JP2010095154A - Vehicular air-conditioning system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vehicular air-conditioning system capable of improving heating performance at the beginning of heating operation. <P>SOLUTION: The vehicular air-conditioning system 1 includes a heat pump circuit 10 and an exhaust heat recovery circuit 30. Furthermore, the exhaust heat recovery circuit 30 includes: a pump 31; an exhaust heat recovery heat exchanger 34 for making a heat medium absorb exhaust heat discharged from a vehicle; and a heat medium/cooling medium heat exchanger 20 for heating a cooling medium circulating through the heat pump circuit 10 with the heat medium heated by the exhaust heat recovery heat exchanger 34 downstream from the exhaust heat recovery heat exchanger 34. In the vehicular air-conditioning system, a heater 35 is further provided which can heat the heat medium circulating through the exhaust heat recovery circuit 30. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a vehicle air conditioning system that cools or heats a vehicle interior by means of a heat pump.

  As a conventional vehicle air conditioning system, for example, there is one disclosed in Patent Document 1. This vehicle air-conditioning system recovers the amount of heat exhausted by the heat pump circuit that is also used for cooling and heating and the ventilation air that is exhausted from the passenger compartment to the outside of the vehicle, and uses the recovered heat to cool the refrigerant in the heat pump circuit during cooling to condense the refrigerant. Exhaust heat utilization means for warming the refrigerant of the heat pump circuit and evaporating the refrigerant during heating.

  The exhaust heat utilization means includes a heat recovery refrigerant that is connected to the exhaust heat recovery heat exchanger disposed in the ventilation passage that communicates between the vehicle interior and the exterior of the vehicle, and the refrigerant flow path connected in parallel to the outdoor heat exchanger of the heat pump circuit. A heat exchanger, a heat medium conduit of a pump connecting the heat medium flow path of the heat medium refrigerant heat exchanger and the exhaust heat recovery heat exchanger, and a refrigerant flow path of the heat medium refrigerant heat exchanger An electromagnetic valve for controlling refrigerant inflow.

The solenoid valve of the exhaust heat utilization means is opened only when the heat medium temperature is lower than the outside air temperature during cooling, and only when the heat medium temperature is higher than the outside air temperature during heating under the control of the control means. It has become so. Therefore, when the refrigerant is used, it is possible to collect the cool air ventilated and exhausted from the passenger compartment to increase the cooling capacity of the heat pump circuit. Heating capacity can be increased.
Japanese Patent No. 3485379

  However, since the vehicle interior temperature is usually low and the heat medium temperature is low at the beginning of heating, the conventional vehicle air-conditioning system cannot warm and assist the refrigerant in the heat pump circuit by the exhaust heat utilization means. Has the disadvantage of being bad.

  In other words, when the refrigerant sucked into the compressor is at a low temperature (when the degree of superheat is low), the compression by the compressor does not proceed (the compressor work does not increase), the refrigerant temperature discharged from the compressor becomes high, and the refrigerant circulation It takes time to increase the amount, and thus it takes time to blow out hot air from the indoor heat exchanger for heating.

  Then, this invention aims at provision of the vehicle air conditioning system which can improve the heating performance at the time of the heating operation initial stage in a low-temperature environment.

  The present invention is a heat pump circuit that enables cooling and heating operation by circulating a refrigerant, a waste heat recovery circuit that can circulate a heat medium and recover waste heat discharged from a vehicle to heat the refrigerant of the heat pump circuit, The waste heat recovery circuit is disposed downstream of the pump that circulates the heat medium, the waste heat recovery heat exchanger that absorbs the waste heat discharged from the vehicle into the heat medium, and the waste heat recovery heat exchanger. A vehicle air conditioning system comprising: a heat medium circulating in the waste heat recovery circuit; and a heat medium refrigerant heat exchanger for exchanging heat between the refrigerant circulating in the heat pump circuit and the heat medium circulating in the waste heat recovery circuit. The gist is that a heater capable of heating is provided.

  According to the present invention, since the heat medium circulating in the waste heat recovery circuit can be heated by the heater even when the temperature in the passenger compartment at the initial stage of heating is low, the refrigerant circulating in the heat pump circuit with the heated heat medium. The heating capacity of the heat pump circuit can be increased early.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a schematic diagram of the vehicle air conditioning system according to the first embodiment, FIG. 2 is a schematic diagram showing the cooling operation of the vehicle air conditioning system, and FIG. 3 is a schematic diagram showing the heating operation of the vehicle air conditioning system. FIG. 4 is a diagram showing a control flow of heating operation, and FIG. 5 is a diagram showing a processing flow of heater output adjustment. FIG. 6 is a graph showing the relationship between the waste heat recovery amount, the refrigerant heat absorption amount, the COP, and the target water temperature.

"Vehicle air conditioning system"
The vehicle air-conditioning system 1 is mainly for air-conditioning of the passenger compartment, and the “heat pump circuit 10” that circulates refrigerant and enables air-conditioning operation and water as a heat medium circulate and discharge from the vehicle. A “waste heat recovery circuit 30” that recovers the waste heat that is collected and applies the recovered heat to the refrigerant circulating in the heat pump circuit 10.

