Air-conditioning system for electric car and method of controlling the air-conditioning system

An air-conditioning system of an electric car has an air-conditioning unit which is configured to perform air-conditioning in a passenger compartment by heater/cooler operation, a setting panel configured to set a target temperature of the passenger compartment, and a control unit which is connected to the air-conditioning unit and setting panel, and has different control of heater operation of the air-conditioning unit, wherein the control unit is configured to select controls of heater operation based on a vehicle speed v.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority from prior Japanese Patent Application No. 2008-266623, filed Oct. 15, 2008, the entire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an air-conditioning system for an electric car and a method of controlling the air-conditioning system, and in particular to temperature control in heater operation.

2. Description of the Related Art

Generally, a car is equipped with an air-conditioning system to keep the interior comfortable and windows clear. The air-conditioning system has functions of cooling, heating, dehumidifying, demisting and defrosting.

A known air-conditioning system of a car powered by an internal combustion engine uses a refrigeration cycle equipment for cooling and dehumidifying, and a heater or waste heat from the engine for heating. Thus a car powered by an internal combustion engine can use waste heat from the engine to heat the car. Jpn. Pat. Appln. KOKAI Publication No. 2000-185548 discloses an air-conditioning system for a car powered by an internal combustion engine. In the air-conditioning system, the capacity of the refrigeration cycle equipment is decreased to prevent a decrease in the temperature of airflow from outlet ports in heater operation when the waste heat from the engine is low when idling, for example.

In contrast to a car powered by an internal combustion engine, an electric car is powered by a traction motor using electrical energy supplied by a battery. The heat produced by the traction motor and battery is less than that produced by an internal combustion engine. Thus, an electric car cannot use waste heat, i.e., the heat of the traction motor to heat the car.

Therefore, an air-conditioning system of an electric car uses electrical energy stored in a battery. For example, an air-conditioning system of an electric car uses a refrigeration cycle equipment using a compressor powered by a motor, for cooling and dehumidifying. An air-conditioning system of an electric car conditions the interior of the car by heating air or water as catalyst by an electric heater, and discharging the temperature-controlled air by means of a blower.

The above air-conditioning system of an electric car has a temperature control dial in the interior of the car. An air-conditioning system of an electric car is configured to set an interior temperature by the temperature control dial. A temperature control dial is also provided in an air-conditioning system of a car powered by an internal combustion engine.

The above air-conditioning system of an electric car has the following problems. Electrical energy stored in the battery is used to power the air-conditioning system. The electrical energy is also used to power the traction motor. As the electrical energy is used for the air-conditioning system, the range of the car is decreased.

Further, heat in the interior of the car is lost by motion-induced airflow while the car is traveling. Therefore, the temperature of a heat exchange medium for heater operation of an air-conditioning system of the car is set to a temperature, so that the interior of the car can be conditioned to a target temperature even while the car is traveling. In other words, the interior of the car is set to a temperature, assuming that the heated air in the interior of the car escapes to the outside. A temperature in the interior of the car is set higher than a target temperature, assuming the escape of heated air to the outside.

In an air-conditioning system of a car powered by an internal combustion, the rotational speed of the internal combustion engine is decreased when idling. Heater output is reduced during idling, even if the temperature setting of the heater stays the same. Therefore, the air-conditioning system of a car powered by an internal combustion engine performs appropriate air-conditioning according to whether the engine is doing work or idling, assuming a decrease in passenger compartment temperature caused by the reduction of heater output during idling.

However, as an electric car is powered by the electrical energy of a battery, the air-conditioning system of the electric car can perform heater operation at a high temperature setting, assuming the escape of heat inside the car by motion-induced airflow even at idling. In other words, the air-conditioning system of an electric car always performs constant heater operation in either during running or at idling.

Therefore, in an electric car equipped with an air-conditioning system, the passenger compartment temperature at idling is higher than that when the motor is doing work. As heater operation is performed at a temperature setting for running even at idling, a passenger compartment temperature at idling is higher than a target temperature. Thus, unnecessary air-conditioning is performed, and the battery energy is wasted. In particular, an air-conditioning system of an electric car uses battery energy, and unnecessary air-conditioning decreases a running distance, and wastes electric energy.

SUMMARY OF THE INVENTION

To solve the above problems and achieve an objective, an air-conditioning system of an electric car and a method of controlling an air-conditioning system according to the invention are configured as follows.

According to an aspect of the invention, there is provided an air-conditioning system of an electric car comprising a secondary battery installed in the car; an air-conditioning unit which is configured to heat and cool a resident space (passenger compartment) in the car by the electrical power supplied from the secondary battery, and is operated based on temperature setting of a heat exchange medium configured to adjust passenger compartment temperature of the resident space to a target passenger compartment temperature; a setting unit configured to optionally set the target passenger compartment temperature; and a control unit which has groups of setting temperatures of the air-conditioning unit, i.e., a combination of setting temperatures for target passenger compartment temperatures set in the setting unit during a heater operation of the air-conditioning unit, and is configured to select one of the groups of setting temperatures according to a travel state of the car, and to perform heater operation of the air-conditioning unit based on the selected group of setting temperatures,

wherein in the groups of setting temperatures, at least some setting temperatures of the combination are set to different temperatures.

