Abstract:
An electric water pump control apparatus actively controls an electric water pump in a high speed range or a high load condition as a vehicle accelerates or overtakes. An electric water pump control method may include determining whether an engine is in a high speed/high load condition or in a normal condition by detecting an engine speed, fuel consumption amount, and coolant temperature, determining whether the coolant temperature is less than a predetermined second temperature, if the engine is in a high speed/high load condition, calculating a speed of the electric water pump by applying fuel consumption amount and engine speed, if the coolant temperature is less than a second temperature and determining a final speed of the electric water pump by applying a compensation coefficient according to the coolant temperature, and operating the electric water pump with the final speed to circulate the coolant.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The present application claims priority of Korean Patent Application Number 10-2010-0123052 filed Dec. 3, 2010, the entire contents of which application is incorporated herein for all purposes by this reference. 
     BACKGROUND OF INVENTION 
     1. Field of Invention 
     The present invention relates to an electric water pump applied to a vehicle. More particularly, the present invention relates to an electric water pump control apparatus that actively controls an electric water pump in a high speed range or a high load condition that a vehicle accelerates or overtakes and the method thereof. 
     2. Description of Related Art 
     A coolant passage is formed between a cylinder block and a cylinder head of an engine, and a water pump circulates a coolant through the coolant passage so as to prevent overheating of the engine and sustain a regular temperature. 
     A water pump is engaged with auxiliary devices through a belt to be continuously operated to circulate the coolant regardless of a warmed up condition or a cold condition of the engine. 
     Accordingly, the fuel efficiency and the exhaust gas are stabilized in a condition that the engine is warmed up, but the fuel efficiency is low and the exhaust gas quality is deteriorated, the warming period of the engine becomes longer, and a friction loss is increased in a condition that the engine is cold. 
     Also, since combustion efficiency is decreased to warm up a cold engine, fuel consumption is increased, an activation time of a exhaust gas catalyst is delayed, and harmful material in the exhaust gas is increased. 
     In addition, as the water pump is always operated, there is a problem that the power of the crankshaft is lost in such a manner that the output of the engine is deteriorated and the fuel efficiency becomes lower. 
     The information disclosed in this Background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art. 
     SUMMARY OF INVENTION 
     Various aspects of the present invention provide for an engine cooling apparatus having advantages of securely protecting an engine by controlling actively an electric water pump in a high speed/high load condition that heat load thereof is high by overtaking or rapid acceleration. 
     Also, various aspects of the present invention provide for an optimized cooling efficiency by actively controlling an electric water pump according to a driving and atmosphere condition of a vehicle. 
     An engine cooling apparatus according to various aspects of the present invention may include a thermostat that determines a coolant circulation direction according to a coolant temperature, a radiator that emits absorbed heat to atmosphere by expanding contact area of the coolant with air through core, an electric water pump that is disposed between an engine and the thermostat and that an operating speed thereof is controlled, a coolant temperature sensor that is configured to detects a coolant temperature, and a control portion that applies an engine speed and fuel consumption amount to determine an operating speed of the electric water pump and applies a compensation coefficient to the operating speed according to a coolant temperature, if the engine is operated at high speed or in a high load condition that the heat load thereof is high. 
     The control portion may determine that the engine is in a high speed or in a high load condition, if the rotation speed of the engine exceeds a predetermined value or the fuel consumption amount exceeds a predetermined value. 
     The control portion may operate the electric water pump at regular speed, if an air-conditioner is being operated in a condition that the coolant temperature detected by the coolant temperature sensor is lower than a predetermined second temperature that a thermostat is opened. 
     The control portion may detect a driving condition and an outside condition of the engine and if an error is detected, it enters into a limp home mode to operate the electric water pump at predetermined regular speed. 
     The control portion may detect a driving condition and an outside condition of the engine and if an error is detected, it enters into a limp home mode to operate the electric water pump at predetermined regular speed. 
     The control portion may determine ON time or OFF time of the electric water pump according to an engine speed and fuel consumption amount and applies a compensation coefficient to the ON time or the OFF time according to the coolant temperature to on/off control the electric water pump, if the coolant temperature is lower than a predetermined first temperature that is a boundary value to determine a cold state of the engine. 
     The control portion may operate the electric water pump at a first speed that the coolant can flow the engine at the least to cool the thermostat, if the coolant temperature detected by the coolant temperature sensor ranges between the first temperature and the second temperature. 
     The control portion may apply an engine speed and fuel consumption amount to determine a coolant target temperature and determines a target speed that can realize the coolant target temperature to operate the electric water pump with the target speed, if the coolant temperature exceeds the second temperature. 
