JP2006220004A - Thermoelectric generator for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermoelectric generator for a vehicle capable of performing stable electric power supply even during an idle stop by a thermoelectric module by ensuring always sufficient temperature difference. <P>SOLUTION: The thermoelectric module 40 is provided between the upper reaches of an exhaust pipe 36 of an engine 1 and a hydraulic line 22 connecting a primary pulley 12 and a secondary pulley 14 of a continuously variable transmission 10, an oil pump 20 and an electric oil pump 24. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a vehicle thermoelectric generator, and more particularly to power supply by thermoelectric power generation using a thermoelectric module.

In recent years, as a technique for reducing exhaust gas and improving fuel consumption, the internal combustion engine (hereinafter referred to as the engine) is automatically stopped when the vehicle is stopped in an idle state due to a signal or the like, and is quickly restarted when starting. So-called idle stop vehicles have been developed that start smoothly.
However, even during idle stop, it is necessary to secure power for restarting the engine and power to the auxiliary equipment such as lamps, air conditioners, audio, etc. used even during idle stop. It was. Conventionally, since the engine is stopped by the idle stop, the power generated by the engine such as an alternator cannot be used for the power during the idle stop, and the power charged in the power storage means such as a battery can be used. Was used.

By the way, as a means for power generation, there is a technique called thermoelectric power generation that generates power by generating a temperature difference between a high temperature portion and a low temperature portion of a thermoelectric module.
For example, a technology has been developed in which this thermoelectric module is provided in a vehicle engine, and heat generated by the engine is used as a high-temperature source and electric power is generated using outside air or a radiator as a low-temperature source. (See Patent Document 1).
JP 2001-332293 A

However, the technique disclosed in Patent Document 1 has a problem that if the engine stops, it is difficult to obtain a large temperature difference and sufficient generated power cannot be obtained.
In order to obtain high generated power by thermoelectric power generation, it is necessary to increase the temperature difference between the low temperature part and the high temperature part of the thermoelectric module.

Although there are relatively many parts that can be a high temperature source in a vehicle, the exhaust system of the engine can be particularly high, and the exhaust gas immediately after exhaust becomes a sufficient high temperature source.
On the other hand, it is difficult to secure a stable low-temperature source in a vehicle. For example, a typical low-temperature source is cooling water, but it is difficult to pass cooling water around an exhaust system. Thus, in a vehicle, it is difficult to obtain a low-temperature source that is in the vicinity of a high-temperature source such as an exhaust system and that can maintain the temperature at a relatively low temperature.

  The present invention has been made to solve such a problem, and the object of the present invention is to always ensure a sufficient temperature difference and to stably supply power even during idling stop by the thermoelectric module. The object is to provide a thermoelectric generator for a vehicle.

  In order to achieve the above-described object, in the thermoelectric power generator for a vehicle according to claim 1, a continuously variable transmission capable of continuously changing the rotation of an internal combustion engine mounted on the vehicle and transmitting it to the drive shaft; An internal combustion engine stop / restart control means for stopping the internal combustion engine when a stop condition is satisfied, and restarting the internal combustion engine when a predetermined restart condition is satisfied, and the internal combustion engine stop / restart control means An electric oil pump that is driven by electric power to supply hydraulic pressure to the continuously variable transmission, a hydraulic path that connects the electric oil pump and the continuously variable transmission, and a hydraulic path that is provided in the hydraulic path. And a thermoelectric module having a high temperature portion provided in the exhaust passage of the internal combustion engine and performing thermoelectric power generation by a temperature difference between the low temperature portion and the high temperature portion.

Thus, thermoelectric power generation is performed using a thermoelectric module in which a low temperature portion is provided in a hydraulic path connecting an electric oil pump and a continuously variable transmission that are driven during idle stop, and a high temperature portion is provided in an engine exhaust system.
In the vehicle thermoelectric power generation apparatus according to claim 2, power is supplied to the vehicle by thermoelectric power generation using the thermoelectric module only when the power generated by the thermoelectric power generation using the thermoelectric module satisfies the required power of the vehicle. It is characterized by.

