JP2014070631A - Vehicle waste heat recovery system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vehicle waste heat recovery system capable of reducing fuel consumption of an internal combustion engine by efficiently recovering waste heat energy of the internal combustion engine.SOLUTION: A vehicle waste heat recovery system comprises: a first cooling liquid passage 61 which allows cooling liquid to circulate between an internal combustion engine 1 and a waste heat recovery device 5; a second cooling liquid passage 62 which allows the cooling liquid to circulate between the internal combustion engine 1 and a radiator 6; a first thermostat 2 which is installed in the first cooling liquid passage 61; a second thermostat 4 which is installed in the second cooling liquid passage 62; and a water pump 3 which circulates the cooling liquid. The first thermostat 2: opens a bypass port when a temperature of the cooling liquid is less than a first valve opening start temperature; and closes the bypass port and opens a heat recovery port when the temperature of the cooling liquid is not less than the first valve opening start temperature. The first thermostat 2 also has a second thermostat port to allow the cooling liquid to continuously flow to a side of the second thermostat 4. The second thermostat 4 opens a radiator port when the temperature of the cooling liquid is not less than a second valve opening start temperature.

Description

  The present invention relates to a vehicle waste heat recovery system.

  In vehicles equipped with an internal combustion engine, waste heat energy of the internal combustion engine is recovered by a waste heat recovery device to improve the thermal efficiency of the internal combustion engine.

According to Patent Document 1, an internal combustion engine, a refrigerant compression compressor driven by the internal combustion engine, a refrigerant heat exchanger, and a waste heat recovery device for transferring heat of the internal combustion engine to the refrigerant, When the temperature of the internal combustion engine is lower than a predetermined value, there is provided control means for stopping heat exchange by the heat exchanger of the waste heat recovery apparatus. A thermostat is used as the control means.
In this way, warm-up of the internal combustion engine is promoted.

According to Patent Document 2, a coolant circulation path through which a coolant that cools an internal combustion engine circulates, a first heat exchanger that heats a working medium by exchanging heat with the coolant, and a first heat exchanger. A Rankine cycle comprising: an expander that expands the heated working medium; a condenser that cools the working medium expanded by the expander; and a pump that circulates the working medium cooled by the condenser. Heated with exhaust gas, the heated coolant is exchanged with heat energy in the first heat exchanger.
However, a technique for adjusting the flow rate of the coolant flowing into the first heat exchanger with a thermostat is disclosed in order to prevent the coolant from becoming too hot and carbonizing the working medium.

JP-A-62-84273 JP 2006-144744 A

However, according to Patent Document 1, the heat exchanger that heats the coolant of the internal combustion engine with the exhaust gas is downstream of the coolant flow passage of the waste heat recovery device, and the heat exchanger that is heated with the exhaust gas warms up the internal combustion engine. The heat of the exhaust gas does not contribute to the improvement of the waste heat recovery efficiency of the waste heat recovery device.
Further, since the cooling liquid is heated by the heat exchanger, the heat load of the internal combustion engine becomes large and there is a problem that adversely affects the internal combustion engine.
In Patent Document 2, the amount of coolant flowing in the heat exchanger of the Rankine cycle circuit and the amount of coolant flowing in the bypass are adjusted by a thermostat to prevent the working medium from being carbonized.
Therefore, both Patent Document 1 and Patent Document 2 adjust the coolant flow path with a thermostat in order to promote warm-up of the internal combustion engine, and the waste heat energy of the internal combustion engine cannot be efficiently recovered by the waste heat recovery device. Has a defect.

  The present invention has been made in view of the above-mentioned problems of the prior art, and is a vehicle waste heat recovery system that can reduce the fuel consumption of an internal combustion engine by efficiently recovering the waste heat energy of the internal combustion engine. The purpose is to provide a system.

To achieve the above object, according to the present invention, an internal combustion engine,
A radiator for cooling the coolant of the internal combustion engine;
Using the coolant as a heat source, a waste heat recovery device that recovers thermal energy;
A first coolant flow passage for circulating the coolant between the internal combustion engine and the waste heat recovery device;
A second coolant flow passage for circulating the coolant between the internal combustion engine and the radiator;
A first thermostat that is interposed in the first coolant flow path and adjusts the flow of the coolant to the waste heat recovery device;
A second thermostat interposed in the second coolant flow passage for adjusting the flow of the coolant to the radiator;
A water pump that is disposed downstream of the joining portion where the first coolant flow passage and the second coolant flow passage merge on the downstream side of the waste heat recovery device and the radiator, and circulates the coolant;
A bypass passage for bypassing the coolant from the waste heat recovery device and the radiator and flowing from the first thermostat to the water pump,
The first thermostat includes a bypass port for flowing the coolant through the bypass passage when the coolant temperature is lower than the first valve opening start temperature, and the coolant temperature is equal to or higher than the first valve opening start temperature. A waste heat recovery port that flows to the waste heat recovery device side, and a second thermostat port that always flows to the second thermostat side,
The second thermostat has a radiator port that causes the coolant to flow to the radiator when the coolant temperature from the first thermostat is equal to or higher than a second valve opening start temperature. A collection system can be provided.

