Exhaust heat recovery apparatus

Abstract

Provided is an exhaust heat recovery apparatus that includes: an exhaust heat recovery unit that recovers thermal energy from exhaust gas discharged from a heat engine; and a power transmission-switching device that cuts off the connection between an output shaft of the heat engine and an output shaft of the exhaust heat recovery unit when the heat engine is started. With the exhaust heat recovery apparatus, the reduction in the power output from the heat engine, from which exhaust heat is recovered, is suppressed when the exhaust heat of the heat engine is recovered.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The features, advantages thereof, and technical and industrial significance of this invention will be better understood by reading the following detailed description of preferred embodiments of the invention, when considered in connection with the accompanying drawings, in which:

FIG. 1 is a sectional view showing a Stirling engine, which functions as an exhaust heat recovery means of an exhaust heat recovery apparatus according to an embodiment;

FIG. 2 is a sectional view showing an example of the construction of an air bearing that the Stirling engine includes, which functions as the exhaust heat recovery means of the exhaust heat recovery apparatus according to the embodiment;

FIG. 3 is an explanatory diagram showing an example of an approximately linear motion linkage, which is used to support a piston;

FIG. 4 is an overall view showing a configuration of the exhaust heat recovery apparatus according to the embodiment;

FIG. 5 is an explanatory diagram showing a configuration of a start controller for controlling the starting of the exhaust heat recovery apparatus according to the embodiment;

FIG. 6 is a flow chart showing a procedure of the starting control of the exhaust heat recovery apparatus according to the embodiment;

FIGS. 7 to 10 are exemplary diagrams for explaining a method of determining an index that is used to determine whether the Stirling engine can operate in a self-sustaining manner, in the starting control of the exhaust heat recovery apparatus according to the embodiment;

FIG. 11 is a flow chart showing a procedure of the starting control according to a modified example of the exhaust heat recovery apparatus according to the embodiment; and

FIG. 12 is a diagram for explaining the starting control according to the modified example of the exhaust heat recovery apparatus according to the embodiment.

Claims

1. An exhaust heat recovery apparatus, comprising: an exhaust heat recovery unit that recovers thermal energy from exhaust gas discharged from a heat engine; anda power transmission-switching device that cuts off the connection between an output shaft of the heat engine and an output shaft of the exhaust heat recovery unit when the heat engine is started.

2. The exhaust heat recovery apparatus according to claim 1, wherein the power transmission-switching device connects the output shaft of the heat engine and the output shaft of the exhaust heat recovery unit when it becomes possible for the exhaust heat recovery unit to operate in a self-sustaining manner.

3. The exhaust heat recovery apparatus according to claim 2, wherein, when a temperature of a heater that the exhaust heat recovery unit includes exceeds a predetermined, starting-time target heater temperature, the power transmission-switching device determines that the exhaust heat recovery unit can operate in a self-sustaining manner.

4. The exhaust heat recovery apparatus according to claim 3, wherein the starting-time target heater temperature is determined so as to keep the temperature of the heater after the exhaust heat recovery unit is started equal to or higher than a heater temperature that is required for the exhaust heat recovery unit to operate in a self-sustaining manner at a cranking speed at which the exhaust heat recovery unit is started.

5. The exhaust heat recovery apparatus according to claim 4, wherein the starting-time target heater temperature has a value obtained by adding a difference between a temperature that the heater has while, although the heater is being supplied with the exhaust gas, the exhaust heat recovery unit is stopped, and a temperature that the heater has when the exhaust heat recovery unit is in steady operation at the cranking speed, to the heater temperature that is required for the exhaust heat recovery unit to operate in a self-sustaining manner.

6. The exhaust heat recovery apparatus according to claim 2, wherein, when a time integral of a difference between a predetermined, starting-time target heater temperature and a temperature of the exhaust gas flowing onto a heater, from when the temperature of the exhaust gas flowing onto the heater exceeds the starting-time target heater temperature, exceeds a predetermined target value for determination, the power transmission-switching device determines that the exhaust heat recovery unit can operate in a self-sustaining manner.

7. The exhaust heat recovery apparatus according to claim 6, wherein the starting-time target heater temperature is determined so as to keep the temperature of the heater after the exhaust heat recovery unit is started equal to or higher than a heater temperature that is required for the exhaust heat recovery unit to operate in a self-sustaining manner at a cranking speed at which the exhaust heat recovery unit is started.

8. The exhaust heat recovery apparatus according to claim 7, wherein the starting-time target heater temperature has a value obtained by adding a difference between a temperature that the heater has while, although the heater is being supplied with the exhaust gas, the exhaust heat recovery unit is stopped, and a temperature that the heater has when the exhaust heat recovery unit is in steady operation at the cranking speed, to the heater temperature that is required for the exhaust heat recovery unit to operate in a self-sustaining manner.