JP2008184906A - Heat recovery system in internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat recovery system in an internal combustion engine enabling miniaturization and weight reduction of the heat recovery system, while allowing a cooling-water circuit and a Rankine cycle circuit to appropriately perform functions. <P>SOLUTION: This heat recovery system comprises an internal combustion engine (6) cooled by cooling water, a heat exchanger (22) for heating the cooling water by conducting the heat exchange between the cooling water and a heating medium, a cooling-water circuit (8) in which the cooling water at a rate of flow corresponding to operation conditions of the internal combustion engine is circulated through the internal combustion engine and the heat exchanger in order, an evaporator (10) for heating a working fluid by heat-exchange between the fluid and the cooling water passed through the heat exchanger, an expansion device (12), and a condenser (14). In the heat recovery system, a Rankine cycle circuit (4) is provided in which the working fluid having been passed through the condenser is passed through the evaporator, the cooling-water circuit is provided with a means for controlling a heat-absorption quantity by which the heat-absorption quantity absorbed by the cooling water in the heat exchanger is restricted in accordance with the operation condition of the internal combustion engine. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an internal combustion engine waste heat utilization device, and more particularly to an internal combustion engine waste heat utilization device suitable for a vehicle.

As a waste heat utilization device for an internal combustion engine, for example, in a vehicle engine, a Rankine cycle circuit is formed using components of a refrigeration cycle to recover power of the waste heat of the internal combustion engine, and the recovered power is used to recover the engine power. A technique for assisting axis output is known.
A Rankine cycle circuit that recovers engine waste heat by further heating the high-temperature cooling water after cooling the engine body with the heat of the exhaust gas from the engine and sending this superheated cooling water to the evaporator of the refrigeration cycle is known. Yes (see, for example, Patent Document 1).
JP-A-57-99222

By the way, at the time of the maximum output of the engine, the engine main body becomes the highest temperature. Therefore, in order to ensure the cooling performance of the engine, the superheated cooling water must be sufficiently absorbed by the evaporator.
However, in the above prior art, assuming the maximum output of the engine, the evaporator that absorbs the superheated cooling water, and the cooling water that has passed through the evaporator is expanded by an expander to recover the power, and then the expanded cooling is performed. There is a problem that the heat capacity of the condenser for condensing water must be increased, and the Rankine cycle circuit including the evaporator and the condenser, and thus the waste heat utilization device cannot be reduced in size and weight.

  The present invention has been made in view of such a problem, and is a waste heat utilization device for an internal combustion engine capable of realizing a reduction in size and weight of the waste heat utilization device while properly functioning a cooling water circuit and a Rankine cycle circuit. The purpose is to provide.

  To achieve the above object, an internal combustion engine waste heat utilization apparatus according to claim 1 is an internal combustion engine cooled by cooling water, and a heat exchanger that heats cooling water by exchanging heat between the cooling water and a heat medium. A cooling water circuit in which cooling water having a flow rate according to the operating state of the internal combustion engine circulates sequentially through the internal combustion engine and the heat exchanger, and a working fluid that exchanges heat with the cooling water through the heat exchanger An evaporator that heats the working fluid, an expander that generates a driving force by expanding the working fluid that passes through the evaporator, and a condenser that condenses the working fluid that passes through the expander. And a Rankine cycle circuit that circulates via the heat sink, and the cooling water circuit has an endothermic amount control means that limits the amount of heat absorbed by the cooling water from the heat medium in the heat exchanger according to the operating state of the internal combustion engine. It is characterized by.

In the invention according to claim 2, the endothermic amount control means comprises a detection end for detecting the operating state of the internal combustion engine and an operation end for limiting the endothermic amount in accordance with a signal from the detection end,
The Rankine cycle circuit further includes a pump that is driven to circulate the working fluid, and the heat absorption amount control means is such that when the operating state of the internal combustion engine detected at the detection end requires warming up of the internal combustion engine, The operation end is driven so that the driving of the pump is stopped and the heat absorption amount is increased.