According to another aspect of the invention, there is provided a method of controlling an air conditioning system which is operated by the electrical power supplied from a secondary battery installed in a car based on temperature setting of a heat exchange medium configured to adjust the passenger compartment temperature to a target passenger compartment temperature, comprising a step of setting the passenger compartment temperature to an optional target temperature; a step of determining a travel state of the car according to a delay in a vehicle speed of the car; a step of selecting one of groups of setting temperatures of an air-conditioning unit, i.e., a combination of setting temperatures for target passenger compartment temperatures set in a setting unit during a heater operation of the air-conditioning unit, in which at least some setting temperatures of the combination are set to different temperatures, according to a delay in the vehicle speed; and a step of performing heater operation of the air-conditioning unit based on the setting temperatures of the selected group.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, an explanation will be given of an electric car1having an air-conditioning system10according to an embodiment of the invention with reference toFIGS. 1 to 4.

FIG. 1is an explanation diagram showing a configuration of an electric car (vehicle)1using an air-conditioning system10according to an embodiment of the invention.FIG. 2is a front view showing a configuration of a setting panel12of the air-conditioning system10.FIG. 3is a graph explaining an example of control by the air-conditioning system10.FIG. 4is a table shows an example of setting temperatures in the air-conditioning system10.FIG. 5is a flowchart showing control of operations of the air-conditioning system10.FIG. 6is a flowchart showing a part of the control of operations of the air-conditioning system10. InFIG. 1, D denotes a passenger compartment, E denotes a machinery compartment, and S denotes electrical wiring.

As shown inFIG. 1, the electric car1has a vehicle main body (car body)2, a battery3, a recharger4, a driving mechanism5, and an air-conditioning system10. In addition to the car body2, battery3, i.e., a secondary battery, recharger4, driving mechanism5, and air-conditioning system10, the electric car1is provided with other components such as an EV-ECU and a steering mechanism. An explanation thereof will be omitted.

The car body2has a passenger compartment D, i.e., an interior space, in which a driver and passengers are seated, and baggage is loaded, and a machinery compartment E, in which the battery3, driving mechanism5, air-conditioning system10, and other components of the electric car1are housed or installed. In the car body2, the passenger compartment D and machinery compartment E are parted by a partition6. The partition6consists of two or more members such as a floor panel and dash panel.

The battery3comprises a large-capacity lithium ion battery, for example. The battery3is connected to the recharger4, driving mechanism5, air-conditioning system10, and other components through a CAN-c CAN cable (electrical wiring) S. The battery3is composed to supply electric power to the driving mechanism5and air-conditioning system10through the electrical wiring S.

The recharger4has an inverter to convert AC voltage input from a wall socket into DC voltage for charging the battery3. The recharger4is configured to be connectable to various power supplies outside the car body2other than a wall socket.

The driving mechanism5is connected to the battery3by the electrical wiring S. The driving mechanism5has a motor7and a driving wheel8. For example, the motor7is configured to be electrically powered by the battery3, when receiving a driving instruction. The driving wheels8are configured to be driven by the motor7. The driving mechanism5is configured to detect a vehicle speed v of the electric car1during travel, from a rotational speed of the driving wheel8.

The air-conditioning system10comprises an air-conditioning unit11able to perform air-conditioning of the passenger compartment D by heater operation and cooler operation, a setting panel12for various setting for air-conditioning operation, and a control unit13for the air-conditioning system10connected to the air-conditioning unit11and setting panel12. The air-conditioning system10is operated by electrical energy of the battery3.

The air-conditioning system10has outlet ports to blow out conditioned air to the passenger compartment D. The blowout ports include an outlet port to blow out air to the passengers' feet, an outlet port to blow out air to the passengers' bodies, and an outlet port to blow out air to the windows (defroster).

The air-conditioning unit11is provided with a refrigeration cycle unit11ausing a heat pump to drive a compressor by a compressor-driving motor in cooler/dehumidifier operation, and an electric water heater11bto heat water in heater operation, for example. For convenience of explanation, the refrigeration cycle unit11ais called referred to an air-conditioner or A/C in some parts of the following explanation. The air-conditioning unit11has a blower (fan), which blows out air cooled by the refrigeration cycle unit11a, and air heated by hot water to the passenger compartment D from the outlet ports. The configuration of the air-conditioning unit11is not limited to this. A setting temperature is set for the heat exchange medium of the air-conditioning unit11. For example, a setting temperature is a temperature of the electric water heater11b, which heats water to achieve a target passenger compartment temperature.

As shown inFIG. 2, the setting panel12is configured to partially project from the partition6into the passenger compartment D. As a part of the setting panel12is projected from the partition6into the passenger compartment D, the setting panel is arranged in the car body2operably from the passenger compartment D. The setting panel12has a decorated panel (panel)15forming a part of the partition6, to prevent the machinery compartment E and electrical wiring S from being exposed to the passenger compartment D. The panel15is formed fixable to the partition6by using claws.

