Abstract:
An electric vehicle includes a frame having a cab; a plurality of hub wheel motors mounted to the frame, each hub wheel motor rotating a wheel; and an air conditioner mounted on the frame and thermally coupled to the cab, wherein the air conditioner includes an inverter driving an electric compressor and the inverter is coupled to an independent battery for air conditioning.

Description:
[0001]    The present invention relates to an automotive air conditioner for electric vehicles. 
       BACKGROUND 
       [0002]    In general, an automotive air conditioner comprises a compressor driven by an automotive engine, a condenser for condensing refrigerant compressed by the compressor, a receiver for separating the condensed refrigerant into gas and liquid phases and storing the liquid refrigerant, an expansion valve for throttling and expanding high-temperature, high-pressure refrigerant into atomized low-temperature, low-pressure refrigerant, and an evaporator for evaporating the atomized refrigerant by heat exchange between the atomized refrigerant and air in the vehicle compartment and then returning the evaporated refrigerant to the compressor. As the expansion valve, a thermostatic expansion valve controls the flow rate of refrigerant delivered into the evaporator by sensing the temperature and pressure of refrigerant at the refrigerant outlet of the evaporator. 
         [0003]    As discussed in United States Patent Application 20080141691, in a conventional internal combustion engine (ICE) car, the compressor, the condenser, and the receiver are arranged in an engine room along with the automotive engine, while the evaporator is disposed in the vehicle compartment. Further, the expansion valve is disposed between the evaporator and the compressor and between the evaporator and the receiver. The expansion valve is typically disposed in a firewall separating the engine room from the vehicle compartment such that the body block of the expansion valve is also used as a pipe joint for connecting between the evaporator in the vehicle compartment and the compressor and the receiver in the engine room. 
         [0004]    In a parallel trend, the rising cost of oil and global warming indications have sensitized manufacturers and consumers to the need to be energy efficient and environmentally responsible. As a result, modern electric cars are becoming popular again. One type of electric car provides a hub wheel motor in each wheel. The advantage of this design is that no additional transmission system is needed, thereby increasing the efficiency of the drive system. However, it is difficult to tap into the electric hub wheel motors to drive an air conditioner to cool the vehicle cab. 
       SUMMARY 
       [0005]    In one aspect, an electric vehicle includes a frame having a cab; a plurality of hub wheel motors mounted to the frame, each hub wheel motor rotating a wheel; and an air conditioner mounted on the frame and thermally coupled to the cab, wherein the air conditioner includes an inverter driving an electric compressor and the inverter is coupled to an independent battery for air conditioning. 
         [0006]    In another aspect, a method for operating an electric vehicle includes providing a plurality of hub wheel motors to a frame with a cab, each hub wheel motor rotating a wheel; providing an independent battery to power an electric compressor and converting the independent battery&#39;s voltage to a compressor voltage with an inverter; driving an electric compressor with the compressor voltage; generating and directing cool air at a vehicle interior with a fan or a blower. 
         [0007]    Implementations of the above aspects may include one or more of the following. The system can provide cooled air to a driver vent or a passenger vent. The system can sense a battery voltage or a battery temperature and turning off the electric compressor and the fan if the battery voltage falls below a battery voltage threshold or if the battery temperature rises above a battery temperature threshold. The controller can adjust the air conditioner based on a cabin temperature sensor. The air conditioner can be powered by a solar cell. The conditioner battery can also be recharged with an on-board recharger. 
         [0008]    Advantages of the system may include one or more of the following. The air conditioning system contributes to the excellence of life and creates a comfortable and vigorous vehicular environment, apart from outside conditions. The air conditioning system keeps the temperature to a comfortable range because of its cooling capability. The system offers the capability of controlling humidity in the temperature while cooling down the air. The system also provides freshening and ventilation. The system can have an efficient purification system that purifies the air as well. Filters can be integrated within the fan assembly or air ducts to purify the air. Dust filters can be used to collect very small particles of dust and microorganisms to avoid the spread of bacteria. The AC, when equipped with filters can assist patients suffering from asthma or allergies. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIG. 1  shows an exemplary air conditioning system. 
           [0010]      FIGS. 2A-2B  show an exemplary embodiment of the air conditioner. 
           [0011]      FIG. 3  shows an exemplary hardware mounting configuration for the air conditioner of  FIGS. 2A-2B . 
           [0012]      FIG. 4  shows an exemplary electric heater/fan used in an electric vehicle with hub wheel motors. 
           [0013]      FIG. 5  shows an exemplary environmentally friendly vehicle control system. 
       
    
    
     DESCRIPTION 
       [0014]    The following description of various disclosed embodiments is provided to enable any person skilled in the art to make or use the present disclosure. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the disclosure. Thus, the present disclosure is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein. 
