JP2013046504A - Power generating system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power generating system which efficiently generates power by maintaining a large temperature difference between a heat of a heating equipment and a cooling medium.SOLUTION: The system is configured such that a heat transfer area at the time of heat exchange via thermoelectric conversion units 51 through 56 located between a cooling liquid W1 of a high temperature side flowing inside high temperature heat sinks (41 though 44) and a cooling liquid W2 of low temperature sides flowing though high temperature heat sinks (45 though 47) is capable of being changed by opening and closing of valves 41a,41b,42a,42b,43a,43b,44a,44b,45a,45b,46a,46b,47a,47b. The opening and closing of each valve is controlled to change the heat transfer area by a power generating process carried out by a control unit 61 which increases a temperature difference at the time of heat exchange without a temperature of a cooling liquid T detected by a temperature sensor 61 exceeding the upper temperature of safety T.

Description

  The present invention relates to a power generation system that generates power using a temperature difference between heat generated in a heat generating device mounted on a vehicle and a cooling medium for cooling the heat.

  Conventionally, as a technology related to a power generation system using a temperature difference between heat generated in a heat source such as a heat generating device mounted on a vehicle and a cooling medium for cooling the heat, Patent Document 1 below discloses The disclosed water-cooled power generation unit is known. This power generation unit is configured such that a thermoelectric module is disposed on the rear surface side of the heat receiving panel, and a cooling unit is disposed on the rear surface side of the thermoelectric module. The thermoelectric module utilizes a so-called Seebeck effect that electromotive force is generated when two different metals or semiconductors are joined together and a temperature difference is generated between the two ends. The cooling unit has a casing made of a metal with good heat conductivity and a plurality of cooling fins provided in the cooling chamber inside the casing. From the water injection hole drilled in the bottom of the casing When the cooling water is injected, the front wall portion and the cooling fin are cooled by this cooling water. Moreover, as a heat source for heating the heat receiving panel, a high-temperature heat source such as a geothermal heat of a hot spring resort, a high-temperature source, or exhaust heat at the time of incineration of garbage is assumed. Then, heat from the high-temperature heat source is transferred to the heat receiving board, and the cooling unit is cooled, so that a temperature difference between the temperature of the high-temperature heat source and the temperature of the cooling unit is added to the thermoelectric module, and power is generated by the thermoelectric module. The

JP 2010-057335 A

By the way, thermoelectric conversion means such as a thermoelectric module is configured to generate power according to a temperature difference between a high temperature side and a low temperature side. However, when the configuration on the high temperature side and the configuration on the low temperature side as disclosed in Patent Document 1 are applied to a power generation system that generates power using the temperature difference between the heat generated by the heat generating device and the cooling medium, the following is performed. Problems arise.
That is, in the configuration as described above, the temperature difference applied to the thermoelectric conversion means depends on the amount of heat from the heat generating device and the temperature and flow rate of the cooling medium. Since the temperature difference applied to the conversion means becomes small, efficient power generation becomes difficult.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to generate power efficiently by maintaining a high temperature difference between the heat of the heat generating device and the cooling medium. Is to provide.

In order to achieve the above object, the power generation system according to claim 1 includes a high temperature side cooling medium (W1) to which heat generated in a heat generating device (11) mounted on a vehicle is transferred, and the high temperature side cooling. Thermoelectric conversion means (51-56) using a temperature difference at the time of heat exchange with the low-temperature side cooling medium (W2) radiated by the radiator (21) after this heat is transferred to cool the medium A power generation system (40) for generating power, wherein the change means (41) is capable of changing a heat transfer area during heat exchange via the thermoelectric conversion means interposed between the high temperature side cooling medium and the low temperature side cooling medium. 47, 41a, 41b, 42a, 42b, 43a, 43b, 44a, 44b, 45a, 45b, 46a, 46b, 47a, 47b) and temperature detecting means (62) for detecting the heat generation temperature (T) of the heat generating device. ) And the temperature detection hand Wherein such heating temperature is increased the temperature difference during the heat exchange without exceeding the acceptable upper limit temperature (T _D) of the heating device, the heat transfer area by controlling the changing means is detected by And a control means (61) for changing.

The invention according to claim 2 is the power generation system according to claim 1, wherein the high-temperature side cooling medium and the low-temperature side cooling medium are not mixed with each other and heat is exchanged via the thermoelectric conversion means, and the high temperature side Switching that can be switched to either a high cooling state in which the cooling of the heat generating device is enhanced rather than the power generation state by mixing the side cooling medium and the low temperature side cooling medium without passing through the thermoelectric conversion means Means (31, 32, 14a, 14b, 24a, 24b, 31a, 31b, 32a, 32b), and the control means sets the heating temperature detected by the temperature detecting means to be lower than the upper limit temperature. When the predetermined temperature (T _H2 ) is reached, the switching means is controlled to switch to the high cooling state.
In addition, the code | symbol in each said bracket | parenthesis shows the corresponding relationship with the specific means as described in each embodiment mentioned later.

  In the invention of claim 1, the changing means is configured such that the heat transfer area during heat exchange via the thermoelectric conversion means interposed between the high temperature side cooling medium and the low temperature side cooling medium can be changed. Then, the control means controls the changing means to change the heat transfer area so that the heat generation temperature of the heat generating device detected by the temperature detecting means does not exceed the upper limit temperature and the temperature difference during heat exchange is increased. The

As a result, even when the amount of heat transferred from the heat generating device to the high-temperature side cooling medium is small, the heat transfer area during heat exchange via the thermoelectric conversion means is controlled so that the heat generation temperature does not exceed the upper limit temperature by controlling the changing means. By reducing the temperature, the cooling of the high-temperature side cooling medium is controlled to the minimum necessary, and the temperature difference during heat exchange applied to the thermoelectric conversion means can be increased. That is, even when the amount of heat from the heat generating device or the temperature and flow rate of the cooling medium changes, the heat transfer area at the time of heat exchange via the thermoelectric conversion means is changed, so that the heat exchange via the thermoelectric conversion means It is possible to maintain a large temperature difference.
Therefore, it is possible to efficiently generate power by maintaining a high temperature difference between the heat of the heat generating device and the cooling medium.

