1. Field of the Invention
This disclosure relates generally to mechanical and/or electro-mechanical power modulation devices and methods, and more particularly to continuously and/or infinitely variable, planetary power modulating devices and methods for modulating power flow in a power train or drive, such as power flow from a prime mover to one or more auxiliary or driven devices.
2. Description of the Related Art
In certain systems, a single power source drives multiple devices. The power source typically has a narrow operating speed range at which the performance of the power source is optimum. It is preferred to operate the power source within its performance optimizing operating speed range. A driven device typically also has a narrow operating speed range at which the performance of the driven device is optimum. It is also preferred to operate the driven device within its performance optimizing operating speed range. A coupling is usually employed to transfer power from the power source to the driven device. Where a direct, non-modulating coupling couples the power source to the driven device, the driven device operates at a speed proportional to that of the power source. However, it is often the case that the optimum operating speed of the driven device is not directly proportional to the optimum operating speed of the power source. Therefore, it is preferred to incorporate into the system a coupling adapted to modulate between the speed of the power source and the speed of the driven device.
Couplings between the power source and the driven devices can be selected such that the input speed from the power source is reduced or increased at the output of a given coupling. However, in frequently implemented systems, typical known power train configurations and/or coupling arrangements allow at best for a constant ratio between the input speed from the power source and the speed of power transfer to the driven device. One such system is the so-called front end accessory drive (FEAD) system employed in many automotive applications. In a typical FEAD system, the prime mover (usually an internal combustion engine) provides the power to run one or more accessories, such as a cooling fan, water pump, oil pump, power steering pump, alternator, etc. During operation of the automobile, the accessories are forced to operate at speeds that have a fixed relationship to the speed of the prime mover. Hence, for example, as the speed of the engine increases from 800 revolutions per minute (rpm) at idle to 2,500 rpm at cruising speed, the speed of each accessory driven by the engine increases proportionally to the increase in engine speed, such that some accessories may be operating at varying speeds ranging between 1,600 rpm to 8,000 rpm. The result of such system configuration is that often any given accessory does not operate within its maximum efficiency speed range. Consequently, inefficiencies arise from wasted energy during operation and oversizing of the accessories to handle the speed and/or torque ranges.
Thus, there exists a continuing need for devices and methods to modulate power transfer between a prime mover and driven devices. In some systems, it would be beneficial to regulate the speed and/or torque transfer from an electric motor and/or internal combustion engine to one or more driven devices that operate at varying efficiency optimizing speeds. In some current automotive applications, there is a need for a power modulating device to govern the front end accessory drive within existing packaging limits. The inventive embodiments of power modulating devices and/or drivetrains described below address one or more of these needs.
The systems and methods herein described have several features, no single one of which is solely responsible for its desirable attributes. Without limiting the scope as expressed by the claims that follow, its more prominent features will now be discussed briefly. After considering this discussion, and particularly after reading the section entitled “Detailed Description of Certain Embodiments” one will understand how the features of the system and methods provide several advantages over traditional systems and methods.
One aspect of the disclosure relates to a refrigeration system having an evaporator, an expansion valve, and a condenser. In one embodiment, the refrigeration system has a compressor in fluid communication with the evaporator, the expansion valve, and the condenser. A continuously variable transmission (CVT) is operably coupled to the compressor. The CVT is adapted to provide a power input to the compressor. In one embodiment, a CVT cooling system is operably coupled to internal components of the CVT. The CVT cooling system is in fluid communication with the compressor, the evaporator, the expansion valve, and the condenser.
Another aspect of the disclosure concerns a refrigeration system having an evaporator, an expansion valve, a compressor, and a condenser, each coupled hydraulically with a refrigerant. In one embodiment, the refrigeration system has a continuously variable transmission (CVT) coupled to the compressor. The CVT is configured to provide an input power to the compressor. The refrigeration system has a cooling system operably coupled to the CVT. The cooling system is in thermal communication with the refrigerant.
