WO2009125276A1

WO2009125276A1 - Engine waste heat collection system

Info

Publication number: WO2009125276A1
Application number: PCT/IB2009/005199
Authority: WO
Inventors: Atsushi Morita
Original assignee: Toyota Jidosha Kabushiki Kaisha
Priority date: 2008-04-08
Filing date: 2009-04-07
Publication date: 2009-10-15
Also published as: JP2009250139A

Abstract

An engine waste heat collection system (1) collects energy of steam of working fluid that has been heated by waste heat of an engine (2) by an energy collection part (34). The engine waste heat collection system (1) includes: a working fluid condenser (35 a) that condenses steam that has passed through the energy collection part (34); and a cooler (35b, 35c) that can cool the working fluid condenser (35a) when the engine (2) is stopped. Accordingly, working fluid condensation performance of the engine cooling water - condenser (35a) can be maintained even when the engine (2) is stopped.

Description

ENGIKE WASTE HEAT COLLECTION SYSTEM

BACKGROUND OF THE INVENTION

1. Field of Invention

[0001] The present invention relates to an engine waste heat collection system or a system that collects energy from waste heat of an engine.

2. Description of Related Art

[0002] As a system of this type, one disclosed in Japanese Patent Application Publication No. 6-88523 (JP-A-6-88523) is known as a related art, for example. In this system, the engine is cooled by vaporization heat of cooling water, and expansion energy of steam that is generated during engine cooling is converted to mechanical energy. Accordingly, energy can be collected from waste heat such as combustion heat and friction heat. Specifically, this system includes a cylinder block, a heater, an expander, and a condenser.

[0003] The cylinder block is provided with a water jacket to which cooling water is supplied. The heater heats steam of the cooling water, which flows out from the water jacket, by heat of exhaust gas. The expander conveits expansion energy of the steam, which has passed through the heater, to mechanical energy. The condenser cools the steam that has lost energy to become low pressure, and condenses the steam into liquid.

[0004] In the engine waste heat collection system with such configuration, the cooling water is supplied to the water jacket. Accordingly, the cylinder block is cooled, and the cooling water is vaporized to produce steam in the water jacket.

[0005] The steam is further heated by the heater through heat exchange with exhaust gas, and then supplied to the expander, Then, the steam is expanded in the expander. Accordingly, mechanical energy is collected.

[0006] Later, the low-pressure steam that has lost the energy is flown into the condenser and condensed into liquid. The cooling water, which has been condensed into liquid by the condenser, is again supplied to the water jacket.

[0007] This type of system (so-called Ranlrine system) can be installed in a iybrid vehicle, etc. (for example, refer to Japanese Patent Application Publication No. 1002-115573 (JP-A-2002-115573), Japanese Patent Application Publication No. 2004- 239179 (JP-A-2004-239179), Japanese Patent Application Publication No. 2007-205283 (JP-A-2007-205283), Japanese Patent Application Publication No. 2008-57340 (JP-A- 2008-57340)).

[0008] The above system is stopped when the engine is stopped (or even when the vehicle is traveling in the case of a hybrid vehicle). Accordingly, when the engine is stopped, condensing operation of steam by the condenser is also stopped. Thus, it could cause a situation that an enough amount of the cooling water to τestait the above system is not maintained when the engine is restarted.

[0009] When the capacity of a reserve tank in which the cooling water iα liquid form is reserved is enlarged, construction of the system is upsized, and thus it can worsen the mountability of the system into a vehicle.

SUMMARY OF THE INVENTION

[0010] The present invention provides an engine waste heat collection system that can be operated immediately when an engine is restarted.

[0011] An aspect of the present invention relates to the engine waste heat collection system that includes an energy collection part, a working fluid condenser, and a cooler. The energy collection part collects energy from steam of the working fluid that is healed by waste heat of the engine. The working fluid condenser condenses, the steam that has passed through the energy collection part. The cooler can cool the working fluid condenser when the engine is stopped.

[0012] The engine waste heat collection system may further include a motor- operated pump. The motor-operated pump is disposed in a circulation path of the working fluid.

[0013] The engine waste heat collection system may further include a working fluid tank that can reserve the working fluid in liquid form. The working fluid tank is disposed in the circulation path on the downstream side of the working fluid condenser in a flowing direction of the working fluid.

