, the process proceeds to step S112, and zero is set as the command additional heat amount ΔQod.

  Finally, in step S113, the base heat quantity Qbs and the command additional heat quantity ΔQod are added to calculate the command heat quantity Qod, and the calculated command heat quantity Qod is output to the engine ECU 40. When the command heat quantity Qod is input, the engine ECU 40 controls the engine operating state based on the command heat quantity Qod. In the present embodiment, the engine ECU 40 determines which of the plurality of waste heat amount adjusting means for increasing the amount of heat generated by the engine 10 to increase the waste heat amount (the amount of heat corresponding to the command heat amount Qod is the engine 10). Switch between them. More specifically, the engine ECU 40 performs waste heat control by selectively using each adjusting means based on the command heat quantity Qod, the engine operating state, and the like. This minimizes inconveniences such as a decrease in engine operation efficiency caused by the implementation of waste heat control.

  According to the embodiment described in detail above, the following excellent effects can be obtained.

  When there is a heat utilization request, the heat cost η is calculated as a parameter indicating the amount of fuel increase relative to the generated heat amount when the waste heat increase is performed in accordance with the heat utilization request, and the calculated heat cost η and the waste heat increase are calculated. Based on the comparison result with the reference heat cost ηth for determining whether or not to implement based on the heat cost η, whether or not to implement waste heat increase by waste heat control (heat creation control) in accordance with the heat utilization request, Or, because it is configured to determine whether or not to implement, even if there is a heat utilization request, it is determined whether or not to implement according to each heat cost η, rather than immediately increasing waste heat according to the request can do. Therefore, it is possible to increase the amount of waste heat when there is a demand for heat utilization, and to reduce the amount of fuel increase accompanying the increase in waste heat on average while satisfying the required amount of heat on average. Can do.

  When increasing waste heat in response to a heat utilization request, in the relationship of heat cost η to additional heat amount ΔQ (heat cost characteristics), the maximum heat amount among additional heat amounts ΔQ corresponding to heat cost η that is equal to or less than reference heat cost ηth is Since it is set as the command additional heat amount ΔQod and the waste heat of the engine 10 is increased based on the set command additional heat amount ΔQod, if the engine waste heat can be generated efficiently, the waste heat increases otherwise. Therefore, heat energy can be generated from the engine 10 in a concentrated manner. In this way, by strengthening the sharpness of the implementation and restriction of waste heat control, the effect of reducing the fuel consumption accompanying the increase in waste heat on average while satisfying the required heat amount on average is preferable. Can get to.

  Since the reference heat cost ηth is variably set according to the required heat quantity Qrq, switching between the increase of waste heat and the implementation restriction can be performed according to the required heat quantity Qrq at the time of heat use request. Engine waste heat commensurate with Qrq can be generated.

  Since the reference heat cost ηth is variably set based on the engine coolant temperature, specifically, the difference between the current value Tac of the engine coolant temperature and the target value Twt of the engine coolant temperature when a heat utilization request occurs. Since the reference heat cost ηth is variably set based on ΔTw, it is possible to ensure immediate warming when a heat use request is generated, and as a result, the heat use request can be satisfied quickly.

  The target value Twt of the engine coolant temperature when a heat utilization request is generated is based on the required outlet temperature Trq and the required outlet air volume Vrq calculated using the air conditioner set temperature Tse, the passenger compartment temperature Tin, and the outside air temperature Tou as parameters. Since the configuration is set, immediate warming immediately after the engine is started can be improved. As a result, driver discomfort can be suppressed.

  Since the lower limit of the target engine water temperature Twt is limited to a predetermined lower limit temperature (for example, 40 ° C.) defined in advance as the minimum temperature required for engine warm-up, combustion stabilization of the engine 10 can be promoted. As a result, it is possible to suppress the deterioration of the emission immediately after the cold start of the engine 10 and the driver's discomfort due to torque fluctuation.

  Since the reference heat cost ηth is variably set based on the outside air temperature Tou, it is possible to quickly satisfy the heat utilization request even when the outside air temperature is low.

(Other embodiments)
The present invention is not limited to the description of the above embodiment, and may be implemented as follows, for example.

  In the above embodiment, the fuel increase rate is the fuel increase amount Δqf (heat cost η) per unit amount of the additional heat amount ΔQ, but the fuel increase rate is a parameter indicating the fuel increase amount with respect to the generated heat amount. For example, the additional heat amount ΔQ per unit amount of the fuel increase amount Δqf (the reciprocal of the heat cost η: 1 / η) may be used. When the fuel increase rate is the reciprocal 1 / η of the heat cost, in the characteristics indicating the relationship of the reciprocal 1 / η to the additional heat amount, there is no reciprocal 1 / η that exceeds the reference heat cost within the setting range of the additional heat amount. Does not increase waste heat. On the other hand, if there is a reciprocal 1 / η that is equal to or higher than the reference heat cost within the set range of the additional heat quantity, the waste heat is increased. In addition, when increasing the waste heat, the maximum value of the additional heat quantity is set as the command additional heat quantity in the region of the reciprocal 1 / η that is equal to or higher than the reference heat cost.