"Heat pump circuit"
First, the heat pump circuit 10 will be described.

  The heat pump circuit 10 heats the interior of the compressor 11, the first condenser 13 that radiates the heat of the refrigerant compressed by the compressor 11, and the heat of the refrigerant compressed by the compressor 11 to the vehicle interior. The second condenser 18, the switching valve 12 that selects whether the refrigerant discharged from the compressor 11 flows toward either the first condenser 13 or the second condenser 18, and the first condenser 13 radiated heat. The first expansion means 15 that expands the refrigerant, the second expansion means 19 that expands the refrigerant radiated by the second condenser 18, and the heat in the passenger compartment are transferred to the refrigerant expanded by the first expansion means 15. A first evaporator 16 that cools the vehicle interior by absorbing heat, and a second evaporator 20 that absorbs heat by the refrigerant expanded by the second expansion means 19. The provided, refrigerant kinetic energy given by the compressor 11, in which is configured to circulate them.

  A liquid receiver 14 is provided downstream of the first condenser 13 and upstream of the first expansion valve 15, and is downstream of the first evaporator 16 and the second evaporator 20 and upstream of the compressor 11. An accumulator 17 is provided.

  That is, the heat pump circuit 10 includes a first circuit 10a (a circuit for indoor cooling) through which a refrigerant flows as indicated by an arrow in FIG. 2 and a second circuit 10b (an indoor room) through which the refrigerant flows as indicated by an arrow in FIG. These circuits 10a, 10b are switched by the switching valve 12.

  Therefore, when the switching valve 12 switches to the first circuit 10a (the circuit for indoor cooling), the refrigerant is the compressor 11 → the switching valve 12 → the first capacitor 13 as shown by the solid line arrow in FIG. The liquid flows in the order of the liquid receiver 14, the first expansion means 15, the first evaporator 16, the accumulator 17, and the compressor 11. Further, when switching to the second circuit 10b (indoor heating circuit) by the switching valve 12, the refrigerant, as indicated by the solid line arrow in FIG. 3, is the compressor 11 → the switching valve 12 → the second capacitor 18 → the second. The second expansion means 19 → the second evaporator 20 → the accumulator 17 → the compressor 11 flows in this order.

  In addition, between the 1st capacitor | condenser 13 and the 1st expansion valve 15 of the 1st circuit 10a, and between the 2nd capacitor | condenser 18 and the 2nd expansion valve 19 of the 10b of a 2nd circuit, They are connected by a bypass passage 10c. Therefore, as shown in FIG. 2, when the refrigerant is circulated in the first circuit 10a (interior cooling circuit), the second circuit 10b (indoor heating circuit) in which no refrigerant is circulated is used. The refrigerant stored in the second capacitor 18 can be drawn into the first first circuit 10a due to the pressure difference, and the refrigerant stored in the second capacitor 18 can be minimized. On the other hand, as shown in FIG. 3, when the refrigerant is circulated through the second circuit 10b (indoor heating circuit), the first circuit 10a (indoor cooling circuit) in which the refrigerant is not circulated. The refrigerant stored in the first capacitor 13 can be drawn into the second circuit 10b by the pressure difference, and the refrigerant sleeping in the first capacitor 13 can be minimized.

  The heat pump circuit 10 is configured as described above, and the first evaporator 16 and the second capacitor 18 of the heat pump circuit 10 are arranged in an air conditioning unit 40 described later.

  As shown in FIG. 2, when the refrigerant is circulated through the first circuit 10a, the first evaporator 16 can generate cool air to cool the vehicle interior. On the other hand, as shown in FIG. 3, when the refrigerant is circulated through the second circuit 10 b, warm air can be generated by the second condenser 18 to heat the vehicle interior. That is, the first evaporator 16 of the heat pump circuit 10 functions as a heat exchanger for indoor cooling, and the second condenser 18 of the heat pump circuit 10 also functions as a heat exchanger for indoor heating.

  The second evaporator 20 of the second circuit 10b functions as a heat medium refrigerant heat exchanger that absorbs heat of the heat medium circulating in the waste heat recovery circuit 30 described later. Details will be described later.

"Air conditioning unit"
As described above, the first evaporator 16 serving as a heat exchanger for indoor cooling and the second condenser 18 serving as a heat exchanger for indoor heating are disposed in the air conditioning unit 40 and are used to adjust the temperature in the passenger compartment. Used for.

  The air conditioning unit 40 is arranged between an instrument panel (not shown) in front of the vehicle and a dash panel (not shown). The air conditioning unit 40 includes a casing 41 and an air blower in the casing 41 to form a ventilation path. The first evaporator 16 and the second capacitor 18 arranged at P on the road, and a front blower 43 are provided.

  An intake box (not shown) for selectively introducing the inside and outside air into the air passage is provided at the upstream end of the air passage of the casing 41. The intake box includes an inside air inlet (not shown) for introducing air inside the vehicle interior, an outside air inlet (not shown) for introducing air outside the vehicle compartment, and an intake door that selectively opens and closes the inside air inlet and the outside air inlet. Thus, it is possible to select whether the air taken into the air passage in the casing 41 is from the vehicle interior or from the outside of the vehicle interior.