Therefore, the power supply of the vehicle by thermoelectric power generation using the thermoelectric module is only performed when the power generated by the thermoelectric power generation satisfies the required power of the vehicle, and the power generated by the thermoelectric power generation satisfies the power supply of the vehicle. If not, the vehicle is not powered by thermoelectric power generation using a thermoelectric module.
4. The vehicle thermoelectric generator according to claim 3, wherein the electric power of the vehicle by thermoelectric power generation using the thermoelectric module is used only when the temperature difference between the low temperature part and the high temperature part is equal to or greater than a predetermined temperature difference set in advance. It is characterized by supply.

  Therefore, the power supply of the vehicle by thermoelectric power generation using the thermoelectric module shall be performed only when a sufficient temperature difference between the low temperature part and the high temperature part of the thermoelectric module can be obtained. When the difference cannot be obtained sufficiently, the vehicle is not supplied with electric power by thermoelectric power generation using a thermoelectric module.

  According to the vehicle thermoelectric generator of the present invention using the above means, the continuously variable transmission is connected to the continuously variable transmission because the electric oil pump operates to maintain the hydraulic pressure during idle stop. The oil in the hydraulic path is always circulated and there is little temperature fluctuation, and by providing a low temperature part in such a hydraulic path and providing a high temperature part in the exhaust system through which high temperature exhaust gas circulates, A temperature difference in the high temperature part can be obtained stably.

As a result, sufficient power generated by thermoelectric power generation using the thermoelectric module can always be obtained, and stable power supply can be performed during idle stop.
According to the vehicle thermoelectric generator of claim 2, when the power generated by the thermoelectric module is less than the power supplied to the vehicle, the power supply by the thermoelectric power generation is not performed so that the vehicle power supply is unstable. Can be prevented.

  According to the vehicle thermoelectric generator of claim 3, when the temperature difference between the low temperature portion and the high temperature portion is low, the power supply of the vehicle becomes unstable by not performing the power supply by the thermoelectric power generation. This can be sufficiently prevented.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
Referring to FIG. 1, there is shown a schematic configuration diagram of a vehicle provided with a thermoelectric generator according to the present invention. Hereinafter, a description will be given based on FIG.
As shown in FIG. 1, a continuously variable transmission 10 is connected to an output shaft 2 extending to one side of an engine (internal combustion engine) 1 mounted on a vehicle via a torque converter 4 and a forward / reverse switching device 6. .

Specifically, the engine 1 is a four-cylinder gasoline engine, for example. The torque converter 4 includes a pump impeller, a turbine liner, and a stator. The forward / reverse switching device 6 has a planetary gear mechanism, and selectively outputs the rotation of the turbine liner output from the torque converter 4 between the forward direction and the reverse direction of the vehicle.
The engine 1, torque converter 4, and forward / reverse switching device 6 are well known and will not be described in detail.

The continuously variable transmission 10 is a belt-type continuously variable transmission, and is connected to the primary pulley 12 connected to the output shaft 2 of the engine 1 via the torque converter 4 and the forward / reverse switching device 6 and to the drive shaft 8 side of the vehicle. Secondary pulley 14 and a V-belt 16 stretched between the primary pulley 12 and the secondary pulley 14.
The primary pulley 12 and the secondary pulley 14 are connected to a hydraulic path 22, and the groove widths of the pulleys 12 and 14 change relatively by controlling the hydraulic pressure to the pulleys 12 and 14. Thus, by changing the groove widths of the primary pulley 12 and the secondary pulley 14, the effective diameter applied to the V-belt 16 is changed, and the gear ratio of the continuously variable transmission 10 is changed.

The hydraulic path 22 is also connected to an oil pump 20 provided between the torque converter 4 and the forward / reverse switching device 6. The oil pump 20 is driven by the engine 1 and discharges oil from an oil pan (not shown) to the hydraulic path 22 at a high hydraulic pressure.
In addition to the oil pump 20, an electric oil pump 24 is mounted on the vehicle. This is because oil pressure is not generated for the continuously variable transmission 10 because the drive of the oil pump 20 stops during idle stop. In order to start the vehicle in this state, it is necessary to start after the engine is started and the oil pump generates a hydraulic pressure for the continuously variable transmission to change to a predetermined speed or to maintain the predetermined speed. It will be late. Therefore, an electric oil pump is provided separately from the engine drive so that hydraulic pressure is generated for the continuously variable transmission 10 even during idling stop so that there is no delay in starting the vehicle. Note that the electric oil pump 24 is also connected to the hydraulic path 22, and the electric oil pump 24 is driven by electric power. Discharge.