     The control portion may decrease a coolant target temperature to operate the electric water pump at a high speed, if the coolant temperature exceeds the second temperature and the engine is in a high speed or in a high load condition that the heat load thereof is high. 
     Also, an electric water pump control method according to various aspects of the present invention may include determining whether an engine is in a high speed/high load condition or in a normal condition by detecting an engine speed, fuel consumption amount, and coolant temperature, determining whether the coolant temperature is less than a predetermined second temperature, if the engine is in a high speed/high load condition, calculating a speed of the electric water pump by applying fuel consumption amount and engine speed, if the coolant temperature is less than a second temperature and determining a final speed of the electric water pump by applying a compensation coefficient according to the coolant temperature, and operating the electric water pump with the final speed to circulate the coolant. 
     A target temperature of coolant may be determined according to fuel consumption amount and engine speed and a speed of the electric water pump is variably controlled to follow the target temperature, if the engine is in a high speed/high load condition and the coolant temperature exceeds the second temperature. 
     The electric water pump may be operated at a first speed, if an air conditioner is operated in a normal driving condition of the engine and the coolant temperature is less than the second temperature. 
     A target temperature of the coolant may be determined according to fuel consumption amount and engine speed and the speed of the electric water pump is variable controlled to follow the target temperature, if the air conditioner is operated and the coolant temperature exceeds the second temperature. 
     An ON time or OFF time of the electric water pump may be respectively calculated according to an engine speed and fuel consumption amount and a compensation coefficient is apply to the ON time or the OFF time according to the coolant temperature to on/off control the electric water pump, if the coolant temperature is lower than a predetermined first temperature that is a boundary value to determine a cold state of the engine in a normal driving condition of the engine. 
     The electric water pump may be operated at a first speed that the coolant can flow the engine at the least to cool the thermostat, if the coolant temperature detected ranges between the first temperature and the second temperature. 
     The electric water pump may be actively controlled by reflecting driving conditions, control conditions, and load conditions of the engine to optimize cooling performance and atmosphere of the engine such that fuel consumption efficiency is improved, abrasion is minimized, and durability is enhanced. 
     Also, warm up time of the engine and activation time of catalyst may be reduced to improve fuel consumption efficiency and quality of exhaust gas and to decrease unnecessary load loss such that efficiency of a battery is improved. 
     The methods and apparatuses of the present invention have other features and advantages which will be apparent from or are set forth in more detail in the accompanying drawings, which are incorporated herein, and the following Detailed Description, which together serve to explain certain principles of the present invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  schematically shows an exemplary electric water pump control apparatus according to the present invention. 
         FIG. 2  is a flow chart showing exemplary electric water pump control procedures according to the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in detail to various embodiments of the present invention(s), examples of which are illustrated in the accompanying drawings and described below. While the invention(s) will be described in conjunction with exemplary embodiments, it will be understood that present description is not intended to limit the invention(s) to those exemplary embodiments. On the contrary, the invention(s) is/are intended to cover not only the exemplary embodiments, but also various alternatives, modifications, equivalents and other embodiments, which may be included within the spirit and scope of the invention as defined by the appended claims. 
     Referring to  FIG. 1 , various embodiments of the present invention includes an engine  100 , a thermostat  110 , a radiator  120 , a coolant temperature sensor  130 , an electric water pump  140 , and a control portion  150 . 
     The thermostat  110  determines a circulation direction of coolant according to a coolant temperature exhausted from the engine  100  to the bypass line or the radiator  120  such that the engine  100  is cooled by the coolant. 
     The radiator  120  expands contact area of the coolant with the air through core to rapidly emit the heat absorbed in the coolant. 
     The cooling fan  121  is disposed at one side of the radiator  120  to blow air through the radiator  120 , wherein the cooling fan  121  is operated in a slow or a high speed by a control signal transferred from the control portion  150  according to driving condition and coolant temperature in a condition that the coolant temperature is higher than a predetermined value. 
     The coolant temperature sensor  130  detects a temperature of the coolant circulating the engine  100  to transmit the detected signal to the control portion  150 . 
     The coolant temperature sensor  130  can be disposed on the thermostat  110 . 
     The electric water pump  140  is disposed between the engine and the thermostat  110  to be turned on/off or an operating speed thereof is controlled according to control signals transmitted from the control portion  150  to circulate the coolant. 
     The electric water pump  140  can be one of a clutch type of water pump and an electric water pump. 
