WO2008035788A1

WO2008035788A1 - Stirling engine for vehicle

Info

Publication number: WO2008035788A1
Application number: PCT/JP2007/068478
Authority: WO
Inventors: Makoto Abe; Yasushi Yamamoto
Original assignee: Isuzu Motors Limited
Priority date: 2006-09-19
Filing date: 2007-09-14
Publication date: 2008-03-27

Abstract

A Stirling engine for a vehicle which provides sufficient cooling of working fluid when a vehicle is traveling and stores temperature difference energy converted from kinetic energy of the vehicle produced during a brake operation, thus enhancing fuel economy. The Stirling engine is equipped with two pistons, and a phase difference alteration mechanism (6) for altering the relative phase between a piston (1) and a piston (2) is installed as an operation state alteration device. Furthermore, a heat accumulator (5) is disposed in the heating section (12) of the engine, and a circulation circuit of cooling medium in which a radiator (2B) is arranged is formed in a cooling section (22). During brake operation of a vehicle, the phase difference alteration mechanism (6) switches the operating state of the Stirling engine to operate it as a heat pump and, at the same time, blocks circulation of cooling medium to a radiator (22B), thus accumulating kinetic energy of the vehicle during a brake operation as temperature difference energy in the heat accumulator (5) and the cooling medium. The regenerated temperature difference energy is utilized during subsequent traveling.

Description

Specification

Stirling engine technology for vehicles

The present invention relates to a so-called Stirling engine, which is a heat engine that converts thermal energy of a heat source into mechanical rotational energy by utilizing a state change caused by heating and cooling of a working fluid sealed in a gaseous state, and more particularly, a vehicle. This is related to the Stirling engine installed in. Background art

The Stirling engine has a high theoretical thermal efficiency, in which the working fluid enclosed in the working chamber is periodically heated and cooled to cause a change in state, and this is used to extract rotating energy from a high heat source. It is an external combustion engine, and its thermal efficiency increases as the temperature difference between the high and low heat sources increases. Unlike an internal combustion engine such as a gasoline engine or diesel engine, the Stirling engine, which is an external combustion engine, heats the heat generated by continuous combustion to the working fluid and heats it. Therefore, it is easy to control the combustion state of the fuel, and there are advantages in that the generation amount of harmful exhaust components such as N O x and C 2 O is small. In addition to heat generated by combustion, various heat sources such as exhaust heat from internal combustion engines can be used, and the engine has excellent characteristics in terms of energy saving and environmental measures.

Taking advantage of the characteristics of such a Stirling engine, it is mounted on a vehicle, and the Stirling engine is operated using the technology that drives the vehicle by the Stirling engine or the exhaust heat of the internal combustion engine that drives the vehicle as a heat source. Development of technology to recover the power from the plant is also underway. In recent years, vehicle engines have been required to reduce emissions of harmful components of exhaust gas, and energy savings have been required to use petroleum alternative fuels. Stirling engines have the potential to meet such demands. It is one of the leading engines. By the way, a Stirling engine executes an engine cycle that generates power from the heat of a high heat source and dissipates exhaust heat to a low heat source. Therefore, it is possible to drive the Stirling engine and execute a heat pump cycle to pump heat from the low heat source and cool the low heat source. Japanese Patent Laid-Open No. 8-2 1 9 5 6 9 discloses that a plurality of devices constituting a Stirling engine are combined with an internal combustion engine, and one of the devices performs an engine cycle to generate power from exhaust heat of the internal combustion engine. In the other device, a “Stirling cycle device” is disclosed which is configured to execute a cycle of a refrigerator or a heat pump by the power of the internal combustion engine and the power generated from the exhaust heat. Yes.