  According to the second aspect of the present invention, the switching means causes the power generation state in which heat is exchanged via the thermoelectric conversion means without mixing both of the high temperature side cooling medium and the low temperature side cooling medium, and both the cooling mediums are converted into the thermoelectric conversion means. It is configured to be able to be switched to either a high cooling state in which cooling of the heat generating device is enhanced by mixing without going through. When the heat generation temperature detected by the temperature detecting means reaches a predetermined temperature set lower than the upper limit temperature, the control means controls the switching means to switch to the high cooling state.

  As a result, when the heat generation temperature reaches the predetermined temperature, heat exchange through the thermoelectric conversion means is not performed, so that there is no heat transfer loss through the thermoelectric conversion means, and the heat exchange efficiency between both cooling media is eliminated. Will improve. As a result, since the cooling performance of the heat generating device using the cooling medium is improved, the heat generation temperature of the heat generating device can be lowered to a temperature lower than the upper limit temperature.

It is explanatory drawing which shows notionally the electric power generation system which concerns on this invention. FIG. 2 is a block diagram schematically showing an electrical configuration of the power generation system of FIG. 1. FIG. 3 (A) is an explanatory view showing the relationship between the flow of the high-temperature side coolant and the low-temperature side coolant and the thermoelectric conversion unit according to the present invention, and FIG. 3 (B) is a diagram of the coolant according to the comparative example. It is explanatory drawing which shows the relationship between a flow and a thermoelectric conversion unit. It is explanatory drawing explaining the heat-transfer path | route from which the heat | fever of an inverter is thermally radiated. FIG. 5A is a graph showing the relationship between the amount of generated heat when the thermal resistance is variable and the inverter temperature, and FIG. 5B is the graph showing the amount of generated heat and the inverter temperature when the thermal resistance is constant. It is a graph which shows the relationship. It is explanatory drawing for demonstrating the temperature difference added to a thermoelectric conversion unit. It is explanatory drawing explaining each step which changed the heat transfer area. It is a flowchart which illustrates the flow of the electric power generation process performed by a control unit. It is explanatory drawing which shows the relationship between the coolant temperature measured with a temperature sensor, and the temperature state of an inverter. It is a timing chart which shows the time change of the coolant temperature measured with a temperature sensor.

Hereinafter, an embodiment of a power generation system according to the present invention will be described with reference to the drawings. FIG. 1 is an explanatory diagram conceptually showing an example of the power generation system 40 of the present invention.
As shown in FIG. 1, the power generation system 40 according to the present invention uses a temperature difference between heat generated by a heat generating device mounted on a vehicle and a cooling medium (coolant) for cooling the heat. It is a system that generates electricity.

First, a cooling configuration for cooling the heat generated in the heat generating device will be described.
In the present embodiment, for example, an inverter 11 is employed as a heat generating device that needs to be cooled, and a water jacket 12 provided on the outer surface of the inverter 11 for cooling the inverter 11 includes a high-temperature water pump 13. Thus, the high temperature side coolant W1 is configured to flow in as a high temperature side cooling medium circulating in the high temperature side piping 14. The high temperature side pipe 14 is provided with a condensation tank 15 into which the high temperature side cooling liquid W1 cooled by heat exchange via a thermoelectric conversion unit described later flows.

  Further, in the present embodiment, a radiator 21 and a cooling fan 22 are employed as radiators for cooling the heat generating equipment, and the radiator 21 is cooled at low temperature side through a low temperature side pipe 24 by a low temperature side water pump 23. The low-temperature side coolant W2 is configured to flow as a medium. Further, the low temperature side pipe 24 is provided with a condensation tank 25 into which the low temperature side coolant W2 radiated by the radiator 21 flows.

  The high temperature side pipe 14 and the low temperature side pipe 24 are provided with a high temperature side bypass 31 and a low temperature side bypass 32 that can connect both pipes. The high temperature side bypass 31 is connected to the high temperature side pipe 14 so that the high temperature side coolant W1 flowing out from the high temperature side water pump 13 through the valve 31a can be drawn, and the high temperature side bypass 31 from the high temperature side pipe 14 through the valve 31b. The side coolant W1 is connected to the low temperature side pipe 24 so as to be able to flow into the radiator 21. The low temperature side bypass 32 is connected to the low temperature side pipe 24 so that the low temperature side coolant W2 flowing out from the radiator 21 through the valve 32a can be drawn, and the low temperature side coolant from the low temperature side pipe 24 through the valve 32b. W2 is connected to the high temperature side pipe 14 so as to be able to flow into the water jacket 12.

  Further, the high temperature side pipe 14 is provided with a valve 14a downstream from a portion where the high temperature side bypass 31 is connected, and a valve 14b is provided upstream from a portion where the low temperature side bypass 32 is connected. Further, the low temperature side pipe 24 is provided with a valve 24a upstream from a portion where the high temperature side bypass 31 is connected, and a valve 24b is provided downstream from the portion where the low temperature side bypass 32 is connected.

  Thereby, the valves 14a and 14b of the high temperature side pipe 14 and the valves 24a and 24b of the low temperature side pipe 24 are opened, and the valves 31a and 31b of the high temperature side bypass 31 and the valves 32a and 32b of the low temperature side bypass 32 are opened. Are switched so as to be in a closed state, so that the high temperature side coolant W1 in the high temperature side pipe 14 and the low temperature side coolant W2 in the low temperature side pipe 24 are independently circulated without being mixed. It becomes a reflux state. In this independent circulation state, heat exchange is performed between the high-temperature side cooling liquid W1 and the low-temperature side cooling liquid W2 via a thermoelectric conversion unit described later, whereby the high-temperature side cooling liquid W1 is cooled and cooled. The inverter 11 is cooled by the water jacket 12 through which the high temperature side coolant W1 flows. The high temperature side bypass 31 and the low temperature side bypass 32 and the valves 14a, 14b, 24a, 24b, 31a, 31b, 32a, 32b may correspond to an example of “switching means” recited in the claims.

