Title of Invention: HYBRID VEHICLE

Technical Field

[0001] The present invention relates to a compressed air vehicle, more particularly a hybrid vehicle of an improved compressed air vehicle using compressed air and electrical energy as sources of driving power. Background Art

[0002] At the present time, almost all automobiles, one type of vehicle, run by internal combustion engines fueled by gasoline, diesel oil, and other fossil fuels. However, in recent years, from the viewpoint of reduction of CO ₂ and other toxic exhaust gases, reduction of use of fossil fuels, and other aspects of environmental protection, "low emission and low fuel consumption" eco cars, that is, electric vehicles and gasoline- electric hybrid cars etc. have been attracting attention. Hybrid cars are already being marketed, while electric vehicles are soon going to be introduced into the market. Development for commercialization of fuel-cell vehicles is accelerating too.

[0003] However, current hybrid cars still use internal combustion engines, so while less than single internal combustion engine cars, toxic exhaust gas is discharged to the atmosphere during their operation. Electric vehicles are being improved in travel distance per charge due to the improved performance of rechargeable batteries, but the problem that their charging takes a long time still remains. Therefore, there are restrictions in modes of use. Furthermore, fuel cell vehicles require very high cost to manufacture. In addition, infrastructure has to be built for the sources of driving power etc. A considerable time is believed to be required until they can be marketed.

[0004] In view of this situation, the inventors invented and filed a patent application for a compressed air vehicle which does not discharge toxic exhaust gas causing air pollution during operation and which can be charged with the source for driving power in a short time (Patent Literature 1). A "compressed air vehicle" is a vehicle where compressed air obtained by compressing air under a high pressure operates an air engine or other motor to obtain driving force.

[0005] Note that the "source for driving power" means gasoline, diesel oil, or other fuel in internal combustion engine cars, electrical energy in electric vehicles, and compressed air in compressed air vehicles. That is, this means the source of energy required for operation of the vehicle and for the air-conditioner, lights, etc. required along with operation.

[0006] Compressed air vehicles are introduced by the internet homepage of French MDI Enterprises SA as well. A compressed air vehicle as explained above has the advantages that it does not discharge toxic exhaust gas during operation and does not require a long time to charge the compressed air, but has the problem that when using only compressed air as the source for driving power, the power is insufficient and the travel distance is short. Even with the compressed air vehicle at the above homepage site, although the vehicle weight is less than 400 kg, the travel distance in city driving (per full charge of compressed air) is 100 km and the maximum speed is about 100 km/hr. These are insufficient in performance wise.

[0007] To solve the above defects of compressed air as a source for driving power, a hybrid apparatus which is equipped with a solar panel and uses electrical energy obtained by the photovoltaic power generation has been proposed (Patent Literature 2). However, this type of hybrid vehicle uses a bulky apparatus and cannot obtain electrical energy at night or otherwise when there is no sunlight, so is not practical. Citation List Patent Literature

[0008] PTL 1: JP 2005-306191 A PTL 2: JP 2000-161001 A Summary of Invention Technical Problem

[0009] The object of the present invention is to provide a hybrid type compressed air vehicle which utilizes the advantages of a compressed air vehicle of not discharging toxic exhaust gas during operation and not requiring a long time for charging the compressed air and is practical enough in terms of power and travel distance per full charge of compressed air. Solution to Problem

[0010] To solve the above problem, a hybrid vehicle using compressed air and electrical energy as the source of driving power and equipped with the following apparatus is provided. Due to this, its energy efficiency is remarkably improved and its power and travel distance are greatly improved. Here, the "energy efficiency" means the efficiency by which the energy of the source for driving power is converted into the driving power of the vehicle.

[0011] That is, the hybrid vehicle of the present invention is a hybrid vehicle using compressed air and electrical energy as the source for driving power, comprising: (a) a first compressed air storage part which stores compressed air; (b) a turbine type air engine which generates power by the compressed air supplied from the first compressed air storage part; (c) a first power division part which divides the power; (d) a first dynamo connected to the first power division part; (e) a wheel actuator connected to the turbine type air engine through the first power division part; (f) an electric motor and a second dynamo which are connected to the wheel actuator; (g) an electrical storage part which stores the electrical energy generated with the first and the second dynamos; (h) an air compression part connected to the turbine type air engine; (i) a second compressed air storage part connected to the air compression part; and (j) a second power division part connected to the wheel actuator, the second dynamo, and the air compression part.

