JPH02102353A - Exhaust heat recovery device for engine - Google Patents

Abstract

PURPOSE:To prevent the overheat of an engine by switching the operation mode to a heat radiating mode so as to radiate the exhaust heat of the engine with a radiator when the temperature of the engine cooling water is elevated to a temperature higher than a specified temperature for starting of the heat radiation for the sake of the reduction of the radiated heat from a heat exchanger for recovery of the exhausted heat of the engine. CONSTITUTION:In the titled device, a water jacket 2 of an engine 1, a heat exchanger 3 for absorption of the exhausted heat and a heat exchanger 6 for recovery of the exhausted heat of the engine are connected successively in series circulatively. In this case, a heat radiating path 10 of a radiator 9 is connected to the heat exchanger 6 in parallel, and a heat supplying path 7 for heat recovery and the heat radiating path 10 are connected to an engine cooling water path 11 freely switchable with a switching valve 12. When the temperature T1 of the engine cooling water detected with a temperature sensor 13 is elevated over a preset temperature T1H for starting of the heat radiation the switching valve 12 is switched to the heat radiating state from the heat recovering state, and when the detected temperature T1 is lowered below a preset temperature T1L (<T1H) for ending of the heat radiation is switching valve 12 is switched to the opposite state.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention absorbs engine exhaust heat through engine cooling water using a water jacket and an exhaust heat absorption heat exchanger, and also absorbs the absorbed heat from the engine exhaust heat. This technology relates to an engine exhaust heat recovery device that recovers heat using a heat recovery heat exchanger, and can prevent engine overheating even when the exhaust heat recovery load is partial or no load.

(Prior Art) Conventionally, this type of engine exhaust heat recovery device is described in US Pat. No. 4,226,214.

As shown in FIG.
The system drives the engine 1 to supply electric power, and also recovers the exhaust heat of the engine 1 to an external heat load 100 such as a water heater, and is configured as follows.

That is, the water jacket 2 of the engine 1 includes the exhaust heat absorption passage 4 of the exhaust heat absorption heat exchanger 3, the hot water passage 5, the heat recovery state passage 7 of the engine exhaust heat recovery heat exchanger 6, and the cold water passage 8.
By sequentially connecting the cold water channels 8 in a series circulation manner,
・Water jacket 2 ・Exhaust heat absorption path 4 and hot water channel 5
This constitutes the engine cooling water channel 101. The exhaust heat of the engine 1 is absorbed by the water jacket 2 and the exhaust heat absorption heat exchanger 3 through the engine cooling water of the engine cooling waterway 101, and the absorbed heat is absorbed by the engine exhaust heat recovery heat exchanger 6. External heat load 100 via heat receiving path 38
It dissipates heat.

(Problems to be Solved by the Invention) In the above-mentioned conventional technology, when the exhaust heat recovery load of the external heat load 100 becomes a partial load or no load, the heat receiving path of the exhaust heat recovery heat exchanger 6 Since the amount of heat dissipated from 38 is reduced or eliminated, the engine cooling water passage 1. There is a problem in that the temperature of the engine cooling water in the oil increases, causing the engine 1 to overheat.

An object of the present invention is to prevent engine overheating even when the exhaust heat recovery load is a partial load or no load.

(Means for Solving the Problems) In order to achieve the above object, the present invention is characterized in that an exhaust heat recovery device is configured as follows.

(1) In claim 1, as shown in FIGS. 1 and 2, for example, the following configuration is adopted.

The water jacket 2 of the engine 1 is connected to the exhaust heat absorption passage 4 of the exhaust heat absorption heat exchanger 3, the hot water passage 5, the heat recovery heat exchange passage 7 of the engine exhaust heat recovery heat exchanger 6, and the cold water passage 8. In an engine exhaust heat recovery device configured by sequentially connecting and communicating in a series circulation, the heat radiation path XO of the radiator 9 is connected in parallel to the heat transfer path 7 for heat recovery of the heat exchanger 6 for engine exhaust heat recovery, The heat transfer passage 7 for heat recovery and the heat radiation passage 10 can be connected to the engine cooling passage 11 consisting of the cold passage 8, the water jacket 2, the exhaust heat absorption passage 4, and the hot passage 5 by switching with the switching valve 12. A temperature sensor 13 is provided in the engine cooling water channel 11, and the temperature sensor 13 is linked to enable switching control of the switching valve 12 via the valve switching control device 14. The valve switching control device 14 switches the switching valve 12 when the detected temperature T of the engine cooling water exceeds the set temperature T170 for starting heat radiation. Switching from the state for heat recovery to the state for heat radiation, the heat transfer path 7 for heat recovery is closed, the heat radiation path 10 is opened, and the detected temperature T of the engine cooling water temperature is changed.
, is lower than the set temperature for heat dissipation end T10, which is lower than the set temperature for heat dissipation start T, , the switching valve 12
The heat radiation path 10 is switched from the heat radiation state to the heat recovery state.
is closed, and the heat transfer path 7 for heat recovery is opened.