The setting panel12has setting dials16on the panel15. The setting dials16include the temperature setting part17, fan setting part18, and outlet selector part19. The control unit13is electrically connected to the temperature setting part17, fan setting part18, and outlet selector part19on the setting panel12, through the electrical wiring S.

The temperature setting part17is configured to set a desired target temperature. The temperature setting part17has an air-conditioner switch21and a temperature control dial22. For example, the air-conditioner switch21is made in the form of a disc, and the temperature control dial22is made in the form of a ring. In the temperature setting part17, the temperature control dial22is rotatable around the air-conditioner switch21at predetermined angles.

The air-conditioner switch21is configured to turn on/off the air-conditioner11a, i.e., selecting operation modes of the air-conditioner11a. The air-conditioner switch21is configured to transmit the operating information about the air-conditioner switch21to the control unit13through the electrical wiring S. The air-conditioner switch21has on the surface an A/C indicator means23to indicate on/off of the air-conditioner11a, and a first guide display24to show the operations of the air-conditioner switch21and temperature control dial22.

The A/C indicator means23is configured to light to indicate that the air-conditioner11ais turned on, when the air-conditioner switch21is pressed and the air-conditioner11ais turned on. In other words, when the air-conditioner switch21is pressed once, the A/C indicator means23lights to indicate the turning-on of the air-conditioner11a. When the air-conditioner switch21is pressed again in this state, the A/C indicator means turns off and indicates the turning-off of the air-conditioner11a.

The first guide display24has a temperature guide display24a, which is provided by printing in the upper half and at the outer periphery of the air-conditioner switch21, and shows the positions of the temperature control dial, approximate temperatures, or a target temperature. The first guide display24has an A/C operation guide display24b, which is provided by printing at about the center of the air-conditioner switch21, and shows the operations of the air-conditioner switch21.

The temperature guide display24ais configured so that approximate setting of cooling/heating temperatures can be seen at the positions where the temperature control dial22is rotated. In particular, the temperature guide display24ais divided into the left-side cooler part and right-side heater part, from the top position of the air-conditioner switch21. The heater part is indicated by “H”; the cooler part, by “C”. The heater part and cooler part are indicated by arcs, separating at the top position of the temperature guide display24a, and increasing the width gradually from the top position to the position about 90° from the top position.

The A/C operation guide display24bis indicated by “PUSH A/C”, for example. The A/C operation guide display24bshows that the air-conditioner switch21can be operated by pressing the switch.

The temperature control dial22has a first position mark22ato indicate a rotation position. The temperature control dial22is configured to rotate about 180° around the air-conditioner switch21, for example. In other words, the temperature control dial22is configured to rotate so that the first position mark22ais moved about 90° in the left and right directions from the top position of the air-conditioner switch21.

The temperature control dial22is configured to set a temperature of the passenger compartment D to a desired target temperature. The temperature control dial22is configured to produce a little resistance when it is rotated by a predetermined angle, thereby the first position mark22acan be moved to a position P, i.e., a predetermined rotation position. The temperature control dial22has a plurality of position P.

For example, the temperature control dial22has a position P1, at which the temperature of the passenger compartment D becomes the lowest, i.e., a target temperature in cooler operation. The temperature control dial22has a position P13, at which the temperature of the passenger compartment D becomes the highest, i.e., a target temperature in heater operation.

The temperature control dial22has equally divided positions between the positions P1and P13. Namely, the temperature control dial22has positions P1to P13. The first position mark22aindicated by a solid line and two-dot chain line inFIG. 2includes the positions P1to P13. The temperature control dial22is configured to transmit the information about the position P to the control unit13through the electrical wiring S.

The temperature control dial22is configured to be rotatable to the positions P1to P6corresponding to desired target temperatures in cooler operation, so that the controller13described later can set the temperatures of the air blow out from the outlet port. Similarly, the temperature control dial22is configured be rotatable to the positions P8to P13corresponding to desired target temperatures in heater operation, so that the controller13can set the temperatures of the air blow out from the outlet port.

The fan setting part18has a fan setting guide26, and a fan setting dial27. For example, the fan setting guide26is made in the form of a disc, and the fan setting dial27is made in the form of a ring. In the fan setting part18, the fan setting dial27is rotatable around the fan setting guide26by predetermined angles.

The fan setting part18is configured to set the airflow from the fan to OFF, or steps from weak to strong, according to the rotated positions. The fan setting part18is configured to set the operation (AUTO), in which the airflow is automatically set according to the temperature of the passenger compartment D. The rotated positions of the fan setting part18are detected by the controller13described later. According to the detection result, the control unit13operates the fan. In the AUTO operation, the control unit13operates the fan according to a predetermined airflow of the fan for the temperature of the passenger compartment D, for example. A detailed explanation thereof is omitted.

The fan setting guide26has a second guide display28to show the operations of the fan setting dial27. The second guide display28has a fan setting guide display28a, which is provided by printing in substantially the upper half and at the outer periphery of the fan setting guide26, and shows the positions of the fan setting dial27, and setting of the fan.

