Abstract:
An integrated electrical generator/starter and air conditioning compressor device driven by a common drive shaft, or other direct linkage. The device includes an electrical generator/starter and a compressor. The electrical generator/starter is coupled to the drive shaft. The compressor is coupled to the electrical generator/starter and to the drive shaft and acts to pressurize a flow of refrigerant in response to rotation of the drive shaft. The electrical generator/starter is operable in first and second states. In the first state, the electrical generator/starter generates electricity in response to rotation of the drive shaft. In the second state, the electrical generator/starter utilizes electrical power from a battery to rotate the drive shaft.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates generally to electrical generator/starters and air conditioning compressors, and more particularly, to an integrated electrical generator/starter and compressor device.  
       BACKGROUND OF THE INVENTION  
       [0002]     In current automotive applications, there are numerous components connected directly to the engine&#39;s crankshaft that are required to perform the various vehicle functions. Three such components are the electrical generator/alternator, the air conditioning compressor, and the starter. The electrical generator/alternator uses an electric machine to generate the vehicle&#39;s electrical energy. The compressor is driven by the crankshaft and is used by the HVAC system to cool the vehicle&#39;s cabin. The starter is mounted on the rear of the engine block and is connected to the crankshaft through the flywheel or flexplate to start the engine. Each of these components adds mass, cost, and requires packaging space.  
         [0003]     As manufacturers pursue improved fuel economy goals, a start/stop engine management concept has emerged. This approach enables the vehicle&#39;s engine to be shut-off periodically during idle stop times, e.g., stop lights/signs, city traffic stop and go driving, and then re-started when requested by the driver (by e.g., actuation of the accelerator pedal). One such approach uses a generator/starter combination device.  
         [0004]     However, some consideration must be given as to how cabin comfort is maintained during these engine off occurrences. Current technology uses an engine-belt drive compressor. When the engine is off, there is no power to drive the compressor and therefore cabin comfort suffers.  
         [0005]     One solution is to simply request that the engine re-starts when cabin comfort, i.e., temperature, suffers. However, this approach will have a negative effect on fuel economy.  
         [0006]     Another solution is to use a fully electrically drive compressor system which could be run at any time cabin cooling is required. However, this may also negatively affect fuel economy, in that the electric power is taken from the battery which must be charged via the alternator. There are significant efficiency losses&#39; associated with the electro-mechanical creation and use of this electrical energy.  
         [0007]     The present invention is aimed at one or more of the problems, as set forth above.  
       SUMMARY OF THE INVENTION AND ADVANTAGES  
       [0008]     In one aspect of the present invention an integrated electrical generator/starter and compressor device is provided. The device is adapted to be driven by a common drive shaft and includes an electrical generator/starter and a compressor. The electrical generator/starter is coupled to the drive shaft. The compressor is coupled to the electrical generator/starter and to the drive shaft and acts to pressurize a flow of refrigerant in response to rotation of the drive shaft. The electrical generator/starter is operable in first and second states. In the first state, the electrical generator/starter generates electricity in response to rotation of the drive shaft. In the second state, the electrical generator/starter utilizes electrical power from a battery to rotate the drive shaft.  
         [0009]     In another aspect of the present invention, a system for use with an engine having a first drive shaft is provided. The system includes a clutch mechanism and a drive belt for coupling the first drive shaft and the clutch mechanism. A second drive shaft is coupled to the clutch mechanism. The clutch mechanism is adapted to controllably engage and release the second drive shaft thereby coupling and de-coupling the first and second drive shafts, respectively. An electrical generator/starter is coupled to the second drive shaft. A battery is coupled to the electrical generator/starter. A compressor is coupled to the electrical generator/starter and to the drive shaft and acts to pressurize a flow of coolant in response to rotation of the second drive shaft. The electrical generator/starter generates electricity in response to rotation of the second drive shaft while in a first state and utilizes electrical power from the battery to rotate the second drive shaft while in the second state. A controller is coupled to the electrical generator/starter, the compressor and the clutch mechanism and controls operation thereof in accordance of a plurality of modes of operation.  