  In the present invention, it is preferable that the second valve opening start temperature of the second thermostat is 5 ± 1 ° C. higher than the first valve opening start temperature of the first thermostat.

According to the present invention, after the warm-up operation of the internal combustion engine is completed, until the coolant temperature becomes equal to or higher than the second valve opening start temperature, the entire amount of the coolant flows to the waste heat recovery device side. Energy recovery can be expected, and the fuel efficiency improvement effect of the internal combustion engine is increased.
In addition, by raising the valve opening start temperature of the second thermostat by 5 ± 1 ° C, the temperature of the coolant flowing to the waste heat recovery device increases, the heat exchange efficiency in the waste heat recovery device increases, and the fuel efficiency improvement effect Becomes larger.
In addition, when the coolant temperature rises, a part of the coolant is diverted to the radiator side, so the existing radiator cooling capacity can be reduced, making it possible to reduce the size and weight of the radiator, reducing fuel consumption and reducing costs. A reduction effect is obtained.
Further, since the coolant flows in the first and second coolant flow passages in parallel, the flow resistance of the coolant flowing in the first and second coolant flow passages is reduced, and the water pump The driving load is reduced and the load on the internal combustion engine is reduced.

  Preferably, in the present invention, a heat exchanger that is interposed between the first thermostat of the first coolant flow passage and the waste heat recovery device and that heats the coolant with the exhaust gas of the internal combustion engine is provided. It is good to arrange.

  With such a configuration, the temperature of the coolant flowing toward the waste heat recovery apparatus can be increased, and the waste heat recovery efficiency in the waste heat recovery apparatus can be increased. The temperature of the coolant flowing toward the waste heat recovery device can be increased, and the waste heat recovery efficiency in the waste heat recovery device can be increased.

  Preferably, in the present invention, the first thermostat is attached to the outer peripheral portion of the internal combustion engine so as to form a part of the coolant flow passage, and the outlet to the waste heat recovery device is connected to the internal combustion engine. It is good to project outward.

By adopting such a configuration, the coolant outlet to the waste heat recovery device side of the thermostat has a structure protruding outward from the internal combustion engine.
Therefore, the passage (rubber hose or metal pipe, etc.) through which the coolant flows to the waste heat recovery device is externally attached, making it unnecessary to refurbish the internal combustion engine, making it possible to install the waste heat recovery device with a small thermostat refurbishment. While suppressing the rise, the fuel saving effect of the internal combustion engine can be obtained.

  In the present invention, it is preferable that the second thermostat port of the first thermostat and the coolant inlet port into which the coolant flows from the second thermostat port of the second thermostat are integrally formed. .

By adopting such a configuration, the first thermostat and the second thermostat are integrally molded, so that the number of parts is reduced, so that the assembling work with the internal combustion engine is reduced and the cost can be reduced.
Furthermore, by integrally molding, the overall shape is reduced, the vehicle mountability is improved, the air permeability around the internal combustion engine is improved, and the heat load on the peripheral equipment can be reduced. The durability of the equipment is improved.

  By doing in this way, the waste heat recovery system for vehicles which can aim at the fuel-saving of an internal combustion engine by recovering the waste heat energy of an internal combustion engine efficiently can be provided.

1 shows a schematic configuration diagram of a waste heat recovery system to which a first embodiment of the present invention is applied. FIG. 1 is a coolant flow path of a thermostat according to the first embodiment of the present invention, in which (A) is a warm-up operation of an internal combustion engine, (B) is a radiator that is not required to be cooled, and (C) is a radiator that is required to be cooled. Shows the case. The valve opening start temperature of a thermostat in this embodiment and a full open temperature list are shown. Explanatory drawing of the valve opening speed of the thermostat in this embodiment is shown. The schematic block diagram of the waste-heat recovery system to which 2nd Embodiment of this invention was applied is shown. FIG. 4 is a thermostat coolant flow path according to a second embodiment of the present invention, where (A) is a warm-up operation of an internal combustion engine, (B) is a radiator that is not required to be cooled, and (C) is a radiator that is required to be cooled. Shows the case. The flow chart of the flow of the cooling fluid by the thermostat on-off valve operation in this embodiment is shown.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention only to specific examples unless otherwise specifically described. Only.

FIG. 1 is a schematic configuration diagram of a vehicle waste heat recovery system in which the first embodiment of the present invention is used.
The vehicle waste heat recovery system 10 includes an internal combustion engine 1 mounted on a vehicle (not shown), a radiator 6 that cools a cooling liquid R that cools the internal combustion engine 1, and heat that the cooling liquid R has cooled the internal combustion engine 1 as a heat source. A waste heat recovery device 5 that recovers thermal energy, a first coolant flow passage 61 that connects the internal combustion engine 1 and the waste heat recovery device 5 so that the coolant R circulates, an internal combustion engine 1 and a radiator 6. A second coolant flow passage 62 connected so that the coolant R circulates;
A first thermostat 2 mounted on the internal combustion engine 1 and constituting a part of the first coolant flow passage 61, and a first heat exchanger 51 of the waste heat recovery device 5 and the first thermostat 2 are connected to each other. The second heat exchanger 7, which is interposed in the pipe constituting the one coolant flow passage 61 and heats the coolant R with the exhaust gas of the internal combustion engine 1, the first thermostat 2, and the radiator 6 A second thermostat 4 interposed in the pipe of the second coolant flow passage 62 to be connected and adjusting the flow of the coolant R to the radiator 6 side according to the coolant temperature; and the downstream side of the first heat exchanger 51; It is composed of a water pump 3 attached to the lower part of the internal combustion engine 1 downstream of the joining portion P where the coolant flow passages on the downstream side of the radiator 6 join.