     If it is determined that the engine  100  is being operated in a high speed/high load condition that heat load thereof is high in a condition that a rotation speed (RPM) of the engine  100  exceeds a predetermined rotation speed (RPM_T) or a fuel consumption amount (Q) exceeds a predetermined amount (Q_T), the control portion  150  applies the engine speed (RPM) and the fuel amount (Q) to determine operating speed of the electric water pump  140  and applies an compensation coefficient thereto according to a coolant temperature detected by the coolant temperature sensor  130  to on/off control the pump  140  or control the speed of the electric water pump  140 . 
     If an air conditioner including a cooler or a heater is operated in a condition that the coolant temperature detected by the coolant temperature sensor  130  is less than a second temperature T 2  (T&gt;WTS), the control portion  150  can control the electric water pump  140  in a predetermined regular speed regardless of the coolant temperature. 
     The second temperature T 2  can be a coolant temperature when the thermostat  110  is opened. 
     The control portion  150  detects atmosphere and driving conditions of the engine  100 , if an error is detected in any position, an alarm message is outputted and simultaneously a limp home mode is performed, and the electric water pump  140  is operated at a predetermined regular speed. 
     If the coolant temperature detected by the coolant temperature sensor  130  is less than a first temperature T 1  (T 1 &gt;WTS), 
     The control portion  150  determines operating time and none-operating time of the electric water pump  140  according to a rotation speed (RPM) and a fuel consumption amount of the engine  100  and applies a compensation coefficient thereto according to the coolant temperature to change (compensate) the operating time and the none-operating time of the electric water pump  140 . 
     The first temperature T 1  is set to a maximum temperature that is compensated by the control portion  150  in a cold state of the engine. 
     In a condition that the coolant temperature detected by the coolant temperature sensor  130  ranges between a first temperature (T 1 ) and a second temperature (T 2 ) (T 1 &lt;WTS&lt;T 2 ), the control portion  150  steadily operates the electric water pump  140  in a first speed such that a coolant at least circulates the engine  100  to cool the thermostat  110 . 
     If the coolant temperature detected by the coolant temperature sensor  130  is larger than a second temperature (T 2 &lt;WTS), the control portion  150  applies an engine speed (RPM) and a fuel amount (Q) to determine a target temperature of the coolant and determines a rotation speed of the pump  140  such that the coolant follows the target temperature. 
     The higher the target temperature of the coolant the better the fuel consumption efficiency. However, if the target temperature is too high, the exhaust gas can violate the emission standard and the heat load of the engine  100  becomes excessive. Therefore, the target temperature is determined in two aspects of the emission standard and the engine protection. 
     If the coolant temperature detected by the coolant temperature sensor  130  exceeds a second temperature (T 2 ) (T 2 &lt;WTS) and heat load of the engine  100  is high by an overtaking or a rapid acceleration, the control portion  150  sets up the target temperature of the coolant low to operate the electric water pump  140  at high speed. 
     Operations of this invention including the function as described above will hereinafter be described in detail with reference to  FIG. 2 . 
     In a condition that a vehicle is running according to various embodiments of the present invention, the control portion  150  detects rotation a speed (RPM) and a fuel amount (Q) of the engine  100  and detects the coolant temperature (WTS) from the coolant temperature sensor  130  in a S 10 . 
     Then, it is determined whether an engine speed (RPM) exceeds a minimum engine speed (RPM_T) that is set to protect the engine  100  or a fuel consumption amount (Q) exceeds a minimum amount (Q_T) that is set to protect the engine  100  in a S 101 . 
     That is, it is determined whether the engine  100  is in a high speed or high load condition by an overtaking or a rapid acceleration. 
     If the engine speed (RPM) exceeds a minimum speed (RPM_T) that is set to protect the engine  100  or the fuel consumption amount (Q) exceeds a minimum amount (Q_T) that is set to protect the engine  100  in the S 101 , the control portion  150  determines whether the coolant temperature detected by the coolant temperature sensor  130  is less than a second temperature T 2  (WTS&lt;T 2 ) in a S 102 . 
     If the coolant temperature detected by the coolant temperature sensor  130  is less than a second temperature T 2  (WTS&lt;T 2 ) in the S 102 , the control portion  150  applies a fuel amount (Q) and an engine speed (RPM) to calculate a speed of the electric water pump  140  in a S 103 . 
     And, the control portion  150  extracts a compensation coefficient according to a present coolant temperature detected by the coolant temperature sensor  130  and applies the extracted coefficient to the speed of the electric water pump  140  to set up a final speed of the electric water pump  140  in a S 104 . 
     Accordingly, the control portion  150  operates the electric water pump  140  with the final speed to circulate the coolant in a S 105 . 