[0014] The engine waste heat collection system may further include a working fluid amount output part. The working fluid amount output part produces the output that corresponds to an amount of the working fluid in liquid form which can be supplied to the engine. The working fluid output part can specifically be installed in the working fluid tank.

[0015] The cooler may further include an air-conditioning condenser and/or a motor-operated cooling medium cooling part. The air-conditioning condenser condenses an air-conditioning cooling medium, which is a cooling medium of an air-conditioning system in the vehicle. The motor-operated cooling medium cooling part cools a motor- operated cooling medium, which is a cooling medium of a motor-operated system in the hybrid vehicle.

[0016] The engine waste heat collection system may further include a control part. The control part controls a condensing operation state in the working fluid condenser when the engine is stopped in accordance with the output of the working fluid amount output part. Specifically, the control part may control an operation state of the motor- operated pump when the engine is stopped in accordance with the output of the working fluid amount output part. Or, the control part may control an operation state of the cooler when the engine is stopped in accordance with the output of the working fluid amount output pail.

[0017] In the engine waste heat collection system in the present invention, the worldng fluid condenser is cooled by the cooler even when the engine is stopped (the motor-operated pump may be driven at this time).

[0018] Specifically, for example, a condensing operation state (worldng states of Hie motor-operated pump and the cooler) in the working fluid condenser during engine stop is controlled in accordance with the output of the working fluid amount output part. That is, when an amount of reserve in the worldng fluid tank is determined to be less than a certain amount based on the output of the working fluid amount output part, the motor- operated pump and the cooler are driven even when the engine is stopped. [0019] According to the present invention, the working fluid condenser can maintain condensation performance of the steam of the working fluid even when the engine is stopped. Thus, when the engine is restarted, a sufficient amount of the working fluid in liquid form, which is necessary to restart the engine waste heat collection system, can be maintained. Accordingly, the system can be immediately operated when the engine is restarted.

[0020] A sufficient amount of the working fluid in liquid form that is used to restart the engine waste heat collection system can favorably be maintained without excessively enlarging the capacity of the working fluid tank. Accordingly, favorable mountabilϊty of the system to the vehicle can be realized.

[0021] Furthermore, further favorable mountability of the system to the vehicle can be realized by using the air-conditioning condenser and/or the motor-operated cooling medium cooling part as a cooler.

BRIEF DESCRIPTION OF THE DRAWINGS [0022] The foregoing and further objects, features and advantages of the invention will become apparent from the following description of exemplary embodiments with reference to the accompanying drawings, wherein like numerals are used to represent like elements and wherein:

FIG. 1 is a schematic configuration diagram of an engine waste heat collection system according to a first embodiment of the present invention; and

FIG. 2 is a schematic configuration diagram of an engine waste heat collection system according to a second embodiment of the present invention.

DETAILED DESCRIPTION OF EMBODIMENTS [0023] A description will hereinafter be made of an embodiment of the present invention with reference to the drawings.

[0024] The present invention should not be limited in any way to the specific configurations of the embodiments described below. Various modifications that may be made to the embodiments will be collectively described at the end of the specification in order to avoid such descriptions from interrupting comprehensive understanding of the description of the embodiments by providing them in the course of the description of the embodiments.

[0025] <System configuration in the first embodiment FIG. 1 is a schematic configuration diagram of an engine waste heat collection system 1 (hereinafter, simply referred to as "system 1") according to the first embodiment of the present invention. The system 1 of the present embodiment is installed in a hybrid vehicle. With reference to FIG. 1, the system 1 includes an engine 2, an energy collection mechanism 3, a cooling water circulation path 4, an electronic control unit 5, and a motor-operated system 6.

[0026] «Engine» A crank shaft pulley 22 is mounted to a crank shaft 21 that is provided in the engine 2. The crankshaft pulley 22 drives a drive transmission belt 22b of an endless belt type. An exhaust pipe 23 is connected to the engine 2. Additionally_;, a temperature sensor 24 is mounted in the engine 2. The temperature sensor 24 produces the output that corresponds to a temperature of the engine 2 (temperature of cooling water in liquid form reserved inside the engine 2, for example).