  Furthermore, in the invention according to claim 3, the cooling water circuit is installed at an evaporator bypass path that bypasses the evaporator, and at a junction point between the evaporator bypass path and the downstream of the evaporator, and the temperature of the cooling water at the junction point. And a mechanical switching valve for passing cooling water through the evaporator when the temperature is equal to or higher than a predetermined temperature set value, and the detection end is a temperature sensor for detecting the temperature of the cooling water circulating in the cooling water circuit. The operation end is driven so that the endothermic amount becomes smaller when the coolant temperature detected by the temperature sensor is larger than a predetermined second temperature set value, and the second temperature set value is set to be equal to or higher than the temperature set value. It is characterized by that.

Furthermore, in the invention according to claim 4, the detection end is a second temperature sensor for detecting the temperature of the heat medium, and the operation end is driven according to the temperature of the heat medium detected by the second temperature sensor. It is characterized by being.
In the invention according to claim 5, the cooling water circuit further includes a heat exchanger bypass passage for bypassing the heat exchanger, and the operation end supplies the cooling water via the internal combustion engine in accordance with a signal from the detection end. It is a linear three-way valve that controls the distribution of the cooling water amount so as to distribute the flow into the heat exchanger bypass and the heat exchanger and limit the amount of cooling water flowing into the heat exchanger.

  Furthermore, in the invention described in claim 6, the heat exchanger is an exhaust gas heat exchanger installed in an exhaust gas pipe through which exhaust gas flows using the exhaust gas of the internal combustion engine as a heat medium, and the operation end is a signal from the detection end. The exhaust gas is distributed to the heat exchanger side and the counter heat exchanger side in the exhaust gas pipe, and the exhaust gas amount distribution control is performed to limit the amount of exhaust gas heat exchanged by the heat exchanger. It is characterized by being.

  Therefore, according to the waste heat utilization apparatus for an internal combustion engine of the first aspect of the present invention, the heat absorption amount control means of the cooling water circuit determines the heat absorption amount that the cooling water absorbs heat from the heat medium in the heat exchanger. Restrict according to the state. Thereby, at the time of the maximum output of the internal combustion engine having the highest cooling request of the internal combustion engine, the heat capacity of the evaporator and the condenser of the Rankine cycle circuit can be reduced by preventing the cooling water from absorbing heat from the heat medium. . Therefore, the Rankine cycle circuit including the evaporator and the condenser and the waste heat utilization device can be reduced in size and weight while properly functioning the cooling water circuit and the Rankine cycle circuit.

According to the second aspect of the present invention, when the internal combustion engine is warmed up, the Rankine cycle circuit function is stopped and heat absorption from the cooling water in the evaporator is not performed, so the internal combustion engine is warmed up quickly. The cooling water circuit and the Rankine cycle circuit can function more appropriately.
Further, according to the invention of claim 3, the operating end is driven so that the endothermic amount becomes small when the coolant temperature detected by the temperature sensor is larger than the second temperature set value, and the second temperature set. The value is set to be equal to or higher than the temperature setting value of the switching valve. That is, when there is a request to reduce the heat absorption amount from the cooling water, the control by the heat absorption amount control means is prioritized over the control of the switching valve to prevent interference between the controls and to make the heat absorption amount control means function more reliably. Can do.

  Furthermore, according to the invention of claim 4, the heat absorption control means limits the heat absorption of the cooling water from the heat medium, and the detection end for detecting the operating state of the internal combustion engine in the heat absorption amount control means is provided. If a second temperature sensor that detects the temperature of the heat medium is used, and the operation end is driven according to the output of the second temperature sensor, the suction is performed as compared with the case where the operation end is driven according to the detected coolant temperature. The control response of heat quantity control can be greatly improved.

  According to the invention described in claim 5, the linear three-way valve as the operation end distributes and flows the cooling water to the heat exchanger bypass and the heat exchanger, and circulates the cooling water in the cooling water circuit. Cooling water amount distribution control is performed to limit the flow rate of cooling water flowing into the heat exchanger while maintaining it. As a result, even if the flow rate of the cooling water circulating in the cooling water circuit increases, the increased amount of cooling water is sent to the heat exchanger while properly controlling the heat absorption amount of the cooling water according to the heat capacity of the Rankine cycle circuit. Without flowing through the heat exchanger bypass, the circulation of the cooling water can be prevented from being hindered by the flow resistance of the cooling water in the evaporator. Therefore, the cooling performance of the internal combustion engine can be maintained while performing the control by the endothermic amount control means.