  Further, the valves 14a and 14b of the high temperature side pipe 14 and the valves 24a and 24b of the low temperature side pipe 24 are closed, and the valves 31a and 31b of the high temperature side bypass 31 and the valves 32a and 32b of the low temperature side bypass 32 are Is switched to be in the valve open state, so that the high temperature side coolant W1 in the high temperature side pipe 14 and the low temperature side coolant W2 in the low temperature side pipe 24 can be mixed. In this mixed flow state, the high temperature side cooling liquid W1 and the low temperature side cooling liquid W2 are mixed, and the mixed liquid is radiated by the radiator 21 and then flows to the water jacket 12, whereby the inverter 11 is cooled. In particular, in a state where the high-temperature side cooling liquid W1 and the low-temperature side cooling liquid W2 are mixed, heat exchange via the thermoelectric conversion unit is eliminated, and the lower temperature cooling liquid flows to the water jacket 12, so that the thermoelectric conversion unit is used. Therefore, the cooling performance of the inverter 11 can be improved as compared with the independent reflux state in which heat is exchanged. Since this mixed flow state is a state in which the cooling performance is improved as compared with the independent reflux state, it is also referred to as a high cooling state.

Next, the configuration of the power generation system 40 will be described with reference to FIG.
As shown in FIG. 1, the power generation system 40 is a system that generates power using a temperature difference between the high temperature side coolant W <b> 1 flowing in the high temperature side piping 14 and the low temperature side coolant W <b> 2 flowing in the low temperature side piping 24. The four high temperature side heat sinks 41 to 44 configured to allow the high temperature side cooling liquid W1 to flow in, and the three low temperature side heat sinks 45 to 47 configured to allow the low temperature side cooling liquid W2 to flow.

  The high temperature side heat sink 41 is connected to the high temperature side pipe 14 via the inlet side valve 41a and the outlet side valve 41b, and both valves 41a and 41b are opened, so that the high temperature side heat sink 41 is heated. The side coolant W1 is allowed to flow. Further, the high temperature side heat sink 42 is connected to the high temperature side pipe 14 via the inlet side valve 42a and the outlet side valve 42b, and both the valves 42a and 42b are opened, thereby allowing the inside of the high temperature side pipe 14 to pass through. The flowing high-temperature side coolant W1 can enter the state. Further, the high temperature side heat sink 43 is connected to the high temperature side pipe 14 via the inlet side valve 43a and the outlet side valve 43b, and both the valves 43a and 43b are opened, thereby allowing the inside of the high temperature side pipe 14 to pass through. The flowing high-temperature side coolant W1 can enter the state. Further, the high temperature side heat sink 44 is connected to the high temperature side pipe 14 via the inlet side valve 44a and the outlet side valve 44b, and both the valves 44a and 44b are opened, thereby allowing the inside of the high temperature side pipe 14 to pass through. The flowing high-temperature side coolant W1 can enter the state.

  The low temperature side heat sink 45 is connected to the low temperature side pipe 24 via the inlet side valve 45a and the outlet side valve 45b, and the low temperature flowing through the low temperature side pipe 24 when both the valves 45a and 45b are opened. The side coolant W2 is allowed to flow. Further, the low temperature side heat sink 46 is connected to the low temperature side pipe 24 via the inlet side valve 46a and the outlet side valve 46b, and both valves 46a and 46b are opened, thereby allowing the inside of the low temperature side pipe 24 to pass through. The flowing low-temperature side cooling liquid W2 is ready to flow. Further, the low temperature side heat sink 47 is connected to the low temperature side pipe 24 via the inlet side valve 47a and the outlet side valve 47b, and both the valves 47a and 47b are opened, thereby allowing the inside of the low temperature side pipe 24 to pass through. The flowing low-temperature side cooling liquid W2 is ready to flow.

  The power generation system 40 includes six thermoelectric conversion units (51 to 56) configured as thermoelectric conversion means in which a plurality of thermoelectric conversion elements that generate electric power according to the applied temperature difference are arranged. The electric power generated by the units 51 to 56 is configured to be stored in the battery B.

  In particular, the thermoelectric conversion unit 51 is disposed so as to be in surface contact with both the high-temperature heat sink 41 and the low-temperature heat sink 45 so that heat exchange is possible. Moreover, the thermoelectric conversion unit 52 is arrange | positioned so that the surface contact may be carried out to both the high temperature side heat sink 42 and the low temperature side heat sink 45 so that heat exchange is possible. Further, the thermoelectric conversion unit 53 is disposed so as to be in surface contact with both the high temperature side heat sink 42 and the low temperature side heat sink 46 so that heat exchange is possible. Moreover, the thermoelectric conversion unit 54 is arrange | positioned so that the surface contact may be carried out to both the high temperature side heat sink 43 and the low temperature side heat sink 46 so that heat exchange is possible. Further, the thermoelectric conversion unit 55 is disposed so as to be in surface contact with both the high temperature side heat sink 43 and the low temperature side heat sink 47 so that heat exchange is possible. Further, the thermoelectric conversion unit 56 is disposed so as to be in surface contact with both the high temperature side heat sink 44 and the low temperature side heat sink 47 so that heat exchange is possible.

Next, the electrical configuration of the power generation system 40 will be described with reference to FIG. FIG. 2 is a block diagram schematically showing an electrical configuration of the power generation system 40 of FIG.
As shown in FIG. 2, in the power generation system 40, the temperature of the coolant flowing out from the water jacket 12 (hereinafter referred to as the coolant temperature T) corresponds to the heat generation temperature of the inverter 11. A temperature sensor 62 that measures the temperature, a temperature sensor 63 that measures the temperature of the coolant flowing out of the radiator 21, a flow sensor 64 that measures the flow rate of the coolant flowing in the high temperature side pipe 14, and the low temperature side pipe 24 And a flow rate sensor 65 for measuring the flow rate of the coolant flowing through the. The control unit 61 is electrically connected to the sensors 62 to 65, and is configured to receive measurement signals from the sensors 62 to 65.

  The control unit 61 also includes a motor 13a for driving the high temperature side water pump 13, a motor 23a for driving the low temperature side water pump 23, a motor 22a for driving the cooling fan 22, Drive control of each valve 14a, 14b, 24a, 24b, 31a, 31b, 32a, 32b, 41a, 41b, 42a, 42b, 43a, 43b, 44a, 44b, 45a, 45b, 46a, 46b, 47a, 47b It is configured to be possible.