[0027] «Energy collection mechanism» The energy collection mechanism. 3 includes the following configuration, so that the engine 2 is cooled by cooling water as a working fluid and that energy can be collected from the steam that is produced at the time of the cooling.

[0028] A gas-liquid separator 31 separates the wet steam (in which moisture and steam coexist), which is produced by the boiled cooling water in the engine 2, into gas and liquid. The cooling water in liquid form that is separated from the steam in the gas-liquid separator 31, and the cooling water in liquid form in the engine 2 are cooled by heat exchange with outside air by a radiator 32.

[0029] A superheater 33 is disposed in the exhaust pipe 23. The superheater 33 heats the steam, which has passed the gas-liquid separator 31, by the heat of exhaust gas in order to produce superheated steam.

[0030] A turbine 34 as an energy collection part collects energy from the superheated steam that has passed the superheater 33. In other words, a turbine pulley 34a is mounted on an output shaft that is connected to a rotor of the turbine 34. The turbine pulley 34a is connected to the crankshaft 21 via the drive transmission belt 22b and the crankshaft pulley 22 described above.

[0031] A multifunction condenser 35 is arranged in front of the radiator 32 so as to be cooled better than the radiator 32 by receiving a headwind of further lower temperature. The multifunction condenser 35 includes an engine cooling water condenser 35a, a hybrid radiator 35b, and an air-conditioning condenser 35c.

[0032] The engine cooling water condenser 35a as a working fluid condenser condenses the steam of low-pressuie cooling water, which has passed the tuibine 34, by heat exchange with outside air and by cooling through the engine cooling water condenser 35a an.d the hybrid radiator 35b, which are used as a cooler.

[0033] The hybrid radiator 35b as a motor-operated cooling medium cooling part cools the motor-operated cooling medium, which is a cooling medium to cool the motor- operated system 6 (for example, an inverter provided in the motor-operated system 6), by heat exchange with outside air. The air-conditioning condenser 35c condenses an air- conditioning cooling medium, which is a medium of an air-conditioning system (not shown), by cooling through the heat exchange with outside air. ,The engine cooling water condenser 35a and the hybrid radiator 35b aie driven under control of the electronic control unit 5, so that the engine cooling water condenser 35a can be cooled even when the engine 2 is stopped.

[0034] A catch tank 36 as a working fluid tank is disposed in the cooling water circulation path 4 on the downstream side of the engine cooling water condenser 35a in the flow direction of cooling water. The catch tank 36 reserves cooling water in liquid form that has passed through the engine cooling water condenser 35a.

[0035] In the cooling water circulation path 4, a motor-operated pump 37 is interposed between the catch tank' 36 and the bottom of a space (water jacket) that can reserve cooling water in the engine 2. In the present embodiment, the motor-operated pump 37 is disposed in the engine 2. [0036] A bypass-switching valve 38 is a so-called three-way valve, which switches a connection state between a state in which the gas-liquid separator 31 and the superheater 33 are connected and a state in which the gas-liquid separator 31 and the radiator 32 are connected while bypassing the superheater 33.

[0037] «Cooling water circulation path» The cooling water circulation, path 4 includes a cooling water supply path 41, a steam lead-out path 42, a separated cooling water lead-out path 43, a hot water lead-out path 44, a cooling water supply path 45, a turbine lead-out path 46, a bypass 47, and a tank connection path 48.

[0038] The cooling water supply path 41 connects the engine cooling water condenser 35a and the bottom of the space (water jacket) that can reserve cooling water in the engine 2. In the cooling water supply path 41, the catch tank 36 and the motor- operated pump 37 are arranged in this order from an upstream side to a down stream side in the flow direction of cooling water.

[0039] The steam lead-out path 42 connects the space in the engine 2 described above and the turbine 34. In the steam lead out path 42, the gas-liquid separator^' 31, the bypass switching valve 38, and the superheater 33 are arranged in this order from an upstream side to a down stream side in the flow direction of steam of cooling water.

[0040] The separated cooling water lead-out path 43 connects the gas-liquid separator 31 with the radiator 32. An upstream end of the hot water lead-out path 44 is connected to the space in the engine 2 described above. The hot water lead-out path 44 is joined with the separated cooling water lead-out path 43 at the downstream end. The cooling water supply path 45 connects the radiator 32 with the bottom of the space in the engine 2 described above.