         [0010]     In still another aspect of the present invention, a method for controlling operation of an electrical generator/starter and a compressor for use with an engine having a first drive shaft is provided. The first drive is coupled to a second drive shaft by a clutch mechanism. The electrical generator/starter and the compressor are mechanically coupled to and integral with each other and coupled to the second drive shaft. The clutch mechanism is adapted to controllably engage and release the second drive shaft thereby coupling and de-coupling the first and second drive shafts respectively. The compressor is adapted to pressurize a flow of coolant in response to rotation of the second drive shaft, The electrical generator/starter is adapted to generate electricity in response to rotation of the second drive shaft while in a first state and for utilizing electrical power from a battery to operate the electrical generator/starter to rotate the second drive while in a second state. The method includes the steps of entering one of a first mode and a second mode, engaging the clutch mechanism and placing the electrical generator/starter in the second state in response to being in the first mode, and engaging the clutch mechanism and placing the electrical generator/starter in the first state in response to entering the second mode. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]     Other advantages of the present invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:  
         [0012]      FIG. 1  is a diagrammatic illustration of an automotive electrical and HVAC system having an integrated generator/starter and refrigerant compressor device, according to an embodiment of the present invention;  
         [0013]      FIG. 2  is a diagrammatic illustration of an automotive electrical and HVAC system having an integrated generator/starter and refrigerant compressor device, according to another embodiment of the present invention;  
         [0014]      FIG. 3  is a three-dimensional view of the integrated generator/starter and refrigerant compressor device of  FIG. 1 ;  
         [0015]      FIG. 4  is a three-dimensional view of the integrated generator/starter and refrigerant compressor device of  FIG. 2 ;  
         [0016]      FIG. 5  is a flow diagram of the operation of the system of  FIGS. 1 and 2 , according to an embodiment of the present invention; and,  
         [0017]      FIG. 6  is a flow diagram of the operation of the system of  FIGS. 1 and 2 , according to another embodiment of the present invention.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0018]     With reference to  FIG. 1 , the reference number  10  generally designates an automotive electrical and HVAC system, including an integrated electrical generator/starter and refrigerant compressor device  12 . The device  12  includes an electrical generator/starter  14  and a compressor  16 . The device  12  is coupled to a first drive shaft  18  of an engine  20  by a clutch mechanism  22 . The engine  20  may be, e.g., the engine  20  of an automobile (not shown). In the illustrated embodiment, the clutch mechanism  22  includes a drive pulley  24  and an electrically activated clutch  26 . The compressor  12  is a variable displacement compressor and may be controller either pneumatically or electronically and is used to compress or pressurize refrigerant.  
         [0019]     In the illustrated embodiment, the drive pulley  24  is coupled to the first drive shaft  18  via a drive belt  28 . The drive pulley  24  is also directly coupled to a second drive shaft  30 . The clutch mechanism  22  is selectively engaged or disengaged to couple and un-couple the first and second drive shafts  18 ,  30 .  
         [0020]     The system  10  further includes a condenser  32 , an expansion device  34 , an evaporator  36 , and a receiver/dehydrator or an accumulator/dehydrator  38  arranged appropriately between a compressor discharge port  40  and a suction port  42 . A typical schematic is shown in  FIGS. 1 and 2 . A cooling fan  44 , operated by an electric drive motor  46 , is controlled to provide supplemental airflow through the condenser  32  for removing heat from the high pressure refrigerant in line  48 . It should be noted that the cooling fan  44  may also be driven by the engine  20 . The expansion device  34  allows the cooled high pressure refrigerant in line  50  to expand before passing through the evaporator  36 . Outside air or recirculated air may be passed or blown over the evaporator  36  and subsequently into an area to be cooled in a manner well known in the art.  
         [0021]     The compressor  16  includes a number of internal reciprocating pistons (not shown) that successively and repeatedly pump refrigerant into the high pressure line  50  when the second drive shaft  30  is being rotated. The refrigerant pressure in line  48  is detected by a pressure transducer  52  which produces a compressor outlet pressure (COP) signal. As in conventional controls, the DC component of the COP signal may be used for one or more control purposes, including cycling the cooling fan motor  46 , when present, to optimize cooling and drivability, cycling the clutch mechanism  22  to account for various ambient conditions, and disengaging the clutch mechanism  22  in the event of an abnormally high compress outlet pressure. These functions are carried out by a microprocessor based control unit or controller  54 , which determines a clutch control signal (CL), and a fan control signal (FC). In one embodiment, the compressor  16  is a clutchless, continuously variable compressor. The stroke of the pistons may be modified between a minimum stroke and a maximum stroke.  
