Engine Cooling Device

Abstract

To suppress a delay of a rise of a temperature of a catalyst.SOLUTION: In a cooling device of an engine having a circulation flow passage of cooling water which is constituted by including a radiator and an exhaust-system flow passage which is formed in an exhaust system of the engine in which a catalyst is attached to the exhaust system, a pump for pressure-sending the cooling water of the circulation flow passage, and a control device for controlling the engine, when a temperature of a catalyst is equal to or higher than a first temperature threshold, the control device executes first control for controlling the pump by setting a basic flow rate based on a rotation number and a load rate of the engine to a requirement flow rate, and when the temperature of the catalyst is lower than the first temperature threshold, the control device executes second control for controlling the pump by setting the requirement flow rate by guarding the basic flow rate by an upper limit at an upper limit flow rate.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to an engine cooling device.

Background Art

[0002] Conventionally, as an engine cooling device of this type, in an engine cooling device in which an exhaust manifold and an exhaust catalyst device are connected in sequence to an exhaust port of an engine body, as a cooling water passage for circulating cooling water between a radiator, the engine body, and a cooling adapter that cools the exhaust manifold, there is provided a first cooling water passage through which cooling water from the radiator flows to the cooling adapter via the engine body, and a second cooling water passage through which cooling water from the radiator flows to the cooling adapter without passing through the engine body. When the water temperature of the cooling adapter is higher than a reference temperature, it has been proposed that the flow rate of the second cooling water passage is increased as compared with when it is low (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Even when the water temperature of the cooling adapter is higher than the reference temperature, there may be a case where the catalyst of the exhaust catalyst device is not sufficiently heated. In this case, if the flow rate flowing through the cooling adapter is increased, the temperature rise of the catalyst becomes moderate, and there is a possibility that the temperature rise of the catalyst becomes slow.

[0005] The main object of the engine cooling device of the present invention is to suppress the slow temperature rise of the catalyst.

Means for Solving the Problems

[0006] The cooling device for the engine of the present invention has adopted the following means to achieve the above-mentioned main object.

[0007] The cooling device for the engine of the present invention includes a circulation flow path of cooling water configured to include an exhaust system flow path formed in the exhaust system of an engine having a catalyst attached to the exhaust system and a radiator, a pump for pumping the cooling water in the circulation flow path, a control device for controlling the pump, and is a cooling device for an engine provided with wherein the control device when the temperature of the catalyst is equal to or higher than a first temperature threshold, sets a basic flow rate based on the engine speed and load factor as a required flow rate and controls the pump, and when the temperature of the catalyst is lower than the first temperature threshold, upper-guards the basic flow rate with an upper limit flow rate, sets the required flow rate, and controls the pump, which is the gist.

[0008] In the cooling device for the engine of the present invention, when the temperature of the catalyst is equal to or higher than a first temperature threshold, a basic flow rate based on the engine speed and load factor is set as a required flow rate to control the pump, and when the temperature of the catalyst is lower than the first temperature threshold, the basic flow rate is upper-guarded with an upper limit flow rate to set the required flow rate and control the pump. In this way, in the latter case, compared with the case of setting the basic flow rate as the required flow rate as in the former case, by restricting the increase in the required flow rate, it is possible to suppress the delay in the temperature rise of the catalyst.

[0009] In the cooling device for the engine of the present invention, the control device may set the basic flow rate such that the lower the engine speed, the more the basic flow rate increases and the higher the load factor, the more the basic flow rate increases. This is based on the fact that the lower the engine speed and the higher the load factor, the higher the temperature of the catalyst tends to be.

[0010] In the engine cooling device of the present invention, the control device may set the upper limit flow rate based on the intake air amount of the engine. In this case, the control device may set the upper limit flow rate such that it decreases as the intake air amount decreases. This is because the lower the intake air amount, the less likely the temperature of the catalyst is to rise.

[0011] In the engine cooling device of the present invention, the control device may not drive the pump when the temperature of the cooling water is less than the second temperature threshold. Further, when the temperature of the catalyst is equal to or higher than the first temperature threshold and the temperature of the cooling water is equal to or higher than the second temperature threshold, the control device may set the basic flow rate to the required flow rate and control the pump. When the temperature of the catalyst is less than the first temperature threshold and when the temperature of the cooling water is less than the second temperature threshold, the control device may upper-limit guard the basic flow rate at the upper limit flow rate, set the required flow rate, and control the pump.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiments for Carrying Out the Invention

[0013] Next, embodiments for carrying out the present invention will be described using examples.

