JP2007040163A - Control device for electronic control thermostat - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electronic control thermostat capable of performing effective temperature control of cooling medium with considering actual weather. <P>SOLUTION: When temperature of the cooling medium cooling an engine is varied by operation of an electronic control thermostat according to load of an engine mounted on a vehicle, an engine control unit 1 detects an operation condition of the engine by an engine operation condition detection part 3 and determines load of the engine, and determines raining quantity based on a detection result input from a raindrop sensor mounted on the vehicle by information from a raining condition detection part 4 and wiper switch signal indicating operation mode of a wiper mounted on the vehicle. The engine control unit 1 establishes target temperature of the cooling medium based on engine load and raining quantity and controls an electronic control thermostat drive unit 2. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a control device for an electronically controlled thermostat that variably sets a temperature of a cooling medium for cooling an engine by an electronically controlled thermostat in accordance with an engine load mounted on a vehicle.

  A vehicle driven by an internal combustion engine (engine) is equipped with an engine cooling system for cooling the engine in order to maintain an appropriate operating state of the engine. The engine cooling system detects the temperature of the cooling medium such as cooling water and oil with a sensor, adjusts the flow of the cooling medium to the heat exchanger such as the radiator with a thermostat, and circulates the cooling medium to the engine and the radiator. The engine is cooled by letting it.

  In such an engine cooling system, when the temperature of the cooling medium is set relatively high, a cooling loss from the cylinder of the engine to the cooling medium can be reduced. Further, in this case, the temperature of the engine is maintained at a high temperature, whereby the viscosity of the lubricating oil is lowered, and the mechanical friction loss (mechanical friction loss) in the engine can be reduced. As a result of these, it is known that the temperature of the cooling medium is set to be relatively high so that the thermal efficiency of the engine is improved and the fuel efficiency of the vehicle is improved.

  However, when the temperature of the cooling medium is set to a high temperature, the temperature of the intake air of the engine rises, so that the air density is lowered and the engine output is lowered. Further, the possibility of abnormal combustion (knocking) of the air-fuel mixture increases.

  Therefore, in order to suppress the occurrence of problems such as engine output decline and abnormal combustion while improving fuel efficiency, a technology that variably sets the coolant temperature using an electronically controlled thermostat according to engine load and environmental conditions is proposed. (See Patent Document 1 and Patent Document 2).

  Specifically, parameters obtained from various sensor groups for detecting the operating state of the engine are input to an engine control unit (ECU), and the engine load is determined based on the input parameters.

  When the ECU determines that the engine load is low, the ECU controls the cooling medium to be maintained at a predetermined high temperature as control in the low load mode. At this time, the ECU controls the temperature of the cooling medium based on the throttle opening of the engine, the engine speed, and the coolant temperature.

When the ECU determines that the engine load is medium or high, the ECU reads out the preset target temperature of the cooling medium as control in the medium / high load mode, so that the cooling medium temperature becomes the target temperature. Control the operation of the control thermostat. At this time, the ECU performs cooling based on at least one or any combination of engine throttle opening, engine speed, cooling water temperature, atmospheric pressure, intake air intake amount, intake air humidity, and intake air temperature. Control the temperature of the medium.
JP 2003-120294 A JP 2003-201844 A

  Incidentally, it is known that the engine efficiency can be improved by setting the coolant temperature higher than that in non-rainy weather because raindrops on the vehicle surface evaporate during rainy weather.

  However, for example, in the known technique represented by Patent Document 1 described above, when the cooling medium temperature is controlled, the target temperature of the cooling medium is determined using the humidity detected by the humidity sensor. In such a method, the humidity corresponding to the water vapor ratio in the atmosphere is detected by the humidity sensor, and it cannot be detected whether or not it is actually raining.

  That is, it is not always raining due to high humidity in a very general natural environment, and even when it is cloudy without rain, the humidity is 90% to 100%, which is the same as when raining. It may become. Therefore, in the conventional cooling water temperature control method, the cooling water temperature cannot be set so as to be higher in the rain than in the non-rainy weather, and there is a limit to improving the engine efficiency.

  Therefore, the present invention is proposed in view of the above-described conventional situation, and provides an electronically controlled thermostat control device capable of efficiently controlling the temperature of a cooling medium in consideration of actual weather. For the purpose.

