Control device for internal combustion engines

Abstract

To accurately calculate a value which is referred to when estimating a wall surface temperature of a cylinder bore.SOLUTION: A control device 100 executes processing for calculating a wall surface temperature of a cylinder bore 4b on the basis of a cooling water flow rate in a water jacket 70 provided in a cylinder block 2 of an internal combustion engine 1, a cooling water temperature in the water jacket 70 and a heat generation amount when fuel supplied to a cylinder of the internal combustion engine 1 is burned. The control device 100 executes flow rate calculation processing for calculating the cooling water flow rate on the basis of engine speed of the internal combustion engine 1 and an opening variable related to an opening of a thermostat 68.SELECTED DRAWING: Figure 1

Claims

1. A control device applied to an internal combustion engine having a cooling water passage comprising a radiator, a bypass passage that bypasses the radiator, a thermostat that adjusts the flow rate of cooling water passing through the radiator according to the temperature of the cooling water, and a mechanical water pump connected to the crankshaft, which performs a process to calculate the wall temperature of the cylinder bore based on the flow rate of cooling water in a water jacket provided in the cylinder block of the internal combustion engine, the temperature of the cooling water in the water jacket, and the amount of heat generated when fuel supplied to the cylinders of the internal combustion engine burns, A flow rate calculation process that calculates the cooling water flow rate based on the engine rotation speed of the internal combustion engine and an opening variable relating to the opening degree of the thermostat, The temperature calculation process involves calculating the temperature difference between the outlet temperature, which is the temperature of the cooling water discharged from the internal combustion engine, and the inlet temperature, which is the temperature of the cooling water flowing into the internal combustion engine, based on the heat flow rate calculated based on the heat output, the cooling water flow rate, the density of the cooling water, and the specific heat of the cooling water, and then calculating the temperature of the cooling water in the water jacket based on the temperature difference between either the outlet temperature or the inlet temperature. Control device for internal combustion engines.

2. The cooling water passage is a passage in which the pressure loss is greater when the cooling water flows through the bypass passage than when it flows through the radiator. The flow rate calculation process, when the opening variable is a value that increases the flow rate of cooling water in the bypass channel, executes a process to calculate the cooling water flow rate such that it is lower than when the opening variable is a value that decreases the flow rate of cooling water. A control device for an internal combustion engine according to claim 1.

3. The temperature calculation process performs a correction process to correct the temperature difference based on the opening variable. A control device for an internal combustion engine according to claim 1.

4. The correction process is a process that corrects the temperature difference so that when the opening variable is a value that increases the flow rate of the cooling water in the bypass passage, the temperature difference becomes smaller compared to when the opening variable is a value that decreases the flow rate of the cooling water. The control device for an internal combustion engine according to claim 3.

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