JP6390511B2 - Water pump control device - Google Patents

Description

  The present invention relates to a control device for a water pump.

  An intercooler is provided in an intake passage of an internal combustion engine equipped with a turbocharger or a supercharger to cool intake air (air) that has been compressed by a supercharger and has risen in temperature. There are two types of intercoolers: an air-cooled type and a water-cooled type. In a water-cooled type intercooler, the intercooler is cooled by circulating cooling water in the intercooler with a water pump.

  Moreover, the following are also known as control regarding a water cooling type intercooler. The target circulation amount of the cooling water by the water pump is calculated by feedback calculation based on the amount of deviation between the temperature of the intake air cooled by the intercooler (hereinafter referred to as the outgas temperature) and the target temperature. When the target circulation amount is equal to or greater than the minimum amount of cooling water circulated by the water pump, the water pump is continuously driven so that the target circulation amount of cooling water circulates, and the target circulation amount is the minimum amount described above. If it is less, the water pump is intermittently driven so that the time average value of the cooling water circulation amount becomes the target circulation amount.

JP 2008-274909 A International Publication No. 2011/111159 JP 2012-117378 A

  As a result of earnest research to improve the performance of the intake air cooling system composed of an intercooler, a water pump, etc., the inventor found that the above-mentioned conventional control caused a large undershoot during the intermittent operation of the water pump. It was found that the target temperature may not converge quickly.

  Accordingly, an object of the present invention is to provide a water pump control device capable of intermittently driving an intercooler water pump so that the outlet gas temperature (the intake air temperature after cooling by the intercooler) quickly converges to the target temperature (target intake air temperature). Is to provide.

In order to solve the above-described problems, an intercooler disposed in an intake passage of an internal combustion engine of the present invention, a cooling water circulation path through which cooling water for cooling the intercooler circulates, and a cooling water in the cooling water circulation path are circulated. A water pump control device for driving a water pump of an intake air cooling system including a water pump to be driven so that an intake air temperature after cooling by the intercooler becomes a target intake air temperature, a target of a cooling water circulation amount in the cooling water circulation path A calculating means for calculating the amount by a feedback calculation based on a deviation amount between the intake air temperature after cooling by the intercooler and the target intake air temperature, and the target amount calculated by the calculating means is equal to or greater than a predetermined continuous operation threshold value The water pump so that the circulating amount of the cooling water in the cooling water circulation path becomes a target amount. When the target amount calculated by the calculation means is less than the continuous operation threshold value, the water amount is adjusted so that the time average value of the circulating amount of the cooling water in the cooling water circulation path becomes the target amount. Drive means for intermittently driving the pump, and the calculating means, under the situation where the water pump is intermittently driven by the drive means, the feedback gain of the feedback calculation, the cooling water in the cooling water circulation path If the temperature is low, make it smaller than if it is high.

  According to the present invention, the water pump for the intercooler can be intermittently driven so that the intake air temperature after cooling by the intercooler quickly converges to the target intake air temperature.

FIG. 1 is a schematic configuration diagram of an internal combustion engine system to which a water pump control device according to an embodiment of the present invention is applied. FIG. 2 is a flowchart of a water pump control process periodically executed by an ECU as a water pump control device according to the embodiment. FIG. 3 is an explanatory diagram of dT. FIG. 4 is an explanatory diagram of correction coefficients. FIG. 5 is an explanatory diagram of the influence of the cooling water temperature on the change in the outgas temperature during intermittent driving of the water pump.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 shows a schematic configuration of an internal combustion engine system to which a water pump control device according to an embodiment of the present invention is applied.

  This internal combustion engine system is a system mounted on a vehicle, and includes an internal combustion engine 10, an ECU (Electronic Control Unit) 40 as a water pump control device according to the present embodiment, and the like.

  The internal combustion engine 10 is a diesel engine having three cylinders. Each cylinder (intake port of each cylinder) of the internal combustion engine 10 is connected to an intake passage 12 via an intake manifold 11. Each cylinder (exhaust port of each cylinder) of the internal combustion engine 10 is connected to an exhaust passage 14 via an exhaust manifold 13.