  Next, the power generation configuration which is a characteristic part of the present embodiment will be described with reference to FIGS. FIG. 3A is an explanatory diagram showing the relationship between the flow of the high-temperature side coolant W1 and the low-temperature side coolant W2 and the thermoelectric conversion unit according to the present invention, and FIG. It is explanatory drawing which shows the relationship between the flow of the cooling fluid Wo which concerns on an example, and a thermoelectric conversion unit. FIG. 4 is an explanatory diagram for explaining a heat transfer path through which heat of the inverter 11 is radiated. FIG. 5A is a graph showing the relationship between the amount of generated heat and the temperature of the inverter 11 when the thermal resistance is variable, and FIG. 5B is a graph showing the amount of generated heat and the inverter 11 when the thermal resistance is constant. It is a graph which shows the relationship with temperature. FIG. 6 is an explanatory diagram for explaining a temperature difference applied to the thermoelectric conversion units (51 to 56).

The amount of power generated by each thermoelectric conversion element constituting the thermoelectric conversion units 51 to 56 is determined by the amount of heat passing through the thermoelectric conversion element and the thermoelectric conversion efficiency, and the amount of heat passing through the thermoelectric conversion element depends on the amount of heat generated by the inverter 11. To do. The thermoelectric conversion efficiency varies depending on the ratio between the internal resistance of the thermoelectric conversion element and the external load resistance, but the maximum efficiency ηmax obtained at the optimum ratio is expressed by the following equation (1) and applied to the thermoelectric conversion element. It depends on the temperature difference and the performance of the thermoelectric conversion element.
_{ηmax = (T H -T L)} / T H
× ((1 + ZT) ^1/2 −1) / ((1 + ZT) ^1/2 + (T _L / T _H )) (1)
Here, _TH is the temperature of the high temperature surface of the thermoelectric conversion element, and _TL is the temperature of the low temperature surface of the thermoelectric conversion element.
For this reason, it turns out that the electric power generation amount in a thermoelectric conversion unit can be enlarged by maintaining a temperature difference as large as possible and improving thermoelectric conversion efficiency.

  Therefore, in order to increase the temperature difference applied to the thermoelectric conversion unit, as illustrated in FIG. 3A, the thermoelectric conversion unit is interposed between the high temperature side cooling liquid W1 and the low temperature side cooling liquid W2 that are not mixed. Arrange so that a temperature difference is applied during heat exchange. Thereby, as illustrated in FIG. 3B, the temperature difference applied to the thermoelectric conversion units 51 to 56 can be increased as compared with the comparative example using the temperature difference of the coolant Wo flowing through one circulation path. it can.

  In the present embodiment, as shown in FIG. 4, the heat generated by the inverter 11 is generated by the water jacket 12, the high-temperature side coolant W <b> 1, the high-temperature side heat sink (41 to 44), and the thermoelectric conversion units (51 to 56). , The low temperature surface of the thermoelectric conversion units (51 to 56), the low temperature side heat sink (45 to 47), the low temperature side coolant W2, and the radiator 21 are radiated to the atmosphere.

  The temperature of the inverter 11 is the sum of the total temperature difference in the heat dissipation process and the atmospheric temperature, and this total temperature difference is determined by the amount of generated heat and the total heat resistance. Here, the total thermal resistance is composed of the high-temperature side path thermal resistance in FIG. 4, the thermal resistance in the thermoelectric conversion unit, and the low-temperature side path thermal resistance, and the thermal resistance in the thermoelectric conversion unit occupies the total thermal resistance. By increasing the ratio, the temperature difference applied to the thermoelectric conversion unit can be increased.

As shown in the following formula (2), the total temperature difference is determined by the amount of generated heat and the total heat resistance. To increase the total temperature difference, the total heat resistance is changed according to the amount of generated heat. It is effective.
Total temperature difference [° C.] = Amount of heat generated [W] × Total thermal resistance [° C./W] (2)

  Therefore, as illustrated in FIG. 5 (A), for example, the atmospheric temperature is 30 ° C., the safe upper limit temperature of the inverter 11 is 90 ° C., and an appropriate total temperature difference is maintained in order to maintain the temperature of the inverter 11 at 80 ° C. When ΔT is 50 ° C., the total heat resistance is changed to 0.1 [° C./W] when the generated heat quantity is 500 [W]. When the generated heat amount is 1000 [W], the total heat resistance is changed to 0.05 [° C./W], and when the generated heat amount is 1500 [W], the total heat resistance is set to 0.033 [° C./W]. By changing to [W], the total temperature difference ΔT is maintained at an appropriate 50 ° C.

  On the other hand, as illustrated in FIG. 5B, for example, when the total thermal resistance is constant at 0.05 [° C./W], if the generated heat amount is 500 [W], the temperature of the inverter 11 is 55 ° C. Although it is safe, the total temperature difference ΔT decreases at 25 ° C. Further, when the generated heat amount is 1500 [W], the temperature of the inverter 11 becomes 105 ° C., which exceeds the safe upper limit temperature (90 ° C.). Thus, it can be seen that if the total thermal resistance is constant, the total temperature difference ΔT cannot be maintained at an appropriate temperature.

Here, from the viewpoint of distribution of thermal resistance, the temperature difference of a certain thermal resistance element is determined by the thermal resistance of the element and the total temperature difference in the total thermal resistance, as shown in the following equation (3). .
Temperature difference of a thermal resistance element [℃]
= Total temperature difference [° C.] × (element thermal resistance [° C./W]/total thermal resistance [° C./W]) (3)

  From this viewpoint, the temperature difference applied to the thermoelectric conversion unit will be described with reference to FIG. In addition, code | symbol S1 of FIG. 6 shows the case where the relationship of high temperature side path | route thermal resistance: thermal resistance in a thermoelectric conversion unit: low temperature side path | route thermal resistance is 2: 1: 2, and code | symbol S2 is a high temperature side path | route. The case where the relationship between thermal resistance: thermal resistance in the thermoelectric conversion unit: low-temperature side path thermal resistance is 1: 3: 1 is shown.