(2) In claim 2, in claim 1, the - part,
For example, as shown in FIGS. 1 and 7, the following changes were made.

Based on the temperature sensor 13 detecting the set temperature T1) for starting heat radiation, the valve switching control device 14 switches the switching valve 1
2 is switched from the heat recovery state to the heat radiation state, the valve switching control device I4 is configured to maintain the heat radiation state for a set time.

(3) In claim 3, in claim 1, the - part,
For example, as shown in Figures 1 and 8, the following? Changed to:

Based on the temperature sensor 13 detecting the heat radiation start set temperature Tl+□, the valve switching control device 14 switches the switching valve 12
When the switch is operated to switch from the heat recovery state to the heat radiation state, the valve switching control device 14 activates the engine coolant temperature high alarm 17 and maintains the switching valve 12 in the heat radiation state. The above-mentioned heat dissipation holding state release operation tool 18 was attached to the valve switching control device 14.

(4) In claim 4, in claim 1, the - part,
For example, as shown in FIGS. 1 and 2, the following changes were made.

Engine cooling water circulation pump 20 in engine cooling water channel 11
The switching valve 12 is connected from the outlet of the engine cooling water circulation pump 20 to the switching valve 12.
A pressure sensor 21 for engine emergency stop is provided in the middle of the engine cooling water channel ■1 leading to the
is configured to be linked to an engine stop device 23 via an engine stop control device 22.

(5) In claim 5, in claim 1, the - part,
For example, as shown in FIGS. 1 and 2, the following changes were made.

An engine emergency stop temperature sensor 25 is provided in the engine cooling water channel 11, and this temperature sensor 25 is configured to be linked to an engine stop device 23 via an engine stop control device 22.

(Function) (1) The invention of claim 1 functions as follows, as shown in FIGS. 1 and 2, for example.

The temperature of the engine cooling water is the set temperature for finishing heat radiation TIL
During the period from 1 to 1, the changeover valve 12 is switched to the recovery state, and the engine cooling water is transferred to the cold water passage 8, water jacket 2, exhaust heat absorption path 4, and engine exhaust heat. It circulates through the heat transfer path 7 for heat recovery of the heat recovery heat exchanger 6. As a result, the exhaust heat of the engine 1 is radiated from the engine exhaust heat recovery heat exchanger 6 to the recovery liquid in the exhaust heat recovery path 45, and the engine cooling water is cooled.
prevent overheating.

In this exhaust heat recovery state, the exhaust heat recovery load becomes a partial load or no load, the amount of heat radiated from the heat receiving path 38 of the engine exhaust heat recovery heat exchanger 6 decreases, and the temperature of the engine cooling water starts to radiate heat. When the temperature rises to the set temperature T18 or higher, the switching valve 12 is switched to the heat dissipation state, and the engine cooling water is transferred to the cold water passage 8, water jacket 2, exhaust heat absorption passage 4,
It circulates through the heat radiation path 10 of the radiator 9. Thereby, the exhaust heat of the engine 1 is radiated from the heat radiation path 10 of the radiator 9, cooling the engine cooling water, and preventing the engine 1 from overheating.

(2) The invention of claim 2 operates as follows, as shown in FIGS. 1 and 7, for example.

When the switching valve 12 is operated to switch from the heat recovery state to the heat radiation state, the heat radiation state is maintained for a set period of time, so that the heat exchanger 6 for recovering engine exhaust heat is transferred from the external heat load 100 such as a water heater. When the amount of the waste heat recovery liquid supplied to the heat receiving path 38 decreases or the water is cut off, it is possible to prevent hunting from occurring when switching between the heat radiation state and the heat recovery state.

That is, by simply switching the switching valve 12 between the heat recovery state and the heat radiation state using the temperature sensor 13, when the amount of exhaust heat recovery water decreases or the water is cut off, the engine exhaust heat recovery heat exchanger 6 The amount of heat dissipated from the engine coolant water is reduced or eliminated. A rapidly rises to a temperature that is two times higher than the heat radiation start set temperature T1H, and the switching valve 12 is switched from the heat recovery state to the heat radiation state. In this state for heat dissipation, the engine coolant is cooled by the radiator 9 and rapidly drops to a temperature equal to or lower than the set temperature T11 for ending heat dissipation, so that the switching valve 12 changes from the state for heat dissipation to Switched to recovery state. Then, due to insufficient heat radiation from the engine exhaust heat recovery heat exchanger 6 due to a decrease in the exhaust heat recovery liquid or a water cutoff, the switching valve 12 is switched from the heat recovery state to the heat radiation state again in a short time, and this is repeated. This causes hunting of the switching valve 12.

According to the present invention, by maintaining the heat dissipation state for a set time, it is possible to secure enough time for switching from the heat dissipation state to the recovery state, thereby preventing the hunting described above.

Therefore, the switching valve 12 needs to be switched less frequently, and wear of the valve seat and valve surface is prevented, so that the service life of the switching valve 12 is extended. Also,
Since the frequency of switching between the heat dissipation state and the heat recovery state is reduced, the range of temperature change in the engine coolant can be reduced. Therefore, the cylinder of the engine 1 and the heat exchanger 3 for absorbing exhaust heat suffer less thermal fatigue, and their durability is improved.