The fan setting guide display28ais configured so that approximate airflow setting of the fan can be seen at a position where the fan setting dial27is set. In particular, the fan setting guide display28ais started from the periphery in substantially the left end portion of the fan setting guide26(at the position of about 270° counterclockwise from the top position) to the right end portion (the position of about 90° from the top position), i.e., the symmetrical position across the top position. “OFF” is indicated in the left end portion. The fan setting guide display28ahas an arc-shaped part indicating the airflow from the fan, whose width is gradually increased from the OFF position to the right end. In the fan setting guide display28a, “AUTO” is indicated under “OFF”.

The fan setting dial27has a second position mark27ato indicate a rotation position. The fan setting dial27is configured to rotate around the fan setting guide26by predetermined angles, for example. The fan setting dial27is configured to rotate around the fan setting guide26in a range, in which the second position mark27ais moved within the range of the fan setting guide display28a.

The fan setting dial27is configured to produce a little resistance when it is rotated between the OFF and AUTO positions of the fan setting guide display28a, and between the OFF position and the arc indicating the airflow from the fan. The fan setting dial27is configured so that the second position mark27ais moved to predetermined rotation positions by this resistance. The fan setting dial27is configured to transmit the information about the positions to the control unit13through the electrical wiring S.

The outlet selector part19has an internal/external air selector switch30, and an outlet port selector dial31. The internal/external air selector switch30is made in the form of a plate. The outlet port selector dial31is made in the form of a circle. The outlet selector part19is configured so that the outlet port selector dial31is rotated around the internal/external air selector switch30by predetermined angles.

The internal/external air selector switch30is configured to set air-intake to internal or external by pressing. When the internal/external air selector switch30is pressed and turn on, internal air circulation is selected. When the internal/external air selector switch30is pressed, the information about the depression of the internal/external air selector switch30is transmitted to the control unit13through the electrical wiring S.

The internal/external air selector switch30has on its surface an internal/external air indicator means32to indicate on/off of the internal/external air selector, and a third guide display33to show the operations of the internal/external air selector switch30and outlet port selector dial31.

The internal/external air indicator means32is configured to light to indicate internal air circulation, when the internal/external selector switch30is pressed and turned on. In other words, when the internal/external selector switch30is pressed, the internal/external air indicator means32lights to indicate internal air circulation. When the internal/external selector switch30is pressed again in this state, the internal/external air indicator means32goes out to indicate external air circulation.

The third guide display33has an outlet port guide display33a, which is provided by printing and starting from substantially the left end portion of the internal/external air selector switch30to the right end portion across the top position. The third guide display33has an internal/external air operation guide display33b, which is provided by printing at about the center of the internal/external air selector switch30, and shows the operations of the internal/external air selector switch30.

The outlet port guide display33ais configured so that the outlet port to blow out conditioned air can be seen. For example, the outlet guide display33ahas of the legend “AUTO”, and icons indicating a passenger body, passenger body and feet, passenger feet, passenger feet and defroster, and defroster, from the left end to the right.

The internal/external air operation guide display33bhas of the legend “PUSH” and an icon indicating internal air circulation, for example, indicating that the internal/external selector switch30is operated by pressing. The internal/external air indicator means32is provided under the mark indicating internal air circulation. Therefore, when the internal/external air indicator means32is lit, the internal/external air selector switch30indicates internal air circulation.

The outlet port selector dial31has a third position mark31ato indicate a rotation position. The outlet port selector dial31is configured to rotate around the internal/external air selector switch30by predetermined angles. The outlet port selector dial31is configured so that the third position mark31ais moved around the internal/external air selector switch30corresponding to the internal/external air indicator means33a.

The outlet port selector dial31is configured to produce a little resistance when it is moved to AUTO, and marks indicating a passenger body, passenger body and feet, passenger feet, passenger feet and defroster, and defroster. By the resistance, the third position mark31aof the outlet port selector dial31is movable to a predetermined position.

The control unit13is configured to receive the positions of the temperature setting part17, fan setting part18and outlet selector part19, and signals whose voltages are different according to operations and setting states. The control unit13is configured to recognize the setting states of the setting panel12, based on the signals from the setting panel12.

The control unit13has groups of setting temperatures, as operating conditions of the air-conditioning unit11previously set based on the setting states of the setting panel12. In this embodiment, as groups of setting temperatures, combination of two groups of setting temperatures indicated in the setting temperature table ofFIG. 4will be explained. The setting temperatures of the group indicates the temperatures of the heat exchange medium of the air-conditioning unit11, i.e., the setting temperatures of the electric water heater11b.

The control unit13is configured to select a setting temperature based on the travel state of the electric car1. The control unit13is configured to operate the electric water heater11bof the air-conditioning unit11, based on setting temperatures corresponding to the positions of the temperature control dial22, among the selected group of setting temperatures. The control unit13is configured to receive and recognize a vehicle speed detected by the driving mechanism5.

The control unit13changes a target passenger compartment temperature of the passenger compartment D based on the positions P1to P6of the temperature control dial22. The control unit13controls an air-conditioner11aof the air-conditioning unit11so that the passenger compartment temperature of the passenger compartment D reaches the target passenger compartment temperature, and operates the air-conditioning unit11. The control unit13operates the air-conditioner11awhen the air-conditioner switch21is turned on, but operates only the fan of the air-conditioning unit11to discharge air when the air-conditioner switch21is turned off.