Yet another aspect of the disclosure concerns an actuator for a continuously variable transmission (CVT) having a plurality of spherical traction planets. Each traction planet is supported by first and second carrier members. The first carrier member is configured to rotate with respect to the second carrier member to facilitate a change in operating condition of the CVT. In one embodiment, the actuator has a hydraulic piston coupled to the CVT. The actuator has a hydraulic control valve in fluid communication with the hydraulic piston. A spool actuator is coupled to the hydraulic control valve. The spool actuator is configured to adjust the hydraulic control valve based at least in part on a operating condition of the CVT. The hydraulic piston, the hydraulic control valve, and the spool actuator hydraulically couple to a working fluid of a refrigeration system.
One aspect of the disclosure concerns a method of improving the performance of a refrigeration system having a compressor, a condenser, an evaporator and refrigerant. In one embodiment, the method includes the step of providing a CVT adapted to vary the speed of the compressor and having a transmission fluid system. The method has the step of varying the operating speed of the compressor by varying the transmission ratio of the CVT. In one embodiment, the method includes transferring heat from the transmission fluid system to the refrigerant.
Another aspect of the disclosure relates to a method of manufacturing a refrigeration system. In one embodiment, the method has the step of providing a first heat exchanger. The first heat exchanger is exposed to an environment at a first temperature. The method includes coupling the first heat exchanger to an expansion valve. The method has the step of providing a second heat exchanger. The second heat exchanger is exposed to an environment at a second temperature. The method includes coupling the second heat exchanger to the expansion valve and providing a compressor. In one embodiment, the method has the step of configuring the compressor to pump a working fluid between the first and second heat exchangers and the expansion valve. The method includes coupling a continuously variable transmission (CVT) to the compressor. The CVT is configured to change operating condition based at least in part to a change in a state of the working fluid.
Another aspect of the disclosure concerns a method of manufacturing a refrigeration system. In one embodiment, the method includes the step of providing a first heat exchanger, the first heat exchanger exposed to an environment at a first temperature. The method has the step of coupling the first heat exchanger to an expansion valve. The method includes providing a second heat exchanger. The second heat exchanger is exposed to an environment at a second temperature. The method has the step of coupling the second heat exchanger to the expansion valve and providing a compressor. In one embodiment, the method includes the step of configuring the compressor to pump a working fluid between the first and second heat exchangers and the expansion valve. The method has the step of coupling a continuously variable transmission (CVT) to the compressor. The method includes providing a third heat exchanger operably coupled to internal components of the CVT. In one embodiment, the method includes hydraulically coupling the third heat exchanger to the working fluid, whereby the working fluid is exposed to a waste heat from the internal components of the CVT.
The preferred embodiments will be described now with reference to the accompanying figures, wherein like numerals refer to like elements throughout. The terminology used in the descriptions below is not to be interpreted in any limited or restrictive manner simply because it is used in conjunction with detailed descriptions of certain specific embodiments of the disclosure. Furthermore, embodiments of the disclosure can include several novel features, no single one of which is solely responsible for its desirable attributes or which is essential to practicing the embodiments described. Certain CVT embodiments described here are generally related to the type disclosed in U.S. Pat. Nos. 6,241,636; 6,419,608; 6,689,012; 7,011,600; 7,166,052; U.S. patent application Ser. Nos. 11/243,484; 11/543,311; 12/198,402; 12/251,325 and Patent Cooperation Treaty patent applications PCT/US2007/023315, PCT/IB2006/054911, PCT/US2008/068929, and PCT/US2007/023315, PCT/US2008/074496. The entire disclosure of each of these patents and patent applications is hereby incorporated herein by reference.