(3) The invention of claim 3 operates as follows, as shown in FIGS. 1 and 8, for example.

When the switching valve 12 is switched from the heat recovery state to the heat radiation state, the engine coolant temperature alarm 17 is activated and the heat radiation state of the switching valve I2 is maintained. When the above-mentioned high temperature alarm 17 is activated, the operator manually cancels the heat radiation holding state via the release operation tool 18, thereby allowing a switch from the heat radiation holding state to the heat recovery state. .

Therefore, the time it takes to switch from the heat dissipation holding state to the heat recovery state can be secured as a relatively long time from when the high temperature alarm 17 is activated until the release operation tool 18 is operated, and ), external heat load such as water heater 100
Hunting of the switching valve 12 can be prevented when the amount of exhaust heat recovery liquid supplied from the exhaust heat recovery liquid to the engine exhaust heat recovery heat exchanger 6 decreases or when water is cut off.

(4) The invention of claim 4 operates as follows, as shown in FIGS. 1 and 2, for example.

During operation of the engine 1, if the pressure of the engine cooling water rises above the set pressure of the pressure sensor 21 due to clogging of the switching valve 12 with foreign matter, etc., this pressure sensor 21 is activated by the engine stop control device 22 and the engine stop device. The engine 1 is stopped via 23.

This prevents the engine cooling water from being blown out from the radiator cap of the radiator 9 due to an abnormal pressure rise, and the engine 1 does not overheat.

(5) The invention of claim 5 operates as follows, as shown in FIGS. 1 and 2, for example.

While the engine 1 is operating in a heat dissipation state, the heat dissipation amount of the radiator 9 is insufficient due to dirt etc. on the heat dissipation path 10 of the radiator 9.
When the temperature of the engine cooling water rises above the set temperature of the temperature sensor 25, the temperature sensor 25 stops the engine 1 via the engine stop control device 22 and the engine stop device 23. This prevents the engine 1 from overheating due to an abnormal temperature rise in the engine cooling water.

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

(1) The invention of claim 1 has the following effects.

In the heat dissipation state, when the exhaust heat recovery load becomes partial load or no load, the amount of heat dissipated by the heat exchanger for engine exhaust heat recovery decreases or becomes non-existent (and the temperature of the engine cooling water becomes higher than the set temperature for starting heat dissipation). Then, the switching valve is switched to the heat dissipation state via the temperature sensor and the valve switching control device, and the exhaust heat of the engine is dissipated from the heat dissipation path of the radiator via the engine cooling water. Since the engine cooling water is sufficiently cooled, engine overheating can be prevented.

(2) The invention of claim 2 has the following effects.

When the switching valve is switched from the heat dissipation state to the heat recovery state, by holding the heat dissipation state for a set time, sufficient time can be secured until the switch valve switches from the heat dissipation state to the heat recovery state. When the amount of exhaust heat recovery liquid supplied from an external heat load such as a water heater to the engine exhaust heat recovery heat exchanger decreases or the water is cut off, hunting occurs when switching between the heat radiation state and the heat recovery state. You can prevent it from happening.

Therefore, the switching valve requires less frequent switching, and wear of the valve seat and valve face is prevented, so that the service life of the switching valve is extended. Furthermore, since the frequency of switching between the heat dissipation state and the heat recovery state is reduced, the range of temperature change of the engine cooling water is reduced, and the durability of the engine cylinder and exhaust heat absorption heat exchanger is improved.

(3) The invention of claim 3 has the following effects.

When the switching valve is operated to switch from the heat recovery state to the heat radiation state, the high temperature alarm is activated and the heat radiation state of the switching valve is maintained.

The time it takes to switch from the heat dissipation holding state to the heat recovery state is a relatively long time from the time the high temperature alarm is activated until the release operation tool is operated, so external heat from the water heater, etc. Hunting of the switching valve can be prevented when the amount of exhaust heat recovery water supplied from the load to the heat radiation path of the engine exhaust heat recovery heat exchanger decreases or the water is cut off.

(4) The invention of claim 4 has the following effects.

If the engine cooling water rises to an abnormal pressure due to foreign matter clogging the switching valve, the engine can be automatically stopped, thereby preventing engine overheating due to a lack of engine cooling water.

(5) The invention of claim 5 has the following effects.

If the engine cooling water rises to an abnormal temperature due to poor heat dissipation of the radiator, etc., the engine can be automatically stopped.
This prevents the engine from overheating due to insufficient heat radiation.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

(First Embodiment) Fig. 1 shows an overall system diagram of an engine exhaust heat recovery device, in which a gas engine 1 (hereinafter simply referred to as engine) drives a generator G to supply electric power, and the engine The system is configured so that the exhaust heat of 1 is recovered by an external heat load 100 consisting of a water heater.

First, the cooling water circuit of the engine 1 will be explained.

