JP2008255871A - Cooling system - Google Patents

Abstract

[PROBLEMS] To quickly raise the temperature of cooling water without depending on the fuel to be burned.
The ECU reads the alcohol concentration of the fuel, the engine speed, the load, and the coolant temperature (steps S100 and S101). Based on the rotation speed, the load, and the coolant temperature, the flow rate of the coolant during normal fuel is determined (step S102). It is determined whether or not the cooling water temperature is below a predetermined threshold value and there is a heating request (steps S103 and S104). A correction amount of the cooling water flow rate according to the read alcohol concentration is determined (step S105). The attenuation rate of the correction amount according to the temperature of the cooling water is determined (step S106). Based on the determined correction amount and attenuation rate, the correction of the coolant flow rate is determined (step S107). The electric W / P is driven so that the determined correction amount is obtained.
[Selection] Figure 4

Description

  The present invention relates to a cooling device for an internal combustion engine, and more particularly to control of a flow rate of a cooling medium.

In a water-cooled cooling device for an internal combustion engine, it is known to install a throttle valve in a bypass cooling water passage (see Patent Document 1). In the water-cooled cooling device of Patent Document 1, the flow rate of the bypass cooling water that the cooling water circulates at a low temperature is decreased by the throttle valve, and the flow rate of the cooling water to the heating device side is increased. By increasing the flow rate of the cooling water to the heating device side, the heating device can sufficiently exhibit the heating capacity even when the cooling water is at a low temperature.
Japanese Patent Laid-Open No. 54-163241

  On the other hand, in recent years, it has been proposed to use various fuels such as alcohol as a fuel for an internal combustion engine. Even if the cooling device as described above is used, there is a problem that the heating capacity becomes insufficient depending on the fuel used.

  An object of this invention is to provide the cooling device which fully exhibits the capability of the apparatus which utilizes the exhaust heat of an internal combustion engine as a heat source like a heating apparatus irrespective of the fuel used for an internal combustion engine.

  A cooling device according to a first aspect of the present invention is a cooling device capable of recovering heat accumulated in a cooling medium that is circulated through the internal combustion engine and used for cooling the internal combustion engine. The cooling device includes a fuel property detection unit, a flow rate adjustment unit, and a flow rate correction unit. The fuel property detection means detects the property of fuel burned in the internal combustion engine. The flow rate adjusting means adjusts the flow rate of the cooling medium. The flow rate correction means corrects the flow rate of the cooling medium in accordance with the properties of the fuel.

  According to the first invention, the heat generated in the internal combustion engine is stored in the cooling medium. The heat stored in the cooling medium is recovered and can be used as a heat source according to the purpose. The temperature of the cooling medium is adjusted by adjusting the flow rate of the cooling medium by the flow rate adjusting means. The amount of heat generated in the internal combustion engine varies depending on the properties of the fuel to be burned. Therefore, the flow rate correction means corrects the flow rate of the cooling medium in accordance with the properties of the fuel used in the internal combustion engine. Therefore, even when the fuel to be burned changes, the flow rate of the cooling medium is corrected, so that it is possible to ensure the amount of heat to be recovered early.

  The cooling device according to the second invention further includes temperature detecting means for detecting the temperature of the cooling medium in addition to the configuration of the first invention. When the temperature of the cooling medium detected by the temperature detection means is lower than a predetermined temperature, the flow rate correction means corrects the flow rate of the cooling medium.

  According to the second invention, the coolant flow rate is corrected only when the temperature of the coolant is low. Therefore, since correction is performed when the amount of heat to be recovered is insufficient because the temperature of the cooling medium is low, cooling of the internal combustion engine more than necessary is prevented.

  The cooling device according to the third aspect of the invention further includes a temperature detection means for detecting the temperature of the cooling medium in addition to the configuration of the first aspect of the invention. After the flow rate correction unit corrects the flow rate of the cooling medium, the correction of the flow rate of the cooling medium by the flow rate correction unit is stopped when the temperature of the cooling medium exceeds a predetermined temperature.