         [0015]      FIG. 1  shows an exemplary air conditioner for electric vehicles. In the embodiment of  FIG. 1 , the electric vehicle is powered by a plurality of hub wheel motors which are motors directly positioned in the wheels and thus can directly drive the electric vehicle with little or no transmission gears. The electric vehicle of  FIG. 1  has an air conditioner that does not use the output of the hub wheel motors. Rather, the air conditioner (AC)  111  of  FIG. 1  provides energy to an electric inverter  114  which drives an electric compressor  120 . 
         [0016]    The power is supplied to a control circuit  108  from the car battery, not shown, when a switch  102  is placed in the on position. The switch  102  can be a 3 way switch to turn on only air conditioning, only fan, or both AC and fan. Alternatively, the switch  102  can provide the user with a fine grain control of the fan speed to precisely adjust the cabin temperature. Power is also supplied by a secondary battery  104  within the housing when the switch connects the battery  104  to the AC control circuit  108 . The control circuit  108  can turn on the AC  111 . Additionally, a solar panel  106  can directly power the air conditioner or the solar panel can recharge the internal battery  104 . When power is supplied to the AC control circuit  108  the power indicator light  110  and AC  111  are turned on. A blower  140  is adapted to generate a flow of air through vents in a passenger compartment of the vehicle only during the receipt of a voltage. 
         [0017]    A battery sensor  114  and a temperature sensor  116  constantly monitor the battery power of the internal battery  104  and/or car battery and the temperature of the outside air, respectively. When either the battery power gets too low or the temperature gets too high the sensors  114  or  116  causes an indicator light  118  to be turned on to inform the user of a problem. 
         [0018]    The AC  111  uses the inverter  114  to convert the DC voltage of the battery  104  to an alternating current to power a main powered air conditioner. To protect the car and AC  111 , the AC  111  has its own fuse going to the inverter  114 . Thus, when the AC  111  draws too much power through the inverter  114 , a fuse will trip to shut down the AC  111  without shutting down the rest of the vehicle. The fuse can be a time delayed fuse in one embodiment. The inverter powers an electric compressor  120 . 
         [0019]    The compressor  120  is an electric compressor is responsible for compressing a refrigerant gas, often freon or R134a. The electric compressor  120  takes the refrigerant (the gas) and pressurizes it so it will cool the air. Conventionally the compressor is driven by an internal combustion engine through an engine belt. The compressor  120  can be electrically turned on and off as the cab occupants request cool air. Once the gas is compressed, it becomes heated and is sent through a set of coils to a condenser  122 . The condenser  122  is where the heat is separated from the gas. Hot air comes off the top of the condenser  122 , while the rest of the gas is condensed into a cool liquid. The output of the condenser  122  is connected to a capillary tube  126  which in turn is connected to an evaporator  128 . The evaporator  128  is connected to an accumulator  124 . The AC  111  can have either have an orifice tube or capillary tube  126  that regulates the flow of liquid to an evaporator  128  and this is what the user controls when the user changes the temperature settings on the vehicle&#39;s dashboard. 
         [0020]    In one embodiment, the processor keeps track of time by using a dedicated clock/timer chip or alternatively by internally counting clock pulses and translating the clock pulses to seconds, minutes, and hours. The user can provide instruction to the processor to turn on the AC at a predetermined time. The user can also specify the cabin temperature to be maintained. Thus, if the user plans to drive at 4 pm after work, then the user can program the AC to be turned on at 3:50 pm to cool the cab temperature so that the vehicle is ready for use at 4 pm. 
         [0021]      FIGS. 2A-2B  show an exemplary embodiment of the air conditioner  111 .  FIG. 2A  shows the power conversion portion of the AC  111 , while  FIG. 2B  shows a portion of the AC  111  which is powered by the power conversion portion of  FIG. 2A . 
         [0022]    Turning now to  FIG. 2A , a charger  150  is provided on board the electric vehicle to recharge the battery of the vehicle. In one embodiment, the AC  111  can be operated while the key  160  is on (driving) or when the vehicle is plugged into a power line such as 110 VAC. The output of the charger  150  is provided to the main battery pack  162  which is connected to a high voltage contactor  164  such as a 72V contactor. The contactor  164  provides power to a secondary DC-DC converter  166  which charges an AC auxiliary battery  168 . Power from the battery  168  is provided to circuits of  FIG. 2B  through a connector A. In parallel, the charger  150  is also connected to a primary DC-DC converter  170  which charges an auxiliary battery  172 . 
         [0023]    Referring now to  FIG. 2B , power from connector A is provided to a relay  145 , which is turned on and controlled by the ignition key  160 . The power gated by the relay  145  travels through a fuse  143 . Power is then controlled by a switch  139  before it is provided to an evaporator blower  140 . 