The water jacket 2 of the engine 1 includes an exhaust heat absorption path 4 of the exhaust heat absorption heat exchanger 3, a hot water channel 5, a heat recovery heat transfer path 7 of the engine exhaust heat recovery heat exchanger 6, and a cold water channel 8. The engine cooling water circulation pump 20 is interposed in the cold water channel 8 while being serially connected to each other in a serial circulation manner. This engine coolant circulation pump 20 is configured to be electric, and is driven by electric power from a battery 27. Further, a heat radiation path 10 of the radiator 9 is connected in parallel to a heat transfer path 7 for heat recovery of the heat exchanger 6 for engine exhaust heat recovery. Cooling air is blown to the radiator 9 by an electric radiator fan 28. Note that a thermostatic valve 27 is provided on the downstream side of the exhaust heat absorption path 4 of the exhaust heat absorption heat exchanger 3, so that when the engine 1 is started cold, engine cooling water is transferred to the exhaust heat recovery heat exchanger 3. 6 and the radiator 9 are bypassed, and the temperature is rapidly raised to a steady state temperature.

The engine cooling channel 11 is composed of the cold channel 8, water jacket 2, exhaust heat absorption channel 4, and hot channel 5. A heat transfer path 7 for heat recovery and a heat radiation path 10 are configured to be switchable and connectable to the engine cooling water path 11 using a switching valve 12 . This switching valve 12 consists of two solenoid valves: a recovery solenoid valve 31 which is a heat recovery valve, and a heat radiation solenoid valve 32 which is a heat radiation valve.

On the other hand, exhaust gas from the engine 1 is discharged to the outside from the muffler 35 via the exhaust gas flow path 34 of the heat exchanger 3 for absorbing exhaust heat.

Next, the exhaust heat recovery liquid circuit will be explained. This transfers the exhaust heat recovery liquid stored in the external heat load 100 to the recovery pump 37.
The heat is then returned to the external heat load 100 via the heat receiving path 38 of the engine exhaust heat recovery heat exchanger 6. The heat receiving path 38, the recovered liquid inlet path 41, and the recovered liquid outlet path 42 constitute an exhaust heat recovery path 45.

Next, the electrical control circuit will be explained.

Reference numeral 40 is a control panel for inputting control power.

A thermostatic valve 29 is installed in the middle of the engine cooling water channel 11.
A temperature sensor 13 is provided on the downstream side.

This temperature sensor 13 detects the temperature of engine cooling water and controls switching of the switching valve 12 via a valve switching control device 14.

That is, the detected temperature T of the engine cooling water temperature of the temperature sensor 13
1 reaches or exceeds the set temperature T 111 for starting heat radiation, the valve switching control device 14 closes the recovery solenoid valve 31 and opens the heat radiation solenoid valve 32 to place the switching valve 12 in the heat recovery state. Switch from to the heat dissipation state. As a result, the heat transfer path 7 for heat recovery of the engine exhaust heat recovery heat exchanger 6 is closed, and the heat radiation path 10 of the radiator 9 is opened.

On the other hand, the measurement temperature T of the engine cooling water temperature of the temperature sensor 13
, is lower than the set temperature for heat dissipation end TI+, which is lower than the set temperature for heat dissipation start T, 11, the heat dissipation solenoid valve 32 is closed, the recovery solenoid valve 31 is opened, and the switching valve 12 is closed. Switch from heat radiation state to heat recovery state. As a result, the heat radiation path 10 of the radiator 9 is closed, and the heat transfer path 7 for heat recovery of the engine exhaust heat recovery heat exchanger 6 is opened.

Further, an engine emergency stop pressure sensor 21 is provided at the outlet of the engine coolant circulation pump 20. This pressure sensor 21 detects abnormally high pressure of engine cooling water,
The engine 1 is stopped by an engine stop device 23 via an engine stop control device 22.

Furthermore, an engine emergency stop temperature sensor 25 is provided between the thermostat valve 29 and the temperature sensor 13 in the middle of the engine cooling water channel 11 . This temperature sensor 25 is
An abnormally high temperature of the engine cooling water is detected, and the engine 1 is stopped by an engine stop device 23 via an engine stop control device 22.

The electrical control of the above configuration is designed to execute a control program shown in FIG.

When the control program starts, first, it is determined whether the engine 1 is in an operating state (Sl). When the engine 1 is in an operating state, it is determined whether the recovery pump 37 is in an operating state (S2). Recovery pump 37
is in operation, the detected temperature T1 of the engine cooling water is the set temperature T, L for ending heat radiation (here, 82°C).
It is determined whether or not it is less than or equal to (S3). Set temperature (8
2°C) or lower, the state is switched to the recovery state.

That is, the timer starts timing (S4), the heat radiation solenoid valve 32 opens (S5), and the recovery solenoid valve 31 opens.
(S6). Next, it is determined whether the set time of the timer has elapsed (S7), and if the set time has elapsed, the heat radiation solenoid valve 32 is closed (S8), and only the recovery solenoid valve 31 is open. is maintained. On the other hand, if the set time of the timer has not elapsed at the step S7, the heat dissipation solenoid valve 3
2 is kept in the questioned state (S9).