  According to the third invention, the correction of the flow rate is stopped when the temperature of the cooling medium rises to a predetermined temperature by the correction of the flow rate. Therefore, the correction is stopped when the temperature of the cooling medium is high and the amount of heat recovered is sufficiently large. Stopping the correction prevents the internal combustion engine from being cooled more than necessary.

  In addition to the configuration of the third invention, the cooling device according to the fourth invention reduces the correction amount by the flow rate correction means as the difference between the temperature of the cooling medium and the predetermined temperature decreases.

  According to the fourth invention, the temperature of the cooling medium is increased by the correction of the cooling medium, and the correction amount is reduced as the temperature approaches the predetermined temperature. As the temperature of the cooling medium approaches a predetermined temperature, the amount of heat recovered is also reduced. Therefore, the correction amount is reduced as the temperature of the cooling medium approaches a predetermined temperature, and the internal combustion engine is prevented from being cooled more than necessary.

  In the cooling device according to the fifth aspect of the invention, in addition to the configuration of the first aspect of the invention, the flow rate correction means corrects the flow rate of the cooling medium in accordance with the heat generation amount of the fuel.

  According to the fifth invention, the temperature of the cooling medium can be raised more appropriately by performing correction according to the amount of heat generated by the fuel that contributes to the amount of heat generated in the internal combustion engine.

  According to the present invention, the ability of a device that uses exhaust heat of an internal combustion engine as a heat source for a predetermined purpose can be sufficiently exerted regardless of the fuel used in the internal combustion engine.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a configuration diagram of a cooling device to which an embodiment of the present invention is applied.

  The cooling device 20 is mounted on a vehicle, for example, and is used for cooling the engine 10 for driving the vehicle. The cooling device 20 includes first to third medium passages 21a, 21b, 21c, a radiator 22, an electric water pump (W / P) 23, a thermostat 24, a heater core 25, an ECU 26, and the like.

  The outlet of the engine 10 and the inlet of the radiator 22 are connected via the first medium passage 21a. Further, the inlet of the engine 10 and the outlet of the radiator 22 are connected via the first medium passage 21a. The electric W / P 23 is provided between the outlet of the radiator 22 and the inlet of the engine 10.

  Cooling water flows through the first medium passage 21a. Cooling water is supplied to the engine 10 by the electric W / P 23. The cooling water supplied to the engine 10 flows from the cylinder block 11 through the cylinder head 12 so as to flow upward from below the engine 10. The heat generated in the engine 10 is recovered in the cooling water, and the engine 10 is cooled. Cooling water flowing out from the engine 10 flows into the radiator 22. The cooling water is cooled by heat exchange with the atmosphere by the radiator 22. In the present embodiment, the cooling water is used as a cooling medium for the engine, but is not limited to the cooling water. Any cooling medium used for heat exchange can be used.

  The second medium passage 21b is connected to the first medium passage 21a on the inlet side and the outlet side of the radiator 22. A thermostat 24 is provided at the end of the second medium passage 21 b on the first medium passage 21 a side on the outlet side of the radiator 22.

  When the engine 10 is started, the engine 10 is warmed up until the temperature of the cooling water rises to a predetermined temperature range. During the warm-up operation of the engine 10, the thermostat 24 is closed, and the cooling water flowing out from the engine 10 bypasses the radiator 22 and flows through the second medium passage 21b. By bypassing the radiator 22, the temperature of the cooling water rises rapidly. When the temperature of the cooling water enters a predetermined temperature range, the thermostat 24 is opened and the cooling water flows into the radiator 22.

  In addition, one end of the third medium passage 21c is connected to the first medium passage 21a on the inlet side of the radiator 22. The other end of the third medium passage 21c is connected to the first medium passage 21a between the thermostat 24 and the electric W / P 23 of the first medium passage 21a. A heater core 25 is provided in the third medium passage 21c. The heater core 25 is a heat exchanger, and heats the cooling water flowing out of the engine 10 and the air in the vehicle interior to heat the vehicle interior.