As can be seen from FIG. 6, but can not be increased temperature difference [Delta] T _E applied to the thermoelectric conversion unit when the temperature difference [Delta] T _L applied to the temperature difference [Delta] T _H and the low temperature side path applied to the high-temperature side passage increases both, high temperature can be a temperature difference [Delta] T _L applied to the temperature difference [Delta] T _H and the low temperature side path applied to the side path when small both to increase the temperature difference [Delta] T _E applied to the thermoelectric conversion unit. That is, by reducing the ratio of the high-temperature side path thermal resistance and the low-temperature side path thermal resistance in the appropriate total thermal resistance, the ratio of the thermal resistance in the thermoelectric conversion unit increases, and the thermoelectric conversion unit A large temperature difference can be secured. Therefore, the thermal resistance on the high-temperature side and the low-temperature side should be designed to be as small as possible, and the temperature difference applied to the thermoelectric conversion unit can be kept large by controlling the total thermal resistance by increasing or decreasing the thermal resistance of the thermoelectric conversion unit. I understand.

  Next, considering the control factor of the thermal resistance in the thermoelectric conversion unit, the thermal resistance in the thermoelectric conversion unit is the high temperature side heat sink (41 to 44), the high temperature surface of the thermoelectric conversion unit (51 to 56), the thermoelectric conversion unit. Since it is comprised from the low temperature surface of (51-56) and the low temperature side heat sink (45-47), it turns out that a thermal conductivity and a heat-transfer area affect this thermal resistance. Here, since the thermal conductivity is a physical property value and an inherent value, it can be seen that the heat transfer area is effective as a control factor.

  Therefore, in this embodiment, the heat exchange state between the thermoelectric conversion units (51 to 56), the high temperature side heat sinks (41 to 44), and the low temperature side heat sinks (45 to 47) is switched in multiple stages, so Change the heat transfer area. This multi-stage change in the heat exchange state will be specifically described with reference to FIGS. FIG. 7 is an explanatory diagram for explaining each stage in which the heat transfer area is changed. FIG. 7 (A) shows the first stage, FIG. 7 (B) shows the second stage, and FIG. Shows the third stage, and FIG. 7D shows the fourth stage. In addition, in FIG. 7, for convenience of explanation, hatched parts are conceptually shown for heat exchange.

  As shown in FIG. 7A, in the first stage, the valves 41a, 41b, 45a, and 45b are opened so that the high-temperature heat sink 41 and the low-temperature heat sink 45 exchange heat via the thermoelectric conversion unit 51. It becomes a state. Further, as shown in FIG. 7B, in the second stage, in addition to the heat exchange state in the first stage, the high temperature side heat sink 42 and the low temperature side heat sink 45 exchange heat through the thermoelectric conversion unit 52. The valves 42 a, 42 b, 46 a, 46 b are further opened so that the high temperature side heat sink 42 and the low temperature side heat sink 46 exchange heat via the thermoelectric conversion unit 53. Further, as shown in FIG. 7C, in the third stage, in addition to the heat exchange state of the second stage, the high temperature side heat sink 43 and the low temperature side heat sink 46 exchange heat through the thermoelectric conversion unit 54. The valves 43a, 43b, 47a, 47b are further opened so that the high-temperature heat sink 43 and the low-temperature heat sink 47 exchange heat through the thermoelectric conversion unit 55. Further, as shown in FIG. 7D, in the fourth stage, in addition to the heat exchange state in the third stage, the high temperature side heat sink 44 and the low temperature side heat sink 47 perform heat exchange via the thermoelectric conversion unit 56. Further, the valves 44a and 44b are further opened. That is, among the first to fourth stages, the first stage has the smallest heat transfer area, and the fourth stage has the largest heat transfer area. The high temperature side heat sinks 41 to 44 and the low temperature side heat sinks 45 to 47 and the valves 41a, 41b, 42a, 42b, 43a, 43b, 44a, 44b, 45a, 45b, 46a, 46b, 47a, 47b This can correspond to an example of “changing means” described in the range.

  Hereinafter, the power generation processing executed by the control unit 61 will be described in detail with reference to FIGS. 8 and 9. FIG. 8 is a flowchart illustrating the flow of power generation processing executed by the control unit 61. FIG. 9 is an explanatory diagram showing the relationship between the coolant temperature T measured by the temperature sensor 62 and the temperature state of the inverter 11. At the start of the power generation process, the heat exchange state via the thermoelectric conversion unit is the first stage in which the valves 41a, 41b, 45a, 45b are controlled to be in the valve open state, and the high temperature side coolant W1 and the low temperature The side coolant W2 is circulated independently by controlling the valves 14a and 14b of the high temperature side pipe 14 and the valves 24a and 24b of the low temperature side pipe 24 to be opened. Such an independent recirculation state is a state accompanied by power generation unlike the mixed flow state, and is also referred to as a power generation state.

First, immediately after the inverter 11 starts driving, the amount of heat generated by the inverter 11 is low, and the coolant temperature T measured by the temperature sensor 62 is also low. Therefore, the addition is sequentially performed in the addition process shown in step S103 of FIG. Until the time constant t exceeds the constant value td, it is determined No in the determination process shown in step S101. When the time constant t exceeds a predetermined value td (Yes in S101), in the determination process shown in step S105, whether the coolant temperature T measured by the temperature sensor 62 is higher than the transition upper producing temperature _{T H2,} Is determined.

Incidentally, the transition maximum temperature T _H2, as shown in FIG. 9, the lower limit value of the temperature region where the inverter 11 can be operated safely, for example in a secure upper limit temperature T _D is the upper limit of this high-temperature region is 90 ° C. In some cases, the transition upper limit temperature _TH2 is set to 80C. Further, a transition upper producing temperature T _H2, and the upper limit value, the high temperature side the transition region to a transition lower limit temperature T _H1 of lower value than this transition limit producing temperature T _H2, and the lower limit value, the heat transfer area during heat exchange is increased It is a temperature range. Further, a transition lower limit temperature T _H1 and the upper limit value, an appropriate temperature region for the proper temperature lower limit temperature T _L1 of a value lower than the transition limit temperature T _H1 and a lower limit value, the temperature region where the heat transfer area during heat exchange is maintained It is.