  On the other hand, at the downstream end of the air passage P of the casing 41, an air outlet for blowing out the air whose temperature is adjusted in the air passage into the vehicle compartment is formed. The air outlet includes, for example, a defroster air outlet that opens toward the vehicle front window, a face air outlet that opens toward the passenger's upper body, a foot air outlet that opens toward the passenger's feet, and the like.

  When the front blower 43 in the air passage is operated, air is introduced from the inside air inlet or the outside air inlet at the upstream end of the air passage, and the refrigerant circulates in the first circuit 10a of the heat pump circuit 10 as shown in FIG. If cold air is generated by the first evaporator 16 of the first circuit 10a, the refrigerant is circulated through the second circuit 10b of the heat pump circuit 10 as shown in FIG. Warm air is generated by the second capacitor 18 of the second circuit 10b, and the generated cool air or hot air is blown into the vehicle interior from one or a plurality of outlets at the downstream end of the air passage. The

  When the inside air introduction port of the intake box of the air conditioning unit 40 is open and the outside air introduction port is closed, the air conditioning unit 40 takes in air from the vehicle interior and blows out temperature-adjusted air into the vehicle interior and blows out from the air conditioning unit 40. The air is again sucked into the air conditioning unit 40 and the temperature is adjusted. That is, it becomes an inside air circulation mode in which air circulates in the passenger compartment.

  Conversely, when the inside air inlet of the intake box of the air conditioning unit 40 is closed and the outside air inlet is open, the air conditioning unit 40 draws air from the outside of the vehicle, adjusts the temperature, and then blows out into the vehicle interior. Thus, the air blown out from the air conditioning unit 40 into the vehicle compartment is discharged to the outside of the vehicle compartment through the ventilation unit 45. That is, the outside air introduction mode for introducing air from the outside of the vehicle is set.

"Ventilation unit"
The ventilation unit 45 is provided, for example, at the rear of the vehicle, and includes a ventilation passage 47 that communicates the interior of the vehicle with the outside of the vehicle. The ventilation passage 47 is closed by a valve (not shown) that opens and closes according to the pressure difference between the vehicle interior and the exterior of the vehicle interior. This on-off valve opens the ventilation passage 47 when the pressure in the vehicle interior becomes higher than the outside of the vehicle interior and the pressure difference becomes a certain value or more, and closes the ventilation passage 47 when the pressure difference between the vehicle interior and the exterior of the vehicle interior becomes less than a certain value. That is, the ventilation passage 47 is closed in the inside air circulation mode, and is exhausted from the ventilation passage 47 in the outside air introduction mode.

  A rear blower 49 is arranged in the middle of the ventilation passage 47, and in the outside air introduction mode, the same air volume as that of the front blower 43 is exhausted. And the waste heat recovery heat exchanger 34 of the waste heat recovery circuit 30 mentioned later is arrange | positioned so that the air exhausted out of a vehicle interior from a vehicle interior may pass. Thereby, the waste heat discharged from the vehicle can be recovered by the waste heat recovery heat exchanger 34.

"Waste heat recovery circuit"
Next, the waste heat recovery circuit 30 in which the waste heat recovery heat exchanger 34 is interposed will be described.

  As shown in FIG. 1, the waste heat recovery circuit 30 includes a waste heat recovery heat exchanger 34, an electric heater 35, a pump 31, and a heat medium refrigerant heat exchanger 20. That is, the waste heat recovery circuit 30 includes a pump 31 that circulates the heat medium, a waste heat recovery heat exchanger 34 that absorbs the waste heat exhausted from the vehicle, and a downstream of the waste heat recovery heat exchanger 34. A basic configuration including a heat medium refrigerant heat exchanger 20 (second evaporator of the heat pump circuit 10) that is disposed and circulates between the heat medium that circulates in the waste heat recovery circuit 34 and the refrigerant that circulates in the heat pump circuit 10. In addition, an electric heater 35 for heating the heat medium circulating in the waste heat recovery circuit 30 is provided. Reference numeral 33 denotes a temperature sensor that detects the temperature of the inlet of the waste heat recovery heat exchanger 34.

  Therefore, when the pump 31 is operated, the heat medium repeats circulation in the path of the pump 31 → the heat medium refrigerant heat exchanger 20 → the waste heat recovery heat exchanger 34 → the electric heater 35 → the pump 31.

  Since the waste heat recovery heat exchanger 34 can recover the heat of the exhaust air discharged from the vehicle interior to the exterior of the vehicle interior as described above, the recovered waste heat is transferred to the heat pump circuit via the heat medium refrigerant heat exchanger 20. 10 second circuits 10b (circuits for room heating) can be used to assist the heating operation.

  As described above, the waste heat recovery circuit 30 can assist the heating operation of the heat pump circuit 10 with the basic configuration including the pump 31, the waste heat recovery heat exchanger 34, and the heat medium refrigerant heat exchanger 20. Since the electric heater 35 is provided, it is possible to assist the heating operation of the heat pump circuit 10 by forcibly increasing the temperature of the heat medium when the temperature of the heat medium is low.

