JPH0681639A - Exhaust heat recovery device for engine - Google Patents

Abstract

(57) [Abstract] [Object] The present invention relates to an exhaust heat recovery apparatus for an engine, which recovers electrical energy from thermal energy of exhaust gas flowing through an exhaust passage of the engine, and is a configuration of an apparatus capable of protecting a heat resistant temperature of a power generation unit. It is an object of the present invention to simplify and downsize and to obtain a stable electromotive force by steplessly adjusting the exhaust flow rate. A heat converter 6 having an exhaust flow rate adjusting valve 11 and a power generation unit 6a is provided downstream of the catalyst 8 in the exhaust passage 2, and a bypass passage 3 branching from the downstream side of the catalyst 8 is provided, and The exhaust temperature detecting means 9 for detecting the exhaust temperature in the exhaust passage 2 and the opening degree of the exhaust flow rate adjusting valve 11 are controlled based on the detection result of the exhaust temperature detecting means 9 so that the exhaust temperature does not exceed the heat resistant temperature of the power generation unit 6a. The control means 5 for controlling is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust heat recovery system for an engine which recovers electric energy from thermal energy of exhaust gas flowing through an exhaust passage of the engine.

[0002]

2. Description of the Related Art Conventionally, a power generation unit for converting heat energy of exhaust gas into electric energy is attached to an exhaust passage of an engine of an automobile or the like, a direct current is taken out, and the direct current is stored in a power storage device to be stored in each electric device. Supply is taking place. This power generation unit is a combination of elements capable of converting heat into electricity, such as a semiconductor element capable of obtaining the Seebeck effect. In order to obtain stable power generation, a predetermined amount of power is required between the high temperature side and the low temperature side of the power generation unit. At the same time as the temperature difference is required, it is necessary to maintain the heat resistant temperature of the power generation unit at about 250 ° C. (solder melting temperature) or less.

Therefore, even when the temperature of the exhaust gas becomes high due to high-speed continuous operation of the automobile, it is necessary to take protective measures so that the exhaust gas temperature does not exceed the heat resistant temperature of the power generation unit. FIG. 5 shows an exhaust heat recovery system for an engine described in Japanese Utility Model Laid-Open No. 63-162916 as a conventional example having such heat-resistant protection measures.

In FIG. 5, 1 is an engine, 2 is an exhaust passage, and 3 is a bypass passage.
Is branched from the exhaust passage 2 by a branch portion composed of four branch pipes 3a to 3d. The branch pipes 3a to 3d are provided with electromagnetic valves 4a to 4d, respectively, and these electromagnetic valves 4a to 4d are connected to the controller 5 and a power generation unit 6a is provided at a predetermined position of the bypass passage 3. A temperature sensor 7 for detecting the exhaust gas temperature passing through the bypass passage 3 is provided near the power generation unit 6a, and the temperature sensor 7 is connected to the controller 5.

In FIG. 5, 8 is a catalyst provided in the main exhaust passage 2 and 12 is a storage battery. With such a configuration, the temperature sensor 7 detects the exhaust gas temperature in the vicinity of the power generation unit 6 in the bypass passage 3, and the exhaust gas temperature is detected.
The solenoid valves 4a to 4d are individually closed by the controller 5 so as not to exceed the heat resistant temperature of a, and the exhaust flow rate in the bypass passage 3 is suppressed.

[0006]

However, in such a conventional exhaust heat recovery apparatus, since the four branch pipes and the solenoid valve are provided, not only the structure is complicated and large, but also the control is gradually performed. However, there is a problem that it is difficult to obtain a stable electromotive force, and because the bypass passage has a power generation unit, exhaust heat recovery is passive.

The present invention was devised in view of the above problems, and an exhaust flow rate adjusting valve and a heat exchanger having a power generation unit are provided in the exhaust passage so that the power generation unit can be heat-resistant depending on the electromotive force of the power generation unit. To provide an exhaust heat recovery device for an engine, in which a structure is simplified and downsized by controlling an exhaust flow rate adjusting valve so that heat above a temperature is not applied and stable electromotive force is obtained by stepless adjustment. With the goal.

[0008]

Therefore, the exhaust heat recovery system for an engine according to claim 1 of the present invention recovers electrical energy from the thermal energy of the exhaust gas flowing through the exhaust passage of the engine. In the device, an exhaust flow rate adjusting valve and a heat converter having a power generation unit for recovering electric energy from exhaust heat are sequentially provided on the downstream side of the catalyst provided in the exhaust passage, and the catalyst in the exhaust passage is provided. An exhaust temperature for detecting an exhaust temperature in the exhaust passage is provided, which is provided with a bypass passage communicating with a portion between the exhaust flow adjustment valve or a portion where the exhaust flow adjustment valve is provided and which is downstream of the heat converter. Detecting means and control means for controlling the opening degree of the exhaust flow rate adjusting valve based on the detection result of the exhaust temperature detecting means so that the exhaust temperature does not exceed the heat resistant temperature of the power generation unit. It is characterized in that it was.

