Intake air temperature estimation method, intake air temperature estimation device, and internal combustion engine

Abstract

To improve the accuracy of intercooler outlet temperature estimation. [Solution] The intercooler outlet intake air temperature estimation unit S2 estimates the intercooler outlet intake air temperature using the cooling efficiency calculated by the intercooler cooling efficiency estimation unit S1 (intercooler cooling efficiency map), the cooling water temperature detected by the cooling water temperature sensor 23, and the intercooler inlet intake air temperature detected by the inlet-side intake air temperature sensor 24. The intercooler cooling efficiency map assigns cooling efficiency values ​​corresponding to the intake air flow rate and cooling water flow rate into the intercooler 5.

Description

Technical Field

[0001] The present invention relates to an intake air temperature estimation method, an intake air temperature estimation device, and an internal combustion engine.

Background Art

[0002] For example, Patent Document 1 discloses a technique for estimating the outlet air temperature of an intercooler that forcibly cools intake air heated by supercharging with a turbocharger using the inlet temperature of the intercooler, the outside air temperature, and the intercooler efficiency. In this Patent Document 1, the intercooler efficiency is obtained by dividing the value obtained by subtracting the intercooler outlet air temperature from the intercooler inlet air temperature by the intercooler inlet air temperature. <00000.gif>

Prior Art Document

Patent Document

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in Patent Document 1, when estimating the intercooler outlet temperature, the flow rate of the refrigerant flowing into the intercooler is not considered, and there is room for further improvement in improving the estimation accuracy of the intercooler outlet temperature.

Means for Solving the Problems

[0005] The present invention is characterized in that the intake air temperature on the outlet side of a water-cooled cooling device capable of cooling the intake air flowing through the intake passage of an internal combustion engine is estimated using the cooling efficiency calculated using a cooling efficiency calculation map to which a cooling efficiency corresponding to the intake air flow rate and the cooling water flow rate flowing through the cooling device is assigned.

Effects of the Invention

[0007] [Figure 1] A cross-sectional view of the main part of an internal combustion engine to which the present invention is applied. [Figure 2] A perspective view of an intake system attached to an internal combustion engine to which the present invention is applied. [Figure 3] A schematic diagram illustrating the procedure for estimating the intake air temperature at the intercooler outlet. [Figure 4] A schematic diagram illustrating an example of an intercooler cooling efficiency map. [Modes for carrying out the invention]

[0008] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. Figure 1 is a cross-sectional view of the main part of an internal combustion engine 1 to which the present invention is applied. Figure 2 is a perspective view of an intake device 3 attached to the internal combustion engine 1 to which the present invention is applied.

[0009] As shown in Figures 1 and 2, an intake device 3 is attached to the cylinder head 2 of the internal combustion engine 1. The intake device 3 is positioned in the intake passage through which the intake air introduced into the internal combustion engine 1 flows and constitutes part of the intake passage. It has a surge tank 4, a water-cooled intercooler 5 connected to the surge tank 4, and a mounting flange 6 that fixes the intercooler 5 to the cylinder head 2. A supercharger (not shown) is positioned upstream of the intake device 3 in the direction of intake air flow. In other words, the internal combustion engine 1 is an internal combustion engine with a supercharger.

[0010] The surge tank 4 includes a tank body 7 that extends along the cylinder row direction of the internal combustion engine 1, and an intake pipe connection portion 8 that is located upstream of the tank body 7 in the intake air flow direction and is continuous with the tank body 7.

[0011] The tank body 7 has a downstream end 9, which is the downstream end in the direction of intake airflow, connected to the intercooler 5. The intake pipe connection part 8 is connected to an intake pipe (not shown) that constitutes the intake passage via a connection flange 10 formed at the upstream end in the direction of intake airflow.

[0012] The intercooler 5 is a cooling device and has an internal intake passage 11 through which intake air flows and an internal cooling water passage (intercooler refrigerant passage) 12 through which cooling water (refrigerant) flows. The first end 13 of the intercooler 5, which is the upstream end of the internal intake passage 11 in the direction of intake air flow, is connected to the downstream end 9 of the main body of the surge tank 4, and the second end 14, which is the downstream end of the internal intake passage 11 in the direction of intake air flow, is connected to the upstream end 17 of the flange of the mounting flange 6. The intercooler 5 is capable of heat exchange between the intake air in the internal intake passage 11 and the cooling water in the internal cooling water passage 12.

[0013] In the intercooler 5, cooling water is supplied from the cooling water inlet 15 to the cooling water passage 12 inside the intercooler, and the cooling water from the cooling water passage 12 inside the intercooler is discharged from the cooling water outlet 16.