[0012] Here, an "air engine" means a motor which is operated by air pressure, namely, compressed air. Moreover, a "wheel actuator" means a power transmission device which transmits the power obtained from compressed air and electrical energy to a wheel and, for example, includes an actuator like a differential gear.

[0013] Preferably, in the hybrid vehicle of the present invention, the turbine type air engine may be operated by not only the compressed air from the first compressed air storage part, but also the compressed air from the second compressed air storage part.

[0014] Preferably, the air compression part is a piston type compressor.

[0015] Preferably, the hybrid vehicle of the present invention is provided with a control means for controlling the proportion of the driving force derived from the compressed air and the driving force derived from the electrical energy transmitted from the turbine type air engine and the electric motor to the wheel actuator.

[0016] Preferably, the hybrid vehicle of the present invention uses regenerated energy generated at the time of deceleration, the time of braking, etc. to operate the second dynamo and store the regenerated energy as electrical energy in the electrical storage part or to operate the air compression part to store it as compressed air in the second compressed air storage part or uses the second power division part to store it as both electrical energy and compressed air in both the electrical storage part and the second compressed air storage part.

[0017] Note that, when storing electrical energy in an electrical storage part, if the electrical storage part is a rechargeable battery, the electrical energy is actually converted to chemical energy for storage. Here, this chemical energy is also called electrical energy or electricity.

[0018] Preferably, the hybrid vehicle of the present invention is provided with a control means for controlling the proportion of storing regenerated energy in the electrical storage part as electrical energy and the proportion of storing it in the second compressed air storage part as compressed air.

[0019] Moreover, in the hybrid vehicle of the present invention, said turbine type air engine and electric motor may be connected to the same wheel actuator or may be connected to different wheel actuators.

[0020] Furthermore, in the hybrid vehicle of the present invention, the electric motor and the second dynamo may be single apparatus, that is, the electric motor may serve as the second dynamo.

Advantageous Effects of Invention

[0021] According to the present invention, it is possible to remarkably improve the energy efficiency of a compressed air vehicle. Further, it is possible to provide a hybrid type compressed air vehicle which can make use of the advantages of compressed air of not discharging toxic exhaust gas during operation and not requiring a long time for charging the compressed air while satisfying practical requirements of power and the travel distance. Furthermore, when provided with an energy regeneration apparatus, it is possible to provide a hybrid type compressed air vehicle with much better energy efficiency. Brief Description of Drawings

[0022] [fig.ljFig. 1 is a schematic view which comprehensively expresses the configuration of a compressed air-electric hybrid car of a preferable embodiment of the present invention.

[fig.2]Fig. 2 is a schematic view showing an example of the operation of the components at the time of start, acceleration, and uphill driving. [fig.3]Fig. 3 is a schematic view showing an example of the operation when starting by only the electric motor 6 using electrical energy.

[fig.4]Fig. 4 is a schematic view showing an example of the operation of the components at the time of constant speed driving.

[fig.5]Fig. 5 is a schematic view showing an example of the operation of the components at the time of deceleration and the time of braking. [fig.6]Fig. 6 is a schematic view showing another embodiment of the hybrid car of the present invention where the turbine type air engine and electric motor are connected different wheel actuators. Description of Embodiments

[0023] When solving the first problem of insufficient power, the present invention focuses on the following point. That is, when the driving load is large and the drive force of only compressed air is insufficient, electrical energy is used to make up for the shortfall. Specifically, this happens at the time of start, acceleration, and uphill driving. That is, when a large driving energy is needed, driving force is obtained not only by energy from compressed air, but also electrical energy.

[0024] As a preparation when first driving the hybrid vehicle of the present invention, firstly the compressed air storage part (the first compressed air storage part) is charged with compressed air by a compressor etc. The storage pressure of air depends on the pressure resistance of the storage part, but practically the storage part should be able to store air at 10 MPa or more, preferably 30 MPa or more. The upper limit of the pressure is inevitably decided by the pressure resistance of the storage part, but within the range permitted by the pressure resistance and safety, the higher this upper limit pressure, the better in terms of the travel distance.