Examples

[0014] FIG. 1 is a configuration diagram showing an outline of the configuration of an engine device 10 including an engine cooling device as an embodiment of the present invention. The engine device 10 of the embodiment includes an engine 12 and a cooling device 20. This engine device 10 is mounted on a general vehicle that runs using the power from the engine 12, various hybrid vehicles including a motor in addition to the engine 12, and the like.

[0015] The engine 12 is configured as an internal combustion engine that outputs power using, for example, gasoline or the like as fuel. A purification device 14 is attached to the exhaust system of this engine 12. The purification device 14 has a catalyst (three-way catalyst) 14a that purifies harmful components such as carbon monoxide (CO), hydrocarbons (HC), and nitrogen oxides (NOx) in the exhaust gas.

[0016] The cooling device 20 is configured as a device for cooling the engine 12 using cooling water. As shown in the figure, it includes a cooling water circulation flow path 22, a radiator 24, an electric pump 26, and an electronic control unit 40. The electronic control unit 40 also controls the operation of the engine 12.

[0017] The circulation flow path 22 is a flow path for circulating cooling water in the order of the electric pump 26, the engine 12, the radiator 24, and the electric pump 26, and includes an engine flow path 23 formed in the cylinder block and cylinder head of the engine 12, the exhaust system (including inside and / or around the purification device 14), and the like. The radiator 24 performs heat exchange between the cooling water and the air. The electric pump 26 is controlled by the electronic control unit 40 and pumps the cooling water in the circulation flow path 22.

[0018] The electronic control unit 40 includes a microcomputer having a CPU, ROM, RAM, flash memory, input / output ports, and communication ports, although not shown. Signals from various sensors are input to the electronic control unit 40 via the input ports. Examples of signals input to the electronic control unit 40 include the crank angle θcr from the crank position sensor 12c that detects the rotational position of the crankshaft of the engine 12, the intake air amount Qa from the air flow meter 12a attached to the intake system of the engine 12, the catalyst temperature Tc which is the temperature of the catalyst 14a from the temperature sensor 14t attached to the catalyst 14a of the purification device 14, and the coolant temperature Tw which is the temperature of the cooling water from the coolant temperature sensor 28 attached to the circulation passage 22. Various control signals are output from the electronic control unit 40 via the output ports. Examples of signals output from the electronic control unit 40 include a control signal to the electric pump 26.

[0019] The electronic control unit 40 calculates the engine speed Ne of the engine 12 based on the crank angle θcr from the crank position sensor 12c. Further, based on the intake air amount Qa from the air flow meter 12a and the engine speed Ne of the engine 12, the load factor KL (the ratio of the volume of air actually inhaled in one cycle to the stroke volume per cycle) of the engine 12 is calculated.

[0020] Next, the operation of the cooling device 20 included in the engine device 10 of the thus configured embodiment, particularly the control of the electric pump 26, will be described. FIG. 2 is a flowchart showing an example of an electric pump control routine executed by the electronic control unit 40. This routine is repeatedly executed.

[0021] When the electric pump control routine of FIG. 2 is executed, the electronic control unit 40 first inputs data such as the intake air amount Qa, engine speed Ne, load factor KL, coolant temperature Tw, and catalyst temperature Tc of the engine 12 (step S100). Here, as the intake air amount Qa, the value detected by the air flow meter 12a is input. The engine speed Ne of the engine 12 is input with a value calculated based on the crank angle θcr from the crank position sensor 12c. The load factor KL of the engine 12 is input with a value calculated based on the intake air amount Qa and the engine speed Ne. The coolant temperature Tw is input with the value detected by the water temperature sensor 28. The catalyst temperature rise Tc is input with the value detected by the temperature sensor 14t.

[0022] After inputting the data in this way, the coolant temperature Tw is compared with the threshold value Twref (step S110). Here, the threshold value Twref is a threshold value used to determine whether the temperature of the engine 12 is high to a certain extent. For example, about 65°C to 75°C is used. When the coolant temperature Tw is less than the threshold value Twref, it is determined that the temperature of the engine 12 is not so high, and the electric pump 26 is not driven (step S120), and this routine ends.

[0023] When the coolant temperature Tw is equal to or higher than the threshold value Twref in step S110, it is determined that the temperature of the engine 12 is high to a certain extent, and a basic flow rate Qwtmp, which is the basic value of the required flow rate Qw, is set based on the engine speed Ne and the load factor KL of the engine 12 (step S130). Here, for the basic flow rate Qwtmp, for example, the relationship between the catalyst temperature Tc and the basic flow rate Qwtmp is determined in advance through experiments, analysis, machine learning, etc. and stored as a basic flow rate setting map. When the engine speed Ne and the load factor KL of the engine 12 are given, the corresponding basic flow rate Qctmp can be derived from this map for setting. FIG. 3 is an explanatory diagram showing an example of the basic flow rate setting map. The basic flow rate Qwtmp is set such that it increases as the engine speed Ne of the engine 12 decreases and increases as the load factor KL of the engine 12 increases. This is because the catalyst temperature Tc is more likely to increase as the engine speed Ne of the engine 12 decreases and the load factor KL increases.