Between the exhaust manifold 13 and the intake manifold 11, an EGR passage (Exhaust Gas Recirculation) 20 a for returning a part of the exhaust gas flowing in the exhaust manifold 13 to the intake manifold 11 is disposed. In the middle of the EGR passage 20a, the EGR passage 20a
An EGR valve 20b for adjusting the amount of exhaust flowing through the inside is provided.

  A turbine 22 b of the turbocharger 22 is disposed in the middle of the exhaust passage 14. Further, in the middle of the intake passage 12, a compressor 22a of the turbocharger 22 and an intercooler 30 for cooling the compressed air from the compressor 22a are disposed.

  An air flow meter 21 for measuring the flow rate of intake air is provided in a portion of the intake passage 12 upstream of the compressor 22a. A temperature sensor 25 for measuring the temperature of the intake air flowing into the intercooler 30 (hereinafter referred to as the inlet gas temperature) is provided at a portion of the intake passage 12 between the compressor 22a and the intercooler 30. Further, a temperature sensor 26 for measuring the temperature of the intake air cooled by the intercooler 30 (hereinafter referred to as the outgas temperature) is provided in a portion of the intake passage 12 on the downstream side of the intercooler 30.

A cooling water circulation path 31 is connected to the intercooler 30 (the cooling water inlet and outlet of the intercooler 30). In the middle of the cooling water circulation path 31, a radiator 32 for cooling the cooling water (LLC (Long Life Coolant), etc.) flowing in the cooling water circulation path 31 with outside air (running wind), and for circulating the cooling water A water pump 33 (hereinafter also referred to as a pump 33) is provided. In addition, a temperature sensor 27 for measuring the temperature of the cooling water flowing in the cooling water circulation path 31 is attached to the cooling water circulation path 31, and a temperature sensor for measuring the outside air temperature is provided in the vicinity of the radiator 32. 28 is provided.

  The ECU 40 is a unit including a CPU (Central Processing Unit), a flash ROM (Read Only Memory), a RAM (Random Access Memory), an EEPROM (Electrically Erasable Programmable Read-Only Memory), various interface circuits, and the like. The flash ROM of the ECU 40 stores a program (firmware) executed by the CPU and various information (maps) referred to by the program.

  In addition to the temperature sensors 25 to 28, the ECU 40 is electrically connected with various sensors (switch accelerator opening sensor, crank angle sensor, etc.) not shown. And ECU40 functions as a unit which controls each part of an internal combustion engine system integratively based on the signal from various sensors, when CPU runs the said program.

  Hereinafter, the function of the ECU 40 will be described focusing on the function as the control device for the water pump according to the present embodiment.

  The ECU 40 is configured (programmed) so as to periodically repeat the water pump control process of the procedure shown in FIG. 2 during operation of the internal combustion engine 10. In the following description, the inlet gas temperature and the outlet gas temperature are respectively defined as the temperature of the intake air flowing into the intercooler 30 (temperature measured by the temperature sensor 25) and after cooling by the intercooler 30, as already defined. The intake air temperature (temperature measured by the temperature sensor 26).

  As shown in FIG. 2, the ECU 40 that has started this water pump control process first sets the target circulation amount Qwp based on the output gas target temperature determined from the operation state (for example, engine speed and accelerator opening). The F / F (feed forward) flow rate used for the calculation is determined (step S101). Here, the output gas target temperature is a target value of the output gas temperature. The target circulation amount Qwp is a target value for the amount of cooling water to be circulated through the pump 33.

  The F / F flow rate is the amount of cooling water circulation that can bring the outlet gas temperature close to the outlet gas target temperature (the outlet gas temperature can be maintained when the outlet gas temperature matches the outlet gas target temperature). I just need it. Therefore, the process of step S101 may be a process for determining the F / F flow rate from the output gas temperature and the output gas target temperature, and the F / F flow rate is also used using other information (intake air amount, etc.). The process to determine may be sufficient.

  ECU40 which finished the process of step S101 performs the following processes in the following step S102.

  The ECU 40 first determines whether the pump 33 is continuously driven or intermittently driven based on the pump state information. Here, the ECU 40 manages the pump state information. It is information indicating whether the pump 33 is continuously driven or intermittently driven.

When the pump 33 is continuously driven, the ECU 40 calculates the target circulation amount Qwp using the following feedback calculation formula.

