JPS621844B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heating device for buses, and its main purpose is to improve the heating effect and save energy in large buses.

As shown in FIG. 5, a heating system for a large bus generally uses a system in which cooling water after cooling the running engine 1 of the bus is circulated through a heating radiator 7 and a defroster 8, and then returned to the engine 1. The radiator 7 of the heating cycle using engine cooling heat
Conventionally, a device has been used in which a hot water boiler 6 is provided upstream of the cooling water to heat the cooling water by operating when the temperature of the cooling water is low (see, for example, Japanese Utility Model Application No. 54-79336).

In the above-mentioned heating system in which a hot water boiler is added to the conventional heating cycle that uses engine cooling heat, the cooling water that flows from the engine 1 through the thermostat 2 to the radiator 4 and returns to the engine 1 is used for cooling. It is common to adopt a configuration in which the circulation circuit branches into the heating cycle from the upstream side of the thermostat 2, and even during heating when the heating water valve 10 is opened and the water pump 5 is operating, the cooling water is not removed from the engine outlet. When the temperature exceeds a set value, for example 75° C., the thermostat 2 opens, the cooling water flows to the radiator 4 side, and the cooling fan 3 rotates to cool the cooling water. Therefore, the average temperature of the cooling water flowing into the heating cycle is kept almost constant at the set temperature of the thermostat 2, that is, 75°C.

On the other hand, the operation of the hot water boiler 6 is normally automatically controlled by a thermoswitch 11 that detects the temperature of cooling water flowing into the hot water boiler 6.

In such a conventional device, the thermo switch 11
If the off-point set temperature of the engine is set higher than the water temperature set by thermostat 2, hot water is always used during normal driving, except when the load on engine 1 increases and the engine outlet temperature of the coolant increases significantly, such as when climbing a hill. This is extremely inconvenient as the boiler 6 will start operating. Furthermore, if the set temperature of the thermoswitch 11 is set lower than the off point set temperature of the thermostat 2, the hot water boiler 6 will not operate at all times during normal driving except when warming up the engine and when going downhill, and the heating capacity will not be added. This is also inconvenient, and it is extremely difficult to select the set temperature for turning on and off the thermoswitch 11.

Furthermore, heating capacity is generally determined by the amount of air blown by the radiator 7 and fan 7' and the temperature difference between the air and hot water.
The air velocity Wa of the fan 7' is generally about 1200m ³ /H, the room temperature Ta is about 20℃, the water temperature Tw is about 75℃, the water flow rate W is about 1.2m ³ /H, and the temperature efficiency of the radiator 7 is φ.
is about 0.6, so the specific heat Cp of air is
0.24Kcal/Kg℃, specific volume r is 1.16Kg/m ³ , specific heat Cpw of water is 1.0Kcal/Kg℃, specific volume rw is 1000Kg/m ³
Then, the amount of heat Q on the air side is: Q=Wa・r・Cp(Tw−Ta)φ=1200×1.16×
0.24×(75−20)×0.6=11024Kcal/H...(1)

Also, the temperature drop △t of water is △t=Q/W・Cpw・rw =11024/1.2×1.0×1000=9.2℃...
…(2) becomes.

If the heating heat amount of the hot water boiler 6 is now 11024 Kcal/H, the water temperature will rise by 9.2℃ due to the boiler 6, and the water temperature entering the radiator 7 will be the engine 1 outlet water temperature.
Tw75℃ rises to 84.2℃, and if this is Tw', the amount of heat Q in the radiator 7 is proportional to the room temperature and the water temperature at the radiator inlet, so the above Tw-Ta becomes Tw'-Ta,
This ratio Tw'-Ta/Tw-Ta=84.2-20/7
The heat increase rate is 5-20=1.167.

This means that the amount of heat on the air side has increased by 16.7%. In other words, even if the boiler 6 provides the same amount of heat as the amount of heat generated by the engine 1, only 16.7% can be used, which is a major drawback in terms of fuel consumption and heating efficiency.

In other words, the water temperature at the outlet of the engine 1 is heated by the boiler 6, and the heat is radiated by the amount of boiler heating using the radiator, so that the engine inlet water temperature becomes the same as the engine outlet water temperature. This means that the cooling heat of the engine 1 is not used at all, which is extremely uneconomical.