There are various types of Stirling engines, and in general, there are many displacers that periodically move the working fluid between the heating space and the cooling space. , A Stirling engine of the type with two pistons of compression side piston and expansion side piston is used. In the equipment that implements the engine cycle and the heat pump cycle, the respective pistons are connected by a planetary gear mechanism so that the phases of both the pistons are variable. The phase of each piston is controlled by adjusting the planetary gear mechanism so that each cycle is a phase in which each cycle is performed efficiently according to the load of the refrigerator or the temperature condition of the exhaust heat of the internal combustion engine. Is done. The load acting on the vehicle varies greatly depending on the running state of the vehicle, such as vehicle speed and road surface conditions. For this reason, it is desirable that the Stirling engine that drives the vehicle has high thermal efficiency and at the same time can follow the load variation with good responsiveness. There are two methods for controlling the output of the Stirling engine to respond to the vehicle load: a method for controlling the amount of fuel supplied to the heating section and a method for adjusting the average pressure of the working fluid. The method of controlling the average pressure is inferior in terms of performance and requires a storage tank for the working fluid, which increases the weight and size of the engine. In addition, in an engine that drives a vehicle, when the vehicle is braked, the engine is driven reversely from the wheels, and the braking force is applied to the vehicle by consuming the kinetic energy of the vehicle, that is, the engine brake is applied. desirable. In particular, when the vehicle goes down a hill, it is necessary to apply an engine brake to assist the braking force of the foot brake and reduce the load on the foot brake. The engine brake consumes the kinetic energy of the vehicle by the engine. The engine brake can be a regenerative brake when the engine is operated to convert energy into another form of energy.

In the Stirling engine mounted on the vehicle, the engine is operated in a state of high thermal efficiency during normal driving of the vehicle, and the kinetic energy of the vehicle is efficiently absorbed and stored during braking. The challenge is to increase the braking effect of engine brakes. Disclosure of the invention

In view of the above problems, the present invention provides a cooling medium that circulates a cooling medium to a cooling unit that cools the working fluid of the Stirling engine to achieve sufficient cooling, and switches the operation state of the Stirling engine when the vehicle is braked. By operating, the temperature of the cooling medium is lowered and the kinetic energy of the two cars is converted to “temperature difference energy” and stored. That is, the present invention, as described in claim 1,

"A Stirling engine that is mounted on a vehicle and drives it,

The Stirling engine includes a heating unit that heats the working fluid and a cooling unit that cools the working fluid.

The Stirling engine includes an operation state change device, and the operation state change device switches the Stirling engine to heat pump operation when the vehicle is braked, while the Stirling engine is operated as an engine during normal operation of the vehicle,

The heating unit is provided with a heat accumulator, and the cooling unit has a cooling medium circulation circuit including a pump that circulates the cooling medium and a radiator that radiates the heat of the cooling medium to the atmosphere. ,

When the operation state change device sets the Stirling engine to engine operation, the pump is driven to circulate the cooling medium, and the operation state change device switches the Stirling engine to heat pump operation. The pump is stopped and the circulation of the cooling medium is prevented, the temperature of the working fluid and the cooling medium on the cooling unit side is lowered, and the temperature of the working fluid and the regenerator on the heating unit side is raised. Configured to do "

It is a Stirling engine characterized by that. The Stirling engine of the present invention for driving a vehicle performs an engine cycle during normal driving of the vehicle, transfers heat from the heating section, which is a high heat source, to the working fluid, and dissipates heat from the cooling section, which is a low heat source. Is called. A cooling circuit circulation circuit is formed in the cooling section, and the heat of the working fluid is transferred to the cooling medium in the liquid state, but since this heat transfer is heat transfer to the liquid, the heat transfer coefficient is large. The working fluid is sufficiently cooled. As a result, the temperature difference between the heated working fluid and the cooled working fluid increases, and the Stirling engine operates in a highly efficient state. When the engine cycle is executed, since the cooling medium is circulated to the radiator, the heat of the working fluid transferred to the cooling medium is finally released from the radiator to the atmosphere.

When the vehicle is braked, it is switched to heat pump operation by the operating state changing device. In other words, the Stirling engine that generates power by heat from the heating unit during normal travel is driven as a heat pump through the power transmission system of the vehicle during braking. During braking, the kinetic energy of the vehicle is consumed in a short time and the vehicle speed decreases, so the driving power when the Stirling engine is operated as a heat pump is very large, and the temperature of the working fluid in the cooling section decreases rapidly. At the same time, the temperature of the working fluid in the heating section rises rapidly.

A heat accumulator is disposed in the heating section of the Stirling engine of the present invention. The temperature of the heat accumulator rises with the heat pump operation during braking, and the cooling medium is cooled in the cooling section. Here, in the cooling section, the pump that circulates the cooling medium is stopped and the circulation of the cooling medium is prevented, so that the temperature of the cooling medium rises by receiving heat from the atmosphere in the radiator. There is no. In other words, the temperature of the cooling medium is lowered to a temperature lower than the atmospheric temperature when the vehicle is braked, and the so-called “cold heat J is stored in the cooling unit. Lugi is regenerated in the form of being stored as temperature difference energy in the regenerator of the heating unit and the cooling medium of the cooling unit.