The control unit13changes a target passenger compartment temperature of the passenger compartment D based on the positions P8to P13of the temperature control dial22. The control unit13controls temperature setting of the electric water heater11bof the air-conditioning unit11so that the passenger compartment temperature of the passenger compartment D reaches the target passenger compartment temperature, and operates the air-conditioning unit11.

The control unit13blows out conditioned air from the outlet port selected in the outlet selector part19according to the airflow volume of the fan set in the fan setting part18.

In particular, the control unit13has at least following functions (1) to (4) as functions to control air-conditioning.

(1) A cooling temperature control function to control a temperature in cooler operation of the air-conditioning system10based on a target passenger compartment temperature set in the temperature setting part17.

(2) A heating temperature control function to control a temperature in heater operation of the air-conditioning system10based on a vehicle speed v and a target passenger compartment temperature set in the temperature setting part17.

(3) An airflow control function to control airflow of the air-conditioning system10based on airflow set in the fan setting part18.

(4) An outlet port control function to select an outlet port of the air-conditioning system10based on an outlet port set in the outlet selector part19.

The above four functions of the control unit13will be explained.

(1) The cooling temperature control function of the control unit13is used to operate the air-conditioning unit11by changing the power consumption of the compressor of the refrigeration cycle unit11a, according to the positions P1to P6of the first position mark22aof the temperature control dial22. By the cooling temperature control function, the control unit13controls the compressor of the refrigeration cycle unit11aprovided in the air-conditioning unit11to a blowout air temperature set by the temperature control dial22, and performs cooler operation. The setting such as rotation speed of the operation control of the refrigeration cycle equipment for the position P can be changed depending on the form and material of the car body2, and the capacity of the air-conditioning system10. Detailed setting values thereof are omitted.

(2) The heating temperature control function of the control unit13is used to set a temperature of the electric water heater11bto a predetermined temperature to blow out the heat of the hot water to the inside of a car, according to the positions P8to P13of the first position mark22aof the temperature control dial22. The heating temperature control function changes the control of the air-conditioning unit11based on a delay in the vehicle speed v while the electric car1is traveling, for example, as shown inFIG. 3. In other words, the control unit13determines a travel state of the electric car1based on a delay in a vehicle speed v, and selects a group of temperatures, in which the air-conditioning unit11can increase a passenger compartment temperature to an appropriate temperature, based on the determined travel state.

For example, as a heating temperature control function, when a vehicle speed is a predetermined v1, the control unit13controls idling (ID) as a control of heater operation. When a vehicle speed is a predetermined v2, the control unit13performs ordinary control.

The vehicle speed v1may be a speed, at which a passenger compartment temperature of the passenger compartment D is lowered a little when idling or by the influence of external air such as motion-induced airflow. The vehicle speed v1, at which the passenger compartment temperature of the passenger compartment D is lowered a little when idling or by the influence of external air such as motion-induced airflow, is different depending on the form and material of the car body2. A detailed explanation thereof is omitted.

The vehicle speed v2may be a speed, at which a predetermined passenger compartment temperature of the passenger compartment D is lowered by external air such as motion-induced airflow. The vehicle speed v2, at which a predetermined passenger compartment temperature of the passenger compartment D is lowered by the influence of external air such as motion-induced airflow, is different depending on the form and material of the car body2. A detailed explanation thereof is omitted.

The vehicle speeds v1and v2, which are the reference for selection of ordinary control and ID control for which setting temperatures are selected, are changeable depending on the form and material of the car body2, and the capacity of the air-conditioning system10. Specific values thereof are not defined here. The vehicle speed v1is slower than the vehicle speed v2(v1<v2).

Namely, when the vehicle speed v≧v2as shown inFIG. 3, the control unit13performs heater operation in ordinary control. When the vehicle speed v≦v1, the control unit13performs heater operation in ID control. When the vehicle speed v is changed to v≦v1during heater operation in ordinary control, the control unit13changes the control of the air-conditioning system10from ordinary control to ID control, and continues the heater operation. When the vehicle speed v is changed to v≧v2during heater operation in ID control, the control unit13changes the control of the air-conditioning system10from ID control to ordinary control, and continues the heater operation.

Further, as shown inFIG. 4, the control unit13has a table of setting temperatures of the electric water heater11bfor heater operation, based on the positions of the temperature control dial22, and a vehicle speed v. The table of setting temperatures for heater operation includes two groups of setting temperatures. Here, the setting temperatures of the electric water heater11bin ordinary control are set to TAto TF(° C.) for the positions P8to P13. These temperatures TAto TF(° C.) constitute a group of setting temperatures in ordinary control. The setting temperatures are the temperatures of the electric water heater11b, at which a passenger compartment temperature of the passenger compartment D can be increased to a target passenger compartment temperature, but any other temperatures such as hot water temperature may be used, as long as it can achieve a target passenger compartment temperature.

Next, an explanation will be given of the relationship between the temperatures TAto TFof the electric water heater11b.