Here, when the coolant temperature T measured by the temperature sensor 62 is equal to or lower than the transition upper limit temperature _TH2 (No in S105), whether or not the stage number N is Nmax in the determination step shown in Step S107. Is determined. The number of stages N indicates the level at which the heat transfer area is changed. Specifically, N = 1 indicates the first stage shown in FIG. 7A, and N = 2 indicates the level shown in FIG. 7B. N = 3 indicates the third stage shown in FIG. 7C, and N = 4 indicates the fourth stage shown in FIG. 7D. Nmax indicates a mixed flow state in which the high temperature side coolant W1 in the high temperature side pipe 14 and the low temperature side coolant W2 in the low temperature side pipe 24 are mixed.

  As will be described later, when each valve is not opened or closed so as to be in a mixed flow state, it is determined No in step S107, and in the determination process shown in step S109, is the time constant t ′ greater than a certain value t′d? It is determined whether or not. Here, it is determined No in step S109 until the time constant t ′ sequentially added in the time constant t ′ addition process shown in step S111 exceeds a certain value t′d, and the processing from step S105 is repeated. It is.

Then, when the constant t 'exceeds a certain value T'd (Yes in S109), in the determination process shown in step S113, lower than the cooling fluid temperature T higher than the optimum temperature lower limit temperature _{T L1} is and transition lower limit temperature _{T H1} It is determined whether or not. Here, when the coolant temperature T is higher than the appropriate temperature lower limit temperature T _L1 and lower than the transition lower limit temperature TH ₁ (Yes in S113), the current stage number N is not changed without changing the heat transfer area during heat exchange. Maintained.

On the other hand, when the coolant temperature T is _{equal to} or higher than the transition lower limit temperature TH1 (No in S113, Yes in S115), the valve opening process shown in Step S117 is performed. In this process, the corresponding valve is opened so that the current stage number N increases. For example, since the current stage number N is the first stage where N = 1 (see FIG. 7A), the first stage is used to change to the second stage where N = 2 (see FIG. 7B). The valves 42a, 42b, 46a, 46b are further opened with respect to the open / closed state of the valve at. Then, in the stage number addition process shown in step S119, N = 2 is set so that the stage number N increases by one stage, and in the time constant t 'reset process shown in step S121, the time constant t' is reset.

In the determination process of step S113 described above, when the coolant temperature T is equal to or less than suitable temperature lower limit temperature _{T L1} (No in No, S115 in S113), the number N of the current in the determination process shown in step S123 is N = 1 It is determined whether or not. Here, when the current stage number N is N = 1 and the heat transfer area cannot be reduced any more, the current stage number N (N = 1) is maintained.

  On the other hand, if the current stage number N is not N = 1, the valve closing process shown in step S125 is performed to increase the temperature difference applied to the thermoelectric conversion unit even if the total heat transfer area is reduced. In this process, the corresponding valve is closed so that the current stage number N is reduced. For example, since the current stage number N is the third stage where N = 3 (see FIG. 7C), the third stage is used to change to the second stage where N = 2 (see FIG. 7B). The valves 43a, 43b, 47a, 47b are closed with respect to the open / closed state of the valve. Then, in the stage number subtraction process shown in step S127, N = 2 is set so that the stage number N decreases by one stage, and in the time constant t 'reset process shown in step S129, the time constant t' is reset.

Further, when the amount of generated heat increases in accordance with the drive of the inverter 11 and the coolant temperature T measured by the temperature sensor 62 becomes higher than the transition upper limit temperature _TH2 (Yes in S105), the inverter 11 rather than the power generation. In order to prioritize the cooling of this, the mixed flow process shown in step S131 is performed. In this process, the valves 14a and 14b of the high temperature side pipe 14 and the valves 24a and 24b of the low temperature side pipe 24 are closed, and the valves 31a and 31b of the high temperature side bypass 31 and the valves 32a and 32b of the low temperature side bypass 32 are closed. 32b is opened.

  As a result, the high-temperature side coolant W1 and the low-temperature side coolant W2 are mixed through the bypasses 31 and 32, and the mixed coolant is radiated by the radiator 21, and then heat is exchanged through the thermoelectric conversion unit. It will flow to the water jacket 12 without. As a result, since the cooling liquid having a lower temperature flows into the water jacket 12, the inverter 11 can be effectively cooled compared to the case where heat is exchanged via the thermoelectric conversion unit.

  In such a mixed flow state (high cooling state), the stage number N is set to N = Nmax in the process shown in step S133, and the time constant t is set in the time constant reset process shown in step S135. Reset.

When the inverter 11 is cooled by the mixed coolant as described above, and the coolant temperature T measured by the temperature sensor 62 becomes equal to or lower than the transition upper limit temperature _TH2 (No in S105), the number of stages N = Nmax. Therefore, it is determined Yes in step S107. Then, the independent recirculation process shown in step S137 is performed, the valves 14a and 14b of the high temperature side pipe 14 and the valves 24a and 24b of the low temperature side pipe 24 are opened, and the valves 31a and 31b of the high temperature side bypass 31 are opened. The valves 32a and 32b of the low temperature side bypass 32 are closed. And the valve opening process shown to step S139 is made, all the valves connected with each heat sink will be in a valve open state, and it will be in the 4th step heat exchange state in which heat exchange is performed in all the thermoelectric conversion units 51-56. In the maximum stage number changing process shown in step S141, the stage number N is set to N = 4.

  As a result, the high-temperature side cooling liquid W1 in the high-temperature side pipe 14 and the low-temperature side cooling liquid W2 in the low-temperature side pipe 24 are independently circulated without being mixed, and a thermoelectric conversion unit is obtained. Heat exchange is performed between the high temperature side coolant W1 and the low temperature side coolant W2 via 51 to 56, and power generation using the temperature difference during this heat exchange is resumed.