The internal combustion engine 1 includes a main body block 1a and a head portion 1b. Inside the internal combustion engine 1 is formed a cooling gallery 1c that constitutes a part of the first coolant flow passage 61 through which the coolant R for cooling the internal combustion engine 1 flows.
Further, the internal combustion engine 1 is provided with a bypass passage 1 d through which the coolant R liquid bypasses the radiator 6 from the first thermostat 2 during the warm-up operation of the internal combustion engine 1.
The first thermostat 2 is attached so as to constitute a part of the cooling gallery 1c in a state where a part of the first thermostat 2 is exposed to the upper outer periphery of the head part 1b on the radiator 6 side.

The first coolant flow passage 61 includes a cooling gallery 1c of the internal combustion engine 1, a first thermostat 2, a fourth pipe 6d connecting the first thermostat 2 and the second heat exchanger 7, and a second heat exchanger. 7, the fifth pipe 6 e that connects the second heat exchanger 7 and the first heat exchanger 51, the first heat exchanger 51, the first heat exchanger 51, and the water pump 3. It is comprised with 6 f of piping.
The second coolant flow passage 62 includes the cooling gallery 1c of the internal combustion engine 1, the first thermostat 2, the second pipe 6b connecting the first thermostat 2 and the second thermostat 4, the second thermostat 4, 2 includes a third pipe 6 c that connects the thermostat 4 and the radiator 6, a radiator 6, and a first pipe 6 a that connects the radiator 6 and the water pump 3.

In the present embodiment, the second valve opening start temperature T2 of the second thermostat 4 is set higher than the first valve opening start temperature T1 of the first thermostat 2. Details will be described later.
On the other hand, the first valve opening start temperature T1 of the first thermostat 2 is the optimum temperature of the internal combustion engine 1.
The optimum temperature is the coolant temperature that is the temperature of the internal combustion engine when the combustion efficiency of the fuel in the combustion chamber of the internal combustion engine 1 is the best.
The reason is that the second valve opening start temperature T2 of the second thermostat 4 is increased because the warm-up operation of the internal combustion engine 1 is completed and the first thermostat 4 starts from the first thermostat 2 until the valve opening of the second thermostat 4 starts. The temperature of the coolant flowing through the heat exchanger 51 (including the second heat exchanger 7) is increased to improve the heat recovery efficiency at an early stage.
In general, the coolant R is obtained by adding ethylene glycol to water.

As schematically shown in FIG. 2, the first thermostat 2 is detachably attached from the outside to the radiator 6 side end portion of the head portion 1 b located in the upper portion of the internal combustion engine 1.
The second thermostat 4 is connected to a second thermostat port 2c (described later) of the first thermostat 2 by a second pipe 6b.
The first thermostat 2 includes a first housing 21 having a plurality of inlets and outlets, and a first on-off valve 22 that opens and closes the plurality of inlets and outlets depending on the temperature of the coolant R.

The first housing 21 includes a first coolant inlet 2 a directly connected to the coolant gallery 1 c of the internal combustion engine 1, and a bypass port 2 d connected to the water pump 3 via a bypass passage 1 d that bypasses the radiator 6. , A waste heat recovery port 2b that is an outlet through which the coolant R from the coolant inlet 2a flows out to the waste heat recovery device 5 side, and a second thermostat port 2c that communicates with the second thermostat 4 are provided.
The waste heat recovery port 2b and the second thermostat port 2c are provided with a cylindrical sleeve-like connecting portion S protruding outward of the internal combustion engine 1.
The cylindrical sleeve-like connecting portion S connects the second pipe 6b (see FIG. 1) that forms a part of the first coolant flow passage 61 for circulating the coolant R to the second heat exchanger 7 side. At the same time, it can be easily connected, and the modification on the internal combustion engine 1 side is not required, so that the cost increase can be suppressed.
Moreover, when connecting the 3rd piping 6c which connects the 1st thermostat 2 and the 2nd thermostat 4, it can connect easily.
The first thermostat 2 and the second thermostat 4 are circulated regardless of the coolant temperature.

As shown in the schematic diagram of FIG. 2, the second thermostat 4 is disposed in a state of being directly connected by the second pipe 6 b on the downstream side of the second thermostat port 2 c of the first thermostat 2.
The second thermostat 4 includes a second housing 41 having a plurality of inlets and outlets, and a second on-off valve 42 that opens and closes the plurality of inlets and outlets according to the temperature of the coolant R.
The second housing 41 includes a second coolant inlet 4a into which the coolant R from the first thermostat 2 flows, and a radiator port 4b connected to the radiator 6 via a third pipe 6c. Yes.