  According to the present invention, when the temperature of the cooling medium for cooling the engine is varied by the operation of the electronic control thermostat in accordance with the load of the engine mounted on the vehicle, the engine load determining means detects the operating state of the engine, Based on at least one of the detection result input from the raindrop sensor mounted on the vehicle and the wiper switch signal indicating the operation mode of the wiper mounted on the vehicle, by determining the engine load and the rainfall amount determining means. When determining the rainfall amount, the target temperature setting means sets the target temperature of the cooling medium based on at least one of the engine load determined by the engine load determination means and the rainfall amount determined by the rainfall amount determination means. The above-described problems are solved by driving and controlling the electronic control thermostat.

  According to the present invention, since the rainfall amount is determined from at least one of the detection result of the raindrop sensor and the wiper switch signal, the wiper switch signal wipes off the raindrop even in a rainy state where the raindrop sensor does not detect the raindrop. In such a case, the target temperature of the cooling medium can be set according to the engine load, and the temperature control of the cooling medium can be performed efficiently in consideration of actual weather.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Below, the engine cooling control system shown as 1st Embodiment comprised by applying this invention is demonstrated, referring drawings.

[First Embodiment]
As shown in FIG. 1, the engine cooling control system controls the operation of an electronically controlled thermostat drive unit 2 by an engine control unit (ECU) 1 for controlling an internal combustion engine (engine) mounted on a vehicle. is there. In the engine cooling control system, an engine operation state detection unit 3 that detects the operation state of the engine and a rainfall state detection unit 4 that detects the weather (rainfall state) at the current position of the vehicle are connected to the engine control unit 1. Yes.

  The engine operating state detection unit 3 includes a plurality of sensors that detect the operating state of the engine. Specifically, the engine operating state detection unit 3 includes a humidity sensor 31 that detects the humidity of air (hereinafter referred to as intake air) that is taken in by the engine, an outside air temperature sensor 32 that detects the temperature around the vehicle, An atmospheric pressure sensor 33 for detecting the atmospheric pressure of the engine, an intake air temperature sensor 34 for detecting the temperature of the intake air, a throttle opening sensor 35 for detecting the opening of the throttle valve of the engine, and an amount of intake air (intake air amount). An air flow meter 36, a cooling water temperature sensor 37 for detecting the temperature of the cooling water circulating in the engine cooling system, a rotational speed sensor 38 for detecting the rotational speed of the engine, and a knock sensor 39 for detecting occurrence of knocking (abnormal combustion). It has. Output signals from the sensors constituting the engine operating state detection unit 3 are input to the engine control unit 1.

  The rainfall condition detection unit 4 includes a raindrop sensor (raindrop detection sensor) 41 that detects the presence or absence of raindrops raining on the exterior of the vehicle, and a wiper switch 42 that controls the operation mode of a wiper that wipes raindrops on the window. .

  The raindrop sensor 41 is attached to a vehicle exterior such as a vehicle hood or a front window peripheral portion, and detects the presence or absence of raindrops. It is desirable that the raindrop sensor 41 is capable of detecting not only the presence / absence of raindrops but also the amount of raindrops per unit time for the purpose of more accurately detecting rainfall conditions. In the present embodiment, the presence / absence and magnitude of a raindrop amount are detected by the raindrop sensor 41, and a raindrop signal indicating the detection result is output to the engine control unit 1.

  The wiper switch 42 can select and operate the wiper operation mode from a stop (OFF) mode, an intermittent operation mode, a low speed operation (Low) mode, and a high speed operation (Hi) mode. The wiper switch signal shown is output. The wiper switch signal is output to a drive unit (not shown) that drives the wiper and the engine control unit 1.

  The electronically controlled thermostat drive unit 2 drives an electronically controlled thermostat that controls inflow / blocking of cooling water circulated between a radiator (heat exchanger) (not shown) and the engine. The electronic control thermostat drive unit 2 controls an actuator that constitutes the electronic control thermostat in accordance with a control signal output from the engine control unit 1.

  The engine control unit 1 performs processing for determining the engine load based on signals input from the sensors constituting the engine operating state detection unit 3, the detection result of raindrops input from the raindrop sensor 41, and the wiper operation. A process for determining the amount of rainfall based on the wiper switch signal indicating the mode is performed. Further, the engine control unit 1 sets the target temperature of the cooling water for the electronically controlled thermostat drive unit 2 based on the engine load and the rainfall amount obtained as a result of the determination.