Although there are conventional examples in which the thermoswitch 11 is provided on the outlet side 11' of the hot water boiler 6 or the outlet side 11'' of the radiator, the temperature of the outlet water of the engine 1 is constant and the amount of heat radiated from the radiator 7 is constant. As described above, only the level of the set temperature is different, but the temperature change width is the same as when the thermoswitch is provided on the inlet side of the hot water boiler 6, and the various drawbacks mentioned above cannot be avoided.

The object of the present invention is to eliminate the various drawbacks of the prior art as described above.

That is, in the present invention, as shown in FIG.
9...and defroster 8, enters the hot water boiler 6, is heated here, flows through the main radiator 7, and is returned to the engine 1.The other configuration is as shown in Fig. 5. This is the same as the conventional device, and the same reference numerals as in FIG. 5 represent the same parts.

The embodiment shown in FIG. 1 shows an example in which a plurality of sub-radiators 9 with fans 9' are fixedly installed on the upstream side of the hot water boiler 6.
As shown in the figure, a tube 9a through which hot water flows may be simply provided with a large number of heat dissipating fins 9b on the outer peripheral surface thereof.

It is desirable that the total amount of heat radiated by the width radiator 9 and the defroster 8 is set to be equal to or greater than the amount of heat radiated by the main radiator 7.

According to the present invention configured as described above, when using heating by opening the heating water valve 10 and operating the water pump 5, the cooling water (hot water) that has taken away the heat from the engine 1 is first transferred to the sub-radiator 9 and the defroster. 8, the heat is radiated into the room, and the water temperature at the inlet of the hot water boiler 6 is much lower than in the conventional system.

Assuming that the amount of heat dissipated on the upstream and downstream sides of the hot water boiler 6 is the same, and that the upstream and downstream sides each radiate 11024 Kcal/H as shown in equation (1) above, the inlet water temperature of the hot water boiler 6 is As shown in equation (2) above, the water temperature on the outlet side of engine 1, that is, 75
The temperature is 65.8℃, which is 9.2℃ lower than ℃.

Therefore, if the hot water boiler 6 heats 11024 Kcal/H, the inlet water temperature of the main radiator 7 will be 75°C, which is the same as the water temperature on the outlet side of the engine 1.
The water temperature decreased by 9.2℃ by dissipating 11024Kcal/H.
It flows into engine 1 at a temperature of 65.8°C.

As is clear from the above calculation, in the present invention, after the cooling heat of the engine 1 is radiated into the room by the sub-radiator 9 and the defroster 8, the heat from the hot water boiler 6 is transferred into the room by the main radiator 7. By dissipating heat, the capacity increase when heating using a hot water boiler was conventionally 16 to 17%, but with the present invention, the capacity increase was 16 to 17%.
100% utilization is now possible, and thermal efficiency can be significantly improved.

The operation of the hot water boiler 6 is controlled by a thermoswitch 11 that is activated by detecting the inlet water temperature, but as described above, in the present invention, a sub-radiator 9 and a defroster 8 are provided on the upstream side of the hot water boiler 6. is provided, so even if the water temperature on the engine outlet side rises due to heavy engine load such as when climbing a slope or driving at high speed, the water temperature at the inlet of the hot water boiler 6 decreases due to heat radiation by the sub-radiator 9, etc., and the thermoswitch 1
Even if the operating point temperature of thermoswitch 1 is set lower than the set temperature of thermostat 2 of the engine coolant cooling circulation circuit, thermoswitch 11 can operate satisfactorily.

This means that when the outside temperature drops and more heating capacity is desired, heating can be performed freely by the hot water boiler 6, and the heating effect can be significantly improved.

It goes without saying that the main radiator 7 can obtain hot air for heating even when the hot water boiler 6 is not heating. Therefore, in the present invention, the operating time of the hot water boiler 6 can be shortened compared to the conventional one.
It is possible to reduce fuel consumption and save energy.

An example of an electric circuit for controlling a heating device according to the present invention is shown in FIG.