  In particular, since the vehicle interior is not warm at the initial stage of the heating operation in a low-temperature environment, the heat medium cannot normally be heated. However, in the structure including the electric heater 35 as in the present embodiment, such a low temperature The heat medium can be heated even in the initial heating operation in the environment, and the heating capacity can be increased early.

"Heating operation"
An example of suitable control of the heating operation of the vehicle air conditioning system configured as described above will be described below with reference to FIG.

  First, when the control unit receives a heating operation command, the switching valve 12 switches the refrigerant circulation path to the second circuit 10b, the compressor 11 is turned on, the front blower 43 is turned on, and the outside air introduction mode is turned on (the intake box is turned on). The outside air inlet is opened and the inside air inlet is closed), the rear blower 49 is turned on, the pump 31 is turned on, the electric heater 35 is turned on, and the heating operation is started.

  As a result, the air taken in from the outside of the passenger compartment by the front blower 43 is heated by the second condenser 18 (indoor heating heat exchanger) and blown out into the passenger compartment as shown in FIG. It is discharged from the passenger compartment to the outside of the passenger compartment through the ventilation unit 45 on the side. At this time, the heat of the air exhausted outside the passenger compartment is absorbed by the heat medium (water in this example) that passes through the waste heat recovery heat exchanger 34. The heat medium that has received and heated the waste heat is heated by the downstream heater 35, passes through the pump 31 and the heat medium refrigerant heat exchanger 20, and returns to the waste heat recovery heat exchanger 34 again. . The heat medium circulating in the waste heat recovery circuit 30 gives heat to the refrigerant circulating in the second circuit 10b (circuit for indoor heating) of the heat pump circuit 10 when passing through the heat medium refrigerant heat exchanger 20. The evaporation of the refrigerant in the heat medium refrigerant heat exchanger 20 (second evaporator of the heat pump circuit 10) can be promoted, and the heating performance of the heat pump circuit 10 can be improved.

  When the heating operation is started in this manner, as shown in FIG. 4, the control unit first reads the vehicle interior temperature Ta, the vehicle interior temperature Tr, and the vehicle interior target temperature Trt set by the occupant (step S1). The front blower output Wbf is adjusted by a known method so that the temperature Tr becomes the vehicle interior target temperature Trt (step S3), and the compressor rotation speed Nc is adjusted (step S5). At this time, the rear blower output Wbr is set so that the air flow rates of the front blower 43 and the rear blower 49 are the same, and the same amount of air sucked into the vehicle interior from the front side is brought out of the vehicle interior from the rear side. Blow out.

  Next, the control unit reads the heat medium temperature (water temperature) Tw detected by the temperature sensor 33 attached upstream of the inlet of the waste heat recovery heat exchanger 34 (step S7), and adjusts the output Wp of the pump 31. (Step S9). In this example, the output Wp of the pump 31 is set to a predetermined constant value.

  FIG. 7 shows the flow rate of the heat medium flowing through the waste heat recovery heat exchanger 34 (flow rate of the heat medium flowing through the waste heat recovery circuit 30) and the amount of heat absorbed by the waste heat recovery heat exchanger 34 (waste heat recovery amount). FIG. As is apparent from FIG. 7, when the flow rate of the heat medium flowing through the waste heat recovery heat exchanger 34 exceeds the inflection point f1, the amount of heat (waste heat recovery amount) that can be recovered by the waste heat recovery heat exchanger 34 is almost equal. In this embodiment, in order to avoid wasting power, in this embodiment, a value having a flow rate larger than the inflection point f1 is set in advance, and the output Wp of the pump 31 is made constant so that the flow rate becomes the set value. And drive. The output Wp of the pump 31 is, for example, the output value of the pump 31 so that the flow rate becomes at least a value greater than the inflection point f1, with the output Wbr of the blower 31, the cabin temperature Tr, and the water temperature Tw as variables. Change control may be performed as needed, or change control may be performed based on other variables.

  As described above, after adjusting the output of the pump 31 in step S9, the output of the heater 35 is adjusted in step S11. In the heater output control of this embodiment, as will be described in detail later, since the heating performance coefficient COP (Coefficient of Peformance) is lowered as a whole system when the heater 35 is operated indiscriminately, the output of the heater 35 is set so that the COP increases. The value is controlled.

  Finally, in step S13, it is determined whether the current vehicle interior temperature T and the target vehicle interior temperature Trt are substantially the same (Tr≈Trt). For example, it is determined whether or not the current vehicle interior temperature T is within the range of error ± 0.5 ° C. of the target vehicle interior temperature Trt. If it is within the range (YES in step S13), the heating operation is terminated, and if it is out of the range (NO in step S13), the process returns to step S1 and is repeated.

"Heater output control"
Next, the output control of the heater 35 in the above-described step S11 will be described in more detail with reference to FIG.

  As described above, when the heater 35 is always operated at the maximum output, the heating performance coefficient COP (Coefficient of Performance) is lowered as a whole system. Therefore, in this embodiment, the output value of the heater 35 is set so that the COP is increased. Is controlling.