  The engine control unit 1 refers to the temperature setting table shown in FIG. 2 when setting the target temperature of the cooling water. The temperature setting table is held in a memory provided in the engine control unit 1, and is a table for determining a preset value (target temperature) of the coolant temperature that is set in advance according to the engine load and the amount of rainfall. It is.

  The temperature setting table may be held in a memory provided in the engine control unit 1 or may be held in a memory connected to the outside of the engine control unit 1. Further, the memory may be a read-only ROM, but is preferably an EEPROM (Electronically Erasable and Programmable Read Only Memory) in which the stored contents can be rewritten.

  Next, the control process of the electronically controlled thermostat by the engine cooling control system configured as described above will be described with reference to the flowchart shown in FIG.

  When the control process of the electronically controlled thermostat is started, the engine control unit 1 determines the engine load by grasping the engine operating state based on the signals input from the sensors constituting the engine operating state detecting unit 3. (Step S1). At this time, the engine control unit 1 multiplies each of the throttle opening detected by each sensor, the intake air amount, the rotation speed, the water temperature, and the vehicle speed detected from a vehicle speed sensor (not shown) by a predetermined coefficient, Thus, the engine load may be determined, or the engine load may be determined using predetermined map data.

  Next, the engine control unit 1 ranks the engine load corresponding to one of the three levels of “large”, “medium”, and “small” based on the magnitude of the engine load determined in step S1. A determination is made (step S2).

  Next, the engine control unit 1 acquires the wiper switch signal output from the wiper switch 42, determines the operation mode of the wiper, and updates the previous determination result held in a memory (not shown) (step S3). ). In this step S3, for example, a case where the wiper is operated for a short period for the purpose of removing dirt adhering to the front window and a case where the wiper is continuously operated for the purpose of removing raindrops on the front window in the rain are distinguished. Therefore, it is desirable to determine that the wiper is operating when the operation of the wiper continues for a predetermined period set in advance.

  Next, the engine control unit 1 acquires the raindrop signal input from the raindrop sensor 41 (step S4).

  Next, the engine control unit 1 determines whether the wiper is operating based on the wiper switch signal, that is, whether the operation mode of the wiper is other than the stop mode (step S5). If the result of this determination is that the wiper is operating (YES in S5 in the figure), the process proceeds to step S6. If the wiper is not operating (NO in S5 in the figure), the process proceeds to step S9. Proceed to

  In step S6, the engine control unit 1 determines whether or not the weather around the vehicle is rainy based on whether or not raindrops are detected from the raindrop signal acquired in step S4 (step S6). As a result of this determination, if raindrops are detected by the raindrop signal (YES in S6 in the figure), the process proceeds to step S7, and if no raindrops are detected by the raindrop signal (NO in S6 in the figure). Advances the process to step S8.

  In step S7, the engine control unit 1 determines whether the current wiper operation mode (intermittent operation mode, low-speed operation mode, high-speed operation mode) based on the wiper switch signal and the current rainfall amount based on the raindrop signal. The surrounding rainfall is determined (step S7). In the present embodiment, rank determination is made as to which of the three levels “large”, “medium”, and “small” corresponds to the magnitude of rainfall. After step S7, the process proceeds to step S9.

  On the other hand, in step S8, the engine control unit 1 causes the raindrops to be generated according to the operation of the wiper switch 42 of the driver (driver) of the vehicle because the wiper operation is continuously performed under non-rainy weather. It can be considered that it exists, and it determines with the control which set the cooling water to the high temperature can be requested | required. In the present embodiment, by performing the processing in step S8, for example, even when the raindrop sensor 41 is not detecting raindrops, the driver continuously operates the wiper in, for example, the intermittent operation mode. When the condition is satisfied, the target temperature of the cooling water can be set to a high temperature as in rainy weather. As a result, the coolant temperature can be controlled by operating the wiper switch 42 of the driver even when it is not raining. Note that after step S8, the engine control unit 1 advances the process to step S9.

  In step S9, the engine control unit 1 determines the engine load obtained in step S2 and the rainfall amount obtained based on the raindrop signal and the wiper switch signal.