  Furthermore, according to the invention described in claim 6, the linear damper as the operation end includes a heat exchanger side for exchanging heat of the exhaust gas with the cooling water, and a counter heat exchanger side for discharging the exhaust gas to the outside without performing heat exchange with the cooling water. The exhaust gas amount distribution control is performed to directly limit the flow rate of the exhaust gas itself which is the heat medium flowing into the exhaust gas heat exchanger. Thereby, the heat absorption amount of the cooling water can be controlled more accurately and quickly in accordance with the heat capacity of the Rankine cycle circuit, and the control accuracy and control response of the heat absorption amount control means can be greatly improved.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
First, the first embodiment will be described.
FIG. 1 is a schematic diagram showing a configuration of a waste heat utilization device 2 for an internal combustion engine according to the present embodiment. The waste heat utilization device 2 cools a Rankine cycle circuit 4 and, for example, a vehicle engine (internal combustion engine) 6. And a cooling water circuit 8 through which the cooling water is circulated.

The Rankine cycle circuit 4 includes an evaporator 10, an expander 12, a condenser 14, a receiver 16, and a pump 18, and the working fluid is converted into the evaporator 10, the expander 12, and the condenser by the operation of the pump 18. 14 circulates sequentially through the liquid receiver 16.
The evaporator 10 is a heat exchanger that heats the working fluid by exchanging heat between the working fluid delivered from the pump 18 and the high-temperature cooling water flowing through the cooling water circuit 8. Although not shown, the evaporator 10 includes a cooling water path that guides the cooling water and a working fluid path that guides the working fluid. The cooling water path and the working fluid are provided between the cooling water path and the working fluid path. A boundary wall that divides the route is provided.

The expander 12 is a fluid device that generates a driving force related to rotation or the like by expansion of a working fluid that is heated by the evaporator 10 and is in a superheated steam state. Further, for example, a generator 20 is connected to the expander 12, and the driving force generated in the expander 12 via the generator 20 can be used outside the waste heat utilization apparatus 2.
The condenser 14 is a heat exchanger that condenses and liquefies the working fluid discharged from the expander 12 by heat exchange with the outside air. Specifically, the condenser 14 includes an electric fan 15 that is driven when the temperature difference ΔT between the outside air temperature To and the condensing temperature Tc specific to the working fluid becomes equal to or greater than a predetermined temperature difference set value ΔTs. The working fluid is actively exchanged heat with the outside air.

The liquid receiver 16 is a receiver that separates the working fluid condensed by the condenser 14 into two layers of gas and liquid. Only the liquefied working fluid separated here is discharged to the pump 18 side, and this liquefied working fluid is pumped. The Rankine cycle circuit 4 as a closed circuit is formed by re-entering the evaporator 10 by the operation of 18.
On the other hand, the cooling water circuit 8 includes an exhaust gas heat exchanger (heat exchanger) 22, a thermostat (switching valve) 24, and a pump 26, and the cooling water is supplied to the engine 6 and the exhaust gas heat exchanger 22 by the operation of the pump 26. The high-temperature cooling water after circulating through the evaporator 10 and the thermostat 24 in order and cooling the engine 6 is further heated by the exhaust gas heat exchanger 22, and then the evaporator 10 absorbs heat into the working fluid of the Rankine cycle circuit 4. To be cooled.

The exhaust gas heat exchanger 22 is provided in the exhaust gas pipe 28 through which the exhaust gas (heat medium) of the engine 6 flows out, and performs heat exchange between the cooling water heated by the engine 6 and the exhaust gas flowing through the exhaust gas pipe 28. Thus, the cooling water is further heated.
The thermostat 24 has two inlet ports and one outlet port, and switches the inlet port according to the cooling water temperature of the cooling water to be passed or sets the flow rate of the cooling water to be passed to each inlet port. This is a mechanical switching valve capable of distribution control. A bypass path (evaporator bypass path) 30 that bypasses the evaporator 10 and joins the flow path 8 a of the cooling water circuit 8 formed between the evaporator 10 and the pump 26 is provided at one inlet port of the thermostat 24. Is connected.