As used here, the terms “operationally connected,” “operationally coupled”, “operationally linked”, “operably connected”, “operably coupled”, “operably linked,” and like terms, refer to a relationship (mechanical, linkage, coupling, etc.) between elements whereby operation of one element results in a corresponding, following, or simultaneous operation or actuation of a second element. It is noted that in using said terms to describe inventive embodiments, specific structures or mechanisms that link or couple the elements are typically described. However, unless otherwise specifically stated, when one of said terms is used, the term indicates that the actual linkage or coupling may take a variety of forms, which in certain instances will be readily apparent to a person of ordinary skill in the relevant technology. For description purposes, the term “axial” as used here refers to a direction or position along an axis that is parallel to a main or longitudinal axis of a driven device, a transmission or variator. The term “radial” is used here to indicate a direction or position that is perpendicular relative to a longitudinal axis of a transmission or variator.
It should be noted that reference herein to “traction” does not exclude applications where the dominant or exclusive mode of power transfer is through “friction.” Without attempting to establish a categorical difference between traction and friction drives here, generally these may be understood as different regimes of power transfer. Traction drives usually involve the transfer of power between two elements by shear forces in a thin fluid layer trapped between the elements. The fluids used in these applications usually exhibit traction coefficients greater than conventional mineral oils. The traction coefficient (μ) represents the maximum available traction forces which would be available at the interfaces of the contacting components and is a measure of the maximum available drive torque. Typically, friction drives generally relate to transferring power between two elements by frictional forces between the elements. For the purposes of this disclosure, it should be understood that the CVTs described here may operate in both tractive and frictional applications. For example, in the embodiment where a CVT is used for a bicycle application, the CVT can operate at times as a friction drive and at other times as a traction drive, depending on the torque and speed conditions present during operation.
Embodiments disclosed here are related to the control of a variator and/or a CVT using generally spherical planets each having a tiltable axis of rotation that can be adjusted to achieve a desired ratio of input speed to output speed during operation. In some embodiments, adjustment of said axis of rotation involves angular displacement of the planet axis in a first plane in order to achieve an angular adjustment of the planet axis in a second plane, wherein the second plane is substantially perpendicular to the first plane. The angular displacement in the first plane is referred to here as “skew”, “skew angle”, and/or “skew condition”. For discussion purposes, the first plane is generally parallel to a longitudinal axis of the variator and/or the CVT. The second plane can be generally perpendicular to the longitudinal axis. In one embodiment, a control system coordinates the use of a skew angle to generate forces between certain contacting components in the variator that will tilt the planet axis of rotation substantially in the second plane. The tilting of the planet axis of rotation adjusts the speed ratio of the variator. The aforementioned skew angle, or skew condition, can be applied in a plane substantially perpendicular to the plane of the page of
Other embodiments disclosed here are related to continuously variable transmissions having spherical planets such as those generally described in U.S. Pat. No. 7,125,359 to Milner, U.S. Pat. No. 4,744,261 to Jacobson, U.S. Pat. No. 5,236,403 to Schievelbusch, or U.S. Pat. No. 2,469,653 to Kopp. Some embodiments disclosed here are related to continuously variable transmissions having belts or chains, see for example U.S. Pat. No. 7,396,311 to Gates. Yet other embodiments disclosed here are related to transmissions having toroidal discs for transmitting power. See for example U.S. Pat. No. 7,530,916 to Greenwood and U.S. Pat. No. 6,443,870 to Yoshikawa et al. The entire disclosure of each of these patents and patent applications is hereby incorporated herein by reference.
Embodiments of the torque/speed regulating devices disclosed here can be used to control the speed of the power delivered to the accessories powered by a prime mover. For example, in some embodiments, the speed regulators disclosed here can be used to control the speed of automotive accessories, such as an air-conditioning (AC) compressor, driven by a pulley attached to the crankshaft of an automotive engine. Usually, refrigeration systems having a compressor must perform suitably both when the engine idles at low speed and when the engine runs at high speed. Often AC compressors operate optimally at one speed and suffer from reduced efficiency at other speeds. Additionally, the AC compressor design is compromised by the need to perform over a large speed range rather than an optimized narrow speed range. In many cases when the engine runs at a speed other than low speed, the AC compressor consumes excess power and, thereby, reduces vehicle fuel economy. The power drain caused by the AC compressor also reduces the engine's ability to power the vehicle, necessitating a larger engine in some cases.