[0025] Moreover, when first storing electrical energy in the electrical storage part, it may be charged from an external power supply like with an electric vehicle. Further, the compressed air stored in the compressed air storage part may be used to operate the turbine type air engine, the obtained power used to operate the first dynamo to generate electricity, and the electrical energy used to charge the electrical storage part. Note that when using compressed air to charge electrical energy, it is preferable to refill the compressed air consumed for charging.

[0026] The electrical storage part is not particularly limited so long as being a device able to store electricity such as a nickel hydrogen rechargeable battery or a lithium ion rechargeable battery or other storage battery or a capacitor etc., but from the viewpoint of the storage capacity and the ease of handling, a storage battery is preferable.

[0027] Air engines operating by compressed air include piston type in addition to the turbine type of the present invention. However, its mechanical loss is larger than a turbine type. This runs counter to the solution for the second problem of increasing the travel distance and therefore is not preferable. That is, a turbine type has a higher energy efficiency than a piston type and can greatly improve the travel distance. However, a turbine type is suitable for high speed operation. It has the demerit that the torque is small at the time of low speed operation and its control is a little difficult.

[0028] The hybrid vehicle of compressed air and electrical energy of the present invention has the advantage that this fault of a turbine type air engine can be solved.

[0029] Next, the role of the other parts of the present invention in solving the above problems will be described below in detail. The first power division part divides the power generated by the operation of the air engine and transmits a part of the power to a wheel actuator part to drive the vehicle. The remaining power is used to operate the first dynamo to generate electrical energy which is then stored in an electrical storage part through an inverter (charges).

[0030] The situation when dividing power between driving the vehicle and storing electricity is when driving on flat roads or downhill at a constant speed or other such driving modes. In this case, the required driving energy is not large, so the part of the power generated is converted to electrical energy to prepare when a large driving energy is required.

[0031] In such a case, the method of reducing the flow rate of compressed air to reduce the generated power may also be considered. However, when the modes of start, acceleration, constant speed, deceleration, and braking are repeated in a short time like in city driving, if trying to handle this situation by just controlling the flow rate of the compressed air, the energy loss would become large and the energy efficiency would end up becoming very low. That is, the first power division part is a device which operates to keep a minimum for the operations by controlling the flow rate of the compressed air so as to prevent energy loss and which contributes to the increase of the travel distance to help solve the second problem.

[0032] The first power division part can be configured in any way and is not particularly limited so long as it can divide the power generated by the turbine type air engine as explained above. For example, it may be operated by a mechanism using a planetary gear. In addition, to optimize the energy efficiency, the division of power is preferably optimally controlled by a computer or other control means in accordance with the operating mode, driving conditions, etc. Therefore, there may be the cases when the generated power is all used for driving the wheel drives and the cases when it is conversely all used for generating electricity.

[0033] Here, "optimize the energy efficiency" means to generate the demanded vehicle driving force according to the driving mode, driving conditions, instructions by operating the accelerator pedal by the driver, and other situations while keeping the energy loss to a minimum.

[0034] When a large drive energy is needed like at the time of acceleration or at the time of uphill driving, the electric motor, one part of the present invention, is operated and generates power by receiving the supply of electrical energy from the electrical storage part, and the power drives the vehicle together with the power from the air engine. This contributes to the solution of the first problem for insufficient power.

[0035] Furthermore, at the time of cruising or other very low speed driving, the vehicle of the present invention may be driven by just the power from the electric motor. In such a case, the energy efficiency of the air engine is poor, so the advantages of an electric motor with good efficiency even at a low speed and a large low speed torque can be made use of it. That is, the electric motor is also an apparatus which contributes to the increase of the travel to solve the second problem.

[0036] In the embodiment of the present invention, the vehicle is further provided with an air compression part connected to a turbine type air engine and a second power division part, and a second compressed air storage part for storing the air compressed in the air compression part. The air compression part performs the role of recovering the compressed air after operating the turbine type air engine (exhausted air) and the role of converting the regenerated energy generated at the time of deceleration of the vehicle, at the time of braking, etc. to compressed air.

[0037] That is, the air compression part is an apparatus recovering the discarded energy so as to improve the energy efficiency and contributes to increase the travel distance of the second problem. [0038] Here, the "regenerated energy" means the energy which can be recovered by regeneration in the kinetic energy of a vehicle at the time of deceleration of the vehicle and/or braking etc. (recovered energy).