Next, it is determined whether the discharge pressure of the engine coolant circulation pump 20 is lower than the pressure high alarm setting pressure P1 (SIO). If the pressure is low, it is determined whether the engine 1 is running (Sll), and if the engine is running, the recovery pump 3
7 is in the operating state or not is determined (S12). When the recovery pump 37 is in operation, the detected temperature T of the engine cooling water is set at the heat radiation start temperature T1H (here, 90°C).
℃) or less is determined (S13). If the set temperature is below TIH (90°C), the engine cooling water detection temperature T3 or the heat radiation abnormality alarm set temperature T,,, (
Here, it is determined whether the temperature is below 100°C (
S14).

If the temperature is lower than the set temperature 73H (100°C), the process returns to step S6 and is maintained in the recovery state.

Next, if the recovery pump 37 is not in operation in the step S2, and if the detected temperature T1 of the engine cooling water is higher than the set temperature T, L (82°C) in the step S3, the recovery pump 37 is in the step S2. 37 is not in operation, the detected temperature T of the engine cooling water at the stage of S13 is the set temperature T for starting heat radiation (90'C).
If it is higher than , it is switched to the heat dissipation state.

That is, as in the case of the recovery state described above, the timer starts timing (515), the recovery solenoid valve 31 opens (S16), and the heat radiation solenoid valve 32 also opens (S17). Next, it is determined whether the set time of the timer has elapsed (
S18), if the set time has elapsed, the recovery solenoid valve 31
is closed (S19), and only the heat radiation solenoid valve 32 is kept open.

On the other hand, if the set time of the timer has not elapsed at step 318, the collection solenoid valve 31 is kept open (
S20).

Next, it is determined whether the discharge pressure of the engine coolant circulation pump 20 is lower than the pressure high alarm setting pressure P1 (S21). When the pressure is low, the detected temperature T3 of the engine cooling water is the set temperature for heat radiation abnormality alarm T31 ((100
℃) or less is determined (822). If the set temperature T3) is below 1 (LOO'C), it is determined whether the engine 1 is in operation (S23), and if it is in operation, it is determined whether the recovery pump 37 is in operation (S24).
). When the recovery pump 37 is in operation, the detected temperature T1 of the engine cooling water is the set temperature T, 4(
Here, it is determined whether or not the temperature is below 82°C (82°C).
25). If the temperature is below the set temperature T.sub.1, L (82.degree. C.), the process returns to step S4 and switches to the recovery state.

Next, if the recovery pump 37 is not in operation at the step S24, and the detected temperature T of the engine cooling water is higher than the set temperature T, (82°C) at the step S25, then the step S17 is performed. It is returned to the stage and kept in a state of heat dissipation.

Note that if the engine 1 is not in an operating state at the step Sll or S23, the process returns to the start of the control program. Further, at the SIO or S21 stage, if the discharge pressure P is equal to or higher than the set pressure PB+, an auxiliary equipment abnormality alarm is issued (826) and the engine 1 is stopped (S27). Furthermore, in the step S14 or S22, whether the detected engine cooling water temperature T3 or the set temperature T3.
．． (100'C), a heat radiation abnormality alarm is issued (828/530) and engine 1 is stopped (
S29・531).

By controlling the exhaust heat recovery device as described above, the following advantages can be obtained.

Since the exhaust heat recovery device is switched to the heat dissipation state and maintained in that state when the recovery pump 37 is not in the operating state, it cannot be switched to the recovery state even if the temperature drops due to cooling by engine cooling water or the radiator 9. It disappears. Thereby, when the recovery pump 37 is stopped, it is possible to prevent the electromagnetic valves 31 and 32 from being damaged by notching due to frequent switching between the heat radiation state and the recovery state.

In addition, when switching the recovery solenoid valve 31 and the heat radiation solenoid valve 32 between the recovery state and the heat radiation state, both the solenoid valves 31
・Since 32 were configured to open at the same time for a set time,
It is possible to prevent water leakage during switching and prevent the pressure of engine cooling water from increasing abnormally. This can prevent engine cooling water from spouting out from the radiator cap of the radiator 9 and overheating the engine l.

Furthermore, when the pressure of the engine cooling water rises to an abnormal level due to clogging of the solenoid valves 31 and 32, or when the temperature of the engine cooling water rises to an abnormal level due to dirt in the radiator 9, etc. , an abnormality alarm is issued and the engine 1 is brought to an emergency stop, so it is possible to prevent the engine 1 from being damaged due to overheating.

FIG. 3 shows that by switching the switching valve 12 consisting of both electromagnetic valves 31 and 32 between the recovery state and the heat dissipation state,
The temperature of the engine cooling water is the set temperature for starting heat radiation T, (9
0'C) and the set temperature TIL (82°C) for ending heat radiation.