Further, an oil temperature sensor 26 is provided in the hydraulic path 22, and the oil temperature sensor 26 detects the temperature of oil flowing through the hydraulic path 22.
A starter generator 32 is connected to the output shaft 3 extending to the other side of the engine 1 via a transmission member 30 such as a gear unit or a chain. The starter generator 32 has a function of generating power with the rotation of the engine 1 during operation of the engine 1 and cranking the engine 1 with the supply of electric power when the engine 1 is started.

An exhaust pipe (exhaust passage) 36 is connected to the exhaust side of the engine 1 via an exhaust manifold 34. An exhaust gas temperature sensor 38 is provided on the exhaust upstream side of the exhaust pipe 36, and the exhaust gas temperature sensor 38 detects the temperature of the exhaust gas flowing through the exhaust pipe 36.
A thermoelectric module 40 is provided between the exhaust upstream side of the exhaust pipe 36 and the hydraulic path 22.

The thermoelectric module 40 has a low temperature portion 40a on one side and a high temperature portion 40b on the other side, and has a function of performing thermoelectric power generation that generates power based on a temperature difference between the low temperature portion 40a and the high temperature portion 40b.
In the thermoelectric module 40, the low temperature part 40 a is in contact with the hydraulic path 22, and the high temperature part 40 b is in contact with the exhaust pipe 36. That is, the thermoelectric module 40 generates power based on a temperature difference between the hydraulic path 22 and the upstream side of the exhaust pipe 36.

The thermoelectric module 40 is electrically connected to the DC / DC converter 42. The DC / DC converter 42 has a function of converting the electric power generated by the thermoelectric module 40 into an appropriate voltage.
In addition, a battery 44 that stores electric power is mounted on the vehicle.
Further, the electric oil pump 24 and the starter generator 32 are electrically connected to an inverter 46, and the inverter 46 has a function of converting direct current to alternating current.

And the DC / DC converter 42, the battery 44, the inverter 46, and the auxiliary machinery 48 mounted in the vehicle are each electrically connected. Here, the auxiliary machines 48 are electric devices mounted on the vehicle such as air conditioners, audios, lamps and the like.
Further, the vehicle is equipped with an ECU (electronic control unit) 50 (internal combustion engine stop / restart control means) that performs various controls including idle stop. The ECU 50 is electrically connected to various devices such as the oil temperature sensor 26, the exhaust gas temperature sensor 38, the DC / DC converter 42, the battery 44, the inverter 46, and auxiliary equipment 48.

The operation of the vehicle thermoelectric generator according to the present invention configured as described above will be described below.
First, vehicle power supply during vehicle travel will be described.
While the vehicle is running, hydraulic pressure is supplied from the oil pump 20 to the primary pulley 12 and the secondary pulley 14 via the hydraulic path 22 in order to control the gear ratio of the continuously variable transmission 10 according to the operating condition of the engine 1. The Thus, by supplying hydraulic pressure to the pulleys 12 and 14, the oil in the hydraulic path 22 circulates, and the temperature of the oil is kept relatively low with little fluctuation. The electric oil pump 24 is stopped during the operation of the engine 1.

In addition, high-temperature exhaust gas discharged from the engine 1 circulates in the exhaust pipe 36.
Thereby, the thermoelectric module 40 in which the low temperature part 40 a is in contact with the hydraulic path 22 and the high temperature part 40 b is in contact with the exhaust pipe 36 is thermoelectrically generated by a temperature difference generated between the hydraulic path 22 and the exhaust pipe 36.
During operation of the engine 1, power generation by the starter generator 32 is also performed with the rotation of the engine 1.

Here, if the power generated by the thermoelectric power generation of the thermoelectric module 40 satisfies the required power of the auxiliary machinery 48 and the like, the thermoelectric power generation of the thermoelectric module 40 supplies power to the auxiliary machinery 48 and the like. In this way, by supplying power to the auxiliary machinery 48 and the like by the power generation of the thermoelectric module 40, the burden of the engine 1 driving the starter generator 32 can be reduced.
Further, when the exhaust gas temperature is low immediately after the engine 1 is started, a sufficient temperature difference cannot be obtained between the low temperature part 40a and the high temperature part 40b, and the generated power of the thermoelectric module 40 does not satisfy the required power, etc. Then, power is supplied by the power generation of the starter generator 32 as in the past.