At the time of re-acceleration after braking of the vehicle, the Stirling engine is operated as an engine to drive the vehicle using the temperature difference energy stored in the regenerator and cooling medium of the heating unit. At this time, the temperature of the heating part has risen more than usual, and the temperature of the cooling part has fallen, and the Stirling engine has increased the temperature difference between the high and low heat sources. Since it operates in a state, its output increases and the vehicle is smoothly accelerated. In addition, fuel economy is improved because the amount of fuel supplied to the heating section can be greatly reduced. The Stirling engine is switched to the heat pump operation by the operation state change device even when the vehicle travels on the downhill road surface. The power required to drive a Stirling engine as a heat pump is much greater than the power it absorbs when acting simply as an engine brake, and therefore the vehicle has a strong braking force. In other words, the Stirling engine can be operated as a so-called speed reducer (retarder), reducing the burden of foot brakes and the like when traveling on a downhill road surface. This effect is particularly effective for large vehicles such as trucks with heavy vehicle weight, and can prevent a fade phenomenon due to overheating of the brake device. The regenerative energy during heat pump operation is converted into temperature difference energy, stored in the heat accumulator, and used during subsequent travel, similar to the operation during the aforementioned control. As described in claim 2, a valve can be installed in the circulation circuit so that when the vehicle is controlled, the pump is stopped and the valve is closed. With this configuration, it is possible to reliably prevent the cooling medium from circulating during braking of the vehicle. For example, even when natural convection occurs due to the temperature difference of the cooling medium, it can be prevented by closing the valve. And, as described in claim 3 of the present invention,

"A Stirling engine that is mounted on a vehicle and drives it,

The Stirling engine includes an operation state change device, and the operation state change device switches the Stirling engine to a heat pump operation when the vehicle is braked, and the Stirling engine is switched to a heat pump operation when the vehicle is braked.

The heating unit is provided with a heat accumulator, and the cooling unit is provided with a pump that circulates the cooling medium and a cooling medium that includes a radiator that radiates the heat of the cooling medium to the atmosphere. A circuit is formed,

The circulation circuit is provided with a heat transfer section temperature detector that detects the temperature of the heat transfer section between the working fluid and the cooling medium, and a cooling medium temperature detector that detects the temperature of the cooling medium. When the temperature detected by the hot section temperature detector is higher than the temperature detected by the cooling medium temperature detector, it is circulated to the radiator, and when it is lower, the circulation to the radiator is prevented. Was done "

It can implement also as a Stirling engine characterized by this. The Stirling engine according to claim 3 is a technical feature common to the Stirling engine according to Claim 1, that is, a Stirling engine having an operating state changing device and having a cooling part by a cooling medium. Switch to heat pump operation during braking and regenerate the kinetic energy of the vehicle as `` cold heat '' in the cooling medium of the cooling unit, and prevent regeneration of the high-temperature cooling medium to the radiator during regeneration Is. In the Stirling engine of item 3, a heat transfer section temperature detector and a cooling medium temperature detector are installed in the circulation circuit, and when the temperature of the heat transfer section is lower than the temperature of the cooling medium, the circulation to the radiator To prevent.

The Stirling engine of Claim 3 has the same technical features as the Stirling engine of Claim 1. Therefore, the Stirling engine operates in the same manner as the Stirling engine of Claim 1, and has the same effects. Play. Further, the circulation circuit of the cooling unit is provided with a heat transfer unit temperature detector that detects the temperature of the heat transfer unit between the working fluid and the cooling medium, and a cooling medium temperature detector that detects the temperature of the cooling medium. When switching to heat pump operation during braking causes a drop in the temperature of the working fluid and the temperature of the heat transfer section drops below the temperature of the cooling medium, circulation of the cooling medium is prevented. Since the circulation of the cooling medium is controlled by both temperature detectors, the temperature of the cooling medium can always be kept at the lowest temperature, and the situation in which the temperature rises by the radiator can be reliably avoided. As described in claim 4, even in the stalling engine described in claim 3, when installing a valve in the circulation circuit to prevent circulation to the radiator, the pump is stopped. The valve can be closed. In this case, the same effect as the Stirling engine in Item 2 can be achieved. In addition, as described in claim 5, a bypass passage for bypassing the radiator and a three-way valve is provided in the cooling medium circulation circuit to prevent circulation to the radiator. The 3-way valve can be switched to bypass the coolant.