  Thus, the thermostat 24 adjusts the flow rate of the cooling water flowing through the evaporator 10 and the bypass passage 30 according to the cooling water temperature to control the heat absorption amount of the cooling water absorbed by the evaporator 10. The temperature Te is kept substantially constant. Specifically, the thermostat 24 is set in advance such that when the temperature of the cooling water is equal to or higher than a predetermined temperature set value Tt, the cooling water is allowed to flow through the inlet port to which the evaporator 10 is connected.

The pump 26 is attached to the engine 6 and operates according to the rotational speed of the engine 6 to circulate the cooling water in the cooling water circuit 8.
Note that a radiator (not shown) may be installed in series with the evaporator 10 so as to assist cooling of the cooling water by heat exchange with the outside air.
By the way, a linear three-way valve (operation end) 32 is installed between the engine 6 and the exhaust gas heat exchanger 22. The three-way valve 32 is an electric valve having one inlet port and two outlet ports, and continuously drives one valve body in a variable manner in proportion to an input signal input to the drive unit of the three-way valve 32. By doing so, the cooling water flowing into the inlet port is distributed and discharged to each outlet port, and these distributed flow rates can be finely adjusted.

  Specifically, the three-way valve 32 is inserted in the flow path 8b of the cooling water circuit 8 between the engine 6 and the heat exchanger 22, and the engine 6 side of the flow path 8b is connected to the inlet port. The heat exchanger 22 side of the flow path 8b is connected to the outlet port. On the other hand, the other outlet port is branched from the flow path 8b via the three-way valve 32, and bypasses the heat exchanger 22 to the flow path 8c between the heat exchanger 22 and the evaporator 10. A joining bypass path (heat exchanger bypass path) 34 is connected. The bypass path 34 is partly shared with the bypass path 30 of the evaporator 10.

  Accordingly, the cooling water flowing through the flow path 8b is distributed to the bypass path 34 and the flow path 8c by the three-way valve 32 (cooling water amount distribution control). Here, if the cooling water flow rate flowing through the flow path 8b is the total flow rate Ft, the cooling water flow rate flowing through the bypass path 34 is the bypass flow distribution flow rate Fb, and the cooling water flow rate flowing through the flow path 8c is the heat exchanger distribution flow rate Fhe, The relational expression of flow rate Ft = bypass passage distribution flow rate Fb + heat exchanger distribution flow rate Fhe is substantially established, and the three-way valve 32 has a structure that does not become a large pressure loss element when viewed from the whole cooling water circuit 8.

  On the other hand, a cooling water temperature sensor (detection end, temperature sensor) 36 for detecting the temperature Tw of the cooling water flowing into the engine 6 is provided in the flow path 8a, and the temperature of the exhaust gas discharged from the engine 6 is provided in the exhaust gas pipe 28. An exhaust gas temperature sensor (detection end, second temperature sensor) 38 for detecting Tg is provided. As other sensors, an engine temperature sensor 40 that directly detects the temperature Te of the main body of the engine 6 and an engine rotation speed sensor (detection end) 42 that detects the rotation speed of the engine 6 are mounted on the engine 6.

These sensors 36, 38, 40, 42 serving as detection ends and the three-way valve 32 serving as an operation end are electrically connected to an electronic control unit (ECU) 44 that performs overall control of the vehicle and the waste heat utilization device 2. The ECU 44 outputs a signal to drive and control a desired outlet port of the three-way valve 32 to a desired opening based on the input signals detected from these sensors.
Specifically, a sub-control routine for controlling the heat absorption amount of the cooling water that drives the three-way valve 32 is executed according to the cooling water temperature Tw detected by the temperature sensor 36, and this sub-control routine is detected by the temperature sensor 40. The control is controlled by a main control routine which is engine warm-up control for controlling execution and stop of the heat absorption amount according to the temperature Te of the engine 6 body, and these control routines are processed in the ECU 44 (heat absorption amount control means).