         [0024]    Power is also supplied to thermostat  131  which is connected to a compressor motor  130 . The compressor motor  130  is also connected to a capacitor  138 . The capacitor  138  receives power through a fuse  133  and is connected to a condenser fan motor  134 . The capacitor  138  is used to provide clean power to the electric compressor motor  130 . 
         [0025]      FIG. 3  shows one exemplary AC hardware configuration mounted on a frame  128 . The compressor  130  provides compressed Freon or R134a to a condenser  136  which provides surfaces to transfer the heat from the high temperature, high pressure gaseous refrigerant to ambient air causing the refrigerant to condense into liquid. The fan  132  is rotated by the condenser fan. The liquid refrigerant passes through the capillary tube  126  and becomes low pressure liquid. This refrigerant then enters the evaporator  128  which provides cool surfaces for an evaporator blower  140  to blow air and circulate cool air to the cabin. 
         [0026]    The air conditioning system keeps the temperature to a comfortable range because of its cooling capability. The system offers the capability of controlling humidity in the cabin while cooling down the air. The system also provides freshening and ventilation. The system can have an efficient purification system that purifies the air as well. Filters can be integrated within the fan assembly or air ducts to purify the air. Dust filters can be used to collect very small particles of dust and microorganisms to avoid the spread of bacteria. The AC, when equipped with filters can assist patients suffering from asthma or allergies. 
         [0027]    The control circuit  108  of  FIG. 1  can be a wired control using discrete components, or alternatively can be microcontroller based. During use, the electric compressor  130  compresses Freon or R134a for cooling only during the receipt of a voltage. Mounted on a control panel of the vehicle is a temperature control dial for selecting a temperature. Associated therewith is an activation switch mounted on the control panel for transmitting an activation signal upon the depression thereof. Finally, control means, in form of the control circuitry is connected between the fan, compressor, temperature control dial, and activation switch. In use, the control means transmits a predetermined voltage amount to both the fan and the compressor only during the receipt of the activation signal. It should be noted that the predetermined voltage is proportional to the temperature selected by way of the temperature control dial. In a microcontroller implementation, the user selects the temperature control through a digital input such as a keypad or an analog input such as a touch screen that is digitized. The microcontroller interprets the user selection and generates the appropriate voltage to control the fan. Alternatively, if the fan is controlled by pulse widths, the microcontroller causes appropriate PWM signals to control the fan speed. The AC fan in turn generates an amount of cooled air flow that are a function of the duty cycle of the pulses from the pulse width modulator. 
         [0028]      FIG. 4  shows an exemplary air conditioner  300  used in an electric vehicle with hub wheel motors  302 - 308 . The motors  302 - 308  and the air conditioner  300  are controlled by a vehicle processor  310  to provide transportation to passengers located in a cab  320 . The temperature of the cab  320  is controlled to provide environmental comfort to the passengers. The hub motor of  FIG. 4  is designed to be small in size. The compact motor assembly is mounted in conjunction with the hub of the car. The motor assembly includes a self contained unit which includes a rotationally driven motor housing that is connected directly to the tire supporting rim of the car wheel. Rotation of the motor housing will result in similar rotation of the tire supporting rim of the wheel. The motor housing has an internal chamber and within that internal chamber is located a stator and a rotor. The stator is fixedly mounted onto a center shaft which passes through the motor housing which is fixedly mounted to the car. The rotor is to be rotated by the electrical energy being supplied to the stator with this rotation being transferred through the drive shaft. 
         [0029]    The exemplary hub wheel motor system includes a motor enclosed by a hub cap and a tire supporting rim. A rubber wheel can be mounted on the rim. The back of the hub cap has an opening through which a cable is inserted there through to provide power as well as control signals to the motor. The motor has outer, ring-shaped permanent magnets (stator) that rotate while the inner metallic core (rotor) is fixed. When the motor is switched on, the static rotor stays still while the stator spins around it. A tire is attached to the motor, and as the outer part of the motor rotates, the wheel (or wheels) powers the vehicle forward. 
         [0030]    Since the motors are hub-wheel motors, the independently operated air conditioner  300  can cool the cab to provide comfort to the vehicle occupants while they are using the vehicle. 