[0024] Subsequently, the catalyst temperature Tc is compared with a threshold value Tcref (step S140). Here, the threshold value Tcref is a threshold value used to determine whether the catalyst temperature Tc is high to a certain extent. For example, about 800°C to 900°C is used. When the catalyst temperature Tc is equal to or higher than the threshold value Tcref, it is determined that the catalyst temperature Tc is high to a certain extent, and the basic flow rate Qwtmp is set to the required flow rate Qw (step S150). The electric pump 26 is controlled using the set required flow rate Qw (step S180), and this routine ends. Thereby, the engine 12 etc. can be cooled using the cooling water with the basic flow rate Qwtmp.

[0025] When the catalyst temperature Tc is less than the threshold value Tcref in step S140, the upper limit flow rate Qwlim is set based on the intake air amount Qa (step S160). The basic flow rate Qwtmp is upper-limited by the set upper limit flow rate Qwlim to set the required flow rate Qw (step S170). The electric pump 26 is controlled using the set required flow rate Qw (step S180), and this routine ends. In this way, compared with setting the basic flow rate Qwtmp to the required flow rate Qw, by restricting the increase in the required flow rate Qw, it is possible to suppress the slow rise in the temperature of the catalyst 14a.

[0026] Here, the upper limit flow rate Qwlim can be set, for example, by determining in advance the relationship between the intake air amount Qa and the upper limit flow rate Qwlim through experiments, analysis, machine learning, etc., storing it as a map for setting the upper limit flow rate, and when the intake air amount Qa is given, deriving the corresponding upper limit flow rate Qwlim from this map. FIG. 4 is an explanatory diagram showing an example of the map for setting the upper limit flow rate. The upper limit flow rate Qwlim is set so that it becomes smaller as the intake air amount Qa becomes smaller. This is because the catalyst temperature Tc is less likely to rise as the intake air amount Qa becomes smaller. By setting the upper limit flow rate Qwlim in this way, it is possible to more appropriately suppress the slow rise in the temperature of the catalyst 14a.

[0027] In the cooling device 20 included in the engine device 10 of the embodiment described above, when the cooling water temperature Tw in the circulation flow path 22 is equal to or higher than the threshold value Twref and the catalyst temperature Tc is equal to or higher than the threshold value Tcref, the basic flow rate Qwtmp based on the rotational speed Ne and the load factor KL of the engine 12 is set as the required flow rate Qw to control the electric pump 26. When the catalyst temperature Tc is lower than the threshold value Tcref, the basic flow rate Qwtmp is upper-limited by the upper limit flow rate Qwlim to set the required flow rate Qw and control the electric pump 26. Thereby, in the latter case, it is possible to suppress the slow temperature rise of the catalyst 14a.

[0028] In the cooling device 20 of the embodiment, the upper limit flow rate Qwlim is set based on the intake air amount Qa, but a constant value may be used.

[0029] In the cooling device 20 of the embodiment, when the cooling water temperature Tw is lower than the threshold value Twref, the electric pump 26 is not driven. However, at this time, similar to the case where the cooling water temperature Tw is equal to or higher than the threshold value Twref and the catalyst temperature Tc is lower than the threshold value Tcref, the basic flow rate Qwtmp may be upper-limited by the upper limit flow rate Qwlim to set the required flow rate Qw and control the electric pump 26.

[0030] In the cooling device 20 of the embodiment, when the cooling water temperature Tw is lower than the threshold value Twref, the electric pump 26 is not driven. When the cooling water temperature Tw is equal to or higher than the threshold value Twref and the catalyst temperature Tc is equal to or higher than the threshold value Tcref, the basic flow rate Qwtmp is set as the required flow rate Qw to control the electric pump 26. When the cooling water temperature Tw is equal to or higher than the threshold value Twref and the catalyst temperature Tc is lower than the threshold value Tcref, the basic flow rate Qwtmp is upper-limited by the upper limit flow rate Qwlim to set the required flow rate Qw and control the electric pump 26. However, without considering the cooling water temperature Tw, when the catalyst temperature Tc is equal to or higher than the threshold value Tcref, the basic flow rate Qwtmp may be set as the required flow rate Qw to control the electric pump 26. When the catalyst temperature Tc is lower than the threshold value Tcref, the basic flow rate Qwtmp may be upper-limited by the upper limit flow rate Qwlim to set the required flow rate Qw and control the electric pump 26.

