JP2008013115A - Vehicular air conditioner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance heating feeling of an occupant by operating a PTC heater efficiently utilizing excess electric power of a vehicle. <P>SOLUTION: The vehicular air conditioner is provided with an air-conditioning unit built-in with the PTC heater 21 and blowing the air heated by the PTC heater 21 into a cabin; an excess electric power obtaining means 20 for determining the excess electric power Po capable of being fed to the PTC heater 21; a power consumption obtaining means 10 for determining consumption power Pptc of the PTC heater 21 varied according to a temperature of a PTC heater element; and a control means 10 for controlling the PTC heater 21 based on the excess electric power Po determined by the excess electric power obtaining means 10 and the consumption power Pptc determined by the consumption power obtaining means 10. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a vehicle air conditioner provided with a PTC heater.

  2. Description of the Related Art Conventionally, an air conditioner in which a PTC heater is provided in an air conditioning unit and air heated by heat generated by the PTC heater is blown into the vehicle is known (see, for example, Patent Document 1). In the apparatus described in Patent Document 1, two PTC heaters are provided in the air conditioning unit, and the number of PTC heaters to be turned on is determined according to the current capacity of the DC-DC converter.

Japanese Patent Laid-Open No. 11-115469

  By the way, the PTC heater has a characteristic that an electrical resistance value increases with an increase in temperature and power consumption decreases. However, since the device described in Patent Document 1 determines the number of PTC heaters to be turned on without considering this characteristic, the surplus power of the vehicle cannot be used efficiently, which is sufficient for the passenger. There is a possibility that a feeling of heating cannot be obtained.

  An air conditioner for a vehicle according to the present invention includes a PTC heater, an air conditioning unit that blows air heated by the PTC heater into the vehicle, surplus power acquisition means for obtaining surplus power of the vehicle that can be supplied to the PTC heater, and a PTC heater. Control for controlling the PTC heater based on the power consumption acquisition means for obtaining the power consumption of the PTC heater that changes according to the temperature of the element, the surplus power obtained by the surplus power acquisition means, and the power consumption obtained by the power consumption acquisition means Means.

  ADVANTAGE OF THE INVENTION According to this invention, the PTC heater can be operated using the surplus electric power of a vehicle efficiently, and a passenger | crew's feeling of heating can be improved.

Hereinafter, an embodiment of a vehicle air conditioner according to the present invention will be described with reference to FIGS.
FIG. 1 is a perspective view showing an appearance of an air conditioning unit constituting the vehicle air conditioner according to the present embodiment. The air conditioning unit 1 is disposed below the instrument panel in the vehicle, and the inside air or the outside air sucked through the inside / outside air switching door by the rotation of a blower fan (not shown) is passed through the air intake 11. It is blown in. After the air blown to the air conditioning unit 1 passes through the evaporator 12 and is cooled, the air passes through or bypasses the heater core 13 at a rate corresponding to the opening of the air mix door, and conditioned air of a predetermined temperature is generated.

  The conditioned air flows out of the air conditioning unit 1 through an outlet door that opens and closes according to the blowing mode, and is blown into the vehicle through the duct. That is, in the vent mode, the air is blown from the vent outlet to the occupant through the vent port 14 and the vent duct. In the defrost mode, the air is blown from the differential outlet to the inside of the window through the differential duct 15 and the differential duct. In the foot mode, the air is blown from the foot outlet through the foot port 16 toward the occupant's feet. The left and right foot ports 16 are connected to the driver's seat foot duct, and the left foot port 16 is connected to the passenger's seat foot duct.

  In the air conditioning unit, the air passage leading to the foot port 16 branches in the middle and communicates with the left and right foot ports 16, and two PTC heaters 21 are disposed on the upstream side of the branched portion. . The PTC heater 21 is an auxiliary heater used to make up for the lack of heating capacity when the air-conditioning air cannot be sufficiently heated by the heater core 13 such as when the outside air temperature is low and the engine cooling water temperature is low. Air heated by the PTC heater 21 can be blown from the opening 16. The PTC heater 21 has a so-called PTC characteristic in which the electric resistance value increases and the power consumption decreases as the temperature of the heater element rises, and the operation is controlled as described later.