[0039] The exhausted air still has residual energy not converted to power at the air engine. If discharged to the atmosphere as is, that energy would be lost. Therefore, the exhausted air is regenerated to compressed air to recover the energy. Therefore, when the air compression part compresses the exhausted air, it can generate compressed air with less energy than the case when taking in and compressing air from the atmosphere. The energy regeneration will be explained later.

[0040] The compressed air stored in the second compressed air storage part may be used after use of the compressed air of the first compressed air storage part or alternately with it or simultaneously with it. If used for driving at the time the fuel alarm light turns on, namely, for backup use, it is preferably used after use of the compressed air of the first compressed air storage part.

[0041] The air compression part is preferably a compressor of the piston type at the point of generating high pressure compressed air. Moreover, for the practical reasons, when storing the compressed air in the second compressed air storage part due to the recovery of the exhausted air and the conversion of the regenerated energy, the storage pressure is preferably maintained at 1 MPa or more, more preferably, 5 MPa or more.

[0042] This embodiment of the present invention is further provided with an energy regenerating means and, preferably, its control means. That is, it regenerates the kinetic energy of the vehicle at the time of deceleration of the vehicle, at the time of braking, etc. and stores the regenerated energy by the following three patterns. First, it uses the regenerated energy to operate the second dynamo and to store it as electrical energy in the electrical storage part through an inverter. Second, as explained above, it uses the regenerated energy to operate the air compression part to produce compressed air which is stored in the second compressed air storage part. Third, it uses the second power division part to divide the regenerated energy into the power for operating the second dynamo and the power for operating the air compression part and stores the regenerated energy in the form of both electrical energy and compressed air.

[0043] The second power division part can be structured in any way and is not particularly limited so long as it can divide the regenerated energy converted to the power. For example, it may be operated by a mechanism using a planetary gear like the first power division part. However, the second power division part works only at the time of energy regeneration and will not become a load in operation during driving when converting the driving force to the wheel actuator.

[0044] Moreover, at the selection of the three patterns, preferably an energy regeneration control means using a computer etc. is used to select the optimum pattern. For example, in principle the regenerated energy is recovered and stored as electrical energy, but when the stored amount of the electrical storage part approaches full charge, the third pattern is selected, while at the time of full charge, the second pattern is selected.

[0045] Furthermore, when using a rechargeable battery as the electrical storage part, since a rechargeable battery has a large natural electric discharge, the second pattern is selected in the situation where the vehicle will not be driven for several days or more after driving. This is because compressed air will not naturally leak out much at all for several months. In such a case, it is preferable that the driver can select the best pattern in the system.

[0046] The above-mentioned energy regenerating means and its control means are means which improve the energy efficiency and contribute to increasing the travel distance of the second problem.

[0047] The turbine type air engine and electric motor of the present invention may be connected to the same wheel actuator of the front wheels or rear wheels or may be separately connected to the front wheels and the rear wheels depending on the size of the vehicle and other restrictions. Furthermore, the electric motor may be connected to all of the wheels so that all of the wheels are driven. Moreover, a rotary type air engine can be used as the air engine instead of the turbine type air engine.

[0048] <Embodiments>

Below, the preferred embodiments of the present invention will be described in detail with the following reference to the drawings.

[0049] Fig.1 shows overall an outline of the configuration of a hybrid car using compressed air and electrical energy as a source of driving power (hereinafter called a "compressed air-electric hybrid car") as one preferred embodiment of the present invention. Note that Figs. 1 to 5 show a case where the electric motor also serves as the second dynamo.

[0050] The compressed air-electric hybrid car of the present invention uses the turbine type air engine 2 and the electric motor (second dynamo) 6 (hereinafter called an electric motor 6 in the case of working as an electric motor and called a second dynamo 6 in the case of working as a second dynamo) as a power generator. That is, when the turbine type air engine 2 or the electric motor 6 or both of the turbine type air engine 2 and the electric motor 6 are operated, the generated power is transmitted through the wheel actuator 8 to the driving wheels 9 whereby the wheels are driven. As an example of an electric motor, a three-phase AC induction motor may be mentioned.