  The engine 10 is provided with a rotation speed sensor 30 that measures the rotation speed of the engine 10. The accelerator 31 is provided with an accelerator opening sensor (not shown) that detects the opening of the accelerator. Although the accelerator opening is detected as a load on the engine 10, any other variable for estimating the load on the engine 10, such as an intake air amount or a fuel injection amount, may be detected as a load. The cylinder head 12 is provided with a temperature sensor 32 for measuring the coolant temperature.

  The ECU 26 acquires the engine speed, the accelerator opening, and the coolant temperature detected by each sensor. The ECU 26 determines an appropriate flow rate for the acquired information based on the map data of the flow rate of the cooling water with respect to the engine speed, the engine load, the cooling water temperature, and the like. The ECU 26 drives the electric W / P 23 so that the flow rate of the cooling water becomes the determined flow rate.

  An alcohol concentration sensor 33 is provided in the fuel tank 13 that stores the fuel of the engine 10. The alcohol concentration sensor 33 detects the alcohol concentration of the fuel stored in the fuel tank 13. Fuel alcohol concentration data is also sent to the ECU 26. The ECU 26 corrects the flow rate of the cooling water obtained based on the correspondence map data based on the alcohol concentration of the fuel.

  For example, as shown in FIG. 2, the ECU 26 drives the electric W / P 23 so that the correction amount of the coolant flow rate increases as the alcohol concentration in the fuel increases. The correction of the coolant flow rate is performed when the coolant temperature is equal to or lower than a predetermined threshold value.

  When the flow rate of the cooling water is increased by the correction, the temperature of the cooling water is increased. As the coolant temperature approaches the predetermined threshold, the correction amount is attenuated. For example, the amount of correction of the flow rate obtained by the ECU 26 is multiplied by an attenuation rate corresponding to the coolant temperature as shown in FIG.

  Next, drive control of the cooling device 20 executed by the ECU 26 in the cooling device 20 according to the present embodiment will be described using the flowchart of FIG.

  In step S100, the ECU 26 acquires fuel alcohol concentration data. In the next step S101, the ECU 26 acquires engine speed data, load data, and water temperature data.

  After obtaining each data, the process proceeds to step S102. In step S102, the flow rate of the cooling water when the normal fuel, that is, the fuel of the engine 10 is gasoline, is determined based on each data acquired in step S101.

  In step S103, it is determined whether or not the coolant temperature detected in step S102 is below a predetermined threshold. When the water temperature falls below the predetermined threshold, the process proceeds to step S104. When the water temperature exceeds the predetermined threshold, step S104 to step S107 are skipped and the process proceeds to step S108.

  In step S104, it is determined whether or not there is a heating request. The heating request may be determined by switching of the heating switch by the driver, or the generation of the heating request may be determined based on the temperature in the vehicle and the set temperature by an automatic air conditioner (not shown). . When there is a heating request, the process proceeds to step S105. On the other hand, when there is no heating request, step S105 to step S107 are skipped and the process proceeds to step S108.

  In step S105, the correction amount of the cooling water flow rate according to the alcohol concentration detected in step S100 is determined using the correspondence map. When the correction amount is obtained, the process proceeds to step S106, and an attenuation rate to be multiplied by the correction amount according to the coolant temperature is determined using the correspondence map. In step S107, the cooling water flow rate is corrected using the correction amount of the cooling water flow rate determined by multiplying the correction amount determined in step S105 and step S106 by the attenuation rate.

  In step S108, the drive of the electric W / P 23 is controlled so that the coolant flow rate obtained in step S102 or step S107 is obtained.

  According to the cooling device 20 configured as described above, when alcohol mixed fuel is used as the fuel, when there is a heating request at the time of starting, the flow rate of the cooling water is corrected according to the alcohol concentration in the fuel. Therefore, even if alcohol fuel, which takes a long time to increase the temperature of the cooling water during the warm-up operation because the calorific value is lower than that of gasoline, the temperature increase of the cooling water can be accelerated. As a result, even during warm-up operation, it is possible to exhibit a greater heating capacity.