Hereinafter, engine warm-up control will be described with reference to the flowchart shown in FIG.
First, when engine warm-up control is started in S0 (hereinafter, S represents a step), the process proceeds to S1.
In S1, it is determined whether or not the temperature Te of the engine 6 body detected by the temperature sensor 40 is equal to or lower than a predetermined temperature set value TL1. When the determination result is true (Yes) and the temperature Te is determined to be equal to or lower than the temperature set value TL1, the process proceeds to S2, and when the determination result is false (No) and the temperature Te is determined to be greater than the temperature set value TL1. To S3.

When the process proceeds to S2, the currently executed heat absorption amount control is stopped, and the already stopped heat absorption amount control is stopped and the process proceeds to S4.
In S4, the pump 18 of the Rankine cycle circuit 4 is stopped and the process proceeds to S5.
In S5, the three-way valve 32 is forcibly fully opened to the heat exchanger 22 side and simultaneously closed to the bypass path 34 side.

On the other hand, when the process proceeds to S3 in S1, the stopped heat absorption amount control is activated, and the already activated heat absorption amount control is left activated.
Thus, when the main control routine related to engine warm-up control is started in S0, a series of control routines of S1 to S5, or S1 and S3 are repeatedly executed.
Hereinafter, the endothermic control executed in S3 will be described with reference to the flowchart shown in FIG.

First, when the endothermic control is started in S00, the pump 18 is operated and the process proceeds to S10.
In S10, it is determined whether or not the coolant temperature Tw detected by the temperature sensor 36 is equal to or lower than a predetermined temperature set value TL2. When the determination result is true (Yes) and the temperature Tw is determined to be equal to or lower than the temperature set value TL2, the process proceeds to S20, and when the determination result is false (No) and the temperature Tw is determined to be greater than the temperature set value TL2. To S30.

When the process proceeds to S20, the three-way valve 32 is driven to open on the heat exchanger 22 side and simultaneously closed on the bypass path 34 side.
On the other hand, when the process proceeds to S30 in S10, the three-way valve 34 is driven to open toward the bypass path 34 and simultaneously closed to the heat exchanger 22 side.
Here, in S10, the exhaust gas temperature sensor 38 is used as a detection end instead of the cooling water temperature sensor 36, and it is determined whether or not the exhaust gas temperature Tg detected by the exhaust gas temperature sensor 38 is equal to or lower than a predetermined temperature set value TL3. May be. Further, the temperature setting value TL2 of the cooling water temperature Tw is set to be equal to or higher than the temperature setting value Tt of the thermostat 24.

In this way, when the sub control routine related to the heat absorption amount control is started in S00, a series of control routines of S10 and S20 or S10 and S30 are repeatedly executed.
As described above, in the present embodiment, the three-way valve 32 is controlled so that the cooling water temperature Tw flowing into the engine 6 becomes equal to or lower than the temperature set value TL2 by executing the heat absorption amount control of the cooling water in the cooling water circuit 8. Drive control is performed, and the amount of heat absorbed by the cooling water from the exhaust gas in the heat exchanger 22 is limited according to the operating state of the engine 6.

  On the other hand, the Rankine cycle circuit 4 absorbs heat in the evaporator 10 from both the main body of the engine 6 and the exhaust gas discharged from the engine 6 through the cooling water circulating in the cooling water circuit 8, and the waste heat of the engine 6 is removed. Collected and used. Here, by limiting the amount of heat absorbed from the exhaust gas by controlling the amount of heat absorbed, the heat absorbed from the cooling water in the Rankine cycle circuit 4, that is, the evaporator 10, is only from the high-temperature cooling water after cooling the main body of the engine 6. Can be limited.

  As a result, the heat capacities of the evaporator 10 and the condenser 14 can be set with only the endothermic amount required for the high-temperature cooling water heated by the engine 6 at the maximum output of the engine 6 as the maximum endothermic amount. Since it is not necessary to consider the amount of heat, the heat capacities of the evaporator 10 and the condenser 14 can be reduced. Therefore, it is possible to reduce the size and weight of the Rankine cycle circuit 4 and thus the waste heat utilization device 2 while causing the coolant circuit 8 and the Rankine cycle circuit 4 to function properly.