Here, the relationship between the open / close state of each valve controlled by the power generation process described above and the coolant temperature T will be described with reference to FIG. FIG. 10 is a timing chart showing the time change of the coolant temperature T measured by the temperature sensor 62.
When the inverter 11 starts to drive, and the amount of heat generated by the inverter 11 increases and the coolant temperature T measured by the temperature sensor 62 becomes _{equal to} or higher than the transition lower limit temperature _TH1 (see P1 in FIG. 10), Yes in step S115. In step S117, the heat exchange state is changed from the first stage to the second stage in order to further cool the high-temperature side coolant W1.

When the heat exchange state is changed to the second stage in this way and the heat exchange amount is increased, the high temperature side coolant W1 is further cooled, and before the time constant t ′ exceeds the constant value t′d, the coolant The temperature T falls below the transition lower limit temperature _TH1 (see P2 in FIG. 10). And since the load of the inverter 11 increases and the amount of generated heat of the inverter 11 further increases, the coolant temperature T rises (see P3 in FIG. 10), and the rising coolant temperature T again exceeds the transition lower limit temperature _TH1. (See P4 in FIG. 10), it is determined Yes in step S115, and the process after step S117 is performed to further cool the high-temperature side coolant W1, and the heat exchange state is changed from the second stage to the third stage. Be changed.

When the heat exchange state is changed to the third stage in this way and the heat exchange amount further increases, the high temperature side coolant W1 is further cooled, and the cooling is performed before the time constant t ′ exceeds the constant value t′d. The liquid temperature T will fall below the transition lower limit temperature _TH1 (see P5 in FIG. 10). Then, the heat generation amount of the inverter 11 decreases the load of the inverter 11 becomes lower coolant temperature T is lowered (see P6 in FIG. 10), when the coolant temperature T drops falls below an appropriate temperature lower limit temperature T _L1 (Fig. 10 In step S113, S115, and S123, it is determined as No, and in order to increase the temperature difference applied to the thermoelectric conversion unit even if the total heat transfer area is reduced, the processing after step S125 is performed, and the heat exchange state is determined. The third stage is changed to the second stage.

When the heat exchange amount is reduced by changing the heat exchange state to the second stage in this way, the cooling of the high temperature side coolant W1 is lowered, and the cooling is performed before the time constant t ′ exceeds the constant value t′d. solution temperature T is to exceed a transition lower limit temperature _{T H1} (see P8 in FIG. 10). Then, the load on the inverter 11 increases again, and the amount of heat generated by the inverter 11 further increases, so that the coolant temperature T rises (see P9 in FIG. 10), and the rising coolant temperature T again changes to the transition lower limit temperature T _H1. If it becomes above (refer P10 of FIG. 10), it will determine with Yes in step S115, and in order to further cool the high temperature side cooling liquid W1, the process after step S117 will be made and a heat exchange state will be 3rd from the 2nd step. Changed to

Then, since the heat generation amount of the inverter 11 is high, even when constant t 'exceeds a predetermined value t'd and the coolant temperature T is a transition lower limit temperature _{T H1} above (see P11 in FIG. 10), step S115 In step S117, the heat exchange state is changed from the third stage to the fourth stage in order to further cool the high-temperature side coolant W1.

Then, when the amount of heat generated from the inverter 11 is high is maintained, when the coolant temperature T exceeds the transition upper limit temperature _{T H2} (see P12 in FIG. 10), it is determined as Yes at step S105, from the generator In order to give priority to the cooling of the inverter 11, the processes in and after step S131 are performed. As a result, a lower temperature cooling liquid in which the high temperature side cooling liquid W1 and the low temperature side cooling liquid W2 are mixed flows into a mixed flow state (high cooling state) in which the water jacket 12 flows, and the inverter 11 is effectively cooled.

Thus inverter 11 in that it has been switched to the mixed flow state is cooled preferentially, time before constant t is above a certain value td, when the coolant temperature T is equal to or less than the transition upper producing temperature T _H2, (Figure 10 P13 Reference), No is determined in step S105, Yes is determined in step S107, and the processing after step S137 is performed. As a result, the mixed flow state (high cooling state) is switched to the independent recirculation state (power generation state), and power generation using the temperature difference during heat exchange by the thermoelectric conversion units 51 to 56 is resumed.

Then, the heat generation amount of the inverter 11 decreases the load of the inverter 11 and becomes lower coolant temperature T is lowered (see P14 in FIG. 10), coolant temperature T to be lowered below a suitable temperature lower limit temperature T _L1, i.e. appropriate temperature region Then (see P15 in FIG. 10), the heat transfer area during heat exchange is maintained.

As described above, in the power generation system 40 according to the present embodiment, the valves 41a, 41b, 42a, 42b, 43a, 43b, 44a, 44b, 45a, 45b, 46a, 46b, 47a, 47b are opened and closed. Heat transfer area during heat exchange via the thermoelectric conversion units 51 to 56 interposed between the high temperature side coolant W1 flowing in the side heat sinks 41 to 44 and the low temperature side coolant W2 flowing in the high temperature side heat sinks 45 to 47 Is configured to be changeable. Then, to increase the temperature difference during heat exchange without coolant temperature T detected by the temperature sensor 62 exceeds the safety limit temperature T _D, the power generation process executed by the control unit 61, the valves Is controlled to change the heat transfer area.

Accordingly, even when the amount of heat transferring heat from the inverter 11 to the high temperature side coolant W1 decreases, the thermoelectric conversion unit 51 to the extent that the coolant temperature T by controlling the opening and closing of the valves does not exceed a safe upper limit temperature T _D By reducing the heat transfer area at the time of heat exchange via 56, the cooling of the high temperature side coolant W1 is controlled to the necessary minimum, and the temperature difference at the time of heat exchange applied to the thermoelectric conversion units 51 to 56 is increased. be able to. That is, even when the amount of heat from the inverter 11 and the temperatures and flow rates of the coolants W1 and W2 change, the heat transfer area at the time of heat exchange via the thermoelectric conversion units 51 to 56 is changed, so that the thermoelectric conversion unit The temperature difference at the time of heat exchange via 51-56 can be largely maintained.
Therefore, power can be generated efficiently by maintaining a high temperature difference between the heat of the inverter 11 and the cooling medium.