Next, the power supply of the vehicle at the time of idling stop will be described.
Referring to FIG. 2, a control routine at the time of idling stop of the vehicle executed by the ECU 50 is shown in a flowchart, and will be described below based on the flowchart.
First, in step S1, it is determined whether or not the vehicle satisfies an idle stop condition (stop condition). Here, the idle stop condition is, for example, a state in which the vehicle is sufficiently warmed, the accelerator is not operated, the brake is depressed, and the vehicle speed is 0. It is assumed that the idle stop condition is satisfied when all are satisfied. If the determination result is true (Yes), the process proceeds to step S2.

In step S2, the temperature difference T between the low temperature portion 40a and the high temperature portion 40b is calculated from the oil temperature detected by the oil temperature sensor 26 and the exhaust gas temperature sensor 38 and the exhaust gas temperature.
In the next step S3, the calculated temperature difference T is compared with a predetermined temperature T1 (for example, 400 ° C.) set in advance, and it is determined whether or not the temperature difference T is equal to or higher than the predetermined temperature T1. If the determination result is true (Yes), the process proceeds to step S4.

In step S <b> 4, the generated power E <b> 1 generated by the thermoelectric power generation of the thermoelectric module 40 is detected from the DC / DC converter 42.
In the next step S5, electric power required for causing various devices such as the electric oil pump 24 and the auxiliary machinery 48 to function, that is, required electric power E2 is calculated.
In step S6, the generated power E1 of the thermoelectric module 40 is compared with the required power E2 of the auxiliary machinery 48, etc., and it is determined whether or not the generated power E1 is equal to or higher than the required power E2. If the determination result is true (Yes), the process proceeds to step S7, where power is supplied to the auxiliary machinery 48 and the like by thermoelectric power generation by the thermoelectric module 40, and the process proceeds to step S8.

  In step S8, if the engine 1 is operating, the engine 1 is stopped, and in the subsequent step S9, the electric oil pump 24 is operated so as to maintain the hydraulic pressure of the primary pulley 12 and the secondary pulley 14, Exit the routine. If the engine 1 is already stopped and the electric oil pump 24 is operating in steps S8 and S9, the engine 1 stopped state and the hydraulic pressure maintaining state are maintained as they are, and the routine is exited.

As described above, when the thermoelectric module 40 can obtain sufficient power generated by thermoelectric power generation with a sufficient temperature difference, power supply by thermoelectric power generation of the thermoelectric module 40 is performed.
On the other hand, when the determination result in step S3 or step S6 is false (No), that is, when the temperature difference T is less than the predetermined temperature difference T1, or when the generated power E1 is less than the required power E1. Advances to step S10.

In step S10, the current charge amount B of the battery 44 is detected.
Then, in the next step S11, it is determined whether or not the charge amount B is equal to or greater than a predetermined charge amount B1 (for example, 60% with respect to the maximum charge amount of the battery 44). If the determination result is true (Yes), the process proceeds to step S11, and the power charged in the battery 44 is supplied to the auxiliary devices 48 and the like. In the subsequent steps S8 and S9, as described above, the engine 1 is stopped, the electric oil pump 24 is operated, and the routine is exited.

As described above, when sufficient electric power cannot be secured by thermoelectric power generation using the thermoelectric module 40, the battery 44 supplies power during idle stop if the charge amount B of the battery 44 is sufficient.
If the idle stop condition is not satisfied in step S1, or if the charge amount B of the battery 44 is less than the predetermined charge amount B1 in step S11, the process proceeds to step S20.

In step S20, if the engine 1 is stopped at this time, the engine 1 is restarted. In the subsequent step S21, the electric oil pump 24 is stopped and the routine is exited. If the engine 1 is already in operation and the electric oil pump 24 is stopped, the routine is directly exited.
As described above, the idle stop condition is satisfied, but when the thermoelectric power generation by the thermoelectric module or the charge amount of the battery 44 is not sufficient, the starter generator is driven by restarting the engine 1, and the starter generator Power is supplied by generated power.

As described above, the oil pump is used to maintain the hydraulic pressures of the primary pulley 12 and the secondary pulley 14 of the continuously variable transmission 10 so that the vehicle can smoothly start from the restart even during the idle stop in which the operation of the engine 1 is stopped. Instead of 20, the electric oil pump 24 is operated.
For this reason, the oil in the hydraulic path 22 always circulates even when the engine 1 is stopped, and even if a part of the hydraulic path 22 passes through the vicinity of the exhaust pipe 36, the temperature fluctuation is small and the temperature is relatively low. Can be maintained.