  In addition, since this heat absorption amount control is governed by the engine warm-up control, when the body temperature Te of the engine 6 becomes equal to or lower than the temperature set value TL1, and the engine 6 needs to be warmed up, the heat absorption amount control is performed. And the pump 18 is stopped so that the Rankine cycle circuit 4 does not function, and the three-way valve 32 is fully opened to the heat exchanger 22 side. Thereby, the cooling water circulating through the cooling water circuit 4 when the engine 6 is warmed up is prevented from being absorbed by the Rankine cycle circuit 4, and the cooling water can be positively heated by the heat of the exhaust gas. The engine 6 can be warmed up quickly.

Furthermore, by making the temperature setting value TL2 of the cooling water, which is the driving condition of the three-way valve 32, equal to or higher than the temperature setting value Tt set by the thermostat 24, the control by the thermostat 24 is prevented from interfering with the heat absorption amount control. Thus, the heat absorption amount control and the engine warm-up control can be functioned more reliably.
Furthermore, if the exhaust gas temperature sensor 38 is used instead of the cooling water temperature sensor 36 as a detection end of the heat absorption control, the maximum heat absorption amount of the cooling water flowing into the evaporator 10 does not exceed the heat capacity of the evaporator 10. In view of the purpose of the heat absorption amount control in which the heat absorption amount control is performed, the control response of the heat absorption amount control is greatly increased compared to the case where the temperature sensor 36 is used as the detection end and the three-way valve 32 is driven and controlled according to the cooling water temperature Tw. Can be improved.

By the way, the total flow rate Ft of the cooling water increases at the maximum output of the engine 6, but the increase in the total flow rate Ft causes the heat exchanger 22 to become a pressure loss element in the cooling water circuit 8 and increase the flow resistance of the cooling water. As a result, the circulation of the cooling water in the cooling water circuit 8 is hindered, and the cooling performance of the engine 6 is deteriorated.
However, in this embodiment, the heat exchanger distribution flow rate Fhe is limited to a substantially constant value or less by bypassing the heat exchanger 22 at the maximum output of the engine 6 by performing the cooling water amount distribution control. Can do. Therefore, the cooling water circulation resistance in the heat exchanger 22 does not hinder the circulation of the cooling water in the cooling water circuit 8, and the cooling performance of the engine 6 can be maintained.

If the cooling water stays in the heat exchanger 22, the staying cooling water is heated by the exhaust gas heat and boils and adversely affects the entire cooling water circuit 8. Therefore, the heat exchanger distribution flow rate Fhe is not set to zero, and a predetermined amount is obtained. Is preferably ensured.
The fan 15 of the condenser 14 is electrically connected to the ECU 44, and is driven when the temperature difference ΔT between the outside air temperature To and the condensation temperature Tc inherent to the working fluid becomes equal to or higher than the temperature difference set value ΔTs. Therefore, when ΔT is smaller than ΔTs depending on the vehicle speed, it is preferable to stop the fan 15 to reduce the amount of power generation related to the driving of the fan 15 and promote energy saving of the waste heat utilization device 2.

Next, a second embodiment will be described.
As shown in FIG. 4, the waste heat utilization device 46 of the second embodiment uses a linear damper (operation end) 48 as an operation end instead of the linear three-way valve 34 and excludes the bypass path 34. Except for these, the configuration is the same as that of the first embodiment, and therefore, differences from the first embodiment will be mainly described.

  The damper 48 is provided in the exhaust gas pipe 28, and the exhaust gas pipe 28 has a passage 28 a (heat exchanger side) on the side where the heat exchanger 22 is installed and a bypass path 28 b (on the side bypassing the heat exchanger 22). It is connected to a partition wall 48a partitioned into a heat exchanger side) via a drive unit 48b. The drive unit 48b is electrically connected to the ECU 44, and the damper 48 is continuously variably driven in proportion to an input signal input to the drive unit 48b, and is in contact with a tube which is a cooling water path in the heat exchanger 22. The exhaust gas amount to be adjusted is finely adjustable and functions as an operation end for controlling the endothermic amount of the cooling water (exhaust gas amount distribution control).