The first on-off valve 22 and the second on-off valve 42 have a complicated structure in which the temperature-sensitive wax accommodated in the on-off valve expands and contracts due to the coolant temperature to open and close each inlet / outlet. It has become.
Therefore, in the present description (FIG. 2), the contents of the invention are schematically shown for easy understanding.
Further, the second coolant inlet 4 a and the radiator port 4 b are provided with a cylindrical sleeve-like connecting portion S protruding outward from the second housing 41.
These outwardly projecting cylindrical sleeve-shaped connecting portions S have an effect that they can be easily connected when the pipes are connected to form the second coolant flow passage 62.

The water pump 3 is attached to the lower part of the main body block 1a of the internal combustion engine 1 on the radiator 6 side.
The water pump 3 is directly connected to the cooling gallery 1 c of the internal combustion engine 1, and the coolant R returning from the bypass port 2 d of the first thermostat 2, the radiator 6 and the first heat exchanger 51 is supplied to the cooling gallery of the internal combustion engine 1. Pump to 1c.
The water pump 3 circulates the coolant R in the coolant flow passage 61 to keep the internal combustion engine 1 at the optimum temperature.
The water pump 3 is connected to a crankshaft (not shown) of the internal combustion engine 1 via a gear train, and is always driven during the operation of the internal combustion engine 1.

The waste heat recovery device 5 uses a coolant R that has cooled the internal combustion engine 1 as a heat medium, and a first heat exchanger 51 that converts the working medium of the waste heat recovery device 5 into a high-temperature and high-pressure steam state with the coolant R; A first heat exchanger expands the working medium in a high-temperature and high-pressure vapor state to extract power, a condenser 53 that cools and condenses the expanded working medium, and a condensed liquid (working medium). The pump 55 is pumped to 51, and each working medium pipe is connected to circulate the working medium by connecting these devices.
A gas-liquid separator that promotes gas-liquid separation of the working medium condensed by the condenser 53 may be disposed between the condenser 53 and the pump 55.
In this case, steam that is likely to be mixed into the working medium can be reliably separated, and the heat exchange efficiency in the heat exchanger 51 can be improved.

  The waste heat recovery device 5 converts the working medium of the waste heat recovery device 5 into high-temperature and high-pressure steam by the first heat exchanger 51 by the heat of the coolant R from the first thermostat 2. The working medium converted into high temperature and high pressure is introduced into the expander 52 through the first waste heat recovery pipe 5a. The working medium expands in the expander 52 and outputs a rotational driving force. The expanded working medium is introduced into the condenser 53 by the second waste heat recovery pipe 5b. The working medium is cooled by the condenser 53 to condense the vapor-like working medium into a liquid state. The liquid working medium is introduced into the pump 55 through the third waste heat recovery pipe 5c, and the pump 55 operates by pumping the working medium to the first heat exchanger 51 through the fourth waste heat recovery pipe 5d. The medium is again converted to high temperature and high pressure steam.

FIG. 2 shows the operation of each thermostat according to the coolant temperature. (A) is a warm-up state of the internal combustion engine, (B) is a warm-up state, but cooling with a radiator is not required. (C) has shown the case where the cooling by a radiator is required at the time of a state.
In the case of FIG. 2A, when the internal combustion engine 1 is started, the entire internal combustion engine 1 is in an atmospheric temperature state (cold temperature state). In order to optimize the fuel combustion efficiency in the combustion chamber of the internal combustion engine 1, it is necessary to raise the temperature of the internal combustion engine 1 to an optimal temperature (warm-up operation) and maintain it.
Therefore, it is necessary to promote the temperature rise of the coolant R in the second coolant flow passage 62.
In this case, the coolant R of the first thermostat 2 is lower than the first valve opening start temperature (optimum temperature).
Accordingly, the first on-off valve 22 is maintained in a state where the bypass port 2d is opened and the waste heat recovery port 2b is closed. The coolant R does not flow to the first heat exchanger 51 side of the waste heat recovery device 5.
On the other hand, the coolant R is introduced from the second thermostat port 2c to the second thermostat 4 side via the second pipe 6b regardless of the coolant temperature.
As described above, the second valve opening start temperature T2 of the second thermostat 4 is higher than the first valve opening start temperature T1 of the first thermostat 2, so that the radiator port 4b of the second thermostat 4 is closed. Is maintained.
When the internal combustion engine 1 is in a warm-up operation, the coolant R flows from the water pump 3 by the pressure of the coolant R → the cooling gallery 1c → the first coolant inlet 2a of the first thermostat 2 → the first thermostat 2 The bypass port 2d, the bypass passage 1d, and the water pump 3 are circulated in this order.
In this state, the coolant R only circulates in the internal combustion engine 1, so that the heat of the coolant R heated by the combustion heat in the cylinder is prevented from being released to the outside as much as possible. 1 temperature increase (warm-up operation) is promoted.