[0051] Moreover, as an electrical energy source which operates the electric motor 6, the electrical storage part 7 which stores the electrical energy generated from the first dynamo 4 etc. is mounted. The electrical energy which is generated from the first dynamo 4 and the second dynamo 6 is stored through the inverter 5 in the electrical storage part 7. Moreover, the electric motor 6 is supplied with electrical energy from the electrical storage part 7 through the inverter 5. The storage and discharge at this time are automatically controlled according to the driving conditions and operation mode of the vehicle by the control means 14 so as to satisfy the power demanded by the driver and to improve the energy efficiency.

[0052] In the present embodiment, the first compressed air storage part 1 is charged with the compressed air at a pressure of 30 MPa.

[0053] A compressed air feed unit adjusting the feed of compressed air from the first compressed air storage part 1 (solenoid valve in this embodiment) is operated by the control means 14 powered by an auxiliary battery 13 so as to feed compressed air by which the turbine type air engine 2 is then operated to obtain power.

[0054] The power generated from the turbine type air engine 2 is divided by the first power division part 3 into power to be transmitted to the wheel actuator 8 and power for operating the first dynamo 4 for storage of electricity. The judgment of this power division is automatically controlled according to driving conditions, the operation mode, etc. by the control means 14. Note that, in this embodiment, as the first power division part 3, a mechanism using a planetary gear is used.

[0055] Next, energy regeneration will be explained. The white arrows in the figures show the flow from recovery of regenerated energy to storage at the storage parts. The actual form of the energy of the regenerated energy is the power which operates the second dynamo 6 or air compression part 11 or both. Next, this power is converted into electrical energy generated from the second dynamo 6 and the energy held by the compressed air generated at the air compression part 11. Namely, the regenerated energy is stored as this electrical energy and compressed air.

[0056] The first mode of energy regeneration is the regeneration from the exhausted air. That is, the compressed air supplied from the first compressed air storage part 1 is consumed by operating the turbine type air engine 2, but the air exhausted at that time is sent to the air compression part 11. In this case, the air compression part 11 basically operates by the electrical energy supplied from the electrical storage part 7 or the auxiliary battery 13. However, when vehicle decelerates, brakes, etc., the air compression part 11 is operated also with the regenerated energy supplied as power from the second power division part 10.

[0057] The exhausted air is compressed by the action of the air compression part 11 and is filled and stored in the second compressed air storage part 12. The compressed air filled in the second compressed air storage part 12 is reused as the compressed air for operation of the turbine type air engine 2 by the action of the compressed air feed unit (solenoid valve in this embodiment) controlled by the control means 14 powered by the auxiliary battery 13.

[0058] The second mode of energy regeneration is the regeneration (recovery) of the kinetic energy of the vehicle at the time of deceleration, the time of braking, etc. First, the second dynamo 6 is operated using this kinetic energy (regenerated energy) as the source of power to recover this as electrical energy. This is a so-called "regenerative brake." Second, as explained above, the air compression part 11 is operated using this kinetic energy as the source of power through the second power division part 10 so as to generate compressed air and recovers the energy as that compressed air for storage in the second compressed air storage part 12. In this case, the air compression part 11 acts as a regenerative brake.

[0059] At this time, the compressed air is generated by not only the exhausted air, but also air taken in from the atmosphere. Furthermore, the heat energy obtained at the time of braking is utilized to preheat the air in the second compressed air storage part 12 and further increase the charging pressure.

[0060] The control means 14 operates to detect and judge the operation mode, the driving conditions, and the instructions from the driver. For example, the control means 14 controls the start and stopping of the turbine type air engine 2, the electric motor and second dynamo 6, the first dynamo 4, etc. Furthermore, the control means 14 in principal automatically controls the rate of the power division at the first power division part 3 and the second power division part 10 according to the driving conditions etc. so that the energy efficiency becomes optimal. Furthermore, the control means 14 controls whether to recover regenerated energy as electrical energy, recover it as compressed air, or recover it as both by judging the storage state of the electrical storage part 7 etc. However, when there are instructions from a driver, the instructions may be accorded priority over energy efficiency.

[0061] Below, the operation of each component according to each operation mode will be explained.