[0031] In the cooling device 20 of the embodiment, when the cooling water temperature Tw in the circulation flow path 22 is equal to or higher than the threshold value Twref, and when the catalyst temperature Tc is equal to or higher than the threshold value Tcref, the basic flow rate Qwtmp is set to the required flow rate Qw to control the electric pump 26. When the catalyst temperature Tc is lower than the threshold value Tcref, the basic flow rate Qwtmp is upper-guarded by the upper limit flow rate Qwlim to set the required flow rate Qw and control the electric pump 26. However, a hysteresis may be provided for the threshold value Tcref1 for the catalyst temperature Tc when shifting from the first control of setting the basic flow rate Qwtmp to the required flow rate Qw to control the electric pump 26, and the threshold value Tcref2 for the catalyst temperature Tc when shifting from the second control of upper-guarding the basic flow rate Qwtmp by the upper limit flow rate Qwlim to set the required flow rate Qw to control the electric pump 26. That is, when the catalyst temperature Tc reaches less than the threshold value Tcref1 during the execution of the first control, the second control is shifted to. When the catalyst temperature Tc reaches equal to or higher than the threshold value Tcref2, which is higher than the threshold value Tcref1, during the execution of the second control, the first control is shifted to. By doing so, hunting between the first control and the second control can be suppressed.

[0032] In the cooling device 20 of the embodiment, the catalyst temperature Tc is detected by the temperature sensor 14a, but it may be estimated based on the cooling water temperature Tw, the rotation speed Ne, and the load factor KL.

[0033] The correspondence between the main elements of the embodiment and the main elements of the invention described in the section of means for solving the problems will be described. In the embodiment, the circulation flow path 22 corresponds to the "circulation flow path", the electric pump 26 corresponds to the "pump", and the electronic control unit 40 corresponds to the "control device".

[0034] Incidentally, the correspondence between the main elements of the embodiments and the main elements of the invention described in the column of means for solving the problems is an example for specifically explaining the mode for carrying out the invention described in the column of means for solving the problems in the embodiments. Therefore, it does not limit the elements of the invention described in the column of means for solving the problems. That is, the interpretation of the invention described in the column of means for solving the problems should be made based on the description in that column, and the embodiments are merely specific examples of the invention described in the column of means for solving the problems.

[0035] As described above, the embodiments have been used to explain the mode for carrying out the present invention. However, the present invention is not limited to such embodiments, and it goes without saying that the present invention can be implemented in various forms without departing from the gist of the present invention.

Industrial Applicability

[0036] The present invention can be used in the manufacturing industry of engine cooling devices and the like.

Explanation of Reference Numerals

[0037] 10 Engine device, 12 Engine, 12a Airflow meter, 12c Crank position sensor, 14 Purification device, 14a Catalyst, 14t Temperature sensor, 20 Cooling device, 22 Circulation flow path, 23 Engine flow path, 24 Radiator, 26 Electric pump, 28 Water temperature sensor, 40 Electronic control unit.

Claims

1. A cooling water circulation passage including an exhaust passage formed in the exhaust system and a radiator in an engine having a catalyst attached to the exhaust system, a pump for pumping the cooling water in the circulation passage, a control device for controlling the pump, and an engine cooling device comprising: The control device, when the temperature of the catalyst is equal to or higher than a first temperature threshold, sets a basic flow rate based on the engine speed and load factor as a required flow rate and controls the pump, when the temperature of the catalyst is lower than the first temperature threshold, upper-guards the basic flow rate with an upper limit flow rate, sets the required flow rate, and controls the pump, The control device sets the upper limit flow rate based on the intake air amount of the engine. Engine cooling device.

2. The engine cooling device according to claim 1, wherein the control device does not drive the pump when the temperature of the cooling water is lower than a second temperature threshold. Engine cooling device.

3. The engine cooling device according to claim 1, The control device, when the temperature of the catalyst is equal to or higher than the first temperature threshold and the temperature of the cooling water is equal to or higher than the second temperature threshold, sets the basic flow rate as the required flow rate and controls the pump, when the temperature of the catalyst is lower than the first temperature threshold and when the temperature of the cooling water is lower than the second temperature threshold, upper-guards the basic flow rate with an upper limit flow rate, sets the required flow rate, and controls the pump. Engine cooling device.

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