The exhaust heat recovery system for an engine according to a second aspect of the present invention is characterized in that the exhaust temperature detecting means is configured as means for detecting power generation information obtained by the power generation unit.

[0010]

In the exhaust heat recovery system for an engine according to the first aspect of the present invention, the exhaust temperature in the exhaust passage is detected by the exhaust temperature detecting means, and the exhaust temperature is based on the detection result. The opening of the exhaust flow rate adjusting valve is controlled by the control means so as not to exceed the limit, and the exhaust flow rate in the exhaust passage is steplessly suppressed. Then, the suppressed excess exhaust gas is discharged through the bypass passage.

In the exhaust heat recovery system for an engine according to the second aspect of the present invention, the voltage obtained by the power generation unit is detected, the temperature difference of the power generation unit is calculated by the control means from this power generation information, and the exhaust gas flow rate is calculated. The opening of the exhaust flow rate adjusting valve is controlled so as to suppress the above.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIGS. 1 to 3 show an embodiment of an exhaust heat recovery apparatus for an engine according to the present invention, and FIG. 1, FIG. 2 is a side view of the exhaust passage, FIG. 3 is a plan view of the exhaust passage, and FIG. 4 is a schematic view showing another example of the location of the exhaust flow rate adjusting valve. The same reference numerals as those in FIG. 5 indicate almost the same parts.

1 to 3, 1 is an engine, 2 is an exhaust passage as a main exhaust passage, and a catalyst 8 is provided in the exhaust passage 2. And the exhaust passage 2
On the downstream side of the catalyst 8, a heat converter 6 is provided at a position relatively close to the catalyst 8 so as to be able to receive high exhaust gas temperature after the catalyst so as to be in contact with the outer periphery of the exhaust passage 2.

In this heat converter 6, the inner side surface (high temperature side) of a power generation unit 6a made of a semiconductor element having a characteristic capable of converting heat energy into electric energy is brought into contact with the peripheral surface of the exhaust passage 2 and its outer surface ( By contacting a cooling part 6b that allows cooling water to pass therethrough, the power generation unit 6
It is configured so that a sufficient temperature difference between the high temperature side and the low temperature side of a can be secured.

A butterfly type exhaust flow rate adjusting valve 11 capable of adjusting the flow rate of exhaust gas is provided between the portion of the exhaust passage 2 where the catalyst 8 is disposed and the portion corresponding to the portion where the thermoelectric generator unit 6 is disposed. The exhaust flow rate control valve 11 is provided so that it can be moved by the actuator 10 via a cable 11a, for example. The power generation unit 6a is connected with a voltage sensor 9 as exhaust temperature detection means for detecting the electromotive force of the power generation unit 6a, which is connected with the controller 5 as control means.
It is connected to the actuator 10 from the controller 5.

That is, the controller 5 calculates the temperature difference of the power generation unit 6a based on the result of detection of the electromotive force generated in the power generation unit 6a by the voltage sensor 9, and then the actuator 10 is moved and the exhaust flow rate adjusting valve 11 is operated. The exhaust flow rate is adjusted so that the power generation unit 6a does not exceed the heat-resistant temperature by controlling the opening degree of. Furthermore, the exhaust passage 2
The bypass passage 3 is provided so as to connect the downstream side of the power generation unit 6a (heat converter 6) from between the portion where the catalyst 8 is disposed and the portion where the exhaust flow rate control valve 11 is disposed in
As a result, when the exhaust flow rate adjusting valve 11 is adjusted and throttled, excess exhaust gas can be released through this bypass passage 3. Since the exhaust flow rate adjusting valve 11 is not fully closed, it is made of a pipe thinner than the exhaust passage 2.

With the above structure, after the exhaust gas discharged from the engine 1 passes through the catalyst 8, a part of the exhaust heat energy is cooled by the cooling unit 6b in the power generation unit 6a of the heat exchanger 6 attached to the main exhaust passage 2. It is converted into electric energy by the temperature difference between and. Then, when the exhaust gas temperature becomes high, the power generation unit 6a is subjected to a high temperature higher than the heat resistant temperature (250 ° C.). Therefore, the voltage generated by the power generation unit 6a is detected by the voltage sensor 9, and this detection result After calculating the temperature difference of the power generation unit 6a on the basis of the controller 5, the controller 5 sends a movable signal to the actuator 10, and further controls the opening degree of the exhaust flow rate adjusting valve 11 via the actuator 10 to control the exhaust flow rate. It suppresses.