  In this embodiment, the temperature (water temperature Tw) of the heat medium at one point of the waste heat recovery circuit 30 (in this example, the inlet of the waste heat recovery heat exchanger 34) is detected, and the water temperature Tw is the highest in COP. The output Wh of the heater 35 is controlled so as to be the water temperature (target water temperature Twt).

  It is known that the water temperature Twt at which the COP becomes the highest is the COP that is the highest at the intersection temperature of the equation expressing the waste heat recovery amount Qe by Tw and the equation expressing the refrigerant heat absorption amount Qe by Tw. (See FIG. 6).

  FIG. 6 shows a coefficient of performance COP and waste heat recovery when variables other than the water temperature Tw (Ta, Tr, Trt, Wbf, Nc, Wp, ζ, Wbr, Wp, etc.) are fixed to a constant value and Tw is a variable. 6 is a graph of the amount Qr and the refrigerant endothermic amount Qe, and as is clear from FIG. 6, at the intersection of the equation representing the waste heat recovery amount Qe with Tw and the equation representing the refrigerant endothermic amount Qe with Tw, COP Is the highest. The heating performance coefficient COP is defined by the heating capacity / power, and represents the heating capacity with respect to work performed from the outside.

  First, before explaining the output control of the heater 35 of this embodiment in detail, how to derive the equations for the waste heat recovery amount Qr and the refrigerant heat absorption amount Qe will be described.

  Expressions of the waste heat recovery amount Qr and the refrigerant heat absorption amount Qe with Tw as a variable are derived as follows.

  The waste heat recovery amount Qr and the refrigerant heat absorption amount Qe can be expressed by the following equations 1 and 2 from the inlet and outlet temperatures.

Qr = (Trout−Tw) × Gw × C × ρ (Equation 1)
Qe = (Teout−Tein) × Gw × C × ρ (Equation 2)
Tw: Water temperature at the inlet of the waste heat recovery heat exchanger 34 (detection temperature of the temperature sensor 33)
Trout: Water temperature at the outlet of the waste heat recovery heat exchanger 34 Tein: Water temperature at the inlet of the heat medium refrigerant heat exchanger 20 Teout: Water temperature at the outlet of the heat medium refrigerant heat exchanger 20 Gw: Flow rate of the waste heat recovery circuit (pump power (Value determined by Wp)
C: Specific heat of the heat medium ρ: Density of the heat medium Here, the water temperature Trout at the outlet of the waste heat recovery heat exchanger 34, the inlet water temperature Tein of the heat medium refrigerant heat exchanger 20 (conditions when the heater 35 is turned off), heat The outlet water temperature Teout of the medium refrigerant heat exchanger 20 can be expressed by the following Equation 3, Equation 4, and Equation 5.

Trout = γr × (Tb−Tw) + Tw (Equation 3)
Tein = Trout + Tp−α (Equation 4)
Teout = Tein−γe (Tein−Tcin) (Equation 5)
Tb: Air temperature at the rear blower outlet (a value determined by a temperature drop from the target vehicle interior temperature Trt and the rear blower waste heat Wbr × k1)
γr: Correction coefficient on the waste heat recovery side (efficiency of waste heat recovery heat exchanger 34, target vehicle interior temperature Trt, rear blower air volume (value determined by rear blower power Wbr), flow rate Gw of waste heat recovery circuit (determined by pump power Wp) Value), a value determined by the water temperature Tw)
Tp: Pump temperature rise (value determined by pump power Wp)
α: Loss Tcin: Refrigerant temperature at the inlet of the heat medium refrigerant heat exchanger 20 (value determined by the compressor speed Nc and the expansion valve opening ζ)
γe: Correction coefficient on the refrigerant recovery side (efficiency of heat medium refrigerant heat exchanger 20, outside air temperature Ta, compressor rotation speed Nc, front blower air volume (value determined by front blower power Wbf), flow rate Gw of waste heat recovery circuit (pump Value determined by output Wp) and value determined by water temperature Tw)
Therefore, if Equation 3 is substituted into Equation 1, Equation 6 is obtained with Tw of the waste heat recovery amount Qr as a variable. If Equations 3, 4, and 5 are substituted into Equation 2, Equation 6 is obtained with Tw of the refrigerant heat absorption amount Qe as a variable. 7 is obtained.

Qr = (γr × (Tb−Tw)) × Gw × C × ρ (Equation 6)
Qe = −γe (γr × (Tb−Tw) + Tw + Tp−α−Tcin)) × Gw × C × ρ ... (Formula 7)
Thus, the equation (Equation 6) with Tw of the waste heat recovery amount Qr as a variable and the equation (Equation 7) with Tw of the refrigerant heat absorption amount Qe as variables are obtained. By substituting the detected value at the time and obtaining the value of Tw at which these two equations intersect, the target water temperature Trt at which the COP becomes highest can be obtained (see FIG. 6).