FIG. 2B shows a case where the warm-up operation of the internal combustion engine 1 is finished, the first thermostat 2 is opened, and the coolant R does not require cooling of the radiator 6.
The coolant temperature rises and exceeds the first valve opening start temperature.
The first on-off valve 22 of the first thermostat 2 closes the bypass port 2d and opens the waste heat recovery port 2b. The coolant R passes through the second heat exchanger 7 from the waste heat recovery port 2b and flows to the first heat exchanger 51 side. (See Figure 1)
At this time, the coolant temperature of the second thermostat 4 does not reach the second valve opening start temperature, so that the radiator port 4b of the second thermostat 4 is kept closed.
Although the coolant R is heated by the exhaust gas in the second heat exchanger 7, the temperature is lowered by the waste heat recovery (heat exchange action) of the first heat exchanger 91, and the second valve opening of the second thermostat 4 is started. The temperature T2 has not been reached.
Therefore, the coolant R in the first coolant flow passage 61 is the coolant R pumped from the water pump 3 → the cooling gallery 1 c → the first coolant inlet 2 a of the first thermostat 2 → the waste of the first thermostat 2. The heat recovery port 2b → the fourth waste heat pipe 6d → the second heat exchanger 7 → the fifth pipe 6e → the first heat exchanger 51 → the sixth pipe 6f → the water pump 3 → the cooling gallery 1c. ing.
Further, the exhaust gas from the internal combustion engine 1 is introduced into the exhaust gas purification device 8 through the first exhaust pipe 8a and purified. The exhaust gas purified by the exhaust gas purification device 8 is introduced into the second heat exchanger 7 through the second exhaust pipe 8b. The exhaust gas introduced into the second heat exchanger 7 heats the coolant R. The coolant R heated by the exhaust gas flows to the first heat exchanger 51 side of the waste heat recovery device 5.

Accordingly, the coolant R is heated by the cooling gallery 1c and the second heat exchanger 7, and the entire amount flows to the waste heat recovery device 5 side, so that the thermal energy recovery efficiency on the waste heat recovery device 5 side is improved. Can do.
Further, in this case, since the coolant R does not flow to the radiator 6 side, the thermal load received by the radiator 6 is reduced, and the durability of the radiator 6 is improved.

FIG. 2C shows a case where the operating load of the internal combustion engine 1 is increased and the heat energy recovery is performed in the waste heat recovery device 5, but the coolant R needs to cool the radiator 6.
In this case, the coolant temperature has reached the second valve opening start temperature at which the second thermostat 4 is opened.
In the first thermostat 2, the first on-off valve 22 closes the bypass port 2d, the waste heat recovery port 2b is opened, and the coolant R flows from the waste heat recovery port 2b to the first heat exchanger 51 side.
On the other hand, since the coolant temperature of the second thermostat 4 has reached the second valve opening start temperature T2, the second opening / closing valve 42 opens the radiator port 4b.
In this case, in addition to the flow of the coolant R in the first coolant flow passage 61 described above, the flow of the coolant R through the second coolant flow passage 62 due to the action of the second thermostat 4 is added.

  In other words, the coolant R in the second coolant flow passage 62 is the coolant R pumped from the water pump 3 → the cooling gallery 1 c → the first coolant inlet 2 a of the first thermostat 2 → the first of the first thermostat 2. 2 thermostat port 2c → second pipe 6b → second thermostat 4 → radiator port 4b of second thermostat 4 → third pipe 6c → radiator 6 → first pipe 6a → junction P → water pump 3 Has been.

When the internal combustion engine 1 is operated in a high load state and the coolant temperature becomes high, and the optimum temperature of the internal combustion engine 1 cannot be maintained only by the amount of decrease in the coolant temperature due to heat exchange in the first heat exchanger 51, The coolant R is caused to flow to the radiator 6 side, the coolant temperature is lowered, and the internal combustion engine 1 is maintained at the optimum temperature.
In this case, since the coolant R is cooled by the first heat exchanger 51 and the radiator 6, the cooling capacity of the radiator 6 can be reduced, and the weight and cost of the radiator 6 can be reduced.
Further, since the coolant R flows through the first coolant flow passage 61 and the second coolant flow passage 62 in parallel, the flow resistance in the coolant passage is reduced, and the flow resistance of the water pump 3 is reduced. Engine load is reduced and fuel-saving operation is achieved.

In the present embodiment, as described above, the second valve opening start temperature T2 of the second thermostat 4 is set higher than the first valve opening start temperature T1 of the first thermostat 2.
The higher the coolant temperature that flows to the waste heat recovery device 5 side, the greater the amount of heat energy recovered in the waste heat recovery device 5.
The second valve opening start temperature T2 of the second thermostat 4 applied to the internal combustion engine 1 was examined.
However, the first thermostat 2 does not change the conventional first valve opening start temperature T1.

