JPS6339768B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heat exchange device that performs heat exchange using cooling water and exhaust heat of an internal combustion engine.

There is a system that performs heat exchange using outlet heat of cooling water and exhaust gas in an internal combustion engine. FIG. 1 shows an example in which a heat exchange device is used as an exhaust heat recovery device for an internal combustion engine.

As shown in FIG. 1, for an internal combustion engine 1, a cooling water heat exchanger 2 that utilizes cooling water heat of the internal combustion engine 1 is provided.
And an exhaust gas heat exchanger 3 that utilizes the exhaust gas of the internal combustion engine 1 is provided. Water supply is water supply pipe 4
The heat-exchanged primary hot water is supplied to the exhaust gas heat exchanger 3 via the primary hot water piping 5. The secondary hot water heat-exchanged by the exhaust gas heat exchanger 3 is taken out via the secondary hot water pipe 6. The cooler of the internal combustion engine 1 and the coolant heat exchanger 2 are connected through coolant pipes 7 and 8, and the coolant circulates between them. Further, the exhaust gas of the internal combustion engine 1 is supplied to the exhaust gas heat exchanger 3 via the exhaust gas pipe 9, and is discharged from the heat exchanger 3 via the exhaust gas pipe 10. With the above configuration, when the internal combustion engine 1 is operating, the feed water is heat exchanged via the two heat exchangers,
The secondary hot water taken out from the secondary hot water pipe 6 is taken out as hot water or steam.

However, when starting an internal combustion engine from a cold state,
In order to rapidly warm up the internal combustion engine by heating the cooling water to a certain value or higher, a method is adopted in which the flow of hot water on the hot water side of the cooling water heat exchanger 2 is stopped. However, since the flow of the exhaust gas heat exchanger 3 is also stopped, if there is no water in the exhaust gas heat exchanger 3 from the beginning, the exhaust gas heat exchanger 3 is heated dry until the exhaust gas heat exchanger 3 is warmed up. The problem was that it caused the deterioration of the gas to progress and there was a risk of an explosion. On the other hand, if water is present in the exhaust gas heat exchanger 3 from the beginning, there is a risk that the exhaust gas heat exchanger 3 will be heated abnormally until it is warmed up. In order to prevent the above-mentioned drawbacks, if the cooling water heat exchanger 2 and the exhaust gas heat exchanger 3 are operated before the internal combustion engine is warmed up, part of the heat of the cooling water of the internal combustion engine is exchanged. As a result, it takes a long time to warm up, resulting in a reduction in fuel efficiency.

In addition, one way to shorten the warm-up time is to reduce the total amount of circulating cooling water, but since the heat capacity of the cooling water system becomes smaller, load fluctuations in the internal combustion engine's load operating state, etc. The problem was that the stability against external disturbances was poor, and unstable phenomena such as hunting were likely to occur.

An object of the present invention is to provide a heat exchange device that prevents overheating deterioration of an exhaust heat recovery device while realizing rapid warm-up of an internal combustion engine.

In order to achieve the above object, the present invention provides a cooling water heat exchanger that uses circulating cooling water of an internal combustion engine as a heat source to heat and discharge water to be heated introduced from the outside, and an exhaust gas of the internal combustion engine as a heat source. and an exhaust gas heat exchanger into which water to be heated drawn out from the cooling water heat exchanger is introduced, reheated, and led out to the outside, the temperature at which the temperature of the circulating cooling water is measured. a first valve that cuts off the water supply to the cooling water heat exchanger when the temperature detector is below a predetermined temperature value; a second valve that prevents the heated water drawn out from the exchanger from flowing out; and when the second valve operates, the heated water drawn out from the exhaust gas heat exchanger is transferred to the heat of the cooling water. It is equipped with a feedback system for returning the water to the input side of the exchanger. That is, hot water heated by exhaust gas exhaust heat in the exhaust gas heat exchanger of the internal combustion engine is returned to the cooling water heat exchanger to heat the circulating cooling water of the internal combustion engine. As a result, rapid warm-up can be achieved without reducing the total amount of cooling water for the internal combustion engine, and overheating of the exhaust gas heat exchanger can be prevented.

FIG. 2 is a system diagram showing an embodiment of the present invention.
In FIG. 2, the same members as used in FIG. 1 are given the same reference numerals.