  From the above-described relational expression, the waste heat recovery amount Qr shown in Expression 6 is obtained by using the expression Qr = f (Trt, Wbr, Wp, Tw). Further, the refrigerant heat absorption amount Qe shown in Expression 7 is an expression using the outside air temperature Ta, the compressor rotation speed Nc, the expansion valve opening ζ, the target vehicle interior temperature Trt, the rear blower power Wbr, the front blower power Wbf, and the pump power wp as input parameters. Qe = f (Ta, Trt, Nc, ζ, Wbr, Wbf, Wp, Tw).

  Next, the heater control method will be described more specifically with reference to FIG.

  When the heater output adjustment control (step S11, see FIG. 4) is started, first, as shown in FIG. 5, the rear blower power Wbr and the pump power Wp are read (step S31), and the above-described correction coefficient on the waste heat recovery side is read. γr is calculated (step S33), and a waste heat recovery amount Qr with Tw as a variable is calculated (step S35). Further, the front blower power Wbf, the outside air temperature Ta, the pump power Wp, the compressor rotation speed Nc, and the expansion valve opening ζ are read (step S37), and the above-described refrigerant heat absorption side correction coefficient γe is calculated (step S39). A refrigerant heat absorption amount Qe with Tw as a variable is calculated (step S41).

  Next, based on the waste heat recovery amount Qr and the refrigerant heat absorption amount Qe, the water temperature (target water temperature Twt) at which the coefficient of performance COP is highest is calculated (step S43).

  Next, it is determined whether or not the current water temperature Tw substantially matches the calculated target water temperature Twt (step S45). In this example, it is determined whether the error d is within ± 0.5 ° C.

  If it is determined in step S45 that the current water temperature Tw is not substantially the same value as the target water temperature Twt (NO in step S45), the process proceeds to step S47, and whether the current water temperature Tw is lower than the target water temperature Twt. Determine whether or not.

  If the current water temperature Tw is higher than the target water temperature Twt (≈Twt-d) (NO in step S47), the current heater power Wh is large, so the heater 35 is turned off to avoid unnecessary power consumption (step S53). Return to step S45.

  Conversely, when the current water temperature Tw is smaller than the target water temperature (≈Twt−d) (YES in step S47), in step S49, the necessary heater power Wh is calculated based on the difference between the current water temperature Tw and the target water temperature Twt. Calculation (step S49), based on this value, change control of the heater output value Wh is performed (step S51), and the process returns to step S45. The heater power Wh is calculated based on the following formula 8.

Wh [W] = (Twt−Tw) * Gw * C * ρ (Equation 8)
If the current water temperature Tw is substantially the same value as the target water temperature Twt in step S45 (YES in the determination in step S45), efficient operation is performed with the current output value Wh of the heater 35. Then, the output control of the heater 35 is terminated with the output value Wh.

"effect"
Next, the main effects of this embodiment are listed.

  (1) The air conditioning system for a vehicle according to the present embodiment collects the heat pump circuit 10 capable of performing an air conditioning operation and the waste heat discharged from the vehicle by circulating a heat medium (water in this embodiment) and collects the heat. A waste heat recovery circuit 30 for supplying waste heat to the refrigerant of the heat pump circuit 10, wherein the waste heat recovery circuit 30 includes a pump 31, a waste heat recovery heat exchanger 34, A heat medium refrigerant heat exchanger 20 that supplies the heat recovered by the waste heat recovery heat exchanger 34 to the refrigerant circulating in the heat pump circuit 10, and a heater 35 that heats the heat medium circulating in the waste heat recovery circuit 30. Is further provided.

  Therefore, according to the present embodiment, the waste heat recovery circuit 30 further includes the heater 35 in addition to the basic configuration including the pump 31, the waste heat recovery heat exchanger 34, and the heat medium refrigerant heat exchanger 20, At the start of heating operation in a low temperature environment, the heat medium is warmed by the heater 35 and the heat medium warmed by the heater 35 is circulated to the heat medium refrigerant heat exchanger 20, so that the heat medium refrigerant heat exchanger 20 is immediately The refrigerant of the heat pump circuit 10 can be warmed through.

  Thereby, even if it is at the time of the heating operation start in a low temperature environment, the refrigerant | coolant of the heat pump circuit 10 can be warmed at an early stage, refrigerant | coolant circulation amount can be raised, and warm-up performance can be improved markedly.

  (2) Further, in the vehicle air conditioning system 1 of the present embodiment, the waste heat recovery heat exchanger 34 is provided downstream of the heat medium refrigerant heat exchanger 20, and downstream of the waste heat recovery heat exchanger 34. A pump 31 and a heater 35 are provided upstream of the heat medium refrigerant heat exchanger 20.

  Therefore, according to such a layout, not only the heat of the heater 35 but also the waste heat of the pump 31 is supplied to the heat medium refrigerant heat exchanger 20, so that the warm-up performance can be further improved.

  Further, according to the above layout, the heat medium circulating in the waste heat recovery circuit 30 is discarded as it is without passing through other components (the heater 35 and the pump 31) after being cooled by the heat medium refrigerant heat exchanger 20. The heat recovery heat exchanger 34 will be distributed. Therefore, since the low-temperature heat medium passes through the waste heat recovery heat exchanger 34, waste heat exhausted from the vehicle can be absorbed more efficiently, and the amount of waste heat recovery can be increased. And the capacity of the entire system can be increased.