[0041] The turbine lead-out path 46 connects the turbine 34 with the engine cooling water condenser 35a. The bypass 47 connects the bypass switching valve 38 with the radiator 32. The tank connection path 48 connects an upper end of the radiator 32 and an upper end of the catch tank 36. That is, the tank connection path 48 introduces the cooling water in liquid form that has overflowed from the radiator 32 into the catch tank 36. [0042] «ElectiOnic control unit» The electronic control unit 5 is electrically connected to sensois such as the temperature sensor 24 and to operating part such as the motor-operated pump 37 and the bypass switching valve 38. The electronic control unit 5 controls operation of the operating part described above based on the outputs from the respective sensors.

[0043] <Operation of the engine waste heat collection system in the first embodiment Hereinafter, with reference to FIG. 1, description is made of operation of the system 1 of the present embodiment that has the configuration described above.

[0044] The engine 2 is stopped when the vehicle is stopped or when the vehicle is traveling only with output of the motor-operated system 6. Meanwhile, when the vehicle is traveling only with output of the motor-operated system 6, and when the motor-operated system 6 is running during the stop of the engine 2 (especially when cooling of the motor- opeiated system 6 is required), cooling operation by the hybrid radiator 35b is performed to cool the motor-operated system 6. When the air-conditioning system is running, condensing operation of the air-conditioning cooling medium is performed in the air- conditioning condenser 35c.

[0045] «When engine temperature is not high» When the engine 2 is running, and when the temperature of the engine 2 is a certain upper limit value (for example, 90⁰C) or less, an upstream side and a downstream side of the bypass switching valve 38 in the steam lead-out path 42 are communicated. At this time, communication between the bypass 47 and a portion of the steam lead-out path 42 that is upstream of the bypass- switching valve 38 is interrupted.

[0046] In this state, when the motor-pump 37 is driven, cooling water in liquid form in the catch tank 36 is supplied to the engine 2. When cooling water is boiled in the engine 2, wet steam is produced in the engine 2. The wet steam is introduced to the outside of the engine 2 through the steam lead-out path 42. Later, the wet steam reaches the gas-liquid separator 31.

[0047] In the gas-liquid separator 31, moisture and steam of the wet stream are separated. The steain that has been separated from moisture is introduced to downstream side of the gas-liquid separator 31 in the steam lead-out path 42. On the otihei hand, the moisture that has been separated from the steam is sent to the radiator 32 through the separated cooling water lead-out path 43.

[0048] The steam that has passed tlnough the gas-liquid separator 31 is heated by the heat of exhaust gas in the superheater 33. The superheated steam is introduced to the turbine 34, and thus energy is collected in the turbine 34. The collected energy is transmitted through the turbine pulley 34a, the drive transmission belt 22b, and the crankshaft pulley 22 to the crankshaft 21. That is, waste heat of the engine 2 is collected as rotational driving force of the crankshaft 21.

[0049] Temperature of the low pressure steam after passing the turbine 34 may be about 60^aC (which is fairly low compared to the upper limit temperature of the cooling water in the radiator 32). Hence, the low pressure steam is cooled in the engine cooling water condenser 35a, which can be cooler than the radiator 32, so as to be condensed into liquid. Then, cooling water in liquid form is collected by the catch tank 36.

[0050] «Immediately after engine stop» Even immediately after the stop of the engine 2, drive of the motor-operated pump 37 is properly continued as long as the system 1 is running. By the drive of the motor-operated pump 37, cooling water in liquid form is circulated. Also, steam is continued to be introduced into the engine cooling water condenser 35a by negative pressure.

[0051] In the present embodiment, even after the engine 2 is stopped, a cooling system of the motor-operated system 6 that includes the hybrid radiator 35b, and the motor-operated pump 37 are driven.

[0052] Accordingly, while the steam in the engine 2 and the steam in the cooling water circulation path 4 is introduced to the engine cooling water condenser 35a, the engine cooling water condenser 35a is continuously cooled by the hybrid radiator 35b and the like. Accordingly, cooling water condensation performance of the engine cooling water condenser 35a is favorably maintained while the engine 2 is stopped.