As described above, the excessive exhaust gas that has been suppressed flows out into the bypass passage 3, and the power generation unit 6a is prevented from having an exhaust temperature exceeding its heat resistant temperature of 250 ° C. It is designed to be protected from high heat. Therefore, in this exhaust heat recovery apparatus, since the exhaust flow rate control as the heat-resistant protection means of the power generation unit 6a is performed by the single exhaust flow rate adjusting valve 11 provided in the main exhaust passage 2, the bypass as in the conventional example is performed. A plurality of branch pipes 3a to 3d are formed in the passage 3, and a plurality of electromagnetic valves 4a to 4d provided therein can be used for stepless adjustment instead of stepwise adjustment as in the case of controlling the exhaust flow rate. As a result, the amount of power generation can be stabilized, the structure of the device can be simplified and the size can be reduced, and the manufacturing is very easy.

The thermoelectric generator unit 6 is connected to the main exhaust passage 2
Since it is provided in the bypass passage 3, the exhaust heat recovery is performed more positively than in the one provided in the bypass passage 3 and the efficiency is high, and it is not necessary to provide a catalyst in the bypass passage 3. Further, since the voltage sensor 9 directly connected to the power generation unit 6a obtains power generation information to serve as the exhaust temperature detecting means, an accurate detection result can be obtained as compared with the case where the temperature sensor 7 is separately provided, and thus a stable starting is always achieved. It is the one that can obtain electric power.

The exhaust flow rate adjusting valve 11 is not limited to the butterfly type. As shown in FIGS. 4A and 4B, the exhaust flow rate adjusting valve 11 ′ (this exhaust flow rate adjusting valve 1
1'is not limited to the butterfly type). That is, in this case, the bypass passage 3 is provided so as to communicate from the portion of the exhaust passage 2 where the exhaust flow rate adjusting valve 11 'is arranged to the downstream side of the heat converter.

[0021]

As described in detail above, according to the exhaust heat recovery system for an engine of the present invention according to claim 1, the exhaust heat of the engine for recovering electric energy from the thermal energy of the exhaust gas flowing through the exhaust passage of the engine is exhausted. In the recovery device, an exhaust flow rate adjusting valve is provided on the downstream side of the catalyst provided in the exhaust passage,
A heat converter having a power generation unit for recovering electric energy from exhaust heat is sequentially provided, and from a portion of the exhaust passage between the catalyst and the exhaust flow rate adjusting valve or a portion where the exhaust flow rate adjusting valve is disposed. A bypass passage communicating with the downstream side of the heat converter is provided, and the exhaust temperature is detected based on the exhaust temperature detecting means for detecting the exhaust temperature in the exhaust passage and the detection result of the exhaust temperature detecting means. Since the control means for controlling the opening degree of the exhaust flow rate adjusting valve is provided so as not to exceed the heat resistant temperature of the power generation unit, the power generation unit is provided in the bypass passage as in the conventional case, and a plurality of branch pipes are provided. Compared to one that controls the exhaust flow rate by providing a solenoid valve,
It has the advantages that the structure is simple and the size can be reduced, and the exhaust flow rate can be controlled steplessly to obtain a stable electromotive force.

According to the exhaust heat recovery system for an engine of the present invention according to claim 2, since the exhaust temperature detecting means is configured as means for detecting power generation information obtained by the power generation unit, the conventional temperature sensor is used. There is an advantage that the control can be performed surely and stably as compared with the detection means by.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an exhaust heat recovery system for an engine showing an embodiment of the present invention.

FIG. 2 is a side view of an exhaust passage according to the present invention.

FIG. 3 is a plan view of an exhaust passage according to the present invention.

FIG. 4 is a schematic diagram showing another example of the location of the exhaust flow rate adjusting valve.

FIG. 5 is a configuration diagram of an exhaust heat recovery device for an engine according to a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 engine 2 exhaust passage 3 bypass passage 3a-3d branch pipe 4a-4d solenoid valve 5 controller (control means) 6 heat converter 6a power generation unit 6b cooling part 7 temperature sensor 8 catalyst 9 voltage sensor (exhaust temperature detection means) 10 actuator 11, 11 'Exhaust flow rate control valve 11a Cable 12 Storage battery

Claims (2)

[Claims] 1. An exhaust heat recovery apparatus for an engine, which recovers electrical energy from thermal energy of exhaust gas flowing through an exhaust passage of an engine, wherein an exhaust flow rate adjusting valve and an exhaust heat control device are provided downstream of a catalyst provided in the exhaust passage. And a heat converter having a power generation unit for recovering electric energy from the exhaust gas, and a heat converter from a portion of the exhaust passage between the catalyst and the exhaust flow rate adjusting valve or a portion where the exhaust flow rate adjusting valve is disposed. A bypass passage communicating with a downstream side of the converter is provided, and an exhaust temperature detecting means for detecting an exhaust temperature in the exhaust passage, and an exhaust temperature of the power generation unit based on a detection result of the exhaust temperature detecting means. And a control means for controlling the opening degree of the exhaust flow rate adjusting valve so as not to exceed the heat resistant temperature of 1. 2. The exhaust heat recovery system for an engine according to claim 1, wherein the exhaust temperature detection means is configured as means for detecting power generation information obtained by the power generation unit.