Moreover, FIG. 4 shows a modified example. As shown in FIG. 1, this means that the temperature sensor 1
3, a temperature sensor 43 is provided in the recovered liquid outlet path 42, and this temperature sensor 43 controls the switching of the switching valve 12 via the valve switching control device 14. Then, by switching the switching valve 12 consisting of both electromagnetic valves 31 and 32 between the recovery state and the heat radiation state, the temperature of the waste heat recovery liquid is adjusted to the set temperature for starting heat radiation T, as shown in FIG.
7. (80°C) and the set temperature T, L (72
°C). In addition, in the control program in this case, in FIG. 2, the steps S3, S13, and S25 may be changed from T1 to T, respectively.

(Second example) 5 and 6 show a second embodiment.

As shown in FIG. 1, a temperature sensor 13 is provided in the engine cooling water channel 11, and a temperature sensor 43 is provided in the recovered liquid outlet channel 42, and the two temperature sensors 13 and 43 control the valve switching control device 14. The switching valve 12 is controlled to be switched through the switching valve 12.

The above configuration is adapted to execute the control program shown in FIG.

7. When the control program starts, the detected temperature T1 of the engine cooling water becomes the set temperature T for starting heat radiation (here, 90
It is determined whether or not the temperature is lower than (°C) (S1). If the detected temperature T2 of the recovered liquid is lower than the set temperature T2M (90°C), the detected temperature T2 is lower than the set temperature T2M (here 8
It is determined whether the temperature is lower than 0°C (S2). When the temperature is lower than the set temperature T, l1 (80°C), the state is switched to the recovery state, the recovery solenoid valve 31 is opened, and (S
3), the heat dissipation solenoid valve 32 is closed (S4), and the process returns to the Sl stage.

Further, in the step S1, if the detected temperature T1 of the engine cooling water is equal to or higher than the set temperature T, (90°C), S
In step 2, the detected temperature T of the recovered liquid is the set temperature T for starting heat radiation.3. (80°C) or higher, the state is switched to the heat dissipation state. That is, the recovery solenoid valve 31 is closed (S5), and the heat radiation solenoid valve 32 is opened (S6). Next, it is determined whether or not the detected temperature T1 of the engine coolant is equal to or lower than the set temperature T, L (here, 82° C.) for ending heat radiation (S7). If the set temperature T,L (82°C) or lower, the detected temperature T of the recovered liquid is the set temperature T,L for ending heat radiation.
(here, 72°C) or less is determined (S8)
. If the temperature is lower than the set temperature T2L (72°C), the process returns to the Sl stage.

At the step S7 above, the detected temperature T1 of the engine cooling water
is higher than the set temperature for finishing heat radiation T, L (82°C), the detected temperature T2 of the recovered liquid is the set temperature for finishing heat radiation T,
If the temperature is higher than L (72°C), the process returns to steps S5 and S6 and is maintained in a heat dissipation state.

With this configuration, by switching the switching valve 12 consisting of both electromagnetic valves 31 and 32 between the recovery state and the heat radiation state, the temperature of the engine cooling water changes to the setting for starting heat radiation, as shown in FIG. The temperature T, +((90°C) is maintained between the set temperature T, , , (82°C) for ending heat radiation, and the temperature of the recovered liquid is maintained between the set temperature T, ,, (80°C) for starting heat radiation.
'C) and the set temperature T for ending heat radiation, which is maintained between 1° (72°C).

Therefore, by keeping the engine cooling water within a certain range, the engine 1
In addition to preventing overheating, external heat load 1
Regardless of load fluctuations, the recovered liquid can be taken out at a desired temperature within a certain range.

(Third Embodiment) FIG. 7 is a control program showing a third embodiment, which is a part of the control program of the second embodiment (see FIG. 5) with the following changes, and is the same as the control program of the second embodiment (see FIG. 5). The stages are indicated with the same reference numerals. That is, if the detected temperature T of the engine cooling water is equal to or higher than the set temperature T111 for starting heat radiation at the stage SL, the timer starts counting (SIO), and the recovery solenoid valve 31 is closed (S5). , the heat radiation solenoid valve 32 is opened (S6) and switched to the heat radiation state. Next, it is determined whether the set time of the timer has elapsed (Sll)
. If the set time has elapsed, the process moves to step S7, and if the set time has not elapsed, the process returns to S5 and S6 to maintain the heat dissipation state.

To explain this with reference to FIG. 1, the temperature sensor 13 provided in the engine cooling water channel 11 detects the set temperature for starting heat radiation T11. When detected, the valve switching control device 14 switches the switching valve 12 from the heat recovery state to the heat radiation state, and maintains the heat radiation state for a set time.

In this way, when the exhaust heat recovery device is switched to the heat dissipation state, it is maintained in the heat dissipation state for a set time, so even if the engine cooling water is rapidly cooled by the radiator 9, it can be switched from the heat dissipation state to the recovery state. This eliminates the possibility of switching over in a short period of time. Therefore, due to an insufficient amount of recovered liquid or a water outage, the heat dissipation state and the recovery state are frequently switched, and both the solenoid valves 31 and
32 can be prevented from being damaged by hunting.