     If the engine speed (RPM) is less than a minimum speed (RPM_T) that is set to protect the engine  100  or fuel amount (Q) is less than a minimum amount (Q_T) that is set to protect the engine  100  in the S 101 , the control portion  150  determines whether a cooler or a heater is operated or not in a S 106 . 
     If it is determined that the air conditioner (cooler or heater) is operated in the S 106 , the control portion  150  determines whether the coolant temperature detected by the coolant temperature sensor  130  is less than a second temperature (T 2 ) (WTS&lt;T 2 ) in a S 107 . 
     If the coolant temperature is less than a second temperature T 2  (WTS&lt;T 2 ) in the S 107 , the control portion  150  operates the electric water pump  140  with a first speed that can at least circulate the coolant through the engine to cool the thermostat  110  in a S 302 . 
     Also, if the coolant temperature detected by the coolant temperature sensor  130  is larger than a second temperature T 2  (WTS&gt;T 2 ) in the S 102 , since it is a high temperature condition that the thermostat  110  is opened to circulate the coolant through the radiator  120 , the control portion  150  applies a fuel amount (Q) and an engine speed (RPM) to calculate a target temperature of the coolant in a S 401 . 
     Then, it variably controls the speed of the electric water pump  140  such that the coolant temperature follows the target temperature in a S 402 . 
     If it is determined that the air conditioner (cooer or heater) is not operated in the S 106 , the control portion  150  determines whether the coolant temperature detected by the coolant temperature sensor  130  is less than a first temperature T 1  (WTS&lt;T 1 ) in a S 201 . 
     If the coolant temperature is less than a first temperature T 1  (WTS&lt;T 1 ) in the S 201 , the control portion  150  applies an engine speed (RPM) and a fuel amount (Q) to calculate an operating time and a none-operating time of the electric water pump  140  in a S 202 , wherein the pump  140  is intermittently operated with the operating time and the none-operating time. 
     And, a compensation coefficient is extracted according to the coolant temperature detected by the coolant temperature sensor  130  and the compensation coefficient is applied to the ON time and the OFF time of the electric water pump  140  to determined a final ON time and a final OFF time in a S 203 , and then electric water pump  140  is controlled thereby in a S 204 . 
     If the coolant temperature is larger than a first temperature T 1  (WTS&gt;T 1 ) in the S 201 , the control portion  150  determines whether the coolant temperature is less than a second temperature T 2  (WTS&lt;T 2 ) in a S 301 . 
     If the coolant temperature detected by the coolant temperature sensor  130  ranges between a first temperature T 1  and a second temperature T 2  (T 1 &lt;WTS&lt;T 2 ) in the S 301 , the control portion  150  operates the electric water pump  140  at a first speed such that the coolant can at least circulate the engine to cool the thermostat  110 . 
     Also, if the coolant temperature detected by the coolant temperature sensor  130  is larger than a second temperature T 2  (WTS&gt;T 2 ) in the S 301 , because it is a high temperature condition that the thermostat  110  is opened to circulate the coolant through the radiator  120 , the control portion  150  applies a fuel amount (Q) and a engine speed (RPM) to calculate a target temperature of the coolant in a S 401 . 
     Then, it variably controls the speed of the electric water pump  140  such that the coolant temperature follows the target temperature in a S 402 . 
     The higher the target temperature of the coolant the better the fuel consumption efficiency. However, if the target temperature is too high, the exhaust gas can violate the emission standard and the heat load of the engine  100  becomes excessive. Therefore, the target temperature is determined in two aspects of the emission standard and the engine protection. 
     Accordingly, if the coolant temperature detected by the coolant temperature sensor  130  is larger than a second temperature T 2  (T 2 &lt;WTS) and heat load of the engine  100  is high by an overtaking or a rapid acceleration, the control portion  150  sets up the target temperature of the coolant low to operate the electric water pump  140  at high speed. 
     Referring to  FIG. 1 , the thermostat  110  is disposed at an outlet side of the radiator  120  between the pump  140  and the radiator  120 . However, the thermostat  110  can be disposed at an inlet side of the radiator  120  between the engine  100  and the radiator  120 . Generally, a mounting position of the sensor  130  is an outlet side of the engine. 
     The foregoing descriptions of specific exemplary embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teachings. The exemplary embodiments were chosen and described in order to explain certain principles of the invention and their practical application, to thereby enable others skilled in the art to make and utilize various exemplary embodiments of the present invention, as well as various alternatives and modifications thereof. It is intended that the scope of the invention be defined by the Claims appended hereto and their equivalents.