In FIG. 3, it is an example which examined the valve opening start temperature and the full opening temperature of the several thermostat 2 currently used in our company.
Type 1 has a conventional first valve opening start temperature T1 of 83 ° C. and a full opening temperature Tm of 98 ° C., and a conventional temperature difference Tm−T1 = 15 from the conventional first valve opening starting temperature T1 to the full opening temperature Tm. It is ℃.
Similarly, Type 2 is 14 ° C. and Type 3 is 14 ° C.
And how much the 2nd valve opening start temperature T2 can be raised was examined.
As shown in FIG. 4, reducing the temperature difference from the first valve opening start temperature T1 to the full opening temperature Tm makes the lift gradient of the embodiment steeper than the lift gradient of the conventional on-off valve.
Therefore, the following considerations are required.
1. Deterioration in durability due to an increase in stress generated in each member supporting the on-off valve due to an increase in the valve opening speed from the new valve opening start temperature T2 (second valve opening start temperature T2) to the full opening temperature Tm.
2. The influence on the cooling performance of the internal combustion engine 1 due to the portion in the cooling gallery 1c of the internal combustion engine 1 where the temperature of the coolant R is likely to rise and the portion where the temperature does not rise so much.
3. This is the effect on the sudden rise in the coolant temperature when the vehicle performs a high load operation immediately after the warm-up operation.

In the present embodiment, confirmation was made for the purpose of uniformly increasing the valve opening start temperature of each thermostat by 5 ° C. That is, in Type 1, the improved temperature difference Tm-T2 was 10 ° C., similarly, Type 2 was 9 ° C., and Type 3 was 9 ° C.
Tests were conducted using thermostats with the new valve opening temperature Tn (second thermostat 4) of Type 1 to 3 increased by 3, 5, and 7 ° C (5 ± 2 ° C), respectively, and it was confirmed that there was no problem with the above examination contents. did.

When the increase width of the new valve opening start temperature Tn was 3 ° C., the amount of recovered heat energy in the waste heat recovery apparatus 5 tended to be slightly reduced, but the target effect was obtained.
On the other hand, a part of the sample with the newly opened valve opening temperature T2 raised to 7 ° C. is temporarily cooled at a high load in a portion where the temperature rise of the coolant R in the cooling gallery 1c of the internal combustion engine 1 is likely to occur. Although R sometimes became higher than a predetermined value (in-house evaluation standard value), it did not affect the performance of the internal combustion engine.

As for the increase in stress generated in each member supporting the on-off valve, the increase in stress was confirmed, but it was not a value causing a problem.
From the above results, it was determined that the new valve opening start temperature T2 of the second thermostat 4 was 5 ± 1 ° C. higher than the first valve opening start temperature T1 of the first thermostat 3 as the optimum range. In this way, by increasing the second valve opening start temperature T2 of the second thermostat 4, the coolant R whose temperature has been increased is allowed to flow to the waste heat recovery device 5 side, so that the waste heat is recovered. It was possible to improve the thermal energy recovery efficiency in the recovery device 5.

Control for switching the flow path of the above-described coolant R by the first and second thermostats 2 and 3 will be described with reference to FIG.
Start in step S1. In step S2, the internal combustion engine 1 is started.
In step S <b> 2, the coolant R is divided into a first coolant circulation circuit 61 and a second coolant circulation circuit 62.
In step S3, the first coolant circulation circuit 61 side looks at the open / close state of the first thermostat 2 according to the coolant temperature.
When the coolant temperature is low, that is, when the coolant temperature is lower than the first valve opening start temperature T1, the first on-off valve 22 of the first thermostat 2 closes the waste heat recovery port 2b and opens the bypass port 2d. Maintain state.
In Step S3, No is selected, and the coolant R is introduced into the water pump 3 through the bypass passage 1d of the internal combustion engine 1 in Step S4.
In step S5, it flows in the cooling gallery 1c of the internal combustion engine 1, and returns to step S3.
On the other hand, in step S7, since the coolant temperature is equal to or lower than the second valve opening start temperature T2 (higher than the first valve opening start temperature T1), the second opening / closing valve 42 closes the radiator opening 4b. Maintained.
Accordingly, No is selected and the process returns to step S2.

If the coolant R exceeds the first valve opening start temperature in step S3, the process proceeds to step S6.
In step S6, when the coolant temperature rises and exceeds the first valve opening start temperature, the on-off valve 22 of the first thermostat 2 opens the waste heat recovery port 2b and closes the bypass port 2d.
The coolant R flows to the waste heat recovery device 5 side.
In step S6, the waste heat recovery apparatus 5 performs waste heat recovery. The coolant R that has recovered the waste heat proceeds to step S4 and is circulated in the first coolant flow passage 61 by the water pump 3.
At this time, the coolant R flows to the waste heat recovery device 5 side in all amounts, and the waste heat recovery efficiency is high.

In step S7, the radiator port 4b of the second thermostat 4 remains closed until the coolant temperature becomes equal to or higher than the second valve opening start temperature.
When the load of the internal combustion engine 1 rises and the coolant temperature becomes equal to or higher than the second valve opening start temperature, the second on-off valve 42 opens the radiator port 4b, and the coolant R flows to the radiator 6 side.
In step S8, the coolant R is cooled by the radiator 6.
The cooled coolant R passes through the junction P and returns to step S4, and circulates in the second coolant flow passage 62 by the water pump 3.
As a result, the coolant R flows through the first coolant flow passage 61 and the second coolant flow passage 62 in parallel, so that the flow resistance in the coolant passage is reduced and the flow resistance of the water pump 3 is reduced. Thus, the engine load is reduced and fuel-saving operation is achieved.

