JPS6229247B2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a vehicle air conditioner.

Air conditioning systems for vehicles such as buses are generally equipped with a cooling unit under the floor of the vehicle, which consists of a compressor, condenser, liquid tank, expansion valve, evaporator, and refrigerant piping that connects these. Those equipped with a hot water heating system that radiates heat into the room are commonly used.

During cooling, the cooling unit operates and a blower fan rotates to feed indoor air into the evaporator, thereby blowing the cooled indoor air into the vehicle interior through the cold air outlet.

Here, let w be the air flow rate passing through the evaporator section by the blower fan, and let △t be the difference between the evaporator inlet air temperature (i.e. room temperature) t _R and the evaporator outlet air temperature t _C , i.e. the air cooling temperature by the evaporator. , the cooling capacity Q is expressed by the formula.

Q=w(cp△t+△qx) where cp represents specific heat and △qx represents the latent heat of condensation of water per unit flow rate.

In the above formula, △t is △t=t _R -t _C as mentioned above, and if t _C falls below 4 to 5 degrees Celsius, frost will form on the evaporator, so t _C should be at least about 7 degrees Celsius or higher. Therefore, △t is room temperature t _R
Once , is determined, its maximum value is inevitably determined. Therefore, in order to increase the cooling capacity Q, it is necessary to increase the air flow rate w.

However, the amount of air blown by a fan is proportional to the number of rotations, and the power required for the fan is proportional to the cube of the number of rotations, so if you try to increase the amount of air blown, the required power becomes extremely large, which is extremely uneconomical. Not only that, but problems arise, such as increased noise and poor indoor comfort.

In addition to the above, heat exchangers such as condensers and evaporators may be made larger to increase the cooling capacity, but in a limited space such as under the floor, there is a limit to the size of the heat exchanger, and the cooling capacity cannot be increased. It was quite difficult to make it bigger.

The present invention aims to increase the cooling capacity through extremely simple measures, and to provide an air conditioner in which the measures for increasing the cooling capacity can also be used for heating purposes. This will be explained with reference to the embodiments shown in the accompanying drawings.

FIG. 1 shows a first embodiment of the present invention, in which 1 is a compressor, 2 is a condenser, 3 is a liquid tank, 4A, 4B are expansion valves, 5A, 5B
indicates an evaporator, and when the compressor 1 is driven to rotate by a power source such as an engine or an electric motor (not shown), the refrigerant discharged from the compressor 1 is cooled and condensed in the condenser 2 by means such as air cooling, and then in the liquid tank 3. Gas and liquid separated,
Only the liquid refrigerant is depressurized by the expansion valves 4A, 4B and flows to the evaporators 5A, 5B, where it absorbs heat from the indoor air and becomes a gas refrigerant, which is sucked into the compressor 1 again.

The two evaporators 5A and 5B are disposed in an evaporator case 6 having an indoor air intake port 7 in front and behind with respect to the air flow direction, and the indoor air sucked through the intake port 7 by the rotation of the ventilation fan 8 is first After being cooled while passing through the first evaporator 5A, it flows into the second evaporator 5B where it is further cooled, and these refrigerant circuit components, the blower fan 8, the blower duct, etc. The blower equipment, drive source, etc. are made into a unit, and the unit A is removably mounted under the floor of a vehicle, and the above configuration is the same as the conventionally used device.

In the present invention, a heat exchanger 9 is provided between the first evaporator 5A and the second evaporator 5B, and a heat exchanger 11 is also provided in the vehicle interior. The heat exchangers 9 and 11 are connected by a pipe 10 so that brine such as water is circulated between the heat exchangers 9 and 11, and a fan 12 is provided for circulating indoor air to the heat exchanger 11 in the vehicle interior. It is something. Note that 10' is a pump for circulating brine, and 13 is a case in which a heat exchanger 11 and a fan 12 are installed.

In the above configuration, the ventilation fan 8 during cooling operation
The indoor air sucked into the evaporator case 6 by the rotation of is cooled while passing through the first evaporator 5A, and then enters the heat exchanger 9.

Here, the inlet air temperature of heat exchanger 9 is the same as that of heat exchanger 1.
Since the inlet air temperature of No. 1 is lower than the indoor air temperature, when the pump 10 is operated and the brine is circulated, the brine is cooled by the circulating air in the heat exchanger section 9 and is cooled by the indoor air in the indoor heat exchanger section 11. warmed by. In other words, the first evaporator 5A
The cooled air is heated by nine heat exchangers, and the indoor air that has passed through eleven heat exchangers is cooled by a fan 12 and blown into the room.