         [0022]     As discussed above, the electrical generator/starter  14  and the compressor  16  are integrated. With reference to  FIGS. 1 and 3  in one aspect of the present invention, the electrical generator/starter  14  includes a generator/starter housing  56  and the compressor  16  includes a compressor housing  58 . As shown, the housings,  56 ,  58  have a generally cylindrical shape and are generally centered on the second drive shaft  30 . In the illustrated embodiment of  FIGS. 1 and 3 , the generator/start housing  56  and the compressor housing  58  are mechanically coupled together by one or more bolts  59  threaded through the housings  56 ,  58 .  
         [0023]     With reference to  FIGS. 2 and 4  in another aspect of the present invention, the electrical generator/starter  14  and the compressor  16  include a single integral housing  60 . The integral housing  60  includes a compartment  62  to house the generator/starter  14  and a compartment  64  to house the compressor  16 . Additionally, the flow of coolant through the compressor  16  may be used to cool the electrical generator/starter  14 .  
         [0024]     The compressor  16  is driven by the second drive shaft  30 . The electrical generator/starter alternatively drives the second drive shaft  30  and is driven by the second drive shaft  30 . In one embodiment of the present invention, the integrated device  12  may be placed in one of first and second states.  
         [0025]     In the first state, the electrical generator/starter  14  acts as an electrical generator. When the second drive shaft  30  is rotated, the electrical generator/starter  14  converts the mechanical energy of the rotating second drive shaft  30  into electrical energy. This electrical energy may be used to power other electrical devices or systems and/or to charge a battery  66 . In the second state, the electrical generator/starter  14  acts as a motor. The electrical generator/starter  14  converts electrical energy into mechanical energy, i.e., electrical energy from the battery  66  is used to impart movement to the second drive shaft  30 . Thus, as discussed below, the electrical generator/starter  14  may be used as a motor to drive the compressor  16 , start the engine  20 , and/or supplement engine power. In one embodiment, the electrical generator/starter  14  includes a fixed speed motor. In a second embodiment, the electrical generator/starter  14  includes a variable speed motor. A suitable electrical generator/starter  14  is available from Delphi Corporation of Troy, Mich.  
         [0026]     In another aspect of the present invention, the controller  54  is operable to control the integrated electrical generator/starter and refrigerant compressor device  10  and the clutch mechanism  22  in accordance to one or more modes of operation.  
         [0027]     In one embodiment of the present invention, the controller  54  may operate in a first mode or a second mode.  
         [0028]     In the first mode, the controller  54  operates to start the engine  20 . For example, the automobile may be at rest with the engine off and a driver may want to start the engine  20 . Typically this is accomplished using a key ignition system, in a manner well known in the art. Alternatively, the system  10  may have shut off the engine during times when engine power is not needed in order to improve fuel economy, e.g., during idle stop times.  
         [0029]     In the first mode, the clutch mechanism  22  must be engaged and the electrical generator/starter  14  is placed in the second state. Thus, electrical energy is transferred from the battery  66  to the electrical generator/starter  14  which acts as a motor to rotate the second drive shaft  30  and to deliver mechanical energy to the engine  20  (through the drive belt  28 ) in order to start the engine  20 . This process is well known in the art and therefore not further discussed.  
         [0030]     Additionally, in order to minimize the load on the electrical generator/starter  14  during this process, the stroke of the piston(s) within the compressor  16  may be minimized.  
         [0031]     After the engine  20  has been started, the controller  54  will generally enter the second control mode. In the second or “normal” control mode, the engine  20  is running and the clutch mechanism  22  is engaged. The electrical generator/starter  14  is in the first state while the system  10  is operating in the second mode. Since the clutch mechanism  22  is engaged, mechanical energy from the first drive shaft  18  is transferred to the second drive shaft  30  by the drive belt  28 . The electrical generator/starter  14  (in the first state) acts as a generator to generate electricity. The generated electricity may be used to charge the batter  66  and/or to power other onboard systems. Additionally, since the second drive shaft  30  is being rotated, the compressor  16  is driven by the engine  20  through the first drive shaft  18 , the drive belt  28 , and the second drive shaft  30 . The stroke of the piston(s) within the compressor  16  are controlled pneumatically or by the controller  54  as required to deliver the needed cooling in a manner well-known in the art.  