The torque/speed regulator systems disclosed here can facilitate reducing the size and weight of the accessories as well as the prime mover, thereby reducing the weight of the vehicle and thus increasing fuel economy. Further, in some cases, the option to use smaller accessories and a smaller prime mover lowers the cost of these components and of the vehicle. Smaller accessories and a smaller prime mover can also provide flexibility in packaging and allow the size of the system to be reduced. Embodiments of the torque/speed regulators described here can also increase fuel economy by allowing the accessories to operate at their most efficient speed across the prime mover operating range. Finally, the torque/speed regulators increase fuel economy by preventing the accessories from consuming excess power at any speed other than low.
Referring now to
Operation of the refrigeration system 1 can be described using a temperature-entropy (T-s) diagram, such as the one depicted in
A representative cycle 24 is shown on the T-s diagram in solid lines to depict an idealized refrigeration system. A representative cycle 26 is depicted on the T-s diagram in dashed lines to illustrate operation of the refrigeration system 1, for example. It should be noted that waste heat from the CVT is rejected to the refrigerant. As shown in the diagram, the impact of adding heat to the system could increase the exit temperature of the evaporator 4 (state 1, depicted on the T-s diagram as “1” for the idealized refrigeration cycle and “1′” for the refrigeration system 1). Waste heat rejection from the CVT 10 will influence the high side temperature (state 2). As the refrigeration system 1 is operated, a new thermodynamic balance will be achieved that ultimately raises the pressures and temperatures in the system as compared to an idealized refrigeration system. If the low side evaporator temperature is increased relative to the fixed cold side temperature (for example “TC” represented by construction line 22), then the amount of heat removed from the cold side will fall, thereby influencing the coefficient of performance of the refrigeration system.
Turning now to
Referring now
Turning now to
During operation of the refrigeration system 80, a differential pressure generated between the first chamber 97 and the second chamber 99 can generate a displacement of the piston 98 in the valve 96. Displacement of the piston 98 is translated through the control coupling 94 to facilitate a change in operating condition of the CVT 90. It should be noted that the differential pressure generated between the first and second chambers 97 and 99, respectively, is generated by the thermodynamic states of the refrigerant in the refrigeration system 80.
Referring now to
During operation of the refrigeration system 100, a differential pressure generated across the compressor 102 can be communicated to the valve 114 through the control valve 116. A differential pressure generated between the first and second chambers 121 and 123, respectively, can generate a displacement of the piston 115. The displacement of the piston 115 can be translated by the CVT control coupling 112 to the CVT 110 to thereby facilitate a change in operating condition of the CVT 110. It should be noted that the control valve 116, in some embodiments, enables the magnitude of the pressure differential between the first and second chambers 121 and 123 to differ from the magnitude of the pressure differential across the compressor 102.
Turning now to
It should be noted that the description above has provided dimensions for certain components or subassemblies. The mentioned dimensions, or ranges of dimensions, are provided in order to comply as best as possible with certain legal requirements, such as best mode. However, the scope of the embodiments described herein are to be determined solely by the language of the claims, and consequently, none of the mentioned dimensions is to be considered limiting on the inventive embodiments, except in so far as anyone claim makes a specified dimension, or range of thereof, a feature of the claim.
The foregoing description details certain embodiments of the disclosure. It will be appreciated, however, that no matter how detailed the foregoing appears in text, the disclosure can be practiced in many ways. As is also stated above, it should be noted that the use of particular terminology when describing certain features or aspects of the disclosure should not be taken to imply that the terminology is being re-defined herein to be restricted to including any specific characteristics of the features or aspects of the disclosure with which that terminology is associated.
This application claims the benefit of U.S. Provisional Patent Application No. 61/542,708 filed on Oct. 3, 2011, which is hereby incorporated by reference in its entirety.
Number | Date | Country | |
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61542708 | Oct 2011 | US |