“F / F” in the equation (1) (feedback calculation equation) is the F / F flow rate calculated by the process of step S101. Gp, Gi, and Gd are a predetermined proportional term gain, integral term gain, and derivative term gain, respectively. dT (dT _n , dT _n-1 ) is a deviation amount between the outgas temperature and the outgas target temperature, as shown in FIG. dT _n is a deviation amount at the time of execution of the current step S102, and dT _n−1 is a deviation amount at the time of the previous execution of step S102.

  Then, the ECU 40 that calculated the target circulation amount Qwp ends the process of step S102.

  On the other hand, when the pump 33 is intermittently driven, the ECU 40 acquires the cooling water temperature from the temperature sensor 27, and uses the acquired cooling water temperature to set the correction coefficients a, b, and c (details will be described later). Identify. Then, the ECU 40 calculates the target circulation amount Qwp using the following feedback calculation formula.

  As is apparent from the equation (2), the correction coefficients a, b, and c are coefficients for changing each F / B (feedback) gain of the feedback arithmetic expression for calculating the target circulation amount Qwp. As schematically shown in FIG. 4, each of the correction coefficients a, b, and c is defined in advance so that the value thereof becomes smaller as the cooling water temperature decreases. In step S102, the value of each correction coefficient is specified using a map that stores the correspondence between the value of the correction coefficient and the coolant temperature and a function that indicates the correspondence.

  The ECU 40 that has finished the process of step S102 needs to change the operation state of the pump 33 based on the calculated target circulation amount Qwp, the current circulation amount of the cooling water by the pump 33 (hereinafter referred to as the current circulation amount), and the like. It is determined whether or not there is (step S103).

  If it is determined that there is no need to change the operation state of the pump 33 (step S103; NO), the ECU 40 ends the current water pump control process (the process of FIG. 2) without performing any particular process.

  On the other hand, when it is determined that the operation state of the pump 33 needs to be changed (step S103; YES), the ECU 40 performs a process of changing the operation state of the pump 33 (step S104).

Specifically, when the target circulation amount Qwp is equal to or greater than the continuous operation threshold value defined as the lower limit value of the coolant circulation amount that allows the pump 33 to be continuously operated, and the pump 33 is being intermittently driven. In step S103, it is determined that the operation state of the pump 33 needs to be changed. And ECU40 performs the process (control) which changes the drive pattern of the pump 33 to the continuous drive of the state through which the cooling water of the target circulation amount Qwp circulates in step S104.

  In addition, when the target circulation amount Qwp is less than the continuous operation threshold value and the pump 33 is continuously driven, the ECU 40 determines in step S103 that the operation state of the pump 33 needs to be changed. And ECU40 performs the process which changes the drive pattern of the pump 33 to the intermittent drive from which the time average value of the circulation amount of a cooling water becomes the target circulation amount Qwp in step S104.

  Further, the ECU 40 determines that the absolute value of the difference between the current circulation amount and the target circulation amount Qwp is equal to or greater than the first specified amount and the pump 33 is continuously driven, or the absolute value of the difference is the second specified amount. As described above, even when the pump 33 is intermittently driven, it is determined in step S103 that the operation state of the pump 33 needs to be changed. The first specified amount and the second specified amount are amounts determined in advance based on the adjustment accuracy of the circulation amount of the pump 33 and the like.

  Then, the ECU 40 performs processing according to the condition found to be established, that is, processing for changing the circulating amount of the cooling water by the pump 33 to the target circulating amount Qwp, and the time average value of the circulating amount of the cooling water. In step S104, a process of changing the intermittent drive pattern (a combination of a time for driving the pump 33 and a time for stopping the pump 33) so as to be the target circulation amount Qwp is performed.

  ECU40 which performed the above processes in step S104 complete | finishes this water pump control process (process of FIG. 2).

  Hereinafter, the reason why the target circulation amount Qwp during intermittent driving of the pump 33 is calculated by the equation (2) will be described.

  When the pump 33 is intermittently driven, there are a period (time period) in which the pump 33 is ON and a pause period in which the pump 33 is paused. Since the circulation of the cooling water is stopped during the suspension period of the pump 33, the heat exchange between the cooling water and the intake air during the suspension period of the pump 33 proceeds substantially only by natural convection of the cooling water. Therefore, the heat exchange rate in the intercooler 30 during the pause period of the pump 33 is extremely slow.