  In the above embodiment, in the region where the heat cost η is equal to or less than the reference heat cost ηth, the maximum heat amount that can be generated by the engine 10 is set as the command additional heat amount Qod, but this is changed, In the region where the heat cost η is equal to or less than the reference heat cost ηth, one of the additional heat amounts that can be generated by the engine 10 is set as the command additional heat amount Qod.

  The first reference heat cost ηt1 calculated based on the required heat amount Qrq and the second reference heat cost ηt2 calculated based on the parameter relating to temperature were compared, and the larger one of them was defined as the reference heat cost ηth. By changing this, the average of the first reference heat cost ηt1 and the second reference heat cost ηt2 is set as the reference heat cost ηth, or the smaller of the first reference heat cost ηt1 and the second reference heat cost ηt2 is set as the reference heat The cost may be ηth. Alternatively, only one of the first reference heat cost ηt1 and the second reference heat cost ηt2 may be used as the reference heat cost ηth.

  ・ Establishing an economy mode that prioritizes fuel consumption and a heat request priority mode that prioritizes heat usage requirements, depending on whether the economy mode or the heat demand priority mode is set by the driver. The upper limit value is variably set. In this case, when the economy mode is set, the upper limit value of the reference heat cost ηth is made lower than when the heat request priority mode is set. Alternatively, when the heat request priority mode is set, the upper limit value of the reference heat cost ηth is not set, whereas when the economy mode is set, the upper limit value of the reference heat cost ηth is set. To do.

  In the above embodiment, the case where there is a heating request as the heat use request has been described, but the case where there is an engine warm-up request as the heat use request may be applied to the present invention.

  In the above system, a heat recovery device 23 that recovers heat energy (exhaust heat) contained in the exhaust gas by transmitting it to engine cooling water or the like is provided downstream of the catalyst 22 in the exhaust pipe 12. The exhaust heat recovered by the above may be used, for example, as heat when heating the passenger compartment. In this case, a part of the exhaust loss is recovered and used as a cooling loss.

  In the above embodiment, the heat management ECU 60 is provided and the heat management ECU 60 calculates the command heat quantity Qod. However, the engine ECU 40 may calculate the command heat quantity Qod without providing the heat management ECU 60.

  DESCRIPTION OF SYMBOLS 10 ... Engine, 13 ... Throttle valve, 15 ... Injector, 17 ... Igniter, 18, 19 ... Valve drive mechanism, 33 ... Circulation path, 35 ... Heater core, 40 ... Engine ECU, 50 ... Air-conditioner ECU, 60 ... Thermal management ECU.

Claims (7)

In a waste heat control apparatus for an engine that is applied to a waste heat reuse system that recovers and reuses waste heat of an engine, and controls the amount of waste heat of the engine based on a required heat amount accompanying a heat use request,
An increase rate calculating means for calculating a fuel increase rate indicating a fuel increase amount with respect to a generated heat amount when the engine waste heat is increased based on the request when there is the heat use request;
Determination value setting means for setting an increase rate determination value for determining whether to perform waste heat increase control for increasing the amount of engine waste heat in accordance with the heat use request, based on the fuel increase rate;
Based on the comparison result between the fuel increase rate calculated by the increase rate calculating means and the increase rate determination value set by the determination value setting means, the waste heat increase control is executed or implemented in accordance with the heat use request. Waste heat control means for switching between
An engine waste heat control device comprising: The increase rate calculating means calculates a fuel increase rate characteristic indicating a magnitude relationship of the fuel increase rate for each generated heat amount with respect to the engine operating state when starting the increase of waste heat,
When the waste heat control means performs the waste heat increase control in response to the heat utilization request, the fuel increase rate characteristic calculated by the increase rate calculation means is less than the increase rate determination value. 2. The engine waste heat control apparatus according to claim 1, wherein when the fuel increase rate on the side of the engine is present, the waste heat increase control is performed based on a generated heat amount corresponding to the fuel increase rate . When the waste heat control means performs the waste heat increase control in response to the heat utilization request, the fuel increase rate characteristic calculated by the increase rate calculation means is less than the increase rate determination value. claims the maximum amount of heat of the heat generation amount corresponding to the fuel increase rate of the side consisting, set as a command value of heat increased by the waste heat increase control, implementing the waste heat increase control based on the command value the set Item 3. The engine waste heat control device according to Item 2.   4. The engine waste heat control apparatus according to claim 1, wherein the determination value setting unit variably sets the increase rate determination value based on the required heat amount. 5.   The engine waste heat control device according to any one of claims 1 to 4, wherein the determination value setting means variably sets the increase rate determination value based on an engine coolant temperature. Temperature detection means for detecting the engine coolant temperature;
A target temperature setting means for setting a target temperature of engine cooling water when the heat utilization request occurs,
The determination value setting means variably sets the increase rate determination value based on a difference between a target temperature set by the target temperature setting means and an engine coolant temperature detected by the temperature detection means. Engine waste heat control device.   The engine waste heat control apparatus according to any one of claims 1 to 6, wherein the determination value setting means variably sets the increase rate determination value based on an outside air temperature.

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