A temperature detector 11 is provided to detect the temperature of cooling water supplied to the internal combustion engine 1. Further, a two-way valve 12 is provided on the inlet side of the cooling water heat exchanger 2, and a distribution three-way valve 13 is provided on the secondary hot water outlet side of the exhaust gas heat exchanger 3.
Further, it branches from the distribution three-way valve 13, and the two-way valve 12
A return piping 14 is provided which joins the merging piping 15 provided on the outlet side. The two-way valve 12 is controlled to open and close by a control device 16 based on the output signal of the temperature detector 11, and similarly the distribution three-way valve 13 is controlled to open and close by the control device 17 based on the output signal of the temperature sensor 11.

If the temperature detected by the temperature detector 11 is below the set value, the two-way valve 12 is closed, and the distribution three-way valve 13 closes the flow path to the secondary hot water piping 6, and the hot water exiting the exhaust gas heat exchanger 3 is closed. is made to flow to the return piping 14.

When the water temperature detected by the temperature detector 11 is higher than the set value, the two-way valve 12 opens, and the distribution three-way valve 13 closes the flow path to the return pipe 14, allowing the water to flow to the secondary hot water pipe 6.

FIG. 3 shows another embodiment of the present invention, in which the same parts as in FIG. 2 are designated by the same reference numerals. The difference from the embodiment shown in FIG. 2 is that a two-way valve 18, a branch pipe 19, and a check valve 20 are used instead of the three-way distribution valve shown in FIG.

If the water temperature detected by the temperature detector 11 is below the set value, the two-way valves 18 and 12 are closed, and the hot water heated by the exhaust gas heat exchanger 3 flows through the return pipe 14 via the branch pipe 19, and the cooling water heat is returned. Exchanger 2 heats engine cooling water. When the water temperature detected by the temperature detector 11 is higher than the set value, the two-way valves 18 and 12 are opened, and the water supplied from the water supply pipe 4 is heated by the heat exchangers 2 and 3 and flows into the secondary hot water pipe 6. At this time, the function of the check valve 20 prevents the water from flowing into the secondary hot water pipe 6 without passing through the heat exchangers 2 and 3. In this embodiment, the flow rate ratio between the piping 6 and the piping 4 is further adjusted by adjusting the opening degree of the two-way valve 18, and the effect of adjusting the output hot water temperature obtained from the secondary hot water piping 6 is achieved. .

According to the present invention, it is possible to quickly warm up the internal combustion engine by heating the internal combustion engine cooling water using the amount of heat recovered from the exhaust gas exhaust heat of the internal combustion engine, and the exhaust gas exhaust heat is recovered by the cooling water. It can cool the equipment and prevent overheating.

[Brief explanation of the drawing]

FIG. 1 is a system diagram of a conventional heat exchange device, FIG. 2 is a system diagram of an embodiment of the present invention, and FIG. 3 is a system diagram of another embodiment of the present invention. 1... Internal combustion engine, 2... Cooling water heat exchanger, 3...
...Exhaust gas heat exchanger, 4...Water supply piping, 5...1
Secondary hot water piping, 6... Secondary hot water piping, 7, 8... Cooling water piping, 9, 10... Exhaust gas piping, 11...
Temperature detector, 12, 18... 2-way valve, 13... Distribution 3-way valve, 14... Return piping, 15... Merging piping,
19...Diversion piping, 20...Return prevention valve.

Claims (1)

[Scope of Claims] 1. A cooling water heat exchanger that uses circulating cooling water of an internal combustion engine as a heat source to heat water to be heated introduced from the outside and draws it out; and A heat exchange device comprising an exhaust gas heat exchanger into which water to be heated led out from the exchanger is introduced, reheated and led out to the outside, comprising: a temperature detector for measuring the temperature of the circulating cooling water; a first valve that cuts off water supply to the cooling water heat exchanger when the temperature detector is below a predetermined temperature value; a second valve that prevents the heated water from flowing out to the outside; and when the second valve operates, the heated water drawn out from the exhaust gas heat exchanger is directed to the inlet side of the cooling water heat exchanger. A heat exchange device comprising a return system for returning to the heat exchanger. 2. In claim 1, the return system comprises the second valve as a distribution three-way valve, and the distribution three-way valve and the inlet piping of the cooling water heat exchanger are connected by piping. A heat exchange device comprising: 3. In claim 1, the return system connects piping between the inlet side of the cooling water heat exchanger and the outlet side of the exhaust gas heat exchanger, and connects the cooling water to the piping. A heat exchange device characterized by being provided with a check valve that prevents backflow from the inlet side of the heat exchanger to the outlet side of the exhaust gas heat exchanger.