By providing the low-temperature part 40a of the thermoelectric module 40 in such a hydraulic path 22 and providing the high-temperature part 40b in the exhaust pipe 36 through which the high-temperature exhaust gas flows, the low-temperature part 40a not only during the engine 1 drive but also during idling stop. And the temperature difference between the high temperature part 40b can be obtained stably.
Thereby, sufficient electric power generated by thermoelectric power generation of the thermoelectric module 40 can be performed, and stable power supply to the auxiliary machinery 48 and the like can be performed even during idle stop.

Further, when the temperature difference between the low temperature portion 40a and the high temperature portion 40b of the thermoelectric module 40 is low, or when the power generated by the thermoelectric power generation is not sufficient, switching to the power supply by the battery 44 or the starter generator 32, the vehicle It is possible to prevent the power supply from becoming unstable.
Although the description about the embodiment of the thermoelectric power generation device for a vehicle according to the present invention is finished above, the embodiment is not limited to the above embodiment.

For example, in the above embodiment, the generated electric power E1 generated by the thermoelectric power generation of the thermoelectric module 40 is detected from the DC / DC converter 42. However, the present invention is not limited to this, and the low temperature part 40a and the high temperature part 40b of the thermoelectric module 40 The generated power E1 may be calculated from the temperature difference T.
Moreover, in the said embodiment, although both the discrimination | determination by the temperature difference T of the low temperature part 40a and the high temperature part 40b of the thermoelectric module 40 and the discrimination | determination by the generated electric power E1 by the thermoelectric power generation of the thermoelectric module 40 are performed, which It does not matter if only one of them is discriminated.

In the above embodiment, the idle stop condition is that the vehicle is sufficiently warmed, the accelerator is not operated, the brake is depressed, and the vehicle speed is 0. However, the present invention is not limited to this, and other conditions may be used.
In the above-described embodiment, power can be supplied by thermoelectric power generation of the thermoelectric module 40 even while the vehicle is running. For example, only power generation by the starter generator 32 can be performed while the vehicle is running. Thermoelectric power generation may be performed only during idle stop.

  In the above embodiment, the starter generator 32 is used on the side opposite to the torque converter 4. However, a structure in which the starter generator 32 is sandwiched between the engine 1 and the torque converter 4 may be used. A combination with may also be used.

1 is a schematic configuration diagram of a vehicle including a thermoelectric generator according to the present invention. It is a flowchart which shows the control routine at the time of the idle stop of the vehicle performed by ECU in the thermoelectric generator of the vehicle which concerns on this invention.

Explanation of symbols

1 engine (internal combustion engine)
10 continuously variable transmission 20 oil pump 22 hydraulic path 24 electric oil pump 26 oil temperature sensor 32 starter generator 36 exhaust pipe (exhaust passage)
38 exhaust gas temperature sensor 40 thermoelectric module 40a low temperature part 40b high temperature part 42 DC / DC converter 44 battery 48 accessories 50 ECU (internal combustion engine stop / restart control means)

Claims (3)

A continuously variable transmission capable of continuously changing the rotation of an internal combustion engine mounted on a vehicle and transmitting it to a drive shaft;
An internal combustion engine stop / restart control means for stopping the internal combustion engine when a predetermined stop condition is satisfied, and restarting the internal combustion engine when a predetermined restart condition is satisfied;
An electric oil pump that is driven by electric power to supply hydraulic pressure to the continuously variable transmission while the internal combustion engine is stopped by the internal combustion engine stop / restart control means;
A hydraulic path connecting the electric oil pump and the continuously variable transmission;
A thermoelectric module having a low temperature section provided in the hydraulic path and a high temperature section provided in an exhaust passage of the internal combustion engine, and performing thermoelectric generation by a temperature difference between the low temperature section and the high temperature section;
A vehicle thermoelectric power generator.   2. The vehicle according to claim 1, wherein power is supplied to the vehicle by thermoelectric power generation using the thermoelectric module only when the power generated by thermoelectric power generation using the thermoelectric module satisfies the required power of the vehicle. Thermoelectric generator.   The power supply of the vehicle by thermoelectric power generation using a thermoelectric module is performed only when the temperature difference between the low temperature part and the high temperature part is equal to or greater than a predetermined temperature difference set in advance. 3. A thermoelectric generator for a vehicle according to 2.

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