[0053] «When engine temperature is high» When the engine 2 is running in a high load operation, temperature of the engine 2 may exceed the upper limit value described above. In this case, the bypass-switching valve 38 is switched from the above state. That is, the communication between the upstream side and the downstream side of the bypass-switching valve 38 in the steam lead-out path 42 is interrupted, and the bypass 47 and the upstream side of the bypass switching valve 38 in the steam lead-out path 42 are communicated.

[0054] In this state, cooling water in liquid form is freely circulated. Accordingly, the engine 2 is cooled favorably, and overheating is prevented.

[0055] <Functions and* effects according to the configuration of the embodiment As desciibed above, in the configuration of the present embodiment, cooling water condensation performance of the engine cooling water condenser 35a is maintained even after engine 2 is stopped.

[0056] Accordingly, when the engine 2 is restarted, a sufficient amount of cooling water in liquid form, which is necessary for the engine waste heat collection system 1 (energy collection mechanism 3) to be restarted, can be maintained in the catch tank 36. Accordingly, the system 1 (energy collection mechanism 3) can smoothly be operated when the engine 2 is restarted.

[0057] In the configuration of the present embodiment, part of the multifunction condenser 35, which is usually provided in the hybrid vehicle, can be used as a condenser in a so-called Ranlάαe cycle. That is, a condenser in the Ranldne cycle can be integrated with the multifunction condenser 35, which is usually provided in the hybrid vehicle.

[0058] Accordingly, favorable mountability to the vehicle can be realized. Also, a Ranldne cycle system can be favorably mounted to lhe hybrid vehicle only with partial change of construction of the multifunction condenser 35 which is usually provided in the hybrid vehicle, without reduction of cooling performance and air-conditioning performance of the motor-operated system 6.

[0059] <Second embodiment FIG. 2 is a schematic configuration diagram of the system 1 according to the second embodiment of the present invention. In the description of the present embodiment, the members that have the same construction and function as those in the first embodiment described above are denoted by the same symbol. Description in the first embodiment described above is applicable as long as technically 005199

reasonable.

[0060] In the present embodiment, the catch tank 36 is provided with a cooling water amount sensor 51. The cooling water amount sensor 51 is electrically connected to the electronic control unit 5.

[0061] The cooling water amount sensor 51 as a working fluid amount output part produces the output that corresponds to an amount of the cooling water in liquid form that can be supplied to the engine 2 (and that is reserved in the catch tank 36). Specifically, in the present embodiment, the cooling water amount sensor 51 produces the output that corresponds to whether or not an amount of reserved cooling water in the catch tank 36 is less than a predetermined amount.

[0062] The electronic control unit 5 as a control part controls a condensation operation state in the engine cooling water condenser 35a when the engine 2 is stopped, in accordance with the output of the cooling water amount sensor 51. Specifically, the electronic control unit 5 controls an operation state of the motor-operated pump 37 and a cooling system of the motor-operated system 6 including the hybrid radiator 35b when the engine 2 is stopped, in accordance with the output of the cooling water amount sensor 51.

[0063] In the above configuration, in the case that an amount of reserved cooling water in the catch tank 36 is determined to be less than the predetermined amount, even when the engine 2 is stopped, the respective parts are driven so that condensation operation in the engine cooling water condenser 35a is continued,

[0064] On the other hand, in the case that a certain amount of reserved cooling water in the catch tank 36 is determined to be maintained, when the engine 2 is stopped, drive of the motor-operated pump 37 iι_ stopped. In this case, when a temperature of the motor-operated system 6 is low, the cooling system of the motor-operated system 6 including the hybrid radiator 35b is also stopped.

[0065] In the present embodiment, only when an amount of reserved cooling water in the catch tank 36 is insufficient, condensing operation in the engine cooling water condenser 35a is continued during the stop of the engine 2. Accordingly, further favorable fuel efficiency enhancement effect can be further preferably obtained. [0066] <List of Modifications>

Hereinafter, several typical modifications will be described. The modifications are not limited to the following lists. In addition, a plurality of modifications may be applied in combination as appropriate without departing from the technical scope of the present invention. The present invention should not be limited by the above embodiments and the below modifications.