  Hereinafter, the engine warm-up control and the heat absorption amount control of the present embodiment executed by the ECU 44 will be described with reference to the flowcharts shown in FIGS. In the control routine of these controls, the steps different from the first embodiment are only S5, S20, and S30. Steps that replace these steps are mainly described as S5 ′, S20 ′, and S30 ′, respectively, and other steps. Description of is omitted.

In engine warm-up control, after passing through S0, S1, and S2, the pump 18 is stopped in S4, and then the process proceeds to S5 ′.
In S5 ′, the movable portion 48b of the damper 48 is forcibly driven so that the flow path on the passage 28a side is maximum, that is, fully opened, and at the same time, the flow path on the bypass path 28b side is driven to be fully closed.

On the other hand, in the endothermic control, if the determination result is true (Yes) in S10 after S00 and the temperature Tw is determined to be equal to or lower than the temperature set value TL2, the process proceeds to S20 ′, and the determination result is false (No). When it is determined that the temperature Tw is higher than the temperature set value TL2, the process proceeds to S30 ′.
When the process proceeds to S20 ′, the damper 48 is driven in the direction in which the flow path on the side of the passage 28a is opened, and at the same time, the damper 48 is driven in the direction in which the flow path on the side of the bypass path 28b is closed.

On the other hand, when the process proceeds to S30 ′ in S10, the damper 48 is driven in a direction in which the flow path on the bypass passage 28b side is opened, and at the same time, is driven in a direction in which the flow path on the passage 28a side is closed.
Thus, when the main control routine related to engine warm-up control is started in S0, a series of control routines of S1 to S5 ′ or S1 and S3 are repeatedly executed, and the heat absorption amount control is executed in S3. Then, a sub control routine related to the heat absorption amount control is started in S00, and a series of control routines of S10 and S20 ′ or S10 and S30 ′ are repeatedly executed (heat absorption amount control means).

As described above, in the waste heat utilization apparatus 46 according to the second embodiment as well as in the first embodiment, the heat absorption amount control using the damper 48 as the operation end is executed, so that the engine 6 is at the maximum output of the engine 6. It is possible to set the heat capacities of the evaporator 10 and the condenser 14 as the maximum heat absorption amount only for the heat absorption amount required for the cooling water heated in step S2.
Further, as in the first embodiment, the heat absorption control is controlled by the engine warm-up control, so that the engine 6 can be warmed up quickly, and the control by the thermostat 24 and the heat absorption control are performed. By preventing the interference, it is possible to make the heat absorption amount control function more reliably.

In particular, in the present embodiment, the exhaust gas amount distribution control is performed, so that the endothermic amount of the cooling water is converted into the evaporator 10 of the Rankine cycle circuit 4 as compared with the case where the cooling water amount distribution control of the first embodiment is performed. Therefore, it is possible to control more accurately and quickly according to the heat capacity, and to greatly improve the control accuracy and control response of the heat absorption control.
Therefore, the Rankine cycle circuit 4 including the evaporator 10 and the condenser 14 and the waste heat utilization apparatus 2 can be reduced in size and weight while further functioning the cooling water circuit 8 and the Rankine cycle circuit 4 more appropriately.

Although the description of the embodiment of the present invention has been completed above, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention.
For example, in each of the above embodiments, the three-way valve 32 and the damper 48 that are operation ends are driven and controlled according to the outputs of the cooling water temperature sensor 36 or the exhaust gas temperature sensor 38 and the engine temperature sensor 40 that are detection ends. The engine speed sensor 42 may be used in place of the temperature sensors 36, 38, and 40. Generally, since the signal of the speed sensor 42 is already taken into the ECU 44, it is easy to use only this signal. The heat absorption amount control can be executed with a simple configuration, and the temperature sensors 36, 38, 40 are not required, and the cost of the waste heat utilization apparatus 2 can be reduced.

It is the schematic diagram which showed the waste-heat utilization apparatus of the internal combustion engine which concerns on 1st Embodiment of this invention. 3 is a flowchart showing a control routine for engine warm-up control executed by the ECU of FIG. 1. 2 is a flowchart showing a control routine of heat absorption control executed by the ECU of FIG. 1. It is the schematic diagram which showed the waste-heat utilization apparatus of the internal combustion engine which concerns on 2nd Embodiment of this invention. 5 is a flowchart showing a control routine for engine warm-up control executed by the ECU of FIG. 4. 5 is a flowchart showing a control routine of heat absorption amount control executed by the ECU of FIG. 4.

Explanation of symbols

2,46 Waste heat utilization equipment 4 Rankine cycle circuit 6 Engine (internal combustion engine)
8 Cooling water circuit 10 Evaporator 12 Expander 14 Condenser 22 Exhaust gas heat exchanger (heat exchanger)
24 Thermostat (switching valve)
28 Exhaust gas pipe 30 Bypass path (evaporator bypass path)
32 Linear three-way valve (operating end)
34 Bypass (heat exchanger bypass)
36 Cooling water temperature sensor (temperature sensor, detection end)
38 Exhaust gas temperature sensor (second temperature sensor, detection end)
42 Engine speed sensor (detection end)
48 Linear damper (operating end)

Claims (6)

An internal combustion engine cooled by cooling water;
A heat exchanger that heats the cooling water by exchanging heat between the cooling water and a heat medium, and the cooling water having a flow rate according to an operating state of the internal combustion engine sequentially passes through the internal combustion engine and the heat exchanger. A circulating cooling water circuit,
An evaporator that heats the working fluid by exchanging heat with the cooling water via the heat exchanger, an expander that generates a driving force by expanding the working fluid that passes through the evaporator, and an operation that passes through the expander A Rankine cycle circuit including a condenser for condensing the fluid, and a working fluid passing through the condenser is circulated through the evaporator,
The cooling water circuit includes an endothermic amount control means for limiting an amount of heat absorbed by the cooling water from the heat medium in the heat exchanger according to an operating state of the internal combustion engine. Heat utilization device. The endothermic amount control means includes a detection end for detecting an operating state of the internal combustion engine, and an operation end for limiting the endothermic amount according to a signal from the detection end,
The Rankine cycle circuit further includes a pump driven to circulate the working fluid;
The heat absorption amount control means stops the driving of the pump and increases the amount of heat absorption when the operating state of the internal combustion engine detected at the detection end requires warming up of the internal combustion engine. 2. The waste heat utilization apparatus for an internal combustion engine according to claim 1, wherein the operation end is driven as described above. The cooling water circuit is installed at an evaporator bypass passage that bypasses the evaporator, and a junction between the evaporator bypass passage and the downstream of the evaporator, and the temperature of the cooling water at the junction is set to a predetermined temperature. A mechanical switching valve that allows the cooling water to flow through the evaporator when the value is equal to or greater than the value;
The detection end is a temperature sensor that detects the temperature of cooling water circulating in the cooling water circuit,
The operation end is driven so that the endothermic amount becomes small when a coolant temperature detected by the temperature sensor is larger than a predetermined second temperature set value set to be equal to or higher than the predetermined temperature set value. The waste heat utilization apparatus for an internal combustion engine according to claim 2, The detection end is a second temperature sensor that detects the temperature of the heat medium,
The waste heat utilization device for an internal combustion engine according to claim 2, wherein the operating end is driven in accordance with the temperature of the heat medium detected by the second temperature sensor. The cooling water circuit further includes a heat exchanger bypass that bypasses the heat exchanger,
The operating end distributes and flows cooling water that has passed through the internal combustion engine to the heat exchanger bypass and the heat exchanger in accordance with a signal from the detection end, and flows into the heat exchanger The waste heat utilization apparatus for an internal combustion engine according to any one of claims 2 to 4, wherein the apparatus is a linear three-way valve that performs cooling water amount distribution control so as to limit the cooling water amount. The heat exchanger is an exhaust gas heat exchanger installed in an exhaust gas pipe through which the exhaust gas flows, using the exhaust gas of the internal combustion engine as the heat medium,
The operation end distributes the exhaust gas to the heat exchanger side and the counter heat exchanger side in the exhaust gas pipe in accordance with a signal from the detection end, and exchanges heat with the heat exchanger. The waste heat utilization apparatus for an internal combustion engine according to any one of claims 2 to 4, wherein the apparatus is a linear damper that performs exhaust gas amount distribution control to limit the exhaust gas amount.

Images