  FIG. 2 is a block diagram showing the configuration of the vehicle air conditioner according to the embodiment of the present invention. The controller 20 includes an operation panel 22 for inputting an air conditioning command, a sensor group 23 for detecting various physical quantities (external temperature, solar radiation amount, internal temperature, evaporator passing air temperature, engine cooling water temperature, etc.) necessary for air conditioning control, A CAN communication line 24 that communicates with other control units is connected.

  Based on these signals, the controller 20 outputs control signals to the air conditioning actuators 25 such as the inside / outside air switching door drive actuator, the blowout door drive actuator, the air mix door drive actuator, and the blower fan drive motor. Then, the intake mode, the outlet mode, the air mix door opening, the air flow rate, and the like are controlled. Further, the PTC heater 21 is controlled as follows.

  FIG. 3 is a flowchart illustrating an example of processing executed by the controller 20. This flowchart starts, for example, when an automatic air conditioner switch on the operation panel 22 is turned on. In step S <b> 1, the engine speed detected by the speed sensor is read via the CAN communication line 24.

  In step S2, the power generation amount P of the alternator driven by the engine is predicted from the engine speed. For example, the relationship between the engine speed and the alternator power generation amount as shown in the figure is stored in advance, and the alternator power generation amount P is predicted using this relationship.

  In step S3, the electric power Pe consumed by electrical components other than the PTC heater 21 is calculated. This power consumption Pe is a power obtained by adding the power by turning on the headlight, the power by turning on the compressor, the power by turning on the electric heater mounted on the rear window, and the like, according to the signal taken in via the CAN communication line 24. The on / off state of each electrical component is determined, and the power consumption Pe is calculated.

  In step S4, the power consumption Pe is subtracted from the alternator power generation amount P. The electric power Po obtained here corresponds to the surplus electric power of the vehicle that can be used for the PTC heater 21. The surplus power Po may be calculated in consideration of not only the power generation amount of the alternator but also the charge amount of the battery.

  In step S5, it is determined whether or not the PTC heater 21 needs to be operated. For example, when the foot mode is set while the outside air temperature detected by the sensor group 23 is not more than a predetermined value and the engine coolant temperature is not more than the predetermined value, the air blown from the foot port 16 is heated by the heater core 13. However, there is a case where the heating capacity is insufficient and the passengers cannot be given a sufficient feeling of heating. In this case, it is determined that the operation of the PTC heater 21 is necessary.

  In step S5, the number of operating PTC heaters 21 is also determined. For example, when the deficiency level of the heating capacity estimated by the outside air temperature and the engine coolant temperature is below a certain level, the discomfort given to the occupant is not so great, so the number of operating PTC heaters 21 is determined as one. On the other hand, when the deficiency level of the heating capacity is equal to or higher than a certain level, the discomfort for the occupant is large, so the number of operating the PTC heaters 21 is determined to be two.

  If it is determined in step S5 that the operation of the PTC heater 21 is unnecessary, the process proceeds to step S6, the heater relay is turned off, and the energization to the PTC heater 21 is stopped. If it is determined in step S5 that the number of operating PTC heaters is one, the process proceeds to step S7. If it is determined that the number is two, the process proceeds to step S10.

  In step S7, an expected power consumption Pptc of the PTC heater 21 when one PTC heater 21 is operated is calculated. The storage unit 20a of the controller 20 stores characteristics P11 to P13 of the predicted power consumption Pptc with respect to the elapsed time since turning on one PTC heater 21 as shown in the drawing. According to these characteristics P11 to P13, the expected power consumption Pptc gradually decreases with the passage of time after the PTC heater is turned on. That is, when the PTC heater 21 is turned on, the temperature of the heater element gradually rises and the electric resistance value increases, so that the expected power consumption Pptc gradually decreases.

  Here, the characteristics P11 to P13 are set according to the fan air volume and the air temperature after passing through the evaporator, respectively. That is, the greater the fan air volume and the lower the air temperature after passing through the evaporator, the greater the heat load on the PTC heater 21, the smaller the rate of temperature rise of the heater element, and the greater the power consumption. Therefore, a plurality of characteristics P11 to P13 for determining the expected power consumption Pptc are set, and one characteristic corresponding to the fan air volume and the air temperature after passing through the evaporator is selected, and the PTC heater 21 is selected based on this characteristic. The expected power consumption Pptc corresponding to the on-time is calculated.

