JP2597232B2 - Engine exhaust heat recovery device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION << Field of Industrial Use >> The present invention relates to an exhaust heat recovery device for an engine in an engine generator or a cogeneration system.

《Basic basic structure》 An engine generator that uses electric power generated by rotating a generator by an engine, and heat energy generated during engine operation is recovered by a heat exchanger for exhaust heat recovery and parallel to the electric power In the cogeneration system to be used, the exhaust heat recovery device of the engine has the following basic structure as shown in FIG.

That is, in the water jacket 1a of the engine 1,
Hot water channel 3a, heat transfer channel 4a of heat exchanger 4 for exhaust heat recovery, cold water channel 3b
Are sequentially connected in a circulating manner to form an engine cooling water passage 3,
The heat transfer path 4a and the heat radiating path 5a of the heat radiating device 5 are connected in parallel to the engine cooling water path 3 by a variable three-way valve 6 so that the engine cooling water can be diverted.

Further, a temperature sensor 7 for engine cooling water is provided in the engine cooling water passage 3, and the temperature sensor 7 is connected to the three-way valve 6 via a radiation control device 8 in a system controller 10.
The three-way valve 6 is provided with a limit switch 9 for detecting a heat radiation operation, and the limit switch 9 is connected to the cooling fan 5b of the heat radiation device 5 via the heat radiation control device 8. They are working together.

The heat dissipation control device 8 is provided with a fan operation start set temperature T2 (eg, about 70 ° C.) lower than the heat dissipation set temperature T1 (eg, about 90 ° C.) for the engine coolant temperature of the engine coolant channel 3. When the cooling water temperature is equal to or higher than the fan operation start set temperature T2, the limit switch 9 operates the cooling fan 5b via the heat radiation control device 8.

<< Conventional Technology >> In the basic structure of the conventional example as described above, the cooling fan operation control of the heat radiating device in the system controller is performed when the engine cooling water temperature of the engine cooling water passage becomes higher than the heat radiation set temperature. The temperature sensor operates the three-way valve to the heat radiating side via the heat radiating control device to operate the engine cooling water to the heat radiating side, and the heat radiating control device controls the cooling fan based on the detection of the operation state by the limit switch. Drive.

On the other hand, when the temperature of the engine cooling water in the engine cooling water passage becomes lower than the set temperature for heat radiation, the temperature sensor operates the three-way valve to the heat radiation releasing side via the heat radiation control device, and the operation state is changed. The cooling fan is stopped after a certain delay time (for example, about 5 minutes) based on the detection by the limit switch.

This prevents the fan motor of the cooling fan from deteriorating due to the residual heat of the radiator.

Furthermore, if the cooling fan stops after a certain delay time after the system is stopped in the heat radiation state and then the system is to be restarted, in order to prevent power loss due to the operation of the cooling fan at the initial stage of the restart, Even if the limit switch of the three-way valve remains on, first detect that the engine coolant temperature is higher than the fan operation start set temperature with the engine coolant channel temperature sensor,
Since the cooling fan is operated, when the engine cooling water temperature is lower than the fan operation start set temperature, the radiation control device does not operate the cooling fan with the cooling fan stopped.

<< Problems to be Solved by the Invention >> The following problems are encountered in the above-described related art.

If the difference between the engine coolant temperature and the set temperature for heat dissipation is small, and the engine coolant temperature becomes slightly higher than the set temperature for heat dissipation due to disturbance or the like, the heat dissipation control device operates the three-way valve to the heat dissipation path side. The limit switch turns on and the cooling fan runs.

Once the cooling fan is operated, it does not stop until after a certain delay time (for example, about 5 minutes), even if the disturbance or the like has subsided and the temperature of the engine cooling water becomes lower than the set temperature for heat radiation. During this time, the engine cooling water is cooled on the heat radiation path side, and the heat energy is wasted.

For this reason, the exhaust heat recovery efficiency during operation near the rated load is deteriorated.

An object of the present invention is to solve such a problem in the related art.

<< Means for Solving the Problems >> In order to achieve the above object, the present invention provides a heat dissipation control device, wherein an engine cooling water temperature of an engine cooling water passage is lower than a set temperature for heat dissipation, and a three-way valve of the heat dissipation control device. When the control output is controlled to the heat release side, the cooling fan is operated after another delay time (for example, about 20 seconds).

Here, a supplementary explanation of the three-way valve control output of the embodiment is given.The three-way valve is PID controlled by inputting the engine coolant temperature, and when the flowing current is about 20 mA, heat is supplied to the exhaust heat recovery heat exchanger. It is 100% controlled on the roadside, and at about 4mA, 100% controlled on the heatsink side of the heatsink.

When the current value is about 18 to 19 mA, the limit switch is turned on, but the valve position is almost on the side of heat release (heat transfer path of the heat exchanger for exhaust heat recovery).

<< Operation >> The present invention operates as follows.

The heat dissipation control device determines whether the three-way valve control output is less than a certain value, that is, whether the valve position is almost on the side of heat release (heat transfer path of the heat exchanger for exhaust heat recovery), and more than a certain value, that is,
Most of the valve position releases heat release (heat transfer path of heat exchanger for exhaust heat recovery)
In the case of the side, a delay time is provided for starting the operation of the cooling fan.