  Next, the engine control unit 1 refers to the set temperature table shown in FIG. 2 and acquires the target temperature of the cooling water (step S10). If it is determined in step S8 that control is performed with the coolant temperature set higher by operating the driver when it is not raining, the raindrop sensor 41 in the rightmost row of the set temperature table shown in FIG. Reference is made to a predetermined target temperature value when no raindrop is detected but the wiper switch 42 is in the ON state.

  Next, the engine control unit 1 outputs a control signal indicating the target temperature acquired in step S10 to the electronic control thermostat drive unit 2, and sets the target temperature in the electronic control thermostat drive unit 2 (step S11). Thereby, the electronically controlled thermostat drive unit 2 drives the electronically controlled thermostat so that the cooling water reaches the set target temperature.

  Here, as shown in FIG. 2, the set temperature table is set such that the target temperature of the cooling water increases as the engine load decreases and the rainfall increases.

  In general, when the vehicle rains, the exterior of the vehicle gets wet, increasing the amount of heat dissipated from the radiator and the heat dissipated from the engine hood (bonnet) and engine block, allowing sufficient cooling capacity of the engine and setting the coolant temperature high. It has been known. In rainy weather, the intake air is cooled by the action of vaporization of raindrops taken together with the air, and the efficiency of filling the air-fuel mixture into the engine cylinder increases. Therefore, the coolant temperature is set higher under a wider range of engine load conditions. can do.

  In the engine cooling system, by setting the temperature of the cooling water high, the cooling loss from the engine cylinder to the cooling water can be reduced, and further, the lubricating oil can be maintained by maintaining the engine temperature at a high temperature. Thus, the mechanical friction loss in the engine can be reduced. As a result, by setting the temperature of the cooling medium to be relatively high, the thermal efficiency of the engine is improved and the fuel efficiency of the vehicle can be improved.

  In the present embodiment, the actual rainfall amount can be determined according to the raindrop detection result by the raindrop sensor 41 and the wiper operation mode based on the wiper switch signal, and the current engine according to the determined rainfall amount. The temperature of the cooling water is set for the electronically controlled thermostat so that the temperature is optimal for the load.

  Therefore, for example, it is not erroneously determined that the rain is determined only by the humidity sensor 31, that is, it is not erroneously determined that it is raining in non-rainy weather where the humidity is high. An electronically controlled thermostat can be operated by setting the water temperature. Thereby, while improving the thermal efficiency of an engine further, the fuel consumption of a vehicle can further be improved.

[Second Embodiment]
Next, an engine cooling control system shown as a second embodiment configured by applying the present invention will be described with reference to the drawings.

  As shown in FIG. 4, the engine cooling control system is different from the engine cooling control system described above in that the rain condition detection unit 4 includes a communication unit 100. Therefore, in the following description, the description of the same or equivalent configuration and operation as in the first embodiment described above will be omitted, and the same or equivalent parts will be assigned the same numbers and step numbers as in the first embodiment. A detailed description thereof will be omitted.

  The communication unit 100 has a function of performing wireless communication with a base station (not shown) and connecting to an external network such as the Internet to acquire weather information around the current position of the vehicle. The weather information acquired by the communication unit 100 is information indicating atmospheric pressure, atmospheric temperature, humidity, rainfall, and the like, for example. The communication unit 100 is connected to the engine control unit 1 and outputs weather information acquired from an external network to the engine control unit 1.

  In the present embodiment, the engine control unit 1 determines the amount of rainfall from the communication unit 100 in addition to the raindrop detection result input from the raindrop sensor 41 and the wiper switch signal indicating the wiper operation mode. The rainfall is determined based on the input weather information.

  The control process of the electronically controlled thermostat by the engine cooling control system configured as described above will be described with reference to the flowchart shown in FIG.

  In the control process of the electronically controlled thermostat in the second embodiment, the difference from the first embodiment described above is that the weather information is acquired from the communication unit 100 after the steps S7 and S8, respectively. It is that it has.

  After determining the rainfall amount in step S7, the engine control unit 1 acquires weather information around the current position of the vehicle from the external network (the Internet in this embodiment) via the communication unit 100 (step S21). After this step S21, the process proceeds to step S9.

  In step S8, after determining that the cooling water temperature is to be controlled based on the presence or absence of raindrops according to the driver's operation, the engine control unit 1 passes the external network (in the present embodiment, the Internet) via the communication unit 100. ) To obtain weather information around the current position of the vehicle (step S12). After step S12, the process proceeds to step S9.