  In Step S8, it is determined whether or not the surplus power Po in Step S4 exceeds the predicted power consumption Pptc in Step S7, that is, whether or not there is surplus power Po that can operate one PTC heater 21. If step S8 is affirmed, the process proceeds to step S9, the heater relay is turned on to energize one PTC heater 21, and only one PTC heater 21 is operated (turned on). On the other hand, if step S8 is negative, the process proceeds to step S6, and energization of the PTC heater 21 is stopped (turned off).

  In step S10, an expected power consumption Pptc of the PTC heater 21 when two PTC heaters 21 are operated is calculated. The storage unit 20a of the controller 20 stores characteristics P21 to P23 of the predicted power consumption Pptc with respect to the elapsed time since the two PTC heaters 21 are turned on as shown in the figure. Here, the characteristics P21 to P23 are set according to the fan air volume and the air temperature after passing through the evaporator, respectively, similarly to the characteristics P11 to P13 in step S7, and according to the fan air volume and the air temperature after passing through the evaporator. A characteristic is selected, and the predicted power consumption Pptc corresponding to the ON time of the PTC heater 21 is calculated based on this characteristic. In this case, in each of the characteristics P21 to P23, the expected power consumption Pptc gradually decreases with the passage of time after the PTC heater is turned on, but the expected power consumption Pptc is larger than that of the characteristics P11 to P13.

  In step S11, it is determined whether or not the surplus power Po in step S4 exceeds the expected power consumption Pptc in step S10, that is, whether or not the two PTC heaters 21 can be operated. If step S11 is affirmed, the process proceeds to step S12, the heater relay is turned on to energize the two PTC heaters 21, and the two PTC heaters 21 are simultaneously operated (turned on). On the other hand, if step S11 is negative, the process proceeds to step S7, and an expected power consumption Pptc when only one PTC heater 21 is operated is calculated.

The operation of the vehicle air conditioner according to the present embodiment is summarized as follows.
Whether or not the PTC heater 21 needs to be operated is determined from the outside air temperature and the engine coolant temperature. If it is determined that the PTC heater 21 needs to be operated, the predicted power consumption Pptc of the PTC heater 21 corresponding to the temperature change of the heater element is calculated using the predetermined characteristics P11 to P13 or P21 to P23 ( Step S7, Step S10). When the predicted power consumption Pptc is smaller than the surplus power Po, one or two PTC heaters 21 are operated (steps S9 and S12).

  If it is determined that two PTC heaters 21 need to be operated, and the surplus power Po is less than or equal to the expected power consumption Pptc, the predicted power consumption Pptc and the surplus power Po when one PTC heater 21 is operated And compare. If the predicted power consumption Pptc in this case is smaller than the surplus power Po, only one PTC heater 21 is operated (step S11 → step S7).

  Thus, by comparing the predicted power consumption Pptc that changes according to the temperature of the heater element and the surplus power Po, the PTC heater 21 can be operated even when the power generation amount of the alternator is small, and the surplus power Po. Can be used efficiently. In this case, since the heater element temperature is estimated and the power consumption Pptc is calculated from the characteristics P11 to P13 and P21 to P23 set according to the fan air volume and the air temperature after passing through the evaporator, the power consumption Pptc is accurately calculated. It can be calculated. Since the number of operating PTC heaters 21 is determined from the outside air temperature and the engine coolant temperature, the PTC heater 21 provides a necessary and sufficient feeling of heating. When two PTC heaters 21 cannot be operated due to a shortage of surplus power Po, it is determined whether or not only one PTC heater 21 can be operated, and the PTC heater 21 is operated. Therefore, the surplus power Po can also be used efficiently in this respect.

According to the present embodiment, the following operational effects can be achieved.
(1) The predicted power consumption Pptc considering the temperature change of the heater element is calculated from the characteristics P11 to P13 and P21 to P23 stored in advance, and the surplus power Po and the predicted power consumption Pptc are compared with each other. Since the operation is controlled, the surplus power Po can be used efficiently, and a feeling of heating sufficient for the passenger can be obtained. On the other hand, for example, when comparing the rated power consumption of the PTC heater 21 and the surplus power Po, if the rated power consumption is larger than the surplus power Po, the actual power consumption Pptc is smaller than the surplus power Po. However, the PTC heater 21 is not turned on, and the surplus power Pptc cannot be used efficiently.