[0014] The mounting flange 6 is roughly cylindrical in shape, with the upstream end 17 of the flange, which is on the upstream side in the intake airflow direction, connected to the second end 14 of the intercooler 5, and the downstream end 18 of the flange, which is on the downstream side in the intake airflow direction, attached to the side wall 2a of the cylinder head 2.

[0015] In Figure 1, reference numeral 19 denotes an intake port that opens into the side wall 2a of the cylinder head 2.

[0016] The internal combustion engine 1 is controlled by a control unit 21. The control unit 21 is a well-known digital computer equipped with a CPU, ROM, RAM, and an input / output interface.

[0017] The control unit 21 receives output signals from various sensors such as an air flow meter 22 that detects the intake air volume, a cooling water temperature sensor 23 that detects the temperature of the cooling water supplied to the intercooler 5, and an inlet side intake air temperature sensor 24 that detects the intake air temperature at the inlet of the intercooler 5.

[0018] Then, as shown in FIG. 3, the control unit 21 uses the output signals from these various sensors to estimate the intercooler outlet intake air temperature, which is the intake air temperature discharged from the outlet of the intercooler 5. FIG. 3 is an explanatory diagram schematically showing the estimation procedure of the intercooler outlet intake air temperature.

[0019] That is, the intercooler outlet intake air temperature is estimated by an intercooler outlet intake air temperature estimator S2 using the cooling efficiency calculated by an intercooler cooling efficiency estimator S1, the cooling water temperature detected by the cooling water temperature sensor 23, and the intercooler inlet intake air temperature detected by the inlet side intake air temperature sensor 24. The intercooler cooling efficiency estimator S1 and the intercooler outlet intake air temperature estimator S2 are included in the control unit 21.

[0020] FIG. 4 is an explanatory diagram schematically showing an example of an intercooler cooling efficiency calculation map used by the intercooler cooling efficiency estimator S1. The intercooler cooling efficiency estimator S1 is assigned a cooling efficiency value corresponding to the flow rate of the intake air (intake air flow rate) flowing into the intercooler 5 and the flow rate of the cooling water (cooling water flow rate). The flow rate of the intake air (intake air flow rate) flowing into the intercooler 5 is calculated by the control unit 21 using, for example, the detection signal of the air flow meter 22. The flow rate of the cooling water (cooling water flow rate) flowing into the intercooler 5 is estimated by the control unit 21 using, for example, the drive duty of an electric pump that supplies cooling water to the intercooler 5.

[0021] The intercooler cooling efficiency calculation map is a representation of the flow rate of intake air (intake air flow rate) and the flow rate of cooling water (cooling water flow rate) entering the intercooler 5 on a coordinate axis, and is stored in the ROM of the control unit 21. The intercooler cooling efficiency calculation map is created in advance by obtaining the cooling efficiency from the actual machine.

[0022] In Figure 4, the intake airflow rate is Q. a1 Q is the largest (most frequent) value. an Q is the smallest (lowest) value. The cooling water flow rate is Q w1 Q is the smallest (least) value. wn This is the largest (most frequent) value. The cooling efficiency of the intercooler 5 is the combination of intake airflow rate and coolant flow rate within the operating range of the internal combustion engine 1, where η is the value when the intake airflow rate is large and the coolant flow rate is small. 11 This represents the smallest value, and as a general trend, the value is set to be larger as the intake airflow rate decreases and the coolant flow rate increases. In the region of low intake airflow rate (right side of the map), the cooling efficiency tends to change less with coolant flow rate, and there is almost no change in the vertical axis direction.

[0023] The cooling efficiency can be read (calculated) from the intercooler cooling efficiency calculation map based on the estimated intake air flow rate and cooling water flow rate.

[0024] The intercooler outlet intake air temperature estimation unit S2 estimates the intercooler outlet intake air temperature using the following equation (1).

[0025]

number

[0026] The above equation (1) is based on the formula for calculating the cooling efficiency of the intercooler 5 shown in the following equation (2).

[0027]

number

[0028] In the internal combustion engine 1 of the above-described embodiment, by using the cooling efficiency of the intercooler 5 calculated using a simple intercooler cooling efficiency calculation map based on the intake air flow rate and cooling water flow rate, it is possible to perform a highly accurate estimation of the intake air temperature on the outlet side of the intercooler 5 without increasing complexity.

[0029] Furthermore, the cooling efficiency of the intercooler 5 is defined by equation (2) described above, making it possible to set the cooling efficiency of the intercooler 5 according to the intake air flow rate and cooling water flow rate of the intercooler 5. Therefore, the intake air temperature at the outlet side of the cooling device of the intercooler 5 can be estimated with high accuracy regardless of the intake air temperature at the inlet of the intercooler 5 and the temperature of the cooling water flowing into the intercooler 5 (for any combination of both temperatures).

