JPH063174Y2 - Exhaust heat recovery device for engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION << Industrial Application Field >> The present invention relates to an exhaust heat recovery device for an engine, and more specifically, a heat exchanger for exchanging heat between exhaust gas of an engine and water, that is, cooling water. The present invention relates to an exhaust heat recovery device for an engine, in which an exhaust heat recovery device is provided.

<< Prior Art >> As an exhaust heat recovery device for an engine of the type described above, for example, Japanese Utility Model Laid-Open No. 61-66644 and Japanese Patent Laid-Open No. 58-58.
The one disclosed in Japanese Patent Publication No. 135313, etc. is known. In such a conventional exhaust heat recovery device, the heat exchanger on the air conditioning equipment side for exchanging heat with the heat load on the refrigerant heating unit side, the circulating water pump, and the exhaust manifold of the engine are connected downstream to recover the exhaust heat. Exhaust passage heat exchanger,
A water jacket provided in the exhaust manifold, a water pump and a water jacket on the engine side are connected in series in a circulating form to form a cooling water passage, and this system cools the engine while collecting exhaust heat. The exhaust heat is effectively utilized.

<Problems to be solved by the invention> However, in the exhaust heat recovery device having the cooling water passage system of the type described above, the cooling water discharged from the air conditioner side heat exchanger is at least 20 ° C even in the steady state. When the cooling water is introduced into the water jacket of the exhaust manifold, the exhaust gas in the exhaust manifold is cooled and condensed liquid may be generated on the inner surface of the exhaust manifold. This condensate has a pH of 2-4
Due to the strong acidity, there is a problem that the exhaust manifold will be corroded and cause perforation.

Therefore, an object of the present invention is to provide an exhaust heat recovery device for an engine that can prevent the exhaust manifold from being excessively cooled.

<< Means for Solving the Problems >> An exhaust heat recovery system for an engine of the present invention is an air conditioner side heat exchanger for exchanging heat with a heat load on a refrigerant heating unit side, a circulating water pump, and an engine exhaust manifold downstream. Connected in series with an exhaust passage heat exchanger for collecting exhaust heat, a water pump and a water jacket on the engine side in series in a circulating form to form a cooling water passage, and a cooling water passage is formed at the downstream end of the water jacket. A temperature valve is provided, which branches from the temperature-sensing valve upstream of the water jacket, is connected to the engine-side water pump upstream, and forms a bypass passage that bypasses the air conditioner-side heat exchanger,
An intermediate part of the bypass passage is connected to an exhaust manifold water jacket provided on the outer periphery of the exhaust manifold.

<< The effect of the device. Effect >> In the exhaust heat recovery device for an engine of the present invention, a bypass passage is formed that branches from the temperature-sensing valve upstream of the water jacket and is connected to the engine-side water pump upstream and bypasses the air conditioner-side heat exchanger. Since the middle of the bypass passage is connected to the exhaust manifold water jacket provided on the outer periphery of the exhaust manifold,
When the cooling water is in a low temperature state, the cooling water does not pass through the air conditioner side heat exchanger and flows through the bypass system. Therefore, the temperature of the bypass system is raised in a short time and is stabilized at a high temperature, so that the exhaust manifold water jacket is also in a high temperature and similar state. Thus, it is possible to prevent the exhaust manifold from reaching a low temperature state, which can prevent the generation of condensate in the exhaust manifold.

<< Embodiment >> Hereinafter, an exhaust heat recovery apparatus for an engine according to an embodiment of the present invention will be described with reference to the accompanying drawings.

First, referring to FIG. 1, an overall system of a heat pump device to which an exhaust heat recovery device for an engine according to an embodiment of the present invention is applied will be described.
A compressor 3 for compressing a refrigerant driven by the crankshaft of the engine 2, a four-way switching valve 4, a pair of outdoor heat exchangers 5, an expansion valve 6, an indoor heat exchanger 7, and connecting them. And a refrigerant circulation passage 8 that operates. In this heat pump device 1, when the cooling operation is performed, the four-way switching valve 4 takes a connected state as shown by the solid line in FIG. 1, the outdoor heat exchanger 5 acts as a condenser, and The inner heat exchanger 7 acts as an evaporator. Also,
This heat pump device 1 is
The four-way switching valve 4 is connected as shown by the broken line in FIG. 1, the indoor heat exchanger 7 acts as a condenser, and the outdoor heat exchanger 5 acts as an evaporator.

Therefore, when the heat pump device 1 is in the cooling operation, the refrigerant compressed and discharged by the compressor 3 is guided from the four-way switching valve 4 to the outdoor heat exchanger 5 and condensed in the outdoor heat exchanger 5. After that, the pressure is reduced in the expansion valve 6 and is guided to the indoor heat exchanger 7, the heat in the room is taken in the indoor heat exchanger 7 to be evaporated, and then returned to the compressor 3 through the four-way switching valve 4. When the heat pump device 1 is in the heating operation, the refrigerant compressed and discharged by the compressor 3 is guided from the four-way switching valve 4 to the indoor heat exchanger 7, and the indoor heat exchanger 7
In the room, the heat is radiated and condensed in the room, is guided to the outdoor heat exchanger 5 through the expansion valve 6, takes the outdoor heat in the outdoor heat exchanger 5, evaporates, and then passes through the four-way switching valve 4. And is returned to the compressor 3.