The air heated in the heat exchanger section 9 is cooled again while passing through the second evaporator 5B downstream thereof, and is blown into the vehicle interior from a cold air outlet through a duct (not shown).

Now, suppose the indoor air temperature is 27 as shown in Figure 5.
℃, while passing through the first evaporator 5A, it is cooled by t ₁ , that is, 17℃ to 10℃, then heated in the heat exchanger 9 to 24℃, which is slightly lower than the indoor air temperature, and then further heated. Second evaporator 5
While passing through B, it is cooled by t ₂ , that is, 17℃, and the temperature drops to 7℃.
It turns into cold air and blows out into the passenger compartment.

In this case, in the conventional device without the heat exchanger 9,
Since the second evaporator outlet air temperature must be 7°C higher than the frosting point, the sensible heat of the evaporator must be determined by the temperature difference _t3 shown by the dotted line in Figure 5, and the sensible heat Q ₀ is Q ₀ = cpw (t ₁ + t ₃ ) = cp x w x 20°C.

However, in the device of the present invention equipped with the heat exchanger 9, the sensible heat Q ₁ is Q ₁ = cpu (t ₁ + t ₂ ) = cp x w x 34°C, and Q ₁ /Q ₀ = cpw x 34/cpw x 20 = 1.7. In the above embodiment, the cooling capacity can be increased by 170% by sensible heat compared to the conventional device with the same air volume as the conventional device. This ability can be increased up to 200%. Regarding latent heat, if the refrigerant evaporation temperature is the same as in the conventional device, the same cooling effect can be obtained.

In the above, the amount of heat corresponding to the temperature rise of the circulating air in the heat exchanger section 9 is used for cooling the circulating indoor air in the indoor heat exchanger section 11, so the heat exchanger 11 and the fan 12 are By placing the air conditioner near the driver's seat, for example, the cool air that has passed through the heat exchanger 11 can be used to spot-cool the driver's seat, improving the sense of cooling for the driver. can be measured.

FIG. 2 shows a second embodiment of the invention,
Figure 1 shows an example in which the present invention is applied to a single refrigeration cycle in which only two expansion valves 4 and two evaporators 5 are provided in parallel, whereas Figure 2 shows two independent refrigeration cycles. This shows an example in which the present invention is applied to a device with
The same reference numerals as in the figures represent the same parts, and their functions and effects are also the same as in FIG. 1.

Although FIGS. 1 and 2 show an example in which brine is used as a heat exchange medium in a circulation circuit consisting of two heat exchangers 9 and 11 and piping 10, brine may be used instead of brine, for example in a refrigeration cycle. The vapor compression cycle may be performed using a refrigerant similar to that used in the present invention, and in this case, the heat exchanger 9 would be a condenser and the heat exchanger 11 would be an evaporator. Further, the number of heat exchangers 9 and 11 may be singular as shown in the figure, or may be plural.

A specific example of the unit A shown in FIGS. 1 and 2 above is shown in FIG.

That is, in the third part, 14 is a frame, and the condenser 2 is mounted on one side of the frame 14, and the evaporators 5A and 5B having expansion valves 4A and 4B, respectively, and the heat exchanger 9 are installed on the other side. An evaporator case 6 having an indoor air inlet 7 and a blower fan 8 attached to the air outlet side is installed, and an engine 15 as a driving source is mounted on the center of the frame 14, and a compressor is rotationally driven by the engine 15. 1 is installed in a vibration-proof manner, and furthermore, although not shown in the figure, a receiver tank 3, refrigerant piping connecting these, a ventilation duct communicating with the ventilation fan 8, etc. are also installed to form an integrated unit A.
It constitutes. By installing the unit A removably at the bottom of the floor 17 of the bus 16 as shown in FIG. (omitted),
The blower duct connected to the blower fan 8 communicates with a rising duct 18 provided on the vehicle body, and cool air is sent from the rising duct 18 to a cold air blowing duct 1 provided on the ceiling.
The cold air is supplied to the cold air blowing duct 9 and is blown into the vehicle interior from a large number of blowing outlets 19A provided in the cold air blowing duct 19.

A case 13 containing a heat exchanger 11 and a fan 12 is installed inside the vehicle, and the heat exchanger 9 of the unit A installed under the floor and the heat exchanger 11 inside the vehicle are connected via piping 10. As mentioned above.