(2) Since the power consumption Pptc is calculated based on the air temperature heated by the PTC heater 21 and the amount of air blown and the operation time of the PTC heater 21, a new sensor is provided to calculate the power consumption of the PTC heater 21. This is not necessary and can reduce the cost.
(3) Since the power consumption Pptc is calculated from the characteristics P11 to P13 and P21 to P23 stored in advance, the configuration can be simplified.
(4) Since different characteristics P11 to P13 and P21 to P23 are stored according to the number of turning on the PTC heater 21, the power consumption Pptc of the PTC heater 21 can be calculated with high accuracy.

  In the above-described embodiment, the air passage in the air conditioning unit is branched to the left and right foot ports 16, and two PTC heaters 21 are arranged on the upstream side of the branch portion. The PTC heaters 21 may be arranged one by one, and each PTC heater 21 may be controlled independently according to the air conditioning command on the driver's seat side and the passenger seat side. Also in this case, the expected power consumption Pptc of the PTC heater 21 is calculated and compared with the surplus power Po, so that the surplus power Po can be efficiently used. Although two PTC heaters 21 are provided in the air conditioning unit, the number of PTC heaters 21 may be one, or three or more.

  The controller 20 calculates the surplus power Po that can be supplied to the PTC heater 21 by subtracting the power consumption Pe of the electrical components other than the PTC heater from the power generation amount P of the alternator. It may be estimated, and the configuration of the surplus power acquisition means is not limited to that described above. The controller 20 calculates the power consumption Pptc of the PTC heater 21 based on the predetermined characteristics P11 to P13 and P21 to P23. However, the power consumption may be detected by a sensor or estimated by an arithmetic expression or the like. The configuration of the power consumption acquisition unit is not limited to that described above. Although the number of PTC heaters 21 to be turned on is determined by the controller 20, if the PTC heater 21 is controlled based on the surplus power Po and the power consumption Pptc, the configuration of the control means is not limited to this.

  The present invention can be applied to various vehicles such as a gasoline vehicle, a hybrid vehicle, and an electric vehicle as long as the vehicle has an air conditioning unit with a built-in PTC heater 21. That is, the present invention is not limited to the vehicle air conditioner according to the embodiment as long as the features and functions of the present invention can be realized.

The perspective view which shows the external appearance structure of the air conditioning unit which comprises the vehicle air conditioner which concerns on embodiment of this invention. The block diagram which shows the structure of the vehicle air conditioner which concerns on embodiment of this invention. The flowchart which shows an example of the process performed with the controller of FIG.

Explanation of symbols

1 Air-conditioning unit 20 Controller 21 PTC heater Po Surplus power Pptc Power consumption

Claims (4)

An air conditioning unit that incorporates a PTC heater and blows air heated by the PTC heater into the vehicle;
Surplus power acquisition means for obtaining surplus power of the vehicle that can be supplied to the PTC heater;
Power consumption acquisition means for determining the power consumption of the PTC heater that changes according to the temperature of the PTC heater element;
A vehicle air conditioner comprising: control means for controlling a PTC heater based on surplus power obtained by the surplus power obtaining means and power consumption obtained by the power consumption obtaining means. In the vehicle air conditioner according to claim 1,
The power consumption acquisition means includes
A vehicle air conditioner characterized in that power consumption is obtained based on the temperature and air flow rate of air heated by a PTC heater and the operating time of the PTC heater. In the vehicle air conditioner according to claim 2,
The vehicle air conditioner is characterized in that the power consumption acquisition means obtains power consumption based on characteristics of power consumption stored in advance using the air temperature, the amount of air blown, and the operation time as parameters. The vehicle air conditioner according to claim 3,
A plurality of PTC heaters are provided in the air conditioning unit,
The power consumption acquisition means obtains power consumption according to power consumption characteristics stored for each number of PTC heaters stored in advance,
The control unit controls the number of operating PTC heaters based on the surplus power obtained by the surplus power obtaining unit and the power consumption obtained by the power consumption obtaining unit.

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