In the heat pump device 1 that performs cooling and heating as described above, particularly when the heating operation is performed in cold weather,
By the outdoor heat exchanger 5 acting as an evaporator,
The function may be impaired by frost generated on the outer surface of the outdoor heat exchanger 5. Therefore, in order to remove the frost generated on the outer surface of the outdoor heat exchanger 5 by using the exhaust heat of the engine 2, the exhaust heat recovery device 10 is arranged in the engine cooling system.

In this exhaust heat recovery device 10, a main heat exchanger 11 that is an exhaust passage heat exchanger is provided in a downstream portion of an exhaust manifold 12 of the engine 2, and the exhaust manifold 1
An exhaust manifold water jacket 13 is provided on the outer periphery of the upstream portion of the No. 2. In the engine cooling system, the cooling water that has undergone heat exchange in the main heat exchanger 11 and is heated is guided to the vicinity of the outdoor heat exchanger 5 in the heat pump device 1 through the cooling water passage 14 and circulated. There is.

In the cooling water passage 14, a pair of cooling water is made to radiate so as to remove the frost generated in the outdoor heat exchanger 5 in the heat exchange section 15 provided in association with the outdoor heat exchanger 5. The external heat exchanger 16 and a circulation pump 17 for circulating cooling water between the engine 2 and the external heat exchanger 16.
And are arranged. In addition, in the vicinity of the heat exchange unit 15,
A fan 18 is provided for promoting heat dissipation.

The cooling water passage 14 and the heat exchange portion 15 are
The circulating water pump 17, the main heat exchanger 11, the water pump 19 and the water jacket 20 on the engine 2 side are connected in series in a circulating manner. At the downstream end of the water jacket 20, there is provided a temperature sensitive valve 21 that opens when the temperature of the cooling water reaches or exceeds a predetermined value. A bypass passage 22 that bypasses the heat exchange section 15 provided in association with the outdoor heat exchanger 5 is provided from the upstream portion of the temperature sensitive valve 21 of the water jacket 20. The bypass passage 22 is connected to the cooling water passage 14 after passing through the water jacket 13 of the exhaust manifold 12.

By this bypass passage 22, when the cooling water is at a low temperature,
The cooling water discharged from the water pump 19 circulates in a path passing only through the water jacket 20 and the water jacket 13 of the exhaust manifold 12, so that the cooling water is
Even at low temperature, it is heated in a short time. Therefore, low-temperature cooling water is hardly introduced into the water jacket 13, and the cooling water temperature of the water jacket 13 is stabilized at a predetermined value or higher, whereby the above-mentioned condensed water is generated in the exhaust manifold 12. Can be prevented, and the exhaust manifold 12 is not corroded.

In the above-described embodiment, the cooling water of low temperature is cooled by the exhaust manifold 1 for a short time immediately after the engine 2 is started.
2 is introduced into the water jacket 13, but in order to completely prevent this, as shown in FIG. 2, the bypass passage 22 has a second bypass passage for bypassing the water jacket 13 of the exhaust manifold 12. 23 may be provided, and a temperature sensitive valve 24 may be provided at a branch portion of the bypass passage 23 so that the cooling water flows into the water jacket 13 only when the cooling water temperature becomes equal to or higher than a predetermined value. Further, in order to use the exhaust heat more effectively, the pipe of the main heat exchanger 11 is connected to the exhaust manifold 1 as shown in FIG.
2 is connected to the water jacket 13 and a temperature sensitive valve 25 is provided at the connection portion thereof, and when the cooling water temperature exceeds a predetermined value,
If this valve 25 is opened, the exhaust manifold 1
It is possible to effectively utilize exhaust heat while preventing the corrosion of 2.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of an engine-driven heat pump device incorporating an exhaust heat recovery device according to an embodiment of the present invention. FIG. 2 is a diagram showing a modification of the exhaust heat recovery device. 1 ... Heat pump device 10 ... Exhaust heat recovery device 11 ... Main heat exchanger (exhaust passage heat exchanger) 12 ... Exhaust manifold 13 ... Exhaust manifold water jacket 14 ... Cooling water passage 16 ... Air conditioning equipment External heat exchanger that is a side heat exchanger 17 ... Circulation (circulating water) pump 19 ... Water pump 20 ... Water jacket 21 ... Temperature sensing valve 22 ... Bypass passage

Claims (1)

[Scope of utility model registration request] 1. A heat exchanger on the side of an air conditioner for exchanging heat with a heat load on the side of a refrigerant heating unit, a circulating water pump, and an exhaust passage heat exchanger connected downstream of an exhaust manifold of an engine for recovering exhaust heat. , A water pump and a water jacket on the engine side are connected in series in a circulating form to form a cooling water passage, and a downstream end of the water jacket is formed.
A temperature sensitive valve is provided, which branches from the temperature sensitive valve upstream of the water jacket and is connected to the engine side water pump upstream to form a bypass passage bypassing the air conditioner side heat exchanger. An exhaust heat recovery device for an engine, characterized in that an intermediate part of the bypass passage is connected to an exhaust manifold water jacket provided on the outer periphery of the exhaust manifold.