[0067] (A) The present invention is not limited to the use in a hybrid vehicle. That is, the hybrid radiator 35b can be omitted. In this case, the engine cooling water condenser 35a can be cooled by the air-conditioning condenser 35c when the engine 2 is stopped.

[0068] (B) Configurations of the energy collection mechanism 3 and the cooling water circulation path 4 can properly be changed from the ones disclosed in the above embodiments.

[0069] For example, the energy collected by the turbine 34 can be converted to electricity. As an energy collection part, a mechanism that includes a piston can be used instead of the turbine 34.

[0070] The radiator 32 and the catch tank 36 may not be connected with each other.

[0071] The motαr-operated pump 37 may be disposed separately from the engine 2. Or₅ a mechanical pump and a clutch mechanism (mechanism that switches the driving force transmission between the mechanical pump and the crankshaft 21) may be used jnstead of the motor-operated pump 37. In addition to the motor-operated pump 37, a pump that circulates cooling water in liquid form between the engine 2 and the radiator 32 may be disposed.

[0072] A working fluid in the energy collection mechanism 3 of the system 1 is not limited to engine cooling water. In this case, the system 1 is provided with a working fluid circulation path in addition to the cooling water circulation path 4. Main pails of the energy collection mechanism 3 (superheater, energy collection part, working fluid condenser, cooler, etc.) are disposed in the working fluid circulation path. [0073] The cooling water amount sensor 51 may be disposed in a place other .than the catch tank 36 (for example, a place between the engine cooling water condenser 35a and the catch tank 36 in the cooling water supply path 41).

[0074] (C) Of the components constituting the means for solving the problem of the present invention, the components described in terms of thek effects and functions may include any structure that can achieve those effects and functions, besides- the specific- structures disclosed in the embodiment and the modifications discussed above.

Claims

Claims:

1. An engine waste lieat collection system comprising: an energy collection part that collects energy of steam of working fluid heated by waste heat of an engine; a working fluid condenser that condenses the steam that has passed through the energy collection part; and a cooler that cools the working fluid condenser when the engine is stopped.

2. The engine waste heat collection system according to claim 1, wherein the cooler comprises an air-conditioning condenser that condenses an air- conditioning cooling medium which is an air-conditioning cooling medium in a vehicle.

3. The engine waste heat collection system according to claim 1 or 1, wherein the cooler comprises a motor-operated cooling medium cooling part that cools a motor-operated cooling medium which is a cooling medium of a motor-operated system in a hybrid vehicle.

4. The engine waste heat collection system according to any one of claims 1 to 3, further comprising: an exhaust pipe of the engine; and a superheater that is disposed in the exhaust pipe and that receives inflow of the working fluid.

5. The engine waste heat collection system according to claim 4, wherein the energy collection part includes a turbine; the working fluid is superheated by the superheater into steam; and the energy collection part collects energy with use of rotation of the turbine caused by the superheated steam.

6. The engine waste heat collection system according to claim 5, wherein the turbine is connected to a crankshaft of the engine.

7. The engine waste heat collection system according to any one of claims 1 to 6, further comprising: a working fluid amount output part that produces output in correspondence with an amount of the working fluid in liquid form that can be supplied to the engine; and a control part that controls a condensing operation state in the worldng fluid condenser when the engine is stopped, in accordance with output of the working fluid amount output part.

8. The engine waste heat collection system according to claim 7, further comprising: an motor-operated pump that is disposed in a circulation path of the working fluid; wherein the control part controls an operation state of the motor-operated pump when the engine is stopped, in accordance with output of the working fluid amount output part.

9. The engine waste heat collection system according to claim 7 or 8, further comprising: a working fluid tank that is disposed in the circulation path on a downstream side ,of the working fluid condenser in a flow direction of the working fluid, wherein the working fluid output part is installed in the working fluid tank.

iθ. The engine waste heat collection system according to claim 9, wherein the worldng fluid amount output part measures an amount of the working fluid reserved in the working fluid tank, and when an amount of the working fluid is less than a certain value during stop of the engine, the motor-operated pump is driven, the working fluid is supplied to the worldng fluid condenser, and the working fluid condenser is cooled by the cooler.