         [0032]     Operation of the system  10  between the first and second modes is illustrated in  FIG. 5 . In a first decision block  68 , if the engine  20  must be started then control proceeds to a first process block  70 . In the first process block  70 , the clutch mechanism  22  is engaged (unless it already is) and the electrical generator/starter  14  is placed in the second state. In a second decision block  72 , if the engine  20  is running in normal operation, then control proceeds to a second process block  74 . In the second process block  74 , the clutch mechanism  22  is engaged (unless it already is) and the electrical generator/starter  14  is placed in the first state.  
         [0033]     In another embodiment of the present invention, the controller  54  may operate in a first, second, third, fourth, or fifth modes.  
         [0034]     The first and second modes are the equivalent of the above described first and second modes, i.e., the start engine and normal modes.  
         [0035]     The third mode is used when the engine  20  cannot provide sufficient power to the compressor and is generally used when the engine is running. In one embodiment, the third mode is entered when a predetermined condition is detected. For example, the predetermined condition may be one or more of the following: engine idle, engine low speed, or maximum desired cooling. Alternatively, the predetermined condition may be a combination of engine speed and desired cooling.  
         [0036]     In the third mode, the clutch mechanism  22  is disengaged to de-couple the engine  20  from the compressor  16 . The electrical generator/starter  14  is placed in the second state. Thus, the electrical generator/starter  14  acts as a motor and uses electrical energy from the battery  66  to rotate the second drive shaft  30 , thus driving the compressor  16 .  
         [0037]     If the electrical generator/starter  14  is variable, its speed may be varied to deliver the desired cooling. If the speed of the electrical generator/starter  14  is fixed, the stroke of the piston(s) within the compressor  16  may be varied.  
         [0038]     The fourth mode is used when the engine  20  is off and it is desired to provide cooling. For example, the fourth mode may be used if the engine  20  has been to turned off, e.g., while at a stop-light to reduce fuel usage, and cabin cooling is required, or to “pre-condition” the cabin before it is entered.  
         [0039]     In the fourth mode, the clutch mechanism  22  is disengaged. The electrical generator/starter  14  is placed in the second stated. Thus, the electrical generator/starter  14  acts as a motor and uses electrical energy from the battery  66  to rotate the second drive shaft  30 , thus driving the compressor  16 . The stroke of the compressor  16  is as required to achieve the desired cooling.  
         [0040]     The fifth mode is used when the engine  20  cannot provide sufficient power for desired vehicle acceleration and/or to improve fuel economy during fuel acceleration. In the fifth mode, the clutch is engaged and the electrical generator/starter  14  is in the second state. Thus, the electrical generator/starter acts as a motor and uses electrical energy from the battery  66  to rotate the second drive shaft  30 . Since the clutch mechanism  22  is engaged, mechanical energy from the rotating second drive shaft  30  is transferred to the engine  20  and may be used to supplement engine output power to achieve the desired acceleration. Additionally, the stroke of the compressor  16  may be minimized to minimize the load on the electrical generator/starter enabling more power to be transferred to the engine  20 .  
         [0041]     Operation of the system  10  between the first, second, third, fourth, and fifth modes is shown in  FIG. 6 . Operation of the first and second modes is similar as described above. In a third decision block  76 , if there is insufficient power to drive the compressor  16  then control proceeds to a third process block  78 . In the third process block  78 , the clutch mechanism  22  is disengaged and the electrical generator/starter  14  is placed in the second stated. In a fourth decision block  80 , if the engine is off and cooling is desired, then control proceeds to a fourth process block  82 . In the fourth process block  82 , the clutch mechanism  22  is disengaged and the electrical generator/starter  14  is placed in the second state. In a fifth decision block  84 , if there is insufficient engine power to provide desired acceleration, then control proceeds to a fifth process block  86 . In the fifth process block  86 , the clutch mechanism  22  is disengaged and the electrical generator/starter  14  is placed in the second state.  
         [0042]     Obviously, many modifications and variations of the present invention are possible in light of the above teachings. The invention may be practiced otherwise than as specifically described within the scope of the appended claims.