  In step S9, the engine control unit 1 determines the engine load obtained in step S2, and in addition to the raindrop signal and the wiper switch signal, the engine control unit 1 determines the surroundings of the vehicle based on the weather information obtained in step S21 or step S22. Establish rainfall. Next, the engine control unit 1 refers to the set temperature table shown in FIG. 2 in step S10, and sets the target temperature obtained as a result of the reference to the electronically controlled thermostat drive unit 2 in step S11.

  In the present embodiment, in addition to the raindrop detection result by the raindrop sensor 41 and the wiper operation mode based on the wiper switch signal, the actual rainfall amount is determined based on the weather information acquired from the external network. Therefore, it is possible to determine the rainfall situation around the vehicle with higher accuracy than in the first embodiment, and to set the cooling water temperature with higher accuracy and certainty and to drive the electronic control thermostat. Thereby, while improving the thermal efficiency of an engine further, the fuel consumption of a vehicle can further be improved.

  In the second embodiment described above, the weather information acquired via the communication unit 100 is supplementarily used when determining the rainfall amount. However, when the accuracy of the acquired weather information is sufficient. The rainfall amount may be determined based mainly on the acquired weather information, and the raindrop signal and the wiper switch signal may be supplementarily used.

  Moreover, in 2nd Embodiment, as shown, for example in FIG. 6, among each sensor group for determining the engine load provided in the engine driving | running state detection part 3, the humidity sensor 31, the external temperature sensor 32, The atmospheric pressure sensor 33 may be omitted, and the engine load may be determined using humidity, atmospheric temperature, and atmospheric pressure included in the weather information obtained via the communication unit 100. Thereby, the apparatus configuration can be simplified and the cost can be reduced as compared with the configuration shown in FIG.

  In FIG. 6, a vehicle speed sensor 120 for detecting the speed of the vehicle is added as one of the sensor groups included in the engine operating state detection unit 3, but the presence or absence of the vehicle speed sensor 120 is arbitrary.

It is a block diagram which shows an example of the engine cooling control system shown as the 1st Embodiment of this invention. 4 is a schematic diagram illustrating an example of a set temperature table referred to by the engine control unit 1. FIG. 3 is a flowchart showing an example of control processing by the engine control unit 1. It is a block diagram which shows an example of the engine cooling control system shown as the 2nd Embodiment of this invention. 5 is a flowchart showing another example of control processing by the engine control unit 1. It is a block diagram which shows the modification of an engine cooling control system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Engine control unit 2 Electronically controlled thermostat drive unit 3 Engine operation state detection part 4 Rainfall condition detection part 31 Humidity sensor 32 Outside temperature sensor 33 Atmospheric pressure sensor 34 Intake air temperature sensor 35 Throttle opening sensor 36 Air flow meter 37 Cooling water temperature sensor 38 Rotation Number sensor 39 Knock sensor 41 Raindrop sensor 42 Wiper switch 100 Communication unit

Claims (3)

In an electronic control thermostat control device that varies the temperature of a cooling medium for cooling the engine by the operation of the electronic control thermostat in accordance with the load of the engine mounted on the vehicle,
Engine load determination means for detecting the operating state of the engine and determining the load of the engine;
A rainfall amount determining means for determining a rainfall amount based on at least one of a detection result input from a raindrop sensor mounted on the vehicle and a wiper switch signal indicating an operation mode of a wiper mounted on the vehicle;
Based on at least one of the engine load determined by the engine load determining means and the rainfall determined by the rainfall amount determining means, the target temperature of the cooling medium is set and the electronic control thermostat is driven and controlled. A control apparatus for an electronically controlled thermostat, comprising: a target temperature setting means. Further comprising communication means for obtaining weather information around the current position of the vehicle;
2. The control apparatus for an electronically controlled thermostat according to claim 1, wherein the rainfall amount determining means determines the rainfall amount using the weather information acquired by the communication means. When no raindrop is detected by the raindrop sensor, and the wiper switch signal detects that the wiper is operating continuously for a predetermined period by the rainfall amount judging means, the target temperature setting means is: The control apparatus for an electronically controlled thermostat according to claim 1 or 2, wherein the target temperature is set to a predetermined temperature according to the state of the wiper.

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