That is, as shown in the operation flowchart of FIG. 3, first, in operation S1, it is determined whether or not the limit switch is ON.
Next, in operation S2, it is determined whether the heat radiation set temperature T1 is higher than the engine cooling water temperature, and if not, the cooling fan is operated immediately.

Further, in the operation S3, the three-way valve control output becomes a constant value (in the embodiment,
17mA) or less, that is, it is determined whether the valve position is almost on the side of heat release (heat transfer path of the heat exchanger for exhaust heat recovery).

Here, when the three-way valve control output is equal to or more than a certain value, that is, when the valve position is almost on the side of releasing heat release (heat transfer path of the heat recovery heat exchanger), the cooling fan is set to the delay time D2 (for example, about 20 seconds). I will drive later.

If the three-way valve control output is equal to or less than a certain value, that is, if the valve position is directed to the heat radiation path side of the corresponding heat radiation device, the cooling fan is operated immediately.

<< Effects of the Invention >> The present invention has the following effects because it is configured and operates as described above.

If the difference between the engine cooling water temperature and the set temperature for heat radiation is small, even if the temperature of the engine coolant is slightly higher than the set temperature for heat radiation due to disturbance or the like, whether the three-way valve control output is below a certain value, that is, Then, it is determined whether the valve position is almost on the heat release side. When the valve position is more than a certain value, that is, when the valve position is almost on the heat release side, a delay time is given to the start of operation of the cooling fan. There is no such thing as running the cooling fan.

Therefore, the heat energy of the engine cooling water is not wasted and the exhaust heat recovery efficiency during operation near the rated load does not deteriorate.

<< Example >> Hereinafter, an example of the present invention will be described with reference to the drawings.

In the configuration of the main part of the exhaust heat recovery device for an engine shown in FIG.
It is operated by supplying fuel gas from 11 and exhausts exhaust gas through muffler 12. Then, the electric power generated by the generator 2 is supplied from the switchboard 13 to each load.

Further, the engine 1 is provided with a fan 1b on its rotating shaft to cool the outer periphery of the engine 1 by air.

The water jacket 1a of the engine 1 has a hot water channel 3a,
The heat transfer passage 4a and the cold water passage 3b of the heat exchanger 4 for exhaust heat recovery are connected in order in a circulating manner to form an engine cooling water passage 3, and the heat transfer passage 4a is connected to the engine cooling water passage 3 by a three-way valve 6 for variable branch. And the heat radiating path 5a of the heat radiating device 5 are connected in parallel so that the engine cooling water pumped by the engine cooling water pump 1c can be divided.

The exhaust heat recovery heat exchanger 4 has a hot water inlet 14 and a hot water outlet 15, and absorbs and uses the heat of engine cooling water passing through the heat transfer path 4a.

In order to recover the heat of exhaust gas, an exhaust gas heat exchanger
4b is directly attached to the exhaust part of the engine 1.

The engine cooling water bypasses the bypass passage 3d by the thermostat 3c installed in the engine cooling water passage 3 when the cooling water temperature is lower than a certain value, such as at the time of starting, and bypasses the cooling water when the cooling water temperature becomes higher than a certain value. Stop and flow through normal waterways.

Further, a temperature sensor 7 for engine cooling water is provided in the engine cooling water passage 3, and the temperature sensor 7 is operatively linked to the three-way valve 6 via a heat radiation control device 8 in a system controller 10 to control the operation. A limit switch 9 for detecting a heat radiation operation is attached to the valve 6, and a cooling fan 5 b of the heat radiation device 5 is linked to the limit switch 9 via a heat radiation control device 8.

The heat dissipation control device 8 is provided with a fan operation start set temperature T2 (eg, about 70 ° C.) lower than the heat dissipation set temperature T1 (eg, about 90 ° C.) for the engine coolant temperature of the engine coolant channel 3. When the cooling water temperature is equal to or higher than the fan operation start set temperature T2, the limit switch 9 operates the cooling fan 5b via the heat radiation control device 8.

Further, in the heat radiation control device 8, the engine cooling water temperature is lower than the heat radiation set temperature T1, and the three-way valve control output of the heat radiation control device 8 almost releases the heat radiation (exhaust heat recovery heat exchanger 4).
If the cooling fan is controlled on the heat transfer path 4a) side,
5b is operated after a delay time D2 (for example, about 20 seconds).

The system controller 10 includes a central processing unit (not shown), various operation switches, a relay, and the like.Input signals such as temperature, pressure, voltage, and rotation speed from each unit in the system, and operation, stop, or The operation of the system is controlled by sending and receiving command signals such as alarms and operating relays and operation switches.

In the control operation of the system controller 10, the operation control of the cooling fan 5b by the heat radiation control device 8 operates as follows.