[0030] Furthermore, the internal combustion engine 1 does not have a temperature sensor for detecting the intake air temperature located downstream of the intercooler 5. In other words, since the internal combustion engine 1 of the above embodiment can estimate the intake air temperature at the intercooler outlet with high accuracy, the temperature sensor for detecting the intake air temperature downstream of the intercooler 5 can be omitted.

[0031] When the intercooler 5 is positioned adjacent to the side wall 2a of the cylinder head 2, the position of the temperature sensor located downstream of the intercooler 5 is limited to immediately behind the intercooler 5 due to layout constraints. This is because it is difficult to install a temperature sensor on the cylinder head 2. In other words, when the intercooler 5 is positioned adjacent to the side wall 2a of the cylinder head 2, it is difficult to install a temperature sensor in a location that can uniformly measure the intake air temperature downstream of the intercooler 5. For example, locations where it is easy to install a temperature sensor may have stagnation in the intake airflow, while locations where there is no stagnation in the intake airflow may be difficult to install a temperature sensor in.

[0032] However, the internal combustion engine 1 in the above-described embodiment can omit a temperature sensor that detects the intake air temperature downstream of the intercooler 5 by estimating the intake air temperature downstream of the intercooler 5, thus resolving the aforementioned problem of difficulty in arranging a temperature sensor that detects the intake air temperature downstream of the intercooler 5.

[0033] Although specific embodiments of the present invention have been described above, the present invention is not limited to the embodiments described above, and various modifications are possible without departing from the spirit of the invention.

[0034] For example, the intercooler 5 may be fixed directly to the cylinder head 2 of the internal combustion engine 1, rather than being fixed to the cylinder head 2 via a mounting flange 6. In other words, the intercooler 5 may be directly connected to the cylinder head 2.

[0035] For example, the present invention is also applicable to cooling devices other than the intercooler 5.

[0036] The above-described embodiments relate to an intake air temperature estimation method, an intake air temperature estimation device, and an internal combustion engine. [Explanation of symbols]

[0037] 1…Internal combustion engine 2…Cylinder head 2a...Side wall 3…Intake system 4… Surge tank 5…Intercooler 6…Mounting flange 7... Tank body 8... Intake pipe connection 9… Downstream end of the main body 10…Connecting flange 11…Intake passage inside the intercooler 12…Cooling water passages inside the intercooler 13...First end 14…Second end 15...Cooling water inlet section 16...Cooling water outlet section 17…Flange upstream end 18… Downstream end of flange 19…Intake port 21…Control Unit 22... Airflow meter 23…Cooling water temperature sensor 24... Inlet side intake air temperature sensor

Claims

1. A method for estimating the intake air temperature at the outlet side of a water-cooled cooling device capable of cooling the intake air flowing through the intake passage of an internal combustion engine, An intake temperature estimation method characterized by estimating the intake air temperature on the outlet side of the cooling device using a cooling efficiency calculated using a cooling efficiency calculation map in which cooling efficiencies corresponding to the intake air flow rate and cooling water flow rate flowing through the above-mentioned cooling device are assigned.

2. The method for estimating intake air temperature according to claim 1, characterized in that the cooling efficiency is defined by equation (2). [Math 2]

3. A water-cooled cooling system capable of cooling the intake air flowing through the intake passage of an internal combustion engine, A cooling efficiency calculation map is provided, in which cooling efficiency values ​​corresponding to the intake air flow rate and cooling water flow rate of the above-mentioned cooling device are assigned. An intake air temperature estimation device characterized by having an estimation unit that estimates the intake air temperature on the outlet side of the cooling device using the cooling efficiency calculated using the above-mentioned cooling efficiency calculation map.

4. A water-cooled cooling system capable of cooling the intake air flowing through the intake passage, A cooling efficiency calculation map is provided, in which cooling efficiency values ​​corresponding to the intake air flow rate and cooling water flow rate of the above-mentioned cooling device are assigned. It includes an estimation unit that estimates the intake air temperature on the outlet side of the cooling device using the cooling efficiency calculated using the above cooling efficiency calculation map, An internal combustion engine characterized in that a sensor for detecting intake air temperature is not located downstream of the above-mentioned cooling device.

5. The internal combustion engine according to claim 4, characterized in that the above-mentioned cooling device is arranged adjacent to the side wall of the cylinder head.

6. The internal combustion engine according to claim 5, characterized in that the above-mentioned cooling device is directly connected to the cylinder head.

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