  (3) Moreover, in the vehicle air conditioning system 1 of the present embodiment, the pump 31 is disposed downstream of the heater 35. That is, in the waste heat recovery circuit 30, the waste heat recovery heat exchanger 34, the heater 35, the pump 31, and the heat medium refrigerant heat exchanger 20 are provided in this order from the upstream side.

  According to such a layout, the heat medium heated by the heater 35 and having a low viscosity is supplied to the pump 31. Then, the flow rate of the heat medium sent out by the pump 31 is increased, the amount of refrigerant heat absorbed in the heat medium refrigerant heat exchanger 20 is increased, and the performance of the entire system can be further improved.

  (4) Further, in the vehicle air conditioning system 1 of the present embodiment, since the heat of the air discharged from the vehicle interior to the outside of the vehicle is used as waste heat to prevent fogging during heating operation, the existing system Can be used effectively.

  (5) In the present invention, the heat of the exhaust air discharged from the vehicle can be recovered without the rear blower 49. However, in this embodiment, the rear blower 49 is provided to forcibly recover the waste heat. Since air can be blown onto the exchanger 34, there is an advantage that waste heat can be recovered more reliably.

  (6) Moreover, in the vehicle air conditioning system 1 of the present embodiment, the temperature of the heat medium with the highest heating performance coefficient COP is calculated as the target temperature Trt (steps S31 to S43), and the target temperature Trt A control unit is provided for controlling the heater 35 based on the difference from the actual detected temperature Tr so that the heat medium reaches the target temperature (steps S49 and S51). Therefore, according to the present embodiment, since the coefficient of performance COP is the best (because power consumption can be reduced), operation control particularly effective for an electric vehicle, a fuel cell vehicle, or a hybrid vehicle that does not run on an engine (internal combustion engine) Become.

  (7) In the vehicle air conditioning system 1 of the present embodiment, the target vehicle interior temperature Trt, the rear blower power Wbr, the water temperature Tw, and the pump output Wp are calculated in order to calculate the target water temperature Twt at which the COP is highest. As input parameters, a waste heat recovery amount Qr = f (Trt, Wbr, Wp, Tw) of the waste heat recovery heat exchanger 34 is obtained, and the outside air temperature Ta, the compressor rotation speed Nc, the expansion valve opening ζ, the target vehicle interior Using the temperature Trt, the rear blower power Wbr, the front blower power Wbf, and the pump power wp as input parameters, the refrigerant heat absorption amount Qe = f (Ta, Trt, Nc, ζ, Wbr, Wbf, Wp, Tw, Tw). ) And the water temperature Tw at the intersection of the waste heat recovery amount Qr and the refrigerant heat absorption amount Qe is set as the target water temperature Trt.

  Therefore, the input parameters (outside air temperature Ta, indoor temperature Tr, target indoor temperature Trt, front blower voltage Wbr (= rear blower voltage Wbf), compressor rotational speed Nc, expansion valve opening ζ necessary for controlling the vehicle interior temperature are detected. In addition to the pump voltage Wp that can detect a value without providing a sensor, only one temperature sensor 33 is attached to the waste heat recovery circuit 30, and control can be performed with a small number of sensors.

  Next, another embodiment will be described.

(Second Embodiment)
FIG. 8 is a flowchart of heater output control of the vehicle air conditioning system according to the second embodiment of the present invention. In addition, since it is the same structure as 1st Embodiment except the output control of a heater, description of the overlapping structure and effect is abbreviate | omitted.

  As shown in FIG. 8, the control flow of the heater output control of the second embodiment includes steps S61 and S63 between step S43 and step S45, and the control flow of the first embodiment shown in FIG. And different.

  That is, after calculating the target water temperature Twt in step S43, it is determined whether or not the calculated target water temperature Twt is higher than the lower limit value T1 of the compressor operable temperature (step S61).

  If the calculated target water temperature Twt is lower than the lower limit value T1 of the compressor operable temperature (NO in step S61), the compressor 11 cannot be operated, and the COP is lowered, but the target water temperature Twt is equal to the compressor operable temperature. The process is replaced with the lower limit value T1 (step S63), and the processing after step S45 similar to that of the first embodiment is performed.

  Conversely, if the calculated target water temperature Twt is higher than the lower limit value T1 of the compressor operable temperature (YES in step S61), the processing from step S45 onward as in the first embodiment is performed as it is.

Note that the lower limit value T1 of the operable temperature of the compressor 11 is, for example, about −5 ° C. in the case of a chlorofluorocarbon refrigerant, but the value varies depending on the type of refrigerant. )
As described above, in the second embodiment, when the target water temperature Twt deviates from the operable temperature of the compressor 11, the compressor 11 is controlled by performing the heater control at the compressor operable temperature and the value closest to the target water temperature Twt. Can be operated at the water temperature Tw at which the COP is best.

  As described above, according to the vehicle air conditioning system 1 of the first and second embodiments, the warm-up performance can be improved at the initial heating stage in a low-temperature environment.