  5 is a schematic configuration diagram of the vehicle waste heat recovery system 15 in which the second embodiment of the present invention is used. Since the second embodiment is the same as the first embodiment except that the first thermostat 2 and the second thermostat 4 of the first embodiment are integrally coupled, the same parts are denoted by the same reference numerals, and description thereof is omitted. .

In FIG. 5, 9 is a third thermostat in which the first thermostat 2 and the second thermostat 4 of the first embodiment are integrally coupled.
The third thermostat 9 is attached so as to constitute a part of the cooling gallery 1c in a state where a part of the third thermostat 9 is exposed to the upper outer periphery of the head part 1b on the radiator 6 side.
As shown in FIG. 6, the housing 91 of the third thermostat 9 includes a third coolant inlet 9a directly connected to the cooling gallery 1c of the internal combustion engine 1, a bypass port 9b communicating with the bypass passage 1d, and a waste heat recovery device. A waste heat recovery port 9c connected to the 5 side, a radiator port 9d connected to the radiator 6 side downstream of the waste heat recovery port 9c and connected to the radiator 6 side, and the coolant temperature is the first valve opening start temperature When the temperature is less than, the waste heat recovery port 9c is closed and the bypass port 9b is opened. When the coolant temperature is equal to or higher than the first valve opening start temperature, the waste heat recovery port 9c is opened and the bypass port 9b is closed. The on-off valve 92 and a fourth on-off valve 93 that opens the radiator port 9d when the coolant temperature is equal to or higher than the second valve opening start temperature are provided.
The coolant R can always flow from the third on-off valve 92 to the fourth on-off valve 93 side.

The third coolant flow passage 65 (corresponding to the first coolant flow passage 61 of the first embodiment) includes the cooling gallery 1c of the internal combustion engine 1, the third thermostat 9, the third thermostat 9, and the second heat. 4th piping 6d which connects the exchanger 7, the 2nd heat exchanger 7, the 5th piping 6e which connects the 2nd heat exchanger 7 and the 1st heat exchanger 51, and the 1st heat exchanger 51 And the 6th piping 6f which connects the 1st heat exchanger 51 and the water pump 3 is comprised.
The fourth coolant flow passage 66 (corresponding to the second coolant flow passage 62 of the first embodiment) connects the cooling gallery 1 c of the internal combustion engine 1, the third thermostat 9, the third thermostat 9, and the radiator 6. The second pipe 6b, the radiator 6, and the first pipe 6a connecting the radiator 6 and the water pump 3 are configured.

FIG. 6 shows the operation of each thermostat according to the coolant temperature. (A) is the warm-up state of the internal combustion engine, (B) is the warm-up state, but cooling with the radiator is required. (C) has shown the case where the cooling by a radiator is required in the state which does not carry out.
In the case of FIG. 6 (A), when the internal combustion engine 1 is started, the entire internal combustion engine 1 is in an atmospheric temperature state (cold temperature state).
The third opening / closing valve 92 opens the bypass port 9b and maintains the waste heat recovery port 9c in a closed state.
On the other hand, since the coolant temperature is lower than the second valve opening start temperature T2, the fourth on-off valve 93 is maintained in a state where the radiator port 9d is closed.
Therefore, when the internal combustion engine 1 is in the warm-up operation, the coolant R flows from the water pump 3 to the coolant R → the cooling gallery 1c → the third coolant inlet 9a of the third thermostat 9 → the third The thermostat 9 circulates in the order of the bypass port 9 b → the bypass passage 1 d → the water pump 3.
In this state, the coolant R only circulates in the internal combustion engine 1, so that the heat of the coolant R heated by the combustion heat in the cylinder is prevented from being released to the outside as much as possible. 1 temperature increase (warm-up operation) is promoted.

FIG. 6B shows a case where the warm-up operation of the internal combustion engine 1 is completed, the third on-off valve 92 is opened, and the coolant R does not require cooling of the radiator 6.
The coolant temperature rises and exceeds the first valve opening start temperature, but is lower than the second valve opening start temperature.
The third on-off valve 92 closes the bypass port 9b and opens the waste heat recovery port 9c.
On the other hand, since the coolant temperature is lower than the second valve opening start temperature T2, the fourth on-off valve 93 is maintained in a state where the radiator port 9d is closed.
Accordingly, the coolant R in the third coolant flow path 65 is the coolant R pumped from the water pump 3 → the cooling gallery 1 c → the third coolant inlet 9 a of the third thermostat 9 → the waste of the third thermostat 9. The heat recovery port 9c → the fourth waste heat pipe 6d → the second heat exchanger 7 → the fifth pipe 6e → the first heat exchanger 51 → the sixth pipe 6f → the water pump 3 → the cooling gallery 1c. ing.

Accordingly, the coolant R is heated by the cooling gallery 1c and the second heat exchanger 7, and the entire amount flows to the waste heat recovery device side, so that the thermal energy recovery efficiency on the waste heat recovery device 5 side can be improved. it can.
Further, in this case, since the coolant R does not flow to the radiator 6 side, the thermal load received by the radiator 6 is reduced, and the durability of the radiator 6 is improved.