The temperatures TAto TFof the electric water heater11bare set to TA<TB<TC<TD<TE<TFin ordinary control. Further, for example, the temperatures TBto TFare set by sequentially adding a predetermined temperature α° C. to TA: TB=TA+α, TC=TB+α, TD=TC+α, TE=TD+α, and TF=TE+α. The predetermined temperature α° C. is optional. The predetermined temperature α° C. in each temperature may be different.

In ID control, the temperatures of the electric water heater11bare set to TGto TL(° C.) for the positions P8to P13. The temperatures TGto TL(° C.) are the setting temperatures in ID control. The temperatures TGto TLof the electric water heater11bare set to TG=TH, and TG(TH)<TI<TJ<TK<TLin ID control, for example. The temperatures TIto TL(or TH) are set by sequentially adding a predetermined temperature α° C. to TG(TH): TI=TG+α, TJ=TI+α, TK=TJ+α, and TL=TK+α.

In the ordinary control and ID control, the temperatures of the electric water heater11bare set to TA=TG=TH. At the position P8, the setting temperature of the electric water heater11bis set to the same for both ordinary control and ID control. In ID control, the temperature of the electric water heater11bat the position P9is set to the same as the temperature at the position P8. In the ordinary control and ID control, the temperature of the electric water heater11bin ordinary control is set α (α° C.) higher than the temperature in ID control at the position P13. In other words, in the group of setting temperatures for ID control, some temperatures are set lower than those for ordinary control.

By the heating temperature control function, the control unit13selects ordinary control and ID control based on a vehicle speed v, controls the electric water heater11baccording to the positions of the temperature control dial of the temperature setting part17, and performs the heater operation.

(3) The airflow control function of the control unit13controls the rotational speed of the fan, and changes the airflow from the outlet port, according to the positions of the fan setting dial27. When the position mark27aof the fan setting dial27is set to the AUTO position, the control unit13compares the temperature of the passenger compartment D with a target temperature, and controls the airflow of the fan depending on the difference between the passenger compartment temperature and target passenger compartment temperature. The airflow control function of the control unit13controls the airflow of the air-conditioning system10according to the positions of the fan setting dial27.

(4) The outlet port control function of the control unit13opens an outlet port to blow out conditioned air according to the positions of the outlet port selector dial31. When the third position mark31aof the outlet port selector dial31is set to the AUTO position, the control unit13selects the selected outlet port according to a passenger compartment temperature of the passenger compartment D. The outlet port control function of the control unit13selects an outlet port according to the positions of the outlet port selector dial31.

Next, an example of the operation of the air-conditioning system10is explained with reference to the flowcharts ofFIGS. 5 and 6.

First, as step ST1, a driver instructs operation of the air-conditioning system10by operating the setting panel12. The control unit13detects the setting of the setting panel12by the driver. When the second position mark27aof the fan setting dial27is set to any position other than the OFF position, the control unit13detects it, and starts the air-conditioning unit11. As the air-conditioning unit11is started, the fan is started, and the air-conditioning system10is started.

By the airflow control function and outlet port control function, the control unit13determines the airflow of the fan, and the outlet port of the air, according to the detected positions of the fan setting dial27and outlet selector dial31on the setting panel12. Next, as step ST2, the control unit13detects the position of the temperature control dial22. Then, as step ST3, the control unit13determines whether the detected position of the temperature control dial22is any one of the positions P8to P13, at which the heating temperature control function is performed.

When the detected position of the temperature control dial22is any one of P8to P13(step ST3), the control unit13detects a vehicle speed v, as step ST4.

Next, as step ST5, the control unit13determines whether the detected vehicle speed v is the same as or slower than a predetermined vehicle speed v1. When the detected vehicle speed v is the same as or slower than the vehicle speed v1(YES in step ST5), the control unit13selects ID control for heater operation, and sets a temperature of the electric water heater11bby selecting a temperature from the group of setting temperatures for ID control. At this time, the temperature T of the electric water heater11bis set to T=TGwhen the detected position is P8, likewise, T=THfor the position P9, T=TIfor the position P10, T=TJfor the position P11, T=TKfor the position P12, and T=TLfor the position P13.

After setting the temperature T of the electric water heater11b, the control unit13performs the heater operation in ID control, as step ST7. In the heater operation, the control unit13heats water by the electric water heater11bbased on the set temperature, heats the air from the fan by the heated water, blows out the heated air from the outlet port, and warms up the passenger compartment D.

The control unit13performs the heater operation in ID control, and detects a vehicle speed v again, as step ST8. As step ST9, the control unit13determines whether the detected vehicle speed v is a speed to change the ID control to ordinary control (vehicle speed v≧v2). When the detected vehicle speed v is slower than the predetermined vehicle speed v2(NO in step ST9), the control unit13continues the heater operation in ID control.

Next, an explanation is given of the case in which the vehicle speed v detected in step ST4is slower than a predetermined vehicle speed V1(NO in step ST5). In this case, as step ST10, the control unit13determines whether the vehicle speed v is the same as or faster than the vehicle speed v2. When the vehicle speed v is the same as or faster than the predetermined vehicle speed v2(YES in step ST10), the control unit13selects ordinary control for heater operation, and sets a temperature of the electric water heater11b, as step ST11. At this time, the temperature T of the electric water heater11bis set to T=TAwhen the position P8is selected, likewise, T=TBfor the position P9, T=TCfor the position P10, T=TDfor the position P11, T=TEfor the position P12is selected, ad T=TFfor the position P13.

