JPH03164516A - Heating apparatus for vehicle - Google Patents

Abstract

PURPOSE:To quickly raise the temperature of cooling water after starting and to shorten the heating stand-by time by controlling a switching valve of a by- pass passage to open, which is adapted to connect an outlet of a water pump and an inlet heat exchanger when the temperature of cooling water of an engine portion is less than a designated value. CONSTITUTION:A heat exchanger 3 is installed in an engine exhaust path E1. There is provided a cooling water passage P which is extended from a water pump 1 through an engine 2 to the heat exchanger 3 and then returned to the water pump 1 through a heater core 4. In the thus constructed apparatus, an engine by-pass passage 6 for connecting an outlet of the water pump 1 and the heat exchanger 3 is added, and a switching valve 81 is disposed in the passage. On the other hand, a flow control valve 82 is disposed in a cooling water passage P1 for connecting the outlet side of the engine and the outlet side of the engine by-pass passage 6. When the temperature of cooling water of an engine portion is less than a designated value, the switching valve 81 is controlled to open by a valve control means 6.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a vehicle heating system, and more particularly to a vehicle heating system that is capable of rapid heating at the initial stage of engine startup.

[Prior art] Most vehicle heaters are hot water type, and in this case, the engine cooling water temperature does not rise sufficiently at the beginning of the engine startup, and the rate of rise is slow, so it is difficult to obtain warm air conditioned air. It took a long time.

Therefore, attempts have been made to provide a heat exchanger in the exhaust path of the engine and rapidly heat the engine cooling water using high-temperature exhaust gas (for example, Japanese Utility Model Application Publication No. 56-43423,
Utility Model Application Publication No. 59-94911). To explain this with reference to FIG. 3, engine cooling water reaches the engine 2 from the water pump 1, passes through the heat exchanger 3 provided in the exhaust bypass flow path E1, and returns to the water pump 1 from the heater core 4 through the cooling water flow path P. be distributed. In the figure, E is an engine exhaust main flow path, and 83 is an electromagnetic switching valve. Further, 9 is a radiator, and the thermostat 7 increases its opening degree when the engine cooling water temperature exceeds a predetermined value, thereby increasing the flow rate of the cooling water passage P2 toward the radiator 9.

In a heating system having such a structure, if the engine is not yet sufficiently warmed up when the engine is started, the engine exhaust gas is introduced into the exhaust bypass passage E1 by the switching valve 83, and the exhaust gas heat is transferred to the heat exchanger 3. It is possible to heat the engine cooling water directly and start heating relatively quickly.

U Problems to be Solved by the Invention] By utilizing exhaust gas heat, the above-mentioned conventional device can advance the heating start time to some extent compared to previous devices, but it is still not sufficient. This is due to the following reasons.

That is, if the calorific value of the engine and the amount of heat recovered from exhaust gas are QE and QH, respectively, the heat capacities of the engine and heater core are CE and CH, respectively, and the rate of increase in cooling water temperature is dT/dt, then dT/dt=1/C.・(Q
E +QH>. Here, C=CE+CH.

The heat capacity CE of the engine is usually large, so even if the recovered heat QH of the exhaust gas contributes, the temperature rise will be slow.

SUMMARY OF THE INVENTION The present invention has been made to solve this problem, and it is an object of the present invention to provide a heating system for a vehicle that disconnects the engine from the cooling water heating system when the engine is cold, thereby making it possible to start heating quickly.

[Means for Solving the Problems] To explain the present invention in detail, the engine exhaust path E1 (first
) is equipped with a heat exchanger 3 and a water pump 1.
In a vehicle heating system having a cooling water passage P which reaches the heat exchanger 3 via the engine 2 and returns to the water pump 1 via the heater core 4, the outlet of the water pump 1 and the inlet of the heat exchanger 3 are connected. A communicating engine bypass flow path 6 is provided, an on-off valve 81 is provided in the engine bypass flow path 6, and a flow rate is provided in a cooling water flow path P1 connecting the outlet side of the engine and the outlet side of the engine bypass flow path 6. A control valve 82 is provided, and a valve control means 5 is provided which opens the on-off valve 81 when the temperature of the cooling water in the engine section is below a predetermined value.

[Function] In the heating device with the above configuration, immediately after starting the engine,
The engine coolant temperature is lower than a predetermined value, and the valve control means 5 opens the on-off valve 81. As a result, water pump 1
Most of the engine cooling water discharged from the exhaust gas directly reaches the heat exchanger 3 through the bypass passage 6 without passing through the engine 2, and is warmed by exhaust gas heat.

In this case, the cooling water heating system uses an engine 2 with a large heat capacity.
is not included, the temperature of the engine cooling water rises rapidly, and the conditioned air warmed by the heater core 4 enables rapid heating.

In the embodiment shown in FIG. 1, a cooling water passage P is provided from the water pump 1 to the heat exchanger 3 via the engine 2, and further returns via the heater core 4, and the outlet of the water pump 1 is connected to the heat exchanger 3. An engine bypass flow path 6 is provided by connecting the inlets of the engine, and an electromagnetic on-off valve 81 is provided in the bypass flow path 6. Further, from the outlet of the engine 2, the bypass flow path 6
A flow control valve 82 is provided in the engine cooling water flow path P1 leading to the connection point.