Further, as the switching means, both the high temperature side cooling liquid W1 and the low temperature side cooling liquid W2 are cooled by the high temperature side bypass 31 and the low temperature side bypass 32 and the valves 14a, 14b, 24a, 24b, 31a, 31b, 32a, 32b. A power generation state (independent circulation state) in which heat is exchanged via at least one of the thermoelectric conversion units 51 to 56 without mixing the liquid, and both cooling liquids W1 and W2 are mixed without passing through the thermoelectric conversion units 51 to 56. Thus, it is configured to be switchable to either a high cooling state (a mixed flow state) in which the cooling of the inverter 11 is enhanced. When the coolant temperature T detected by the temperature sensor 62 reaches the transition upper limit temperature _TH2 , the switching means is switched to the high cooling state (mixed flow state) by the power generation process executed by the control unit 61. Controlled.

Thus, when the coolant temperature T reaches the transition limit producing temperature T _H2, because the heat exchange through the thermoelectric conversion unit 51 to 56 is not performed, there is no heat transfer loss caused by through the thermoelectric conversion unit 51-56 The heat exchange efficiency between the coolants W1 and W2 is improved. As a result, the cooling performance of the inverter 11 using the cooling liquid is increased, it is possible to lower the heating temperature of the inverter 11 to a temperature lower than the safety limit temperature T _D.

In addition, this invention is not limited to the said embodiment, You may actualize as follows.
(1) The power generation system 40 according to the present invention is not limited to generating power using the temperature difference between the heat generated in the inverter 11 and a cooling medium (cooling liquid) for cooling the heat, but also an engine or the like It may be configured to generate power by using a temperature difference between heat generated in a heat generating device mounted on the vehicle and a cooling medium (coolant) for cooling the heat. Further, even if the heat generating device is not mounted on the vehicle, the power generation system 40 according to the present invention may be employed as long as it is a heat generating device that is cooled using a radiator such as the radiator 21.

(2) The number of thermoelectric conversion units is not limited to six, but may be two to five, or seven or more. In this case, each thermoelectric conversion unit can be disposed so as to be interposed between the high temperature side heat sink and the low temperature side heat sink that can control the inflow of the coolant. The heat exchange state is not limited to being changed in four stages from the first stage to the fourth stage, and may be changed in, for example, two or three stages, or may be changed in five or more stages. May be.

(3) The temperature sensor 62 is not limited to measuring the temperature of the coolant flowing out of the water jacket 12 as the coolant temperature T, and may be configured to directly measure the heat generation temperature of the inverter 11. In this case, the safe upper limit temperature T _D , the transition lower limit temperature T _H1 , the transition upper limit temperature T _H2 , the appropriate temperature lower limit temperature T _{L1, and the} like can be appropriately changed according to the measurement position of the temperature sensor 62 and the like.

(4) In the power generation processing executed by the control unit 61, not only the coolant temperature T measured by the temperature sensor 62 but also the temperature and flow rate of the coolant flowing out from the radiator 21 measured by the temperature sensor 63. Depending on the flow rate of the coolant flowing in the high temperature side pipe 14 measured by the sensor 64 and the flow rate of the coolant flowing in the low temperature side pipe 24 measured by the flow rate sensor 65, not only each valve but also the high temperature side The motor 13a for driving the water pump 13, the motor 23a for driving the low temperature side water pump 23, and the motor 22a for driving the cooling fan 22 are driven and controlled to cool the inverter 11 and to generate power by the thermoelectric conversion units 51 to 56. May be controlled.

11 ... Inverter (heating device)
14 ... High temperature side piping 14a, 14b ... Valve (switching means)
21 ... Radiator (heat radiator)
24 ... Low temperature side piping 24a, 24b ... Valve (switching means)
31 ... High temperature side bypass (switching means)
32 ... Low temperature side bypass (switching means)
31a, 31b, 32a, 32b ... valve (switching means)
40 ... Power generation system 41-44 ... High temperature side heat sink (changing means)
41a, 41b, 42a, 42b, 43a, 43b, 44a, 44b ... valve (changing means)
45 to 47 ... low temperature side heat sink (changing means)
45a, 45b, 46a, 46b, 47a, 47b ... valve (changing means)
51-56 ... thermoelectric conversion unit (thermoelectric conversion means)
61 ... Control unit (control means)
62 ... Temperature sensor (temperature detection means)
T ... Coolant temperature (heat generation temperature)
T _D ... Safe upper limit temperature (upper limit temperature)
T _H1 ... Transition lower limit temperature T _H2 ... Transition upper limit temperature (predetermined temperature)
T _L1 ... lower limit temperature suitable temperature W1 ... high temperature side coolant (high temperature side coolant)
W2 ... Low temperature side coolant (low temperature side coolant)

Claims (2)

A high-temperature side cooling medium to which heat generated by a heat generating device mounted on the vehicle is transferred, and a low-temperature side cooling that is radiated by a radiator after the heat is transferred to cool the high-temperature side cooling medium. A power generation system that generates power by thermoelectric conversion means using a temperature difference during heat exchange with a medium,
Changing means capable of changing the heat transfer area during heat exchange via the thermoelectric conversion means interposed between the high temperature side cooling medium and the low temperature side cooling medium;
Temperature detecting means for detecting the heat generation temperature of the heat generating device;
The heat transfer area is controlled by controlling the change means so as to increase the temperature difference during the heat exchange without the heat generation temperature detected by the temperature detection means exceeding the allowable upper limit temperature of the heat generation equipment. Control means for changing
A power generation system comprising: A power generation state in which heat exchange is performed via the thermoelectric conversion means without mixing the high temperature side cooling medium and the low temperature side cooling medium, and the high temperature side cooling medium and the low temperature side cooling medium via the thermoelectric conversion means. A switching means capable of switching to any state of a high cooling state in which cooling of the heat generating device is enhanced rather than the power generation state by mixing without any flow,
The control means controls the switching means to switch to the high cooling state when the heat generation temperature detected by the temperature detection means reaches a predetermined temperature set lower than the upper limit temperature. The power generation system according to claim 1, characterized in that:

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