In the operation block diagram shown in FIG. 2 and the operation flowchart shown in FIG. 3, when the engine cooling water temperature of the engine cooling water passage 3 becomes higher than the heat radiation set temperature T1 (that is, the fan operation start set temperature T2). In the above case), the temperature sensor 7 operates the three-way valve 6 to the heat radiation side via the heat radiation control device 8 to operate the engine cooling water to the heat radiation path 5a, and the limit switch 9 detects this operation state. Based on this, the heat radiation control device 8 operates the cooling fan 5b.

On the other hand, when the temperature of the engine coolant in the engine coolant channel 3 becomes lower than the set temperature T1 for heat dissipation, the temperature sensor 7 operates the three-way valve 6 to the heat dissipation release side via the heat dissipation control device 8. At the same time, based on the detection of this operation state by the limit switch 9, the cooling fan 5b is stopped after a predetermined delay time D1 (for example, about 5 minutes).

This prevents the fan motor 5c of the cooling fan 5b from deteriorating due to the residual heat of the radiator 5.

Further, when the cooling fan 5b stops after a certain delay time D1 after the system is stopped in the heat radiation state and the system is to be restarted thereafter, the limit switch 9 of the three-way valve 6 is used.
Is turned on, the cooling fan 5b is operated after the temperature sensor 7 of the engine cooling water passage 3 detects that the engine cooling water temperature is higher than the fan operation start set temperature T2. Therefore, when the engine cooling water temperature is lower than the fan operation start set temperature T2, the radiation control device 8 does not operate the cooling fan 5b with the cooling fan 5b stopped.

For this reason, a power cross due to the operation of the cooling fan does not occur at the initial stage of the restart.

On the other hand, the heat dissipation control device 8 determines whether the three-way valve control output is equal to or less than a certain value, that is, whether the valve position is almost at the side of heat release (heat transfer path 4a of the exhaust heat recovery heat exchanger 4). If the value is equal to or more than the value, that is, if the valve position is almost at the side of heat release (heat transfer path 4a of the heat exchanger 4 for exhaust heat recovery), a delay time D2 (for example, about 20 seconds) is given to start the operation of the cooling fan 5b. Therefore, if the difference between the engine cooling water temperature and the set temperature for heat dissipation T1 is small, even if the temperature of the engine coolant becomes slightly higher than the set temperature for heat dissipation T1 due to external disturbance, the cooling fan No more driving 5b.

Therefore, the heat energy of the engine cooling water is not wasted and the exhaust heat recovery efficiency during operation near the rated load does not deteriorate.

[Brief description of the drawings]

1 to 3 show an embodiment of the present invention. FIG. 1 is a configuration diagram of a main part of an exhaust heat recovery device for an engine, FIG. 2 is an operation block diagram, and FIG. 3 is an operation flowchart. FIG. 4 is an operation flowchart of a conventional example. 1 ... Engine, 1a ... Water jacket, 3 ... Engine cooling water channel, 3a ... Hot water channel, 3b ... Cold water channel, 4 ...
Exhaust heat recovery heat exchanger, 4a: heat transfer path, 5: heat dissipation device,
5a: heat dissipation path, 5b: cooling fan, 6: three-way valve for variable branch, 7: temperature sensor, 8: heat dissipation control device, 9:
Limit switch, D1 / D2: Delay time, T1: Set temperature for heat radiation.

Claims (1)

(57) [Claims] 1. A water jacket (1) for an engine (1).
In (a), the hot water path (3a), the heat transfer path (4a) and the cold water path (3b) of the heat exchanger for exhaust heat recovery (4) are connected in order in a circulating manner, and heat is radiated to the heat transfer path (4a). The heat radiation path (5a) of the device (5) is connected in parallel, and the heat transfer to the engine cooling water path (3) composed of the water jacket (1a), the hot water path (3a) and the cold water path (3b) is performed. The path (4a) and the heat radiating path (5a) are configured such that the engine cooling water can be divided by the variable three-way valve (6). The three-way valve (6) is operably linked to the temperature sensor (7) via a heat dissipation control device (8). The three-way valve (6) is connected to a limit switch (9) for detecting the heat dissipation operation. ), And a cooling fan (5b) is linked to the limit switch (9) via the heat radiation control device (8) to When the temperature of the engine cooling water in the water passage (3) becomes higher than the set temperature for radiation (T1), the temperature sensor (7) is connected to the three-way valve (6) via the radiation control device (8). To the heat radiating side, and based on the detection of the operating state by the limit switch (9), the heat radiating control device (8) operates the cooling fan (5b).
On the other hand, when the temperature of the engine cooling water in the engine cooling water passage (3) becomes lower than the set temperature for heat radiation (T1), the temperature sensor (7) is operated by the heat radiation control device. The three-way valve (6) is operated to the heat release side via (8), and based on the detection of the operation state by the limit switch (9), the cooling fan (5) is operated.
b) stopping after a delay time (D1), wherein the engine cooling water temperature of the engine cooling water passage (3) is lower than the heat radiation set temperature (T1) and the heat radiation control is performed. When the three-way valve control output of the device (8) is controlled to the heat release side, the cooling fan (5b) is operated after another delay time (D2), The exhaust heat recovery of the engine characterized by the above-mentioned. apparatus.