  Moreover, when the temperature of cooling water falls, the viscosity of cooling water will fall, and when a viscosity falls, a heat exchange rate will become slow. Therefore, when the temperature of the cooling water is low, the heat exchange rate in the intercooler 30 during the pause period of the pump 33 is further slowed down.

  Therefore, as schematically shown in FIG. 5, when the pump 33 is intermittently driven, the lower the coolant temperature is, the lower the cooling water temperature, even if the amount of deviation between the output gas target temperature and the output gas temperature is the same. The response delay of the outgas temperature with respect to the control 33 is increased.

  Then, if it takes time for the outgas temperature to reach the outgas target temperature, the F / B correction amount increases due to the integral term. It is determined so that the outlet gas temperature can be converged to the outlet gas target temperature in a short time under the circulating condition. Therefore, when the target circulation amount Qwp at the time of intermittent driving of the pump 33 is calculated by the equation (1), the target circulation amount Qwp is excessively increased / decreased by the integral term, the output gas temperature is large, and it is easy to undershoot / overshoot. . Further, when the target circulation amount Qwp at the time of intermittent driving of the pump 33 is calculated by the equation (1), each F / B gain is not an appropriate value, so the outgas temperature becomes a temperature near the outgas target temperature. It takes time to stabilize.

  On the other hand, if the target circulation amount Qwp at the time of intermittent drive of the pump 33 is calculated by the equation (2), F / B gains (Gp · a, Gi · b, Gd) of the proportional term, integral term, and derivative term Since c) becomes small, it is possible to prevent excessive F / B correction by the integral term. In addition, since each F / B gain is changed to a value (small value) suitable for a long response delay (dead time), the output gas temperature can be quickly stabilized when the output gas target temperature is changed. Is possible.

<Deformation>
The above-described technique can perform various modifications. For example, the water pump control process (FIG. 2) is transformed into a process that specifies the values of the correction coefficients a, b, and c not from the cooling water temperature itself but from a temperature correlated with the cooling water temperature (for example, the outside air temperature). Also good. Further, the water pump control process can be modified to a process of changing the values of Gp, Gi, Gd itself when calculating the target circulation amount Qwp when the pump 33 is intermittently driven. In addition, when calculating the target circulation amount Qwp when the pump 33 is intermittently driven, the water pump control processing is performed by using one or two F / B gain values in the F / B gains of the proportional term, the integral term, and the differential term. It can also be transformed into a process that changes according to the cooling water temperature. However, in order to increase the convergence speed, it is preferable that all the three types of F / B gain values are changed according to the coolant temperature as described above.

DESCRIPTION OF SYMBOLS 10 Internal combustion engine 11 Intake manifold 12 Intake passage 13 Exhaust manifold 14 Exhaust passage 20a EGR passage 20b EGR valve 21 Air flow meter 22 Turbocharger 22a Compressor 22b Turbine 25-28 Temperature sensor 30 Intercooler 31 Cooling water circulation path 32 Radiator 33 Water pump 40 ECU

Claims (1)

A water pump for an intake air cooling system comprising an intercooler disposed in an intake passage of an internal combustion engine, a cooling water circulation path through which cooling water for cooling the intercooler circulates, and a water pump for circulating cooling water in the cooling water circulation path A water pump control device for driving the intake air temperature after cooling by the intercooler to be a target intake air temperature,
A calculation means for calculating a target amount of the cooling water circulation amount in the cooling water circulation path by a feedback calculation based on a deviation amount between the intake air temperature after cooling by the intercooler and the target intake air temperature;
When the target amount calculated by the calculation means is equal to or greater than a predetermined continuous operation threshold, the water pump is continuously driven so that the cooling water circulation amount in the cooling water circulation path becomes the target amount, When the target amount calculated by the calculation means is less than the continuous operation threshold, the water pump is intermittently driven so that the time average value of the circulating amount of the cooling water in the cooling water circulation path becomes the target amount. Driving means;
With
In the situation where the water pump is intermittently driven by the driving means, the calculating means reduces the feedback gain of the feedback calculation when the cooling water temperature in the cooling water circulation path is low compared to when it is high. A control device for a water pump.

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