Other device configurations are the same as those of the conventional example, and are further provided with a valve control circuit 5 that controls the operations of the electromagnetic on-off valve 81, the flow rate control valve 82, and the electromagnetic switching valve 83. An operation start signal is input from the thermostat 7, which operates when the temperature reaches a predetermined temperature.

In the heating device configured as described above, if the cooling water temperature has not reached the predetermined value immediately after the engine starts, the valve control circuit 5
In this case, the switching valve 83 is operated to introduce the engine exhaust gas into the exhaust bypass flow #IE1, the on-off valve 81 is fully opened, and the flow rate control valve 82 is set to a level that prevents the cooling water from boiling in the engine 2 (e.g. Set to flow about 1ρ/min with a 2000cc class water-cooled gasoline engine.

In this state, most of the engine cooling water does not pass through the engine 2, but directly reaches the heat exchanger 3 via the engine bypass passage 6, where it is heated by exhaust gas heat. The heat equation in this path is dTH/d
t is expressed as dTH/dt=QH/CH, while
The heat equation in the engine cooling water flow path P1 is dTE /d t =Q, where the change in cooling water temperature is dTE/dt.
It is expressed as E/CF. Here, QE and QH are the calorific value of engine 2 and the amount of heat recovered from exhaust gas, respectively.
CE and CH are the heat capacity of the engine 2 and the heat capacity of the heater core 4, respectively.

Therefore, if CH<QHCE /QE holds true, the rate of increase in the cooling water temperature by the heat exchanger 3 dTH/dt is equal to the rate of increase in the cooling water temperature in the engine cooling water flow path P1 dTE/
Exceeds dt. In a water-cooled gasoline engine, the exhaust loss is considered to be equivalent to the engine starting QE, and if the heat recovery efficiency of the heat exchanger 3 is 50%, the recovered heat amount QH is QH = 0.5
It becomes QE. Also, the heat capacity CE of a 2000cc class engine is generally around 10Kcal/℃, so after all,
The heat capacity CH of the heater core 4 is CH<5 (Kca 1.
/”C).

In this way, the engine cooling water passes through the bypass flow path 6 and is rapidly heated by the heat exchanger 3, and the engine cooling water whose temperature has increased heats the conditioned air flowing through the heater core 4, thereby quickly starting heating.

As the engine 1 warms up, the cooling water temperature at the engine outlet rises, and the thermostat 7 starts operating, the valve control circuit 5 closes the electromagnetic on-off valve 81, fully opens the flow control valve 82, and then The flow of exhaust gas is returned to the exhaust main flow path E by the switching valve 83. Thereafter, the cooling water is heated by the engine 2 whose temperature has risen sufficiently, and the heating state is maintained.

FIG. 2 shows the effects of the present invention, in which line X is the present invention, line y is the conventional example with a heat exchanger, and line Z is the case without the heat exchanger. As can be seen from the figure, engine starting f&
In one minute, the temperature of hot water discharged from the air conditioner increases by about 13 degrees Celsius compared to conventional equipment equipped with a heat exchanger.

In the above embodiment, instead of using the signal from the thermostat 7 to switch the cooling water flow path, a thermistor sensor is provided in the engine bypass flow path 6 and the engine cooling water flow path P1, respectively, so that the temperature of the engine cooling water changes depending on the bypass cooling water temperature. The electromagnetic on-off valve 81 may be closed when the water temperature exceeds the water temperature.

[Effects of the Invention] As described above, according to the heating device of the present invention, the engine cooling water temperature can be raised quickly when the engine is started, and the heating standby time can be significantly shortened.

[Brief Description of the Drawings] Fig. 1 and Fig. 2 show an embodiment of the present invention, Fig. 1 is an overall system diagram of the device, Fig. 2 is a characteristic diagram showing changes over time in air conditioner outlet temperature, and Fig. Figure 3 is an overall system diagram of the conventional device. 1...Water pump 2...Engine 3...Heat exchanger 4...Heater core 5...Valve control circuit (valve control means) 6...Engine bypass flow path 81...Opening/closing valve 82 ...Flow rate control valve El...Exhaust bypass flow path (engine exhaust path)...Cooling water flow path Pl...Engine part cooling water flow path malfunctioning air; 1'+a degrees ta ('C)

Claims (1)

[Claims] In a vehicle heating system, a heat exchanger is provided in an engine exhaust path, and a cooling water flow path is provided from a water pump through the engine to the heat exchanger, and further returns to the water pump via a heater core. An engine bypass flow path communicating with the inlet of the heat exchanger is provided, an on-off valve is provided in the engine bypass flow path, and a cooling water flow path connects the outlet side of the engine and the outlet side of the engine bypass flow path. A heating system for a vehicle, comprising: a flow rate control valve; and a valve control means for opening the opening/closing valve when the temperature of the cooling water in the engine section is below a predetermined value.