After setting the temperature T of the electric water heater11b, the control unit13performs heater operation in ordinary control, as step ST12. In the heater operation, the control unit13heats water by the electric water heater11bbased on the set temperature, heats the air from the fan by the heated water, and blows out heated air from the outlet port, and wars up the passenger compartment D.

Next, the control unit13performs the heater operation in ordinary control, and detects a vehicle speed v again, as step ST13. As step ST14, the control unit13determines whether the detected vehicle speed v is a speed to change the ordinary control to ID control (vehicle speed v≦v1). When the detected vehicle speed v is faster than the predetermined vehicle speed v1(NO in step ST14), the heater operation in ordinary control is continued.

When NO in steps ST9and ST14, the control unit13continues heater operation, and determines whether a driver rotates the temperature control dial22, as step ST15.

If a driver does not rotate the temperature control dial22(NO in step ST15), the control unit13determines whether a driver instructs to stop the operation, i.e., a driver rotates the fan setting dial27to the OFF position, as step ST16. If a driver rotates the fan setting dial27to the OFF position and stops the heater operation (YES in step ST16), the control unit13stops the operation of the air-conditioning system10, as step ST17. If a driver does not instruct to stop the operation in step ST16(NO in step ST16), the control unit13returns to step ST4, and detects a vehicle speed v again. Thereafter, steps at and after ST5are repeated.

If a driver rotates the temperature control dial22, and the position P is changed in step ST15(YES in step ST15), the control unit13returns to step ST2, and confirms the position of the temperature control dial22. Thereafter, steps at and after ST3are repeated.

If the vehicle speed v detected in step ST8is the same as or faster than the vehicle speed v2(YES in step ST9), the control13returns to step ST11, sets a temperature for ordinary control, and performs heater operation. Thereafter, steps at and after ST12are repeated.

If the vehicle speed v detected in step ST13is the same as or slower than the vehicle speed v1(YES in step ST14), the control13returns to step ST6, sets a temperature for ID control, and performs heater operation. Thereafter, steps at and after ST7are repeated.

Next, an explanation is given of the case in which the vehicle speed v detected in step ST4is faster than a predetermined vehicle speed V1(NO in step ST5), and slower than the predetermined vehicle speed v2(NO in step ST10).

When the vehicle speed v detected in step ST4is faster than a predetermined vehicle speed V1(NO in step ST5), and slower than the predetermined vehicle speed v2(NO in step ST10) (v1<v<v2), the steps of the flowchart X inFIG. 6are executed. As shown in step ST30inFIG. 6, when the vehicle speed v detected in step ST4is faster than the vehicle speed v1and slower than the vehicle speed v2, the control unit13determines whether the operation is heater operation in ordinary control or not, as step ST31.

If the operation is heater operation in ordinary control (YES in step ST31), the control unit13performs heater operation in ordinary control, and goes to Y inFIG. 5, and detects a vehicle speed v, as step ST13. Thereafter, steps at and after ST14are repeated.

If the operation is not heater operation in ordinary control (NO in step ST31), the control unit13determines whether the operation is heater operation in ID control, as step ST33, as shown inFIG. 6. If the operation is heater operation in ID control (YES in step ST33), the control unit13continues the heater operation in ID control, as step34. The control unit13performs the heater operation in ID control, and goes to Z inFIG. 5, and detects a vehicle speed v, as step ST8. Thereafter, steps at and after ST9are repeated.

If the operation is not heater operation in ID control (NO in step ST33), i.e., the air-conditioning system10is initiated from a stop state, the control unit13selects heater operation in ordinary control as step ST35, and sets a temperature of the electric water heater11b, as shown inFIG. 6.

After setting the temperature of the electric water heater11bfor ordinary control, the control unit13warms up the passenger compartment D by heater operation according to the set temperature, as step ST36. Then, the control unit13performs heater operation in ordinary control, goes to Y inFIG. 5, and detects a vehicle speed v, as step ST13. Thereafter, steps at and after ST14are repeated.

If the position of the temperature control dial22detected in step ST2is any one of P1to P7(NO in step3), the control unit performs cooler operation or blowing operation according to the position of the temperature control dial22. The cooler operation and blowing operation are performed according to different temperatures set by the temperature control dial22. A detailed explanation thereof is omitted.

If the temperature control dial22is rotated during cooler operation or blowing operation (YES in step ST19), the control unit13returns to step ST2, and confirms the position of the temperature control dial22. After the position of the temperature control dial22is confirmed, the steps at and after ST3are repeated.

If the temperature control dial22is not rotated during cooler operation or blowing operation (NO in step ST19), the control unit13determines whether a driver instructs to stop the operation, i.e., a driver rotates the fan setting dial27to the OFF position, as step ST20. If a driver rotates the fan setting dial27to the OFF position and stops the heater operation (YES in step ST20), the control unit13stops the operation of the air-conditioning system10, as step ST17. If a driver does not stop the operation in step ST20(NO in step ST20), the control unit13returns to step ST18, and continues the cooler operation or blowing operation, until the temperature control dial22is operated or the operation is stopped in step ST19or20.