[0062] <Time of start>

An example of the operation of the components at the time of start is shown in Fig. 2. At the time of start, compressed air supplied from the first compressed air storage part 1 is used to operate the turbine type air engine 2 so as to generate power. Further, basically, all of this power is transmitted to the wheel actuator 8 where it is used for the drive force of the vehicle. In addition, energy is also regenerated from the exhausted air (hereinafter, same when the turbine type air engine 2 is operated). Note that in Fig. 2, the case is shown where compressed air is not supplied from the second compressed air storage part 12, but, as explained above, compressed air may also be supplied from the second compressed air storage part 12 (same for following Figs. 4 and 5).

[0063] However, whatever the case, as explained above, the turbine type air engine 2 alone is insufficient as the start power, so the electrical energy already stored in the electrical storage part 7 is supplied to the electric motor 6, and the power generated from the electric motor 6 is also transmitted to the wheel actuator 8 for use for the drive force of the vehicle. Due to this, sufficient starting power can be obtained.

[0064] At this time, the control means 14 senses the strength of the start power (start acceleration) demanded by a driver's operation of the accelerator pedal etc. and controls the flow rate of compressed air and the supply of electrical energy from the electrical storage part 7 to obtain the perfect balance. For example, at the time of an instruction for a slow start, the control means 14 gives priority to energy efficiency and orders start by only with the electric motor 6 using electrical energy, while at the time of an instruction for a full throttle start, it controls the combination of compressed air and electrical energy so that the maximum power is obtained. Fig. 3 shows an example of the case of start by only the electric motor 6 using electrical energy.

[0065] <Time of acceleration and uphill driving>

In this case, basically, in the same way as the time of start, the vehicle is driven by both the power obtained from the turbine type air engine 2 and the power obtained from the electric motor 6 (Fig. 2). At this time, again, the control means 14 judges the strength of an acceleration order or the degree of the slope of an uphill road etc. and controls the flow rate of compressed air and the supply of electrical energy from the electrical storage part 7 to the perfect balance. Due to this, the fault of a compressed air car of insufficient power can be improved.

[0066] <Time of constant speed driving>

An example of the operation of the components at the time of constant speed driving on a flat road is shown in Fig. 4. At the time of constant speed driving on a flat road, basically, only the turbine type air engine 2 is operated. The vehicle runs only by the power generated by this. When the speed is not so fast like at the time of driving on city streets etc., a small driving power is enough, so part of the power generated is split off at the first power division part 3 to operate the first dynamo 4 and generated electrical energy which is then stored in the electrical storage part 7.

[0067] On the other hand, when driving like on a highway even when driving at a constant speed, the electric motor 6 is also operated and the vehicle is driven by both the power obtained from the turbine type air engine 2 and the power obtained from the electric motor 6.

[0068] <Time of deceleration and braking>

An example of the operations of the components at the time of deceleration and the time of braking is shown in Fig. 5. At the time of deceleration and the time of braking, the second dynamo 6 connected to the wheel actuator 8 is operated by the kinetic energy transmitted from the wheel side, whereby resistance is caused by rotation of the second dynamo 6 (regenerative brake), induction power is generated, and the electrical storage part 7 is charged.

[0069] In addition, the second power division part 10 transmits regenerated energy as power to the air compression part (piston type compressor) 11 to operate the same. Then, it utilizes the inertial rotation of the crankshaft of the compressor 11 to convert regenerated energy to compressed air which it then charges and stores in the second compressed air storage part 12. Furthermore, the heat energy generated by the braking operation is utilized to preheat the air in the second compressed air storage part 12 and further increase the charging pressure.

[0070] Fig. 5 shows the state at the time of deceleration and the time of braking in the state of operating the turbine type air engine 2, but the turbine type air engine 2 may also be stopped. Reference Signs List

[0071] 1... first compressed air storage part (1st C.A.S.P.), 2... turbine type air engine

(T.T.A.E.), 3... first power division part (1st P.D.P.), 4... first dynamo (1st dynamo), 5... inverter, 6... electric motor and second dynamo (E.M./2nd dynamo) , 7... electrical storage part (E.S.P.), 8,8a,8b... wheel actuator (W.A.), 9,9a,9b... wheels (drive wheels), 10... second power division part(2nd P.D.P.), 11... air compression part (A.C.P.), 12... second compressed air storage part (2nd C.A.S.P.), 13... auxiliary battery (A.B.), 14... control means (CM.)