When water or the like is used as the cooling medium, if the circulation circuit pump is stopped during the heat pump operation of the Stirling engine, the accumulated cooling medium locally becomes extremely low in the heat transfer section between the working fluid and the cooling medium. The medium may freeze. When the cooling medium is circulated through the bypass passage without stopping the pump during heat pump operation as in Section 5, the entire temperature becomes uniform and freezing due to local supercooling can be prevented. As described in claim 6, the Stirling engine is provided with a cylinder provided with a heating part and a cylinder provided with a cooling part, a piston is disposed in each cylinder, and communicated with each other. It is preferable that a working fluid is enclosed in the cylinder, and a liquid cooling jacket to which a cooling medium for the circulation circuit is supplied is preferably formed in the cylinder provided with the cooling unit. Such a configuration can be commonly applied to the Stirling engine of the first term and the Stirling engine of the third term.

Stirling engines include various types of engine mechanisms, such as those with displacers and those without them, but as described in claim 6, a cylinder with a heating unit and a cooling unit are installed. If a mechanism of a type in which pistons are arranged in the cylinders and the working fluid is sealed in communication with each other is used, the configuration of the operating state change device becomes simple. In other words, it is possible to adjust the output by changing the relative phase of the two pistons, and to switch the operating state of the Stirling engine from the engine operation to the heat pump operation. Then, the heat transfer between the working fluid and the cooling medium is improved by forming a liquid cooling jacket in which the cooling medium of the circulation circuit is supplied to the cylinder in which the cooling unit is installed. When operating the, the temperature of the working fluid in the cooling section can be sufficiently lowered. Brief Description of Drawings

FIG. 1 is a schematic view showing a first embodiment of the Stirling engine of the present invention. FIG. 2 is a diagram showing a phase difference changing mechanism of the Stirling engine.

Fig. 3 is a control system diagram of the Stirling engine.

Fig. 4 is a graph showing the relationship between Stirling engine output and phase. FIG. 5 is a schematic view showing a second embodiment of the Stirling engine of the present invention. FIG. 6 is a schematic view showing a third embodiment of the Stirling engine of the present invention. FIG. 7 is a schematic view showing a modified example of the Stirling engine of the present invention. BEST MODE FOR CARRYING OUT THE INVENTION

The Stirling engine of the present invention will be described below with reference to the drawings. Here, first, with reference to FIGS. 1 to 4, the configuration and operation of the Stirling engine of the first embodiment of the present invention will be described. The Stirling engine of the first embodiment shown in FIG. 1 is of an engine type having two cylinders arranged in parallel, with the piston 1 being the expansion side piston and the viston 2 being the compression side piston. It has become. The cylinder space above the piston 1 is the heating space 1 1, and the cylinder space above the piston 2 is the cooling space 2 1, and the heating space 1 1 and the cooling space 2 1 are communicated via the communication path 3. ing. Both spaces 1 1 and 2 1 constitute the working chamber of the Stirling engine, in which a working fluid made of a gas having a small specific heat such as hydrogen or helium is enclosed. The communication path 3 may be provided with a regenerator that stores the heat of the working fluid moving between both the spaces 1 1 and 1 2 and increases the cycle efficiency.

The piston 1 is connected to the crankpin of the crankshaft 13 by a rod, and the piston 2 is connected to the crankshaft 23 in the same manner. The crankshaft 23 is connected to the drive wheels of the vehicle via a vehicle power transmission device, and the vehicle is driven by the output of the Stirling engine during normal vehicle travel. A flywheel 4 is fixed to the crankshaft 1 3.

A heating unit 1 2 for heating the working fluid in the heating space 1 1 is disposed above the heating space 1 1. Here, combustion of fuel supplied from a fuel supply device (not shown) is performed. And the working fluid in the heating space 11 is heated. On the upper part of the cooling space 21, a cooling part denoted as a whole by reference numeral 22 is arranged to cool the working fluid in the cooling space 21. In the Stirling agency of FIG. 1, a heat accumulator 5 made of a massive object having a certain heat capacity, such as metal or ceramics, is installed in the heating section 12. The cooling unit 22 cools the working fluid using a cooling medium such as water, and includes a pump 2 2 A that circulates the cooling medium and a radiator 2 2 B that radiates the heat of the cooling medium to the atmosphere. It is a circulation circuit. As the cooling medium, liquids other than water can be used. For example, in order to prevent freezing due to a decrease in temperature, an antifreeze composed of ethylene glycol or the like can be mixed and used.