In the electric car1equipped with the air-conditioning system10configured as described above, the control unit13selects one of ID control and ordinary control at different setting temperatures as control of heater operation, based on a vehicle speed v that is one of the conditions of the electric car1.

The control unit13performs heater operation at a temperature assuming heat loss of the electric car1during travel as ordinary control, while the electric car1is traveling. Therefore, the air-conditioning system keeps a temperature in the passenger compartment D at a target temperature set by the setting dials16, and the passenger compartment D is kept comfortable while the car is traveling.

The control unit13performs heater operation at a temperature assuming heat loss not caused by motion-induced airflow as ID control, while the electric car1is idling or traveling at low speed. The air-conditioning system keeps a temperature in the passenger compartment D at a target temperature set by the setting dials16, and the passenger compartment D is kept comfortable while the car is stationary or traveling at low speed. In other words, a passenger compartment temperature is not unnecessarily increased by using a setting temperature not assuming heat loss by motion-induced airflow.

Heater operation is possible by setting a temperature unnecessarily high, and the power consumption of the air-conditioning system10may be minimum required. By operating the air-conditioning system10in ID control, the passenger compartment D can be kept at a conformable temperature, and waste of electrical energy of the battery3can be prevented. This increases the running distance of the electric car1.

Further, by setting the vehicle speeds v1and v2for switching the ordinary control and ID control to v1<V2, frequent control change is unnecessary at acceleration/deceleration of the electric car1or in traffic jams. If the vehicle speeds v1and v2for switching the ordinary control and ID control to a range including v1-v2, for example, when the vehicle speed v is v1(v2), the ordinary control and ID control are frequently switched. In such a case, heater operation in ordinary control may be performed even if a vehicle speed is suitable for ID control. In this case, temperature setting for heater operation may generate unnecessary heat, and the electrical energy may be wasted. However, as in this embodiment, by setting vehicle speeds v1and v2for switching the ordinary control and ID control to v1<V2, unnecessary switching of the controls for heater operation can be prevented.

In the electric car1equipped with the air-conditioning system10configured as described above, the interior of the car can be kept at a comfortable temperature by controlling a passenger compartment temperature by using two or more heater temperature setting tables based on a vehicle speed v. Further, the power consumption can be decreased by preventing an unnecessary passenger compartment temperature increase and unnecessary heater operation. This increases the running distance of the electric car1.

As described herein, it is possible to provide the air-conditioning system10of the electric car1and a method of controlling the air-conditioning system10of the electric car1capable of performing comfortable heater operation according to a travel state of the car and decreasing the power consumption.

The invention is not limited to the embodiments described herein. The invention may be embodied in practical phases by modifying the constituent elements without departing from its spirit or essential characteristics. For example, the setting panel12of the air-conditioning system10is not limited to the configuration described herein. Of the setting dials16on the setting panel12, the temperature control dial22is rotatable about 180°, and has the positions P1to P13. The rotatable angle may be 120°. The position P may be more minutely divided into P1to P18, for example.

Further, in the above example, the setting dials16are rotatable for setting various conditions. The setting dials may be linearly slidable. The dials may be modified, as long as they can set various conditions for operating the air-conditioning system10.

The control unit13performs heater operation of the air-conditioning unit11in ID or ordinary control based on a vehicle speed v. The control unit may have the other control methods. In ID control, setting temperature for the positions P8to P13are TGto TL(° C.), and the relationship between the setting temperatures is TG=TH<TI<TJ<TK<TL. The setting temperatures are not limited to them. For example, the setting temperatures may be TG=TH=TI. The setting temperature T for the position P may be changed depending on the capacity of the air-conditioning system10, the form of the car body2, and other various factors.

Further, in the above example, the control unit13has two groups of setting temperatures. The number of the groups of setting temperatures is not limited to two. If more than two groups of setting temperatures are provided, a certain vehicle speed may be added for the control different from the ID control and ordinary control. In other words, a vehicle speed vx other than the vehicle speeds v1and v2may be set, and the air-conditioning unit11is controlled based on the setting temperature added for the vehicle speed vx. The control unit13stores setting temperatures (a table of heater operation setting temperatures). A memory may be provided, and setting temperatures may be stored in the memory.

Further, in the above example, a travel state to select a group of setting temperatures (control) is determined by a delay in a vehicle speed of the electric car1. The travel state is not limited to this. The travel state may be determined by an external air temperature. For example, certain external air temperatures may be set, and the ID and ordinary control for heater operation may be selected by the predetermined external temperatures. A setting temperature for a travel state may be changed by selecting the control for heater operation by combining a delay in a vehicle speed and external temperatures. The travel state may be any condition, as long as it influences the escape of the heat of the passenger compartment D to the outside. Weather and humidity may be counted as a travel state, in addition to a vehicle and external air temperature.

The invention may be embodied by combining the constituent elements disclosed in the embodiments described herein. For example, some constituent elements may be removed from all constituent elements shown in the embodiments. The constituent elements of different embodiments may be combined. The invention may be embodied in other forms without departing from its spirit and essential characteristics.