(Fourth Embodiment) Fig. 8 shows a control program showing a fourth embodiment, which is a part of the control program of the second embodiment (see Fig. 5) with the following changes, and is the same as the control program of the second embodiment. The stages are indicated with the same reference numerals. That is, if the detected temperature T1 of the engine cooling water is equal to or higher than the heat radiation start set temperature T I+
1 (S5), and opens the heat radiation solenoid valve 32 (S6) to switch to the heat radiation state. Next, it is determined whether or not to cancel the alarm (S21). If the alarm is canceled, proceed to step S7; if the alarm is not canceled, proceed to step S5.
and returns to S6 to maintain the heat dissipation state.

To explain this with reference to FIG. 1, the temperature sensor 13 detects the set temperature for starting heat radiation T10. When the valve switching control device 14 switches the switching valve 12 from the heat recovery state to the heat radiation state based on the detection of
However, the engine coolant temperature alarm 17 is activated and the switching valve 12 is maintained in the heat dissipation state. and,
The heat dissipation holding state is released by manually operating the release operation tool 18. As a result, the heat dissipation state is maintained from the time the alarm is issued until the release operation is performed, so that hunting due to insufficient amount of recovered liquid or water cut-off can be prevented, similar to the fourth embodiment.

(Fifth Example) FIGS. 9 to 13 show a fifth example. This is done by making the following changes to part of the control program of the second embodiment (see Figure 5), so that the abnormality alarm of the fourth embodiment (see Figure 8) can be issued individually for each cause of the abnormality. The same steps are indicated by the same reference numerals.

That is, following steps S5 and S6, it is determined whether the temperature difference ΔT between the detected temperatures T2 of the recovered liquid is equal to or less than the upper limit temperature difference ΔTH (S30). This temperature difference T becomes the upper limit temperature difference TH
In the following cases, it is determined whether the temperature difference ΔT is larger than the lower limit temperature difference ΔTL (S31). If the temperature difference ΔT is larger than the lower limit temperature difference ΔTt, an abnormality alarm for the engine exhaust heat recovery heat exchanger 6 is issued 532);
Maintain the heat dissipation state (S33/534). At the step of S30 above, the temperature difference T is the upper limit temperature difference TI! 835), S
If the temperature difference T is less than the lower limit temperature difference ΔTL in step 31, a water cutoff alarm for the recovered liquid is issued (836), and the heat dissipation state is maintained (S35 and 836). Next, it is determined whether or not to cancel the alarm (S37), and if the alarm is canceled, the process moves to S7, and if the alarm is not canceled, the process returns to step S33/3.34. The heat dissipation state is maintained.

The operation of the above alarm will be explained in detail with reference to FIGS. 10 to 12. Each figure shows temperature changes of engine cooling water and recovered liquid.

FIG. 10 shows a case where the amount of recovered liquid decreases abnormally during operation in the recovery state, the temperature on the outlet side of the recovered liquid increases, and the recovery state is switched to the heat dissipation state. In this case, the temperature on the outlet side of the recovered liquid at the time of the switching is measured, and the temperature on the outlet side of the recovered liquid after Δt (about several minutes) has passed since the switching, and the temperature difference T is calculated from the difference between these two. . When the amount of recovered liquid sent is reduced, the temperature difference between the inlet and outlet of the recovered liquid increases, and the outlet temperature of the recovered liquid increases rapidly, so that the temperature difference T becomes larger than the upper limit temperature difference ΔT. Based on this, an alarm for insufficient amount of collected liquid is issued.

FIG. 11 shows a case where the recovery liquid is cut off during operation in the recovery state, the temperature of the engine cooling water rises, and the recovery state is switched to the heat radiation state. When the recovered liquid is cut off, the temperature drop on the outlet side of the recovered liquid is so small that it only decreases due to natural heat radiation, so the temperature difference T becomes less than the lower limit temperature difference ΔTL. Based on this, a recovered liquid water outage warning is issued.

FIG. 12 shows a case where the exhaust heat recovery heat exchanger 6 is switched from the recovery state to the heat radiation state due to insufficient heat radiation due to dirt on the heat transfer surface or the like. In this case, the temperature difference between the inlet and outlet of the recovered liquid is not much different from the normal operating state, and the temperature difference ΔT is less than or equal to the lower limit temperature difference T1□ and larger than the lower limit temperature difference ΔTL. Based on this, An abnormality alarm for the exhaust heat recovery heat exchanger 6 is issued.

FIG. 13 shows a modification of the above alarm activation. This is configured to change the upper limit temperature difference T1□, the lower limit temperature difference ΔT +, and the lower limit temperature difference ΔTN in the normal region in response to changes in the engine load. Thereby, an appropriate warning can be issued in response to fluctuations in exhaust heat recovery capacity due to fluctuations in engine load.