In this embodiment, in order to cool the working fluid in the cooling space 21, a liquid cooling tank portion 2 2 C having a large volume is provided, and a liquid cooling jacket 2 2 D is provided in the cylinder of the cooling space 21. The cooling medium formed is pumped to the liquid cooling tank section 2 2 C and the liquid cooling jacket 2 2 D by the pump 2 2 A, circulates to the radiator 2 2 B after cooling the working fluid. A valve 2 2 E is arranged in the middle of the circulation circuit. In addition, the crankshaft 1 3 to which the piston 1 is connected and the crankshaft 2 3 to which the piston 2 is connected are connected via a phase difference changing mechanism 6 which is an operating state changing device. And the phase difference between Piston 2 can be changed. As shown in FIG. 2, the phase difference changing mechanism 6 is configured as a gear transmission mechanism similar to a planetary gear device using a bevel gear. A through hole is formed in the frame body 61 of the phase difference changing mechanism 6, and an annular ring body 62 is rotatably fitted therein. The ring body 62 includes two support shafts extending inward in the radial direction, and bevel gears 6 3 A and 6 3 B are rotatably attached to the support shafts. The bevel gear 14 is fixed to the crankshaft 13 of the piston 1 as a whole, and the bevel gear 2 4 is fixed to the crankshaft 2 3 of the piston 2 as a whole. The bevel gears 1 4 and 2 4 mesh with the support shaft bevel gears 6 3 A and 6 3 B. All four bevel gears have the same shape and the same number of teeth.

When Biston 1 reciprocates and crankshaft 1 3 rotates in the direction of arrow 1 A, when the position of ring body 6 2 is fixed, bevel gear 1 4 supports bevel gear 6 3 on the support shaft. A, 6 3 B rotate around the support shaft, and the bevel gear 2 4 that meshes with this rotates in the opposite direction to the bevel gear 14. Therefore, the crankshaft 2 3 of the piston 2 rotates at the same speed as the crankshaft 1 3 in the direction of the arrow 2 A, which is the direction opposite to the rotation direction of the crankshaft 13. At this time, if the position of the ring body 62 is moved in the direction of arrow C, the bevel gears 6 3 A and 6 3 B of the support shaft rotate slightly according to the amount of movement, and the crank shaft 13 The phase of axes 2 and 3 can be changed. In other words, by adjusting the position of the ring body 62 using an actuator or the like, it is possible to adjust the phase difference between the piston 1 and the piston 2 that reciprocate in the same cycle. Adjustment of the phase difference is performed according to the control system diagram shown in Fig. 3 by detecting the operating state of the accelerator pedal and brake pedal operated by the vehicle driver. Here, the operation of the Stirling engine of the first embodiment will be described with reference to FIGS.

During normal driving of the vehicle, the Stirling engine operates as the engine that drives the vehicle. The phase difference between the piston 1 and the piston 2 is set to approximately 90 ° which is optimal for the operation of the engine by the phase difference changing mechanism 6. That is, in the operation state of the engine cycle, the volume of the cooling space 21 is set to change at a phase delayed by 90 ° from the volume change of the heating space 11. The working fluid in the working chamber composed of the heating space 1 1 and the cooling space 21 1 performs a Stirling cycle in which the state change is repeated while moving in both spaces according to the volume change of the working chamber. As a result, the heat from the heating unit 12 is converted into power, and the drive wheels of the vehicle are driven to rotate from the crankshaft 23. When operating as an engine, as shown in Fig. 4, if the phase difference is less than 90 °, the output of the Stirling engine will decrease. Therefore, it is possible to control the output of the Stirling engine by the phase difference changing mechanism 6, and the control for adjusting the phase is more responsive than that for adjusting the amount of fuel supplied to the heating section 1 or 2. Excellent control can be realized.

During normal travel of the vehicle that executes the Stirling cycle, in the cooling section 2 2, the pump 2 2 A is driven and the valve 2 2 E is opened. The pump 2 2 A pumps the cooling medium to the liquid cooling tank section 2 2 C and the liquid cooling jacket 2 2 D, and the expansion of the cooling medium in the liquid state mainly exists in the cooling space 21 Cool the fluid. This cooling is performed by heat transfer to the liquid, and the liquid cooling jacket 2 2 D is formed so as to surround it in the vicinity of the cooling space 21, so that the working fluid is sufficiently cooled. As a result, the temperature difference between the heated working fluid and the cooled working fluid increases, and the Stirling engine operates in a highly efficient state. When braking the vehicle, the brake system hydraulic pressure increases as the brake pedal of the foot brake is operated. Detecting a rise in hydraulic pressure, phase change mechanism 6 switches the phase between piston 1 and piston 2, and the volume of cooling space 2 1 is 90 ° ahead of the volume change of heating space 1 1. Set to change. By this switching, the state change of the working fluid becomes a so-called reverse Stirling cycle, and the Stirling engine operates as a heat pump. During braking, the kinetic energy of the vehicle is consumed in a short period of time, so a large amount of power is supplied from the drive wheels to the Stirling engine, and the cooling space 21 becomes cold and the heating space 11 becomes hot.