         [0031]    The electric car with hub-wheel motors can be the Alias, available from ZAP, Inc. of Santa Rosa, Calif. The Alias is 100% electric, 100% of the time. Recharging is simple and effortless via any 110V outlet at home or on the road. The Alias has aerodynamic contours, low profile, wide stance with double-wishbone suspension, and sport styling. The vehicle can also be a truck with hub-wheel motors called ZAP Truck XL. Roomy, durable, rugged yet whisper quiet, the ZAPTRUCK XL is the affordable green solution for fleet operations. The electric truck is a utilitarian workhorse providing a roomy cab for two and a convertible bed/platform for moving up to 1600 lbs. of cargo during off-road use. The vehicle is ideal for corporate campuses, warehouses, universities, factories, municipal operations and around the ranch or farm. 
         [0032]      FIG. 5  shows an exemplary environmentally friendly vehicle control system.  FIG. 5  shows how a central controller receives various inputs, draws on necessary information (driving profiles, vehicle specifications and navigation information), and produces the appropriate outputs. The central controller makes use of a range of inputs from sensors. The central controller combines this information with driver inputs received through a “user interface.” Typically, these driver inputs include braking, steering, accelerator and the various switch controls. The central controller can then combine these inputs with stored driving profiles, vehicle specifications, and navigation information. Based on all this information, the central controller optimizes for best performance. This requires sending control signals to the motors to continuously control motor torque and speed. 
         [0033]    In one embodiment, the central controller senses temperature conditions and issues a command to maintain constant temperature given the weather condition and the occupant&#39;s desired temperature range. The central controller linearly ramps down the fan when the temperature is too high and vice versa. The user, through the user interface, can override the processor when conditions change or for any reason. In this manner, the vehicle can increase its efficiency and user comfort while minimizing environmental pollution. 
         [0034]    The software controlling the air conditioner  300  can be tangibly stored in a machine-readable storage media or device (e.g., program memory or magnetic disk) readable by a general or special purpose programmable computer, for configuring and controlling operation of a computer when the storage media or device is read by the computer to perform the procedures described herein. The inventive system may also be considered to be embodied in a computer-readable storage medium, configured with a computer program, where the storage medium so configured causes a computer to operate in a specific and predefined manner to perform the functions described herein. 
         [0035]    Portions of the system and corresponding detailed description are presented in terms of software, or algorithms and symbolic representations of operations on data bits within a computer memory. These descriptions and representations are the ones by which those of ordinary skill in the art effectively convey the substance of their work to others of ordinary skill in the art. An algorithm, as the term is used here, and as it is used generally, is conceived to be a self-consistent sequence of steps leading to a desired result. The steps are those requiring physical manipulations of physical quantities. Usually, though not necessarily, these quantities take the form of optical, electrical, or magnetic signals capable of being stored, transferred, combined, compared, and otherwise manipulated. It has proven convenient at times, principally for reasons of common usage, to refer to these signals as bits, values, elements, symbols, characters, terms, numbers, or the like. 
         [0036]    It should be borne in mind, however, that all of these and similar terms are to be associated with the appropriate physical quantities and are merely convenient labels applied to these quantities. Unless specifically stated otherwise, or as is apparent from the discussion, terms such as “processing” or “computing” or “calculating” or “determining” or “displaying” or the like, refer to the action and processes of a computer system, or similar electronic computing device, that manipulates and transforms data represented as physical, electronic quantities within the computer system&#39;s registers and memories into other data similarly represented as physical quantities within the computer system memories or registers or other such information storage, transmission or display devices. 
         [0037]    The system has been described in terms of specific examples which are illustrative only and are not to be construed as limiting. In addition to control or embedded system software, the system may be implemented in digital electronic circuitry or in computer hardware, firmware, software, or in combinations of them. Apparatus of the invention may be implemented in a computer program product tangibly embodied in a machine-readable storage device for execution by a computer processor; and method steps of the invention may be performed by a computer processor executing a program to perform functions of the invention by operating on input data and generating output. Suitable processors include, by way of example, both general and special purpose microprocessors. Storage devices suitable for tangibly embodying computer program instructions include all forms of non-volatile memory including, but not limited to: semiconductor memory devices such as EPROM, EEPROM, and flash devices; magnetic disks (fixed, floppy, and removable); other magnetic media such as tape; optical media such as CD-ROM disks; and magneto-optic devices. Any of the foregoing may be supplemented by, or incorporated in, specially-designed application-specific integrated circuits (ASICs) or suitably programmed field programmable gate arrays (FPGAs). 
         [0038]    The present invention has been described in terms of specific embodiments, which are illustrative of the invention and not to be construed as limiting. Other embodiments are within the scope of the following claims. The particular embodiments disclosed above are illustrative only, as the invention may be modified and practiced in different but equivalent manners apparent to those skilled in the art having the benefit of the teachings herein. Furthermore, no limitations are intended to the details of construction or design herein shown, other than as described in the claims below. It is therefore evident that the particular embodiments disclosed above may be altered or modified and all such variations are considered within the scope and spirit of the invention.