[Brief explanation of the drawing]

1 to 13 show embodiments of the invention. FIG. 1 shows an overall system diagram common to each embodiment. Figures 2 to 4 show the first embodiment, Figure 2 is a control program diagram, Figure 3 is a diagram showing changes in engine cooling water temperature, and Figure 4 is a modified example of the recovery liquid. FIG. 3 is a diagram showing temperature changes. 5 and 6 show the second embodiment, FIG. 5 is a control program diagram, and FIG. 6 is a diagram showing temperature changes of engine cooling water and recovered liquid. FIG. 7 is a control program diagram showing a third embodiment. FIG. 8 is a control program diagram showing a fourth embodiment. 9 to 13 show the fifth embodiment, FIG. 9 is a control program diagram, and FIGS. 10 to 12 are diagrams showing temperature changes of engine cooling water and recovered liquid, respectively. The figure is a diagram showing the relationship between engine load and temperature difference for alarm setting. FIG. 14 is an overall system diagram showing a conventional example. ■...Engine, 2...Water jacket, 3.
...Exhaust heat absorption heat exchanger, 4...Exhaust heat absorption path, 5
Hot water channel, 6... Heat exchanger for engine exhaust heat recovery, 7...
・Heat transfer path for heat recovery, 8. Cold water channel, 9... radiator,
10... Heat radiation path, 11... Engine cooling channel, 12
...Switching valve, 13...Temperature sensor, 14...Valve switching control device, 17...Engine coolant temperature high alarm, 18...Cancellation operation tool, 20...Engine cooling Water circulation pump, 21... Pressure sensor for engine emergency stop, 22... Control device for engine stop, 23... Engine stop device, 25... Temperature sensor for engine emergency stop, T1...
Detection temperature of engine cooling water temperature, TIH... Set temperature for heat radiation start, TIL... Set temperature for heat radiation end. Agent Hisashi Chatan-jXI: 1'-7'i45 bottle

Claims (1)

[Claims] 1. The water jacket (2) of the engine (1) includes an exhaust heat absorption path (4) of the exhaust heat absorption heat exchanger (3), a hot water channel (5), and an engine exhaust heat recovery path. In an engine exhaust heat recovery device configured by sequentially connecting a heat transfer path (7) and a cold water channel (8) for heat recovery of a heat exchanger (6) in a serial circulation manner, a heat exchanger for engine exhaust heat recovery is used. Heat transfer path for heat recovery of vessel (6) (
The heat radiation path (10) of the radiator (9) is connected in parallel to 7), and the engine cooling system consists of a cold water channel (8), a water jacket (2), an exhaust heat absorption channel (4), and a hot water channel (5). Waterway (
11), a heat transfer path for heat recovery (7) and a heat radiation path (10)
) can be switched and connected by a switching valve (12), a temperature sensor (13) is provided in the engine cooling water channel (11), and the temperature sensor (13) is switched via a valve switching control device (14). The temperature sensor (13) detects the temperature of the engine cooling water passing through the engine cooling water channel (11), and the temperature sensor (13) detects the temperature of the engine cooling water (T_1). ) becomes equal to or higher than the set temperature for starting heat radiation (T_1_H), the valve switching control device (14) switches the switching valve (12) from the heat recovery state to the heat radiation state, and starts the heat recovery mode. The heat path (7) is closed, and the heat radiation path (10) is opened, and the detected temperature (T_1) of the engine cooling water temperature is set to a heat radiation end set temperature (T_1_L) that is lower than the heat radiation start set temperature (T_1_H). If the following happens, switch valve (1
2) from the heat radiation state to the heat recovery state to close the heat radiation path (10) and close the heat transfer path (7) for heat recovery.
An exhaust heat recovery device for an engine, characterized in that it is configured to open the engine. 2. The temperature sensor (13) detects the set temperature for starting heat radiation (T_
1_H), the valve switching control device (
Claim 1, wherein when the switching valve (12) is operated to switch from the heat recovery state to the heat radiation state, the heat radiation state is maintained for a set time by the valve switching control device (14). Exhaust heat recovery device for the engine described. 3. The temperature sensor (13) detects the set temperature for starting heat radiation (T_
1_H), the valve switching control device (
14) switches the switching valve (12) from the heat recovery state to the heat radiation state, the valve switching control device (14)
is configured to operate the engine coolant temperature high alarm (17) and hold the switching valve (12) in the heat radiation state, and the heat radiation holding state release operation tool (18) is used to switch the valve. The engine exhaust heat recovery device according to claim 1, which is attached to the engine control device (14). 4. An engine cooling water circulation pump (20) is interposed in the engine cooling water channel (11), and a midway portion of the engine cooling water channel (11) from the outlet of the engine cooling water circulation pump (20) to the switching valve (12) is installed. A pressure sensor (21) for engine emergency stop is provided in the engine stop control device (21), and this pressure sensor (21) is connected to the engine stop control device (2
2. The engine exhaust heat recovery device according to claim 1, wherein the engine exhaust heat recovery device is configured to be linked to an engine stop device (23) via the engine stop device (23). 5. A temperature sensor (25) for engine emergency stop is installed in the engine cooling water channel (11), and this temperature sensor (25) is connected to the engine stop control device (2).
2. The engine exhaust heat recovery device according to claim 1, wherein the engine exhaust heat recovery device is configured to be linked to an engine stop device (23) via the engine stop device (23).