During braking of the vehicle, the pump 2 2 A is stopped and the valve 2 2 E is closed in the cooling section 2 2 to prevent the cooling medium from circulating, and the cooling medium is connected to the liquid cooling tank section 2 2 C and the liquid. Stay in cold jacket 2 2 D. When the cooling space 21 becomes cold, the temperature of the cooling medium decreases, and since the heat in the atmosphere is prevented from entering from the radiator 2 2 B by preventing the circulation of the cooling medium, the temperature of the cooling medium Drops below the atmospheric temperature and accumulates “cold heat”. In this embodiment, the volume of the liquid cooling tank section 2 2 C is set large, and a large amount of “cold heat” can be accumulated. On the other hand, when the heating space 11 becomes high temperature, the heat accumulator 5 also becomes high temperature, and heat energy is accumulated here. Thus, at the time of braking of the vehicle, the kinetic energy of the vehicle is converted into temperature difference energy and stored in the heat accumulator 5 and the cooling medium. The temperature difference energy stored when the vehicle is braked is used when the vehicle is re-accelerated. In other words, the phase difference changing mechanism 6 is switched at the time of reacceleration, and the phases of the piston 1 and the piston 2 are in a phase state in which the engine cycle is executed. At this time, the temperature stored in the heat accumulator 5 and the cooling medium The Stirling engine operates with the difference energy. Since the temperature difference between the regenerator 5 and the cooling medium is larger than that during normal driving, the Stirling engine can generate a large output commensurate with the acceleration of the vehicle. Also, Since the accumulated temperature difference energy is used, the amount of fuel supplied to the heating section can be greatly reduced.

Even when the vehicle travels on a downhill road surface, the Stirling engine is switched to the heat pump operation by the phase difference changing mechanism 6 in accordance with the operation of the driver's brake pedal. The power to drive the Stirling engine as a heat pump is much larger than the power absorbed when acting as an engine brake, so a strong braking force acts on the vehicle, reducing the load on the foot brake, etc. be able to. The energy regenerated as temperature difference energy while traveling on a downhill road surface is used for subsequent vehicle travel, as in the case after braking. Fig. 3 shows the control system for implementing such control. A position signal of the accelerator pedal of the vehicle and a pressure signal of the brake device are input to the electronic control unit (E C U) that controls the phase difference changing mechanism. If the accelerator pedal is depressed, E C U adjusts the position of the ring body of the phase difference changing mechanism so that the Stirling engine operates as an engine, and optimizes the phase of both pistons for engine operation. It is also possible to control the phase difference changing mechanism to change the output according to the position of the accelerator pedal. When the brake pedal is depressed, this is detected by the brake system pressure sensor, and ECU switches the position of the phase difference changing mechanism so that the Stirling engine operates as a heat pump. Next, a Stirling engine according to a second embodiment (corresponding to claim 3) of the present invention shown in FIG. 5 and a third embodiment (corresponding to claim 5) of FIG. 6 will be described. In these drawings, parts corresponding to those of the first embodiment of the present invention are denoted by the same reference numerals as those in FIG.

The Stirling engines of the second and third embodiments have the same technical features as the Stirling engine of the first embodiment, and basically operate in the same manner as the Stirling engine of the first embodiment. . In other words, it is an engine type equipped with two cylinder / piston mechanisms arranged in parallel.Piston 1 is the expansion side piston and piston 2 is the compression side piston. Connected by device 6. The driving state changing device 6 is the same as that shown in FIG. For this, the Stirling engine is switched to heat pump operation according to the same control method as the control system shown in FIG. 3, and the kinetic energy of the vehicle is stored as “cooling heat” in the cooling medium of the cooling unit 22. As shown in FIG. 5, in the circulation circuit in the cooling section 22 of the second embodiment, two temperature detectors, that is, a heat transfer section temperature detector S 1 and a cooling medium temperature detector S 2 are installed. The motor that drives the pump 2 2 A is controlled according to the temperature detected by these two temperature detectors. The heat transfer section temperature detector S 1 detects the temperature of the heat transfer section between the working fluid and the cooling medium, and is attached to the bottom wall surface of the liquid cooling tank section 2 2 C. On the other hand, the cooling medium temperature detector S 2 detects the temperature of the cooling medium, and is attached to the outlet of the heat radiator 2 2 B. Heat transfer section temperature detector S 1 may be installed in liquid cooling jacket 2 2 D ', and coolant temperature detector S 2 detects the temperature of the coolant on the discharge side of pump 2 2 A You may do it.

During normal driving of a vehicle that performs the Stirling cycle, the temperature of the expanded working fluid that is mainly present in the cooling space 21 is higher than the temperature of the cooling medium, and the temperature detected by the heat transfer section temperature detector S1 is cooled. It is higher than the detection temperature of the medium temperature detector S2. Therefore, in the cooling unit 22, the pump 2 2 A is driven and the valve 2 2 E is opened. Pump 2 2 A pumps the cooling medium to liquid cooling tank section 2 2 C and liquid cooling jacket 2 2 D, and the cooling medium in the liquid state cools the working fluid in cooling space 21 1 內. The heat transferred to the cooling medium is dissipated from the radiator 2 2 B into the atmosphere, so that the working fluid is sufficiently cooled to near atmospheric temperature.

When braking a vehicle in which the Stirling engine is switched to heat pump operation, a large amount of power is supplied from the drive wheels to the Stirling engine, so that the cooling space 21 becomes cold and the heating space 11 becomes hot. When the temperature of the cooling space 2 1 decreases, the bottom wall surface of the liquid cooling tank 2 2 C, which is the heat transfer part between the working fluid and the cooling medium, becomes low temperature, and the detection temperature of the heat transfer part temperature detector S 1 It becomes lower than the detected temperature of the coolant temperature detector S2. In the cooling section 2 2, the pump 2 2 A is stopped and the valve 2 2 E is closed to prevent the cooling medium from circulating to the radiator 2 2 B. The cooling medium is connected to the liquid cooling tank section 2 2 C. Stays in liquid-cooled jacket 2 2 D. Blocking the circulation of the cooling medium prevents the heat from entering the air from the radiator 2 2 B. The temperature of the medium drops below the atmospheric temperature and “cold heat” accumulates. In this embodiment, the volume of the liquid cooling tank section 2 2 C is set large, and a large amount of “cold heat” can be accumulated. On the other hand, when the heating space 11 becomes high temperature, the regenerator 5 also becomes high temperature, and heat energy is accumulated here. Thus, at the time of braking of the vehicle, the kinetic energy of the vehicle is converted into temperature difference energy and stored in the heat accumulator 5 and the cooling medium. The fact that this temperature difference energy is used when the vehicle is re-accelerated is the same as in the first embodiment. In the third embodiment of the present invention shown in FIG. 6, a bypass passage 2 2 F and a three-way valve 2 2 G for bypassing the radiator 2 2 B are provided in the cooling medium circulation circuit. In this third embodiment, when the detection temperature of the heat transfer section temperature detector S 1 is lower than the detection temperature of the cooling medium temperature detector S 2 and the circulation of the cooling medium to the radiator 2 2 B is prevented Switch the three-way valve 2 2 G so that the coolant flows through the bypass passage 2 2 F without stopping the pump 2 2 A.

If the pump 2 2 A is stopped during the operation of the heat pump of the Stirling engine, the accumulated cooling medium becomes extremely low locally in the heat transfer section between the working fluid and the cooling medium, and water or the like is used as the cooling medium. If used, the cooling medium may freeze. As in the third embodiment, when the cooling medium is circulated through the bypass passage 2 2 F during heat pump operation, the entire temperature becomes uniform and freezing due to local supercooling can be prevented. By the way, to switch the Stirling engine to heat pump operation, there is a method of reversing the engine itself. In other words, a transmission device that can be reversed on the output shaft of the Stirling engine is arranged as an operation state change device, and when the Stirling engine is switched to the heat pump operation, the Stirling engine may be configured to be reversed. Applicable to Stirling engines of the form As an operation state change device at this time, a transmission device that can continuously change the rotation speed of the output shaft with respect to the rotation speed of the input shaft and can reverse the rotation speed (such a transmission device is, for example, JP-A 2 0 0 1-1 2 4 1 6 6) is preferred. FIG. 7 shows a modified example of the Stirling engine of the present invention in which the engine is reversely rotated to perform the heat pump operation. Stalin in the variation of FIG. The basic configuration of the engine is the same as that of the embodiment shown in FIG. 1 and the like, and the corresponding components are denoted by the same reference numerals. However, Piston 1 and Piston 2 are connected to an integral crankshaft, and their phase is fixed at the optimum phase for engine operation. As the operating state changing device, the output shaft rotational speed can be continuously changed with respect to the input shaft rotational speed, and a transmission device 7 that can be reversed is placed at the output portion of the crankshaft. When the heat pump operation is performed during braking or the like, the same operation as that of the embodiment of FIG. 1 can be realized by reversing the steering engine. Industrial applicability