  Note that the above-described embodiment is a preferred example for explaining the present invention, and the present invention should not be construed as being limited to the above-described embodiment.

  For example, in the above-described embodiment, the waste heat exhausted from the vehicle is the heat of exhaust air exhausted from the vehicle interior to the exterior of the vehicle interior. However, in the present invention, the engine, motor, and battery for vehicle travel are used. Waste heat may be used, or the waste heat of equipment mounted on other vehicles may be used.

  In the present invention, various modifications of the heat pump circuit are possible. That is, at least an evaporator that can absorb the heat in the vehicle interior by the refrigerant circulating in the heat pump circuit and cool the vehicle interior, a condenser that can radiate the heat of the refrigerant circulating in the heat pump circuit to the vehicle interior, and the waste heat recovery circuit flow If the heat pump comprises a heat medium refrigerant heat exchanger that exchanges heat between the heat medium and the refrigerant circulating in the heat pump circuit, and can exchange the heat-exchanged and heated refrigerant through the condenser, the circuit configuration is Various changes are possible.

  In the above-described embodiment, the compressor used in the heat pump circuit has been described by way of an example of a fixed-capacity compressor in which the discharge capacity is unchanged and the refrigerant discharge amount can be changed by the rotation speed. In this way, a variable displacement compressor capable of changing the discharge capacity may be used. When a variable capacity compressor is used, the refrigerant flow rate flowing through the heat pump circuit is calculated by a well-known method based on the degree of opening of a capacity control solenoid valve or the like for changing the capacity in addition to the rotation speed of the compressor. it can.

  In addition, the above-described embodiment is suitable for application to an electric vehicle, a fuel cell vehicle, or the like that does not include an engine (internal combustion engine) as a travel drive source by controlling the COP to be an optimal value. However, the present invention can be applied to a vehicle that is driven by an engine (internal combustion engine) or the like.

FIG. 1 is a schematic view of a vehicle air conditioning system according to the first embodiment. FIG. 2 is a schematic diagram showing an operation during cooling operation of the vehicle air conditioning system. FIG. 3 is a schematic diagram showing the operation of the vehicle air conditioning system during heating operation. FIG. 4 is a diagram showing a control flow of heating operation by the control unit of the vehicle air conditioning system. FIG. 5 is a flowchart showing heater output control processing. FIG. 6 is a graph showing the relationship between the waste heat recovery amount Qr, the refrigerant heat absorption amount Qe and COP, and the water temperature Tw. FIG. 7 is a diagram showing a correlation between the flow rate of water flowing through the waste heat recovery circuit and the amount of heat absorbed by the refrigerant from the water in the heat medium refrigerant heat exchanger. FIG. 8 is a flowchart showing heater output control processing according to the second embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Vehicle air conditioning system 10 Heat pump circuit 10a 1st circuit (Circuit for cooling)
10b Second circuit (heating circuit)
DESCRIPTION OF SYMBOLS 11 Compressor 12 Switching valve 13 1st capacitor | condenser 14 Liquid receiver 15 1st expansion means 16 1st evaporator (heat exchanger for room cooling)
17 Accumulator 18 Second condenser (heat exchanger for indoor heating)
19 Second expansion means 20 Second evaporator (heat medium refrigerant heat exchanger)
30 Waste heat recovery circuit 31 Pump 34 Waste heat recovery heat exchanger 35 Electric heater 40 Air conditioning unit 41 Casing 43 Front blower 45 Ventilation unit 47 Ventilation passage 49 Rear blower

Claims (5)

A heat pump circuit that enables cooling and heating operations by circulating refrigerant,
A waste heat recovery circuit that circulates the heat medium, recovers waste heat exhausted from the vehicle, and applies it to the refrigerant of the heat pump circuit;
With
The waste heat recovery circuit is
A pump that circulates the heat medium, a waste heat recovery heat exchanger that absorbs waste heat exhausted from the vehicle into the heat medium, and heat that is disposed downstream of the waste heat recovery heat exchanger and circulates in the waste heat recovery circuit And a heat medium refrigerant heat exchanger for exchanging heat between the medium and the refrigerant circulating in the heat pump circuit, and further comprising a heater for heating the heat medium circulating in the waste heat recovery circuit. Air conditioning system. The vehicle air conditioning system according to claim 1,
The vehicle air conditioning system, wherein the waste heat recovery circuit is provided with the pump and the heater downstream of the waste heat recovery heat exchanger and upstream of the heat medium refrigerant heat exchanger. The vehicle air conditioning system according to claim 2,
The vehicle air conditioning system, wherein the pump is disposed downstream of the heater. The vehicle air conditioning system according to any one of claims 1 to 3,
Calculate the temperature of the heat medium with the highest coefficient of performance COP as the target temperature, and control the heater so that the heat medium reaches the target temperature based on the difference between the target temperature of the heat medium and the detected temperature of the heat medium An air conditioning system for a vehicle, comprising a control unit that performs the operation. The vehicle air conditioning system according to claim 4,
When the target temperature falls below a lower limit value of the operable temperature of the compressor, the control unit sets the target temperature to the lower limit value of the operable temperature and controls the heater.

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