FIG. 6 shows a third embodiment of the present invention,
In this example, piping 1 connecting heat exchangers 9 and 11
0, a hot water inlet pipe 25 that guides the cooling water (hot water) after cooling the engine 20 for running the vehicle to the pipe 10 through the preheater 21 and the valve 22, and a hot water inlet pipe 25 that leads the cooling water (hot water) after cooling the engine 20 for running the vehicle to the pipe 10, and a hot water inlet pipe 25 that flows into the pipe 10 from the pipe 25. A hot water return pipe 25' is connected to the hot water return pipe 25' through which the hot water after passing through the heat exchanger 11 flows from the heat exchanger 9 into the driving engine 20 via the valve 23, and the pipes 25, 2 of the pipe 10 are connected.
A valve 24 is provided between the connecting portions of 5', and the other structure is the same as that shown in the second figure, and the same reference numerals as in FIG. 2 represent the same parts.

In the above configuration, during cooling operation, valve 2
4 is opened, and valves 22 and 23 are closed. Then piping 1
0 is completely separated from the hot water system of the driving engine 20, and a water circulation circuit is formed in which the heat exchangers 9 and 11 are connected through piping 10, and as in the case of FIG. After being cooled by the first evaporator 5A, it is heated by the heat exchanger 9, further cooled by the second evaporator 5B, and blown into the passenger compartment, and the indoor air is cooled by the heat exchanger 11 and is then heated by the heat exchanger 9. As explained in FIG. 5, the cooling capacity can be significantly improved compared to the conventional device that does not have the heat exchanger 9.

When the outside temperature is low, such as in winter, close valve 24 and close valve 2.
2 and 23 (at this time, of course, the engine 15 of unit A is stopped and the refrigeration cycle is not operating), and the blower fans 8, 12, and pump 10' are operated.

Then, the hot water after cooling the driving engine 20 is further heated by operating the preheater 21 as required, enters the pipe 10, passes through the heat exchanger 9, and then passes through the heat exchanger 11. Hot water return pipe 25'
A hot water circulation circuit is formed which returns to the driving engine 20 through the heat exchangers 9 and 11, and the indoor air flowing through the heat exchangers 9 and 11 is heated and hot air is blown into the vehicle interior, thereby heating the vehicle interior.

6 shows an example in which heating hot water pipes 25, 25' are added to the embodiment shown in FIG. 2, but the heating hot water pipes 25 and 25' are added to the embodiment shown in FIG.
5 and 25' may be connected, and the number of heat exchangers 9 and 11 is not limited to one each as shown in the figure, but may be plural.

As described above, according to the present invention, cooling capacity can be increased by simply providing a heat exchange medium circulation circuit consisting of two heat exchangers and piping connecting them in a conventional refrigeration cycle. In addition to being able to achieve a significant improvement, the two heat exchangers for improving the cooling capacity can also be used as heating radiators for a hot water heating system that uses cooling water from the driving engine. This can have a huge effect.

[Brief explanation of the drawing]

1 and 2 are explanatory diagrams of cooling systems showing the first and second embodiments of the present invention, respectively. Fig. 4 is a side explanatory view showing an example of how the device shown in Figs. 1 and 2 is mounted on a vehicle, Fig. 5 is a diagram showing the heat exchange temperature characteristics of the device shown in Figs. FIG. 3 is an explanatory diagram of a heating and cooling system showing a third embodiment. 1... Compressor, 2... Capacitor, 3
...Liquid tank, 4A, 4B...Expansion valve, 5
A, 5B... Evaporator, 6... Evaporator case, 8... Blower fan, 9, 11... Heat exchanger, 10... Piping, 12... Fan, 20... Traveling engine, 21... Preheater ,22,23,2
4... Valve, 25, 25'... Hot water piping.

Claims (1)

[Claims] 1. In a vehicle air conditioner having at least two evaporators, the two evaporators are disposed in the same ventilation path in front and behind the direction of ventilation by a blower fan. A heat exchanger is installed between the evaporators, and the heat exchanger installed between the evaporators and other heat exchangers installed inside the vehicle are connected through piping, so that the heat exchange medium circulates through both heat exchangers. A vehicle air conditioner characterized by forming a circulation circuit. 2. In a vehicle air conditioner that has at least two evaporators and the two evaporators are arranged in the same ventilation path in the front and back direction with respect to the direction of ventilation by the blower fan, heat is generated between the two evaporators. A circulation circuit is provided in which water circulates through both heat exchangers by installing an exchanger and connecting another heat exchanger installed in the vehicle interior with the heat exchanger installed between the evaporator and the evaporator through piping. A hot water pipe for circulating cooling water for the engine for driving the vehicle is connected to the circulation circuit, and water is circulated between the two heat exchangers during cooling operation, and water is circulated between the two heat exchangers to the circulation circuit and hot water pipe during heating operation. An air conditioner for a vehicle, characterized in that a valve is provided for controlling switching so that cooling water for a running engine flows through both heat exchangers.