As described above in detail, in the Stirling engine mounted on the vehicle, the present invention switches the operating state of the Stirling engine to operate as a heat pump when the vehicle is braked, etc., and converts the kinetic energy of the vehicle to temperature difference energy. It is converted and stored in the heat accumulator and cooling medium. Therefore, it is obvious that the Stirling engine of the present invention can be used for various vehicles as a power source for vehicles.

In the above embodiment, a Stirling engine provided with two pistons of expanded and compressed pistons is described. However, the present invention is, for example, a power that takes out one piston as a displacer and takes out the output from the other piston. It is clear that it can be applied to various types of engines, such as the Stirling engine of the Biston type. It goes without saying that various modifications can be made to the embodiment, such as using phase changing means of another mechanism instead of a phase difference changing mechanism using a bevel gear.

Claims

A Stirling engine mounted on and driving a vehicle, wherein the Stirling engine includes a heating unit that heats the working fluid and a cooling unit that cools the working fluid, and

The Stirling engine includes an operation state changing device, and the operation state changing device switches the Stirling engine to engine operation during normal operation of the vehicle, and switches the Stirling engine to heat pump operation during braking of the vehicle,

The heating unit is provided with a heat accumulator, and the cooling unit is formed with a cooling medium circulation circuit including a pump that circulates the cooling medium and a radiator that radiates the heat of the cooling medium to the atmosphere. ,

When the operating state changing device sets the Stirling engine to engine operation, the pump is driven to circulate the cooling medium, and when the operating state changing device switches the Stirling engine to heat pump operation, The pump is stopped and the circulation of the cooling medium is prevented, the temperature of the working fluid and the cooling medium on the cooling unit side is lowered, and the temperature of the working fluid and the heat accumulator on the heating unit side is raised. Stirling engine characterized by being. A valve is installed in the circulation circuit, and when the operation state change device switches the steering engine to heat pump operation, the pump is stopped and the valve is closed, and The Stirling engine according to Item 1, wherein circulation is prevented.

A Stirling engine that is mounted on a vehicle and drives the Stirling engine, the Stirling engine comprising a heating unit that heats the working fluid and a cooling unit that cools the working fluid,

The Stirling engine includes an operation state change device, and the operation state change device sets the Stirling engine to engine operation during normal operation of the vehicle, and sets the Stirling engine to heat pump operation during braking of the vehicle. Switching,

A heat accumulator is disposed in the heating unit, and a cooling medium is provided in the cooling unit. A circulation circuit for the cooling medium is formed with a circulating pump and a radiator that radiates the heat of the cooling medium to the atmosphere.

The circulation circuit is provided with a heat transfer section temperature detector that detects the temperature of the heat transfer section between the working fluid and the cooling medium, and a cooling medium temperature detector that detects the temperature of the cooling medium. When the temperature detected by the hot section temperature detector is higher than the temperature detected by the cooling medium temperature detector, it is circulated to the radiator, and when it is lower, circulation to the radiator is blocked. A Stirling engine characterized by being configured as follows.

The Stirling engine according to claim 3, wherein a valve is installed in the circulation circuit, and when the circulation to the radiator is prevented, the pump is stopped and the valve is closed.

The circulation circuit is provided with a bypass passage that bypasses the radiator and a three-way valve. When the circulation to the radiator is prevented, the three-way passage is performed so that a cooling medium flows through the bypass passage. The Stirling engine according to Item 3, which switches the valve.

The Stirling engine has a cylinder in which the heating unit is installed and a cylinder in which the cooling unit is installed. In each cylinder, pistons are arranged and communicated with each other to enclose a working fluid. The Stirling engine according to claim 1 or 3, wherein a liquid cooling jacket to which a cooling medium of the circulation circuit is supplied is formed in the cylinder in which the cooling unit is installed.