  In this embodiment, the correction amount of the coolant flow rate is changed according to the alcohol concentration in the fuel. However, the correction amount may be increased as the heat generation amount of the fuel decreases. More precise heating control is possible by directly measuring the amount of heat generated by the fuel. However, as in this embodiment, by measuring the correspondence relationship between the calorific value of the mixed fuel corresponding to the alcohol concentration from the theoretical calorific value of alcohol and gasoline in advance, and changing the correction amount according to the alcohol concentration, It is possible to easily correct the flow rate. Further, the correction amount of the cooling water flow rate may be obtained using any fuel property that affects the heat exchange with the cooling water.

  Further, in the present embodiment, the correction amount is attenuated according to the difference between the predetermined threshold value and the coolant temperature, but it may not be attenuated. This is because even if it is not attenuated, it is possible to raise the temperature of the cooling water as soon as possible after starting and to exhibit a sufficient heating capacity. However, by attenuating the correction amount as in this embodiment, it becomes possible to raise the temperature of the engine 10 at an early stage and stabilize combustion.

  In this embodiment, the cooling water flow rate is corrected when the cooling water temperature falls below a predetermined threshold. However, sufficient heating can be achieved even if the flow rate is corrected without comparing the cooling water temperature with the predetermined threshold. It is possible to demonstrate performance. However, if the cooling water temperature exceeds a certain temperature, sufficient heating is possible, but fuel consumption deteriorates due to deviation from the ideal flow rate determined by the correspondence map. Therefore, it is preferable not to correct the flow rate when the cooling water temperature exceeds a predetermined threshold as in this embodiment.

  In the present embodiment, the ECU 26 controls the electric W / P 23 to adjust the flow rate. However, the flow rate may be adjusted by any other flow rate adjusting means. For example, the flow rate may be adjusted by providing a throttle valve at the inlet of the engine 10 and adjusting the opening of the throttle valve.

  In the present embodiment, the heat recovered from the cooling water by the heater core 25 is used for heating the vehicle, but the recovered heat may be used for any other purpose.

It is a block diagram which shows typically the structure of the cooling device to which one Embodiment of this invention is applied. It is a figure which shows the correction amount of the cooling water amount with respect to alcohol concentration. It is a figure which shows the attenuation factor of the correction amount with respect to cooling water temperature. It is a flowchart which shows the control structure of the program which ECU performs.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Engine 11 Cylinder block 12 Cylinder head 13 Fuel tank 20 Cooling device 21a, 21b, 21c 1st, 2nd, 3rd medium channel | path 23 Electric water pump (W / P)
25 Heater core 26 ECU
32 Temperature sensor 33 Alcohol concentration sensor

Claims (5)

A cooling device capable of recovering heat accumulated in a cooling medium used for cooling the internal combustion engine through circulation to the internal combustion engine,
Fuel property detecting means for detecting the property of fuel burned in the internal combustion engine;
Flow rate adjusting means for adjusting the flow rate of the cooling medium;
A cooling device comprising: a flow rate correcting means for correcting the flow rate of the cooling medium according to the property of the fuel. Temperature detecting means for detecting the temperature of the cooling medium,
2. The cooling device according to claim 1, wherein the flow rate correction unit corrects the flow rate of the cooling medium when the temperature of the cooling medium detected by the temperature detection unit is lower than a predetermined temperature. Temperature detecting means for detecting the temperature of the cooling medium,
The correction of the flow rate of the cooling medium by the flow rate correction unit is stopped when the temperature of the cooling medium exceeds a predetermined temperature after the flow rate correction unit corrects the flow rate of the cooling medium. Item 2. The cooling device according to Item 1.   The cooling device according to claim 3, wherein the correction amount by the flow rate correction unit is reduced as a difference between the temperature of the cooling medium and the predetermined temperature is reduced.   The cooling device according to any one of claims 1 to 4, wherein the flow rate correction unit corrects the flow rate of the cooling medium in accordance with a heat generation amount of the fuel.