In FIG. 6C, the operating load of the internal combustion engine 1 is in a high load state, and thermal energy recovery is performed in the waste heat recovery device 5, but the coolant temperature has reached the second valve opening start temperature.
The third on-off valve 92 closes the bypass port 2b and maintains the open state of the waste heat recovery port 2c.
On the other hand, since the coolant temperature of the fourth on-off valve 93 has reached the second valve opening start temperature, the fourth on-off valve 93 opens the radiator port 4b.
Accordingly, in addition to the coolant circulation in the third coolant flow passage 65, the coolant R in the fourth coolant flow passage 66 is the coolant R pumped from the water pump 3 → the cooling gallery 1c → the third thermostat 9 The third coolant flow inlet 9a → the radiator port 9d of the third thermostat 9 → the second pipe 6b → the radiator 6 → the first pipe 6a → the junction P → the water pump 3 is configured to flow in this order.

When the internal combustion engine 1 is operated in a high load state and the coolant temperature becomes high, and the optimal temperature of the internal combustion engine 1 cannot be maintained only by the amount of decrease in the coolant temperature due to heat exchange in the first heat exchanger 91, The coolant R is caused to flow to the radiator 6 side, the coolant temperature is lowered, and the internal combustion engine 1 is maintained at the optimum temperature.
In the present embodiment, the second valve opening start temperature T2 of the fourth on-off valve 93 is 5 ± 1 ° C. higher than the first valve opening start temperature T1 of the third on-off valve 92.
This is because the temperature of the coolant that is circulated to the waste heat recovery device 5 side is increased to increase the amount of heat energy recovered in the waste heat recovery device 5.

By doing so, the coolant R flows through the third coolant flow passage 65 and the fourth coolant flow passage 66 in parallel, so the flow resistance in the coolant passage is reduced, and the water pump 3 The driving load is reduced, the engine load is reduced, and the fuel-saving operation is performed. Furthermore, the flow resistance of the coolant R is reduced, so that the flow of the coolant R in the cooling gallery 1c of the internal combustion engine 1 is improved. 1 cooling performance is improved.

  It can be used to save fuel in vehicles equipped with waste heat recovery devices.

DESCRIPTION OF SYMBOLS 1 Internal combustion engine 1b Head part 1c Cooling gallery 1d Bypass passage 2 1st thermostat 2a 1st coolant inlet 2b Bypass 2c Waste heat recovery port 3 Water pump 4 2nd thermostat 4a 2nd coolant inlet 4b Radiator port 5 Waste Heat recovery device 6 Radiator 7 Second heat exchanger (heat exchanger)
8 exhaust gas purifier 9 third thermostat 10, 15 vehicle waste heat recovery system 21 first housing 22 first on-off valve 41 second housing 42 second on-off valve 51 first heat exchanger 52 expander 53 condenser 55 pump 61 first 1 Coolant flow passage 62 Second coolant flow passage

Claims (5)

An internal combustion engine;
A radiator for cooling the coolant of the internal combustion engine;
Using the coolant as a heat source, a waste heat recovery device that recovers thermal energy;
A first coolant flow passage for circulating the coolant between the internal combustion engine and the waste heat recovery device;
A second coolant flow passage for circulating the coolant between the internal combustion engine and the radiator;
A first thermostat that is interposed in the first coolant flow path and adjusts the flow of the coolant to the waste heat recovery device;
A second thermostat interposed in the second coolant flow passage for adjusting the flow of the coolant to the radiator;
A water pump that is disposed downstream of the joining portion where the first coolant flow passage and the second coolant flow passage merge on the downstream side of the waste heat recovery device and the radiator, and circulates the coolant;
A bypass passage for bypassing the coolant from the waste heat recovery device and the radiator and flowing from the first thermostat to the water pump,
The first thermostat includes a bypass port for flowing the coolant through the bypass passage when the coolant temperature is lower than the first valve opening start temperature, and the coolant temperature is equal to or higher than the first valve opening start temperature. A waste heat recovery port that flows to the waste heat recovery device side, and a second thermostat port that always flows to the second thermostat side,
The second thermostat has a radiator port for flowing the coolant to the radiator when the coolant temperature from the first thermostat is equal to or higher than a second valve opening start temperature. Waste heat recovery system.   2. The vehicle waste heat recovery system according to claim 1, wherein the second valve opening start temperature of the second thermostat is 5 ± 1 ° C. higher than the first valve opening start temperature of the first thermostat.   A heat exchanger that is interposed between the first thermostat of the first coolant flow passage and the waste heat recovery device and that heats the coolant with the exhaust gas of the internal combustion engine is disposed. The vehicle waste heat recovery system according to claim 1 or 2.   4. The vehicle waste heat recovery according to claim 1, wherein the first thermostat is attached to an outer peripheral portion of the internal combustion engine, and an outlet to the waste heat recovery device protrudes. 5. system.   5. The first thermostat port of the first thermostat and the coolant inlet port through which the coolant R flows from the second thermostat port of the second thermostat are integrally molded. The vehicle waste heat recovery system according to any one of the above.

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