In FIG. 4, 12 is a room temperature sensor that detects the indoor temperature and operates, and 13 is a heating switch. When the heating water valve 10 is opened manually or electrically and the heating switch 13 is turned on, the water pump 5 is activated. At the same time as the cooling water of the engine 1 flows in the heating cycle, the fan 9' of the sub-radiator 9 rotates, and if the room temperature is below a predetermined value at that time, the room temperature sensor 12 is activated.
is on, so the fan 7' of the main radiator 7
It also rotates. In this case, if the hot water boiler switch 14 (described later) is turned off, the thermo switch 1
1 is on or off, the hot water heater 6 does not operate, resulting in a weak heating state using only the cooling heat of the engine 1, and normal heating at times other than extremely cold or when the engine is warmed up is in this weak heating mode. Almost enough.

When it is necessary to improve the heating effect, the hot water boiler switch 14 is turned on.

Then, when the inlet water temperature of the hot water boiler 6 is below the set value, the thermoswitch 11 is turned on, the hot water boiler 6 is activated, and the inlet water temperature of the main radiator 7 is increased.
The temperature of the hot air blown from the main radiator 7 rises, resulting in a strong heating state.

During both the weak heating and the strong heating, the room temperature is maintained at a substantially constant value by turning the room temperature sensor 12 on and off.

By connecting the operation control circuit of the hot water boiler 6 and the operation circuit of the water pump 5 through the current backflow prevention element 16, the heating water valve can be turned on while the heating switch 13 is turned off during engine warm-up. 10
When you open the door and turn on the hot water boiler switch 14,
At that time, the temperature of the engine cooling water is extremely low, so the thermoswitch 11 is on, and the water pump 5 is energized from the thermoswitch 11 via the backflow prevention element 16, and the water pump 5 is activated to cool the engine cooling water. As the water circulates through the heating cycle, the hot water boiler 6 operates to heat the cooling water, raising the temperature of the cooling water flowing into the engine 1, significantly shortening the warm-up time, and increasing the inlet water temperature of the hot water boiler 6. When the temperature reaches a predetermined value, the thermo switch 11 is turned off, and the hot water boiler 6 and water pump 5 jointly stop operating, which is extremely convenient.

In addition, if the fans 7' and 9' consume a large amount of power and require the power generated by the bus's running engine 1 to rotate them, the fans 7' and 9'
An engine operating sensor 15 such as an engine oil pressure switch that is turned on when the engine 1 is operating is provided in the operation control circuit of the fan 9', so that when the engine 1 is stopped, even if the heating switch 13 is on, the fan 7', It is desirable to stop the rotation of 9'.

As described above, in the present invention, it is possible to use a weak heating state in normal times and a strong heating state when necessary such as in extremely cold weather, which can significantly improve the heating effect, and improve the thermal efficiency mentioned above. Together with various effects such as improvement and energy saving, this can bring great practical value.

[Brief explanation of the drawing]

Fig. 1 is a heating system diagram showing a first embodiment of the present invention, Fig. 2 is a heating system diagram showing a second embodiment of the invention, and Fig. 3 is a partial enlargement of the sub-radiator in Fig. 2. A sectional view, FIG. 4 is a diagram showing an example of a control electric circuit of the device shown in FIG. 1, and FIG. 5 is a heating system diagram showing a conventional example. 1...Travel engine, 2...Thermostat, 4...Radiator, 5...Water pump, 6...
Hot water boiler, 7... Main radiator, 8... Defroster, 9... Sub-radiator, 11... Thermo switch.

Claims (1)

[Claims] 1. A heating system for a bus in which cooling water for a running engine of a bus is heated in a hot water boiler, circulated through an indoor radiator, and then returned to the engine,
A heating device for a bus, characterized in that a sub-radiator for discharging engine cooling heat into the room is provided upstream of the hot water boiler, and a main radiator for heating is provided downstream of the hot water boiler. 2. The bus heating device according to claim 1, wherein the heat radiation amount of the sub-radiator is set to be equal to or greater than the heat radiation amount of the main radiator. 3 The operation of the hot water boiler is controlled by a thermoswitch that is activated by detecting the temperature of the cooling water that flows through the sub-radiator, and the rotation of the main radiator fan is controlled by a room temperature sensor that is activated by detecting the room temperature. The heating device for a bus according to claim 1 or 2, characterized in that the bus heating device has the following characteristics: