JP2011052662A - Waste heat recovery device for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve heating capacity in starting and also improve energy recovery efficiency by a rankine cycle. <P>SOLUTION: This waste heat recovery device for a vehicle includes: a heat storage 16 provided on the upstream side of the air conditioning heater 17 of the cooling water circulation passage 10 of an engine 1 and storing cooling water; a rankine cycle system 30 provided with a first heat exchanger 32 performing heat exchange between exhaust gas from the engine 1 and working fluid circulating in the circulation passage and a second heat exchanger 33 performing heat exchange between the cooling water introduced from the upstream side of the heat storage 16 and the working fluid; a first operating valve 18 and a second operating valve 19 which open/close the cooling water inlet of the heat storage 16; and a third operating valve 20 for opening/closing the cooling water outlet of the heat storage 16. When the engine is stopped or when the engine is started, the first operating valve 18 and second operating valve 19 are closed, and also the third operating valve 20 is opened. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a vehicle waste heat recovery apparatus, and more particularly, to a waste heat recovery technique for an engine equipped with a Rankine cycle system.

For the purpose of improving fuel efficiency, vehicles equipped with a Rankine cycle system that uses the waste heat of the engine have been proposed.
The Rankine cycle system is configured by interposing a heat exchanger and an expander in a circulation path for circulating a working fluid such as Ra134. For example, the thermal energy of the exhaust gas of the engine is recovered by the heat exchanger and expanded. It is a system that converts power into power. And, for example, by driving a generator with this power, it is possible to effectively utilize the energy that has been discarded so far.

  Furthermore, a system has been developed that effectively utilizes the thermal energy remaining in the working fluid after passing through the expander by warming the engine coolant with the working fluid after passing through the expander. The system includes, for example, a heat exchanger that exchanges heat with cooling water supplied to an air conditioning heater at the rear stage of the expander of the Rankine cycle (Patent Document 1).

JP 2005-42618 A

  However, even if the waste heat in the Rankine cycle system is used for heating the engine cooling water as described above, for example, when the exhaust temperature is not sufficiently increased in the winter, such as when the engine is stopped or the engine is started, Even if waste heat is supplied from the Rankine cycle system, the engine coolant cannot be heated sufficiently, and it is difficult to ensure the heating capacity.

  In addition, air conditioning heaters are often unnecessary in summer, so the need for positive heating of the cooling water by the waste heat of the Rankine cycle system is reduced as described above. It is desired to recover more energy as motive power through effective utilization.

  The present invention has been made in order to solve such problems. The object of the present invention is to improve the heating capacity at the start and to improve the energy recovery efficiency by the Rankine cycle. It is to provide a recovery device.

  In order to achieve the above object, an invention according to claim 1 is provided upstream of an air conditioning heater in a cooling water circulation path of an engine, a heat storage means for storing cooling water, a working fluid that recirculates the exhaust gas and the circulation path of the engine. An exhaust heat exchanger for exchanging heat with the cooling water, and a cooling water heat exchanger for exchanging heat between the cooling water introduced from the upstream side of the heat storage means and the working fluid. Rankine cycle means for recovering heat from exhaust and cooling water and converting it into power, inlet on-off valve for opening and closing the cooling water inlet of the heat storage means, outlet on-off valve for opening and closing the cooling water outlet of the heat storage means, and engine stop Control means for controlling the inlet on / off valve and the outlet on / off valve so that the inlet on / off valve is closed and the outlet on / off valve is opened at the time of engine start.

The invention of claim 2 provides the heat storage amount detection means for detecting the heat storage amount in the heat storage means according to claim 1, and the control means has an inlet when the heat storage amount detected by the heat storage amount detection means is a predetermined value or more. The on-off valve is controlled to be closed.
According to a third aspect of the present invention, in the first or second aspect, the engine includes a water-cooled EGR cooler that cools the exhaust gas returning to the intake passage, and the cooling water heat exchanger includes the cooling water and the EGR cooler that have passed through the engine. Heat is exchanged between each of the cooling water that has cooled the working fluid and the working fluid.

  According to a fourth aspect of the present invention, in any one of the first to third aspects, the control means closes the outlet on-off valve when the air conditioning heater is stopped.

  As described above, according to the vehicle waste heat recovery apparatus of the first aspect of the present invention, the heat of the exhaust gas can be recovered by the exhaust heat exchanger, and the heat of the cooling water can be recovered by the cooling water heat exchanger. Therefore, thermal energy can be recovered by Rankine cycle means independently of any heat source. Therefore, Rankine cycle means can be used efficiently, and the recovery rate of engine waste heat can be improved.

Moreover, since the heat energy of the cooling water can be stored by the heat storage means, the air conditioner heater can be operated by the heat energy stored in the heat storage means by opening the outlet opening / closing valve when the engine is started or stopped. it can.
In particular, when the engine is started, the inlet on / off valve is closed to prevent the cooling water from flowing into the heat storage means, so that the low-temperature cooling water is prevented from flowing into the heat storage means, and the heat storage means Temperature drop can be suppressed. Therefore, it is possible to improve the performance of the air conditioning heater when starting the engine.

  According to the vehicle waste heat recovery apparatus of the second aspect of the present invention, when the heat storage amount in the heat storage means is equal to or greater than a predetermined value, the cooling water does not flow into the heat storage means, and accordingly, cooling to the cooling water heat exchanger is performed. Increase in water inflow. Therefore, the heat recovery rate by the Rankine cycle means can be improved.

  According to the vehicle waste heat recovery device of the invention of claim 3, the cooling water heat exchanger can exchange heat with the working fluid in both the cooling water that has passed through the engine body and the cooling water that has cooled the EGR cooler. The waste heat of the engine can be recovered more efficiently.

  According to the vehicle waste heat recovery device of the invention of claim 4, when the air conditioning heater is stopped, the outlet on / off valve is closed to prevent the cooling water from flowing from the heat storage means to the heater. The wasteful flow of thermal energy from the means can be prevented, and the recovery rate of waste heat can be improved.

It is a block diagram of embodiment of the waste heat recovery apparatus of this invention. It is a flowchart which shows the control point of each on-off valve at the time of engine operation. It is a flowchart which shows the control point of each on-off valve at the time of an engine stop.

Hereinafter, an embodiment of the waste heat recovery apparatus of the present invention will be described. The waste heat recovery apparatus of the present invention is a system that can recover waste heat of a vehicle running engine (hereinafter referred to as engine 1) and convert it into power.
FIG. 1 is a configuration diagram of the waste heat recovery apparatus of the present embodiment.

  As shown in FIG. 1, the engine 1 according to the present embodiment includes a turbocharger 2. The turbocharger 2 includes a compressor 4 interposed in the intake passage 3 of the engine 1 and a turbine 6 interposed in the exhaust passage 5. The intake passage 3 on the downstream side of the compressor 4 is provided with an intercooler 7 for cooling the intake air compressed by the compressor 4 and heated to a high temperature.

Further, the engine 1 is provided with an EGR flow path 8 for returning a part of the exhaust gas from the exhaust passage 5 to the intake passage 3. The EGR flow path 8 is provided with an EGR cooler 9 that cools the recirculated exhaust gas in order to improve the effect. The EGR cooler 9 cools the recirculated exhaust gas using the cooling water of the engine 1.
A cooling water circulation path 10 of the engine 1 indicated by a broken line in the figure includes a main cooling water path 11, a heater cooling water path 12, and an EGR cooling water path 13. The main cooling water channel 11 is a channel that circulates between the radiator 14 and the inside of the engine 1 body. A main cooling water passage 11 on the downstream side of the radiator 14 is provided with a pump 15 for circulating the cooling water.

  The heater cooling water channel 12 is configured to branch from the main cooling water channel 11 from the main body of the engine 1 to the radiator 14, pass through the heat storage 16 and the air conditioning heater 17 in order, and return to the radiator 14. The heat storage 16 is, for example, a cooling water storage tank covered with a heat insulating material, and has a function of storing thermal energy of the flowing high-temperature cooling water. The air conditioning heater 17 has a function of heating the air supplied toward the vehicle interior or the windshield of the vehicle.

The EGR cooling water channel 13 branches on the downstream side of the pump 15, passes through the EGR cooler 9, and is connected to the heat storage 16.
At the cooling water inlet of the heat storage 16, a first on-off valve 18 that opens and closes the heater cooling water passage 12 and a second on-off valve 19 that opens and closes the EGR cooling water passage 13 are provided. The first on-off valve 18 and the second on-off valve 19 correspond to the inlet on-off valve of the present invention. Between the heat storage 16 and the air conditioning heater 17, a third on-off valve 20 (exit on-off valve) that opens and closes the heater cooling water passage 12 is provided.

  A Rankine cycle system 30 is mounted on the vehicle. The Rankine cycle system 30 includes a circulation path 31 through which a working fluid such as Ra 134 circulates, a first heat exchanger 32 (exhaust heat exchanger), a second heat exchanger 33 (cooling water heat exchanger), and an expander. 34, a condenser 35 and a pump 36. In the circulation path 31, a second heat exchanger 33, a first heat exchanger 32, an expander 34, a condenser 35, and a pump 36 are interposed in this order.

  The first heat exchanger 32 has a function of heating the working fluid using the exhaust of the engine 1 as a heat source. The second heat exchanger 33 introduces cooling water after passing through the engine body from upstream of the first on-off valve 18 and introduces cooling water after passing through the EGR cooler 9 from upstream of the second on-off valve 19. The heated fluid is used as a heat source to heat the working fluid. The first heat exchanger 32 and the second second heat exchanger 33 have a function of vaporizing the working fluid as a whole.

  Specifically, the expander 34 is a turbine that is driven by a vaporized working fluid, and converts the thermal energy of the working fluid into power (rotational force). The condenser 35 has a function of liquefying the working fluid after passing through the expander 34. The pump 36 has a function of pumping the working fluid after passing through the condenser 35 to the first heat exchanger 32.

  The Rankine cycle system 30 can recover exhaust heat and heat of cooling water as power by driving the pump 36 and circulating the working fluid in the circulation path. For example, the generator can be driven by the inflator 34 so that the power can be used as electric energy or can be used as the auxiliary driving force of the engine 1, thereby reducing the load on the engine 1 and improving the fuel consumption. It becomes possible.

The heat storage 16 is provided with a heat storage temperature sensor 40 (heat storage amount detection means) that detects the temperature of the heat storage 16, specifically, the temperature of the stored cooling water. The heat storage temperature sensor 40 corresponds to the heat storage amount detection means of the present invention that detects the heat storage amount in the heat storage 16.
An exhaust temperature sensor 41 is provided in the exhaust passage 5 of the engine 1. Further, a fourth opening / closing valve 45 for opening and closing the introduction path 42 is provided in the exhaust introduction path 42 from the exhaust path 5 to the first heat exchanger 32.

The ECU 50 is a control device for performing comprehensive control including operation control of the engine 1, and includes an input / output device, a storage device (ROM, RAM, nonvolatile RAM, etc.), a central processing unit (CPU), and the like. Consists of including.
Further, the ECU 50 according to the present embodiment includes the first on-off valve 18, the second on-off valve 19, the first on-off valve 18 based on the operation status of the heat storage temperature sensor 40, the exhaust temperature sensor 41, the heating switch, and the operating status of the engine 1. 3, the fourth on-off valve 45, and the pump 36 are controlled to operate.

The ECU 50 controls the drive of the pump 36 when the engine is operating. Therefore, when the engine is operating, energy is recovered by the Rankine cycle system 30 from the waste heat of the exhaust, the engine cooling water, and the EGR cooler cooling water.
2 and 3 are flow charts showing the operation control procedure of the first on-off valve 18, the second on-off valve 19, the third on-off valve 20, and the fourth on-off valve 45 in the ECU 50. FIG. During operation, FIG. 3 shows when the engine is stopped.

The control shown in FIG. 2 starts when the engine is started and continues to be executed while the engine is running.
First, in step S10, the first on-off valve 18, the second on-off valve 19, and the third on-off valve 20 are closed as engine starting initial conditions. Then, the process proceeds to step S20.

  In step S20, the temperature THS of the heat storage 16 is input from the heat storage temperature sensor 40, and it is determined whether or not the temperature THS is lower than a predetermined temperature T1. The predetermined temperature T1 may be set to a threshold value capable of determining whether or not heat energy that can sufficiently operate the air conditioning heater 17 is stored. If the temperature THS of the heat storage 16 is lower than the predetermined temperature T1, the process proceeds to step S30.

In step S30, the first on-off valve 18 and the second on-off valve 19 are closed. Then, the process proceeds to step S40.
In step S40, it is determined whether or not the temperature THS in the heat storage 16 input from the heat storage temperature sensor 40 is higher than a predetermined temperature T1. If the temperature THS in the heat storage 16 is higher than the predetermined temperature T1, the process proceeds to step S50. If the temperature THS in the heat storage 16 is equal to or lower than the predetermined temperature T1, the process returns to step S30.

In step S50, it is determined whether or not heating is started. Specifically, it may be determined whether or not the heater switch is ON or based on an operation control signal in the vehicle air conditioner. When heating is started, the process proceeds to step S60.
In step S60, the third on-off valve 20 is opened. Then, the process returns to step S20.

When it determines with heating not being started in step S50, it progresses to step S70.
In step S70, the third on-off valve 20 is closed. Then, the process returns to step S20.
If it is determined in step S20 that the temperature THS of the heat storage 16 is equal to or higher than the predetermined temperature T1, the process proceeds to step S80.

In step S80, the first on-off valve 18 and the second on-off valve 19 are opened. Then, the process proceeds to step S90.
In step S90, it is determined whether or not heat recovery is started. Specifically, it is determined whether or not the exhaust temperature Te detected by the exhaust temperature sensor 41 is equal to or higher than a predetermined temperature T2. The predetermined temperature T2 may be set to a threshold value at which it is possible to determine whether or not heat can be recovered from the exhaust by the first heat exchanger 32. When heat recovery is started, that is, when the exhaust temperature Te is equal to or higher than the predetermined temperature T2, the process proceeds to step S100.

In step S <b> 100, the fourth on-off valve 45 is opened and exhaust gas is introduced into the first heat exchanger 32. Then, the process proceeds to step S50.
If it is determined in step S90 that heat recovery is not started, that is, the exhaust temperature Te is lower than the predetermined temperature T2, the process proceeds to step S110.
In step S110, the fourth on-off valve 45 is closed. Then, the process proceeds to step S50.

Next, the control point of each on-off valve 18, 19, 20 when the engine is stopped will be described with reference to FIG.
The control shown in FIG. 3 starts when the engine is stopped.
First, in step S200, the first on-off valve 18 and the second on-off valve 19 are closed as an engine stop initial condition. Then, the process proceeds to step S210.

In step S210, it is determined whether or not heating is started as in step S50 described above. When heating is started, the process proceeds to step S220.
In step S220, the third on-off valve 20 is opened. Then, the process returns to step S210.

If it is determined in step S210 that heating is not necessary, the process proceeds to step S230.
In step S230, the third on-off valve 20 is closed. Then, the process returns to step S210.

  By controlling as described above, in this embodiment, the first on-off valve 18, the second on-off valve 19, and the third on-off valve 20 are closed immediately after the engine is started. When the temperature THS of the heat storage 16 is lower than the predetermined temperature T1, the first on-off valve 18 and the second on-off valve 19 are opened. The temperature THS of the heat storage 16 also rises as the coolant temperature rises as the operating time of the engine 1 elapses. Then, after the temperature THS of the heat storage 16 becomes higher than the predetermined temperature T1, the third on-off valve 20 opens when heating is necessary. As a result, the air conditioning heater 17 can be operated using the thermal energy of the cooling water stored in the heat storage 16. When heating is unnecessary, the third on-off valve 20 is closed, so that unnecessary heat is not supplied to the air conditioning heater 17 and the heat storage property of the heat storage 16 can be ensured.

  When the engine is stopped, the first on-off valve 18 and the second on-off valve 19 are closed, and when heating is required, the third on-off valve 20 is opened, so that the cooling stored in the heat storage 16 is stored. It becomes possible to operate the air conditioning heater 17 using the thermal energy of water.

Therefore, for example, even when idling is stopped when the vehicle is stopped, it is possible to operate the air conditioning heater 17 using the heat storage 16, so there is no need to operate the engine 1 for the air conditioning heater 17, and fuel consumption can be improved. it can.
The Rankine cycle system 30 includes a first heat exchanger 32 that uses the heat of exhaust gas and a second heat exchanger 33 that uses the heat of cooling water, and can be operated using any heat source. is there. Therefore, the Rankine cycle can be operated efficiently.

  Further, in this embodiment, when the temperature THS of the heat storage 16 is equal to or higher than the predetermined temperature T1 during engine operation, the first on-off valve 18 and the second on-off valve 19 are closed to operate the main body of the engine 1. And since the inflow of the cooling water from the EGR cooler 9 to the air conditioning heater 17 is blocked, the cooling water led to the second heat exchanger 33 increases. Therefore, in the case where the heat storage 16 is sufficiently stored and the operation of the air conditioning heater 17 is ensured, the heat energy is supplied to the heat storage 16 more than necessary, and the heat storage 16 is led to the Rankine cycle system 30 without being discarded. Therefore, the recovery rate of waste heat can be improved.

  Further, when the temperature of the heat storage 16 is equal to or higher than the predetermined temperature T1, the third on-off valve 20 may be closed and the intake air of the engine 1 may be warmed using the heat of the heat storage 16. If comprised in this way, intake air temperature can be improved at the time of cold start, and warm-up time can be shortened.

1 Engine 9 EGR cooler 10 Cooling water circulation path 16 Heat storage (heat storage means)
32 1st heat exchanger (exhaust heat exchanger)
33 Second heat exchanger (cooling water heat exchanger)
30 Rankine cycle system 18 First on-off valve (inlet on-off valve)
19 Second open / close valve (inlet open / close valve)
20 Third open / close valve (exit open / close valve)
40 Heat storage temperature sensor (heat storage amount detection means)

Claims (4)

A heat storage means provided on the upstream side of the air conditioning heater in the cooling water circulation path of the engine;
An exhaust heat exchanger for exchanging heat between the exhaust of the engine and the working fluid returning through the circulation path;
A cooling water heat exchanger for exchanging heat between the cooling water introduced from the upstream side of the heat storage means and the working fluid, and recovering heat from the engine exhaust and cooling water via the working fluid Rankine cycle means to convert to,
An inlet on-off valve that opens and closes the inlet of the cooling water of the heat storage means;
An outlet on-off valve that opens and closes the outlet of the cooling water of the heat storage means;
Control means for controlling the inlet on / off valve and the outlet on / off valve so that the inlet on / off valve is closed and the outlet on / off valve is opened when the engine is stopped or started. Vehicle waste heat recovery equipment. A heat storage amount detection means for detecting the heat storage amount in the heat storage means is provided,
2. The waste heat of the vehicle according to claim 1, wherein the control unit controls the inlet on / off valve to close when the amount of stored heat detected by the stored heat amount detecting unit is equal to or greater than a predetermined value. Recovery device. The engine includes a water-cooled EGR cooler that cools the exhaust gas returning to the intake passage,
3. The heat exchanger according to claim 1, wherein the cooling water heat exchanger performs heat exchange between the cooling water that has passed through the engine and the cooling water that has passed through the EGR cooler and the working fluid. Vehicle waste heat recovery device.   The waste heat recovery apparatus for a vehicle according to any one of claims 1 to 3, wherein the control means closes the outlet opening / closing valve when the air conditioning heater is stopped.

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