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Air conditioning systems for vehiclesRelated Patent Categories: Pumps, Condition Responsive Control Of Drive Transmission Or Pump DisplacementAir conditioning systems for vehicles description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20060204368, Air conditioning systems for vehicles. Brief Patent Description - Full Patent Description - Patent Application Claims
BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to air conditioning systems for vehicles, and more specifically, to air conditioning systems for vehicles which improve the acceleration performance of a vehicle by appropriately reducing the displacement of a compressor during acceleration, without adversely affecting operation of air conditioning or performance of the vehicle, or both. [0003] 2. Description of Related Art [0004] In a known technology, a refrigeration cycle has a variable displacement compressor, and the power consumed by driving the compressor is reduced by reducing the displacement of the compressor during vehicle acceleration. An amount of power made available to the vehicle by reducing power consumption by the compressor is utilized to improve the acceleration performance of the vehicle. An example of the known technology is described in Japanese Published Patent Application No. JP-A-57-175422. [0005] Nevertheless, there are problems with this known technology for reducing a displacement of a compressor during acceleration. Because the displacement of the compressor is controlled at a minimum displacement or a clutch for the compressor is disengaged during acceleration, the cooling ability of the system approaches zero, the temperature of air blown into the vehicle interior increases. Therefore, the driver's comfort may be adversely affected. On the other hand, if the above-described compressor control is not performed during acceleration, the power consumption of the compressor increases along with the increase in engine rotational speed. The acceleration performance of the vehicle may be degraded, and fuel consumption may increase. Because a variable displacement compressor varies a stroke of a piston in order to control a control object, such as a drawn-refrigerant pressure (Ps), at a constant value relative to variations of the engine rotational speed; when the engine rotational speed increases, the piston stroke is controlled, so that the torque of the compressor is reduced. Nevertheless, if the drawn-refrigerant pressure (Ps) is a control object, when a thermal load of an evaporator is elevated, i.e., when an actual Ps is larger than a target Ps, even if the engine rotational speed varies, the compressor is driven at a maximum stroke. Therefore, the power consumption of the compressor increases along with the elevation of the engine rotational speed, and the acceleration performance of the vehicle may deteriorate significantly. SUMMARY OF THE INVENTION [0006] Accordingly, a need has arisen to provide air conditioning systems for vehicles, which prevent a compressor from being driven at a maximum displacement during acceleration, avoid excessive power consumption by the compressor during acceleration, and realize improved acceleration performance of the vehicle and reduced fuel consumption. [0007] Further, a need has arisen to provide air conditioning systems for vehicles, which appropriately reduce the displacement of the compressor during acceleration to improve the acceleration performance of the vehicle, and, at the same time, which prevent the degradation of the driver's comfort, by suppressing the excessive elevation of the temperature of the air blown into a vehicle interior. [0008] In an embodiment of the present invention, an air conditioning system for vehicles comprises a refrigeration cycle comprising a variable displacement compressor with a displacement control valve for controlling a discharge amount of the compressor, so that a pressure difference (Pd-Ps) between a discharged refrigerant pressure (Pd) and a drawn-refrigerant pressure (Ps) of the compressor equals a set value, means for detecting acceleration of a vehicle, and means for detecting an engine rotational speed of the vehicle. The air conditioning system further comprises means for determining a condition in which acceleration is detected or a condition in which the engine rotational speed is greater than or equal to a set value as an elevated compressor load condition, and during such elevated compressor load condition, for controlling the discharge amount of the compressor by the displacement control valve, so that the pressure difference (Pd-Ps) after discharge is less than or equal to a pressure difference (Pd-Ps) immediately before discharge in the elevated compressor load condition. [0009] This air conditioning system for vehicles further may comprise means for estimating a present value of the pressure difference (Pd-Ps), and for estimating the pressure difference (PD-Ps) during the elevated compressor load condition, the compressor may be driven by setting an estimated value of the pressure difference (Pd-Ps) immediately before said elevated compressor load condition as a target control value of the displacement control valve. [0010] In this structure, the air conditioning system further may comprise means for estimating a torque of the compressor, and the means for estimating the pressure difference (Pd-Ps) may estimate the pressure difference (Pd-Ps) based on an estimated torque of the compressor or an outside air temperature or a physical value having a correlation with an amount of air flowing into a heat exchanger provided outside of a vehicle interior per a unit time or an engine rotational speed or a vehicle running speed, or combinations thereof. [0011] Moreover, in air conditioning systems for vehicles according to the present invention, the pressure difference (Pd-Ps) during the elevated compressor load condition may be controlled at or less than the pressure difference (Pd-Ps) immediately before the elevated compressor load condition, by controlling the discharge amount of the compressor, so that power consumed by driving the compressor is equal to or less than a set value. In this case, the set value of the power consumed by driving the compressor may be determined with reference to a physical value having a correlation with an accelerator actuating amount and a vehicle running speed. Further, a sufficient cooling ability may be determined from a vehicle interior air temperature or an evaporator exit air temperature or an outside air temperature, or combinations thereof, and the set value of the power consumed by driving the compressor may be determined in accordance with the determined sufficient cooling ability. [0012] In addition, in air conditioning systems for vehicles according to the present invention, the above-described means for detecting the acceleration state may detect the acceleration state of the vehicle with reference to at least a physical value having a correlation with an accelerator actuating amount and a vehicle running speed. [0013] Further, the air conditioning systems for vehicles according to the present invention may be configured as a heat pump cycle. [0014] Thus, in air conditioning systems for vehicles according to the present invention, the compressor is not always driven at a maximum displacement during acceleration, excessive power consumption of the compressor during acceleration may be avoided, and improved acceleration performance of the vehicle and reduced fuel consumption may be achieved. [0015] Further, because the displacement of the compressor is controlled, so that the pressure difference between the discharged refrigerant pressure and the drawn-refrigerant pressure is a target value both before acceleration and during acceleration, the cooling ability is not reduced during acceleration, and the comfort level in the vehicle interior may be maintained. [0016] Further objects, features, and advantages of the present invention will be understood from the following detailed description of preferred embodiments of the present invention with reference to the accompanying figures. BRIEF DESCRIPTION OF THE DRAWINGS [0017] Embodiments of the invention now are described with reference to the accompanying figures, which are given by way of example only, and are not intended to limit the present invention. [0018] FIG. 1 is a schematic diagram of an air conditioning system for vehicles according to an embodiment of the present invention. [0019] FIG. 2 is a graph showing an example of a relationship between a displacement control signal and a pressure difference (Pd-Ps) in the present invention. [0020] FIG. 3 is a graph showing an example of a relationship between a vehicle running speed and a power consumed by a compressor when a pressure difference (Pd-Ps) is constant in the present invention. [0021] FIG. 4 is a time chart comparing respective properties showing an example of a difference between a case in which the control method according to the present invention is performed and a case in which the control method according to the present invention is not performed. Continue reading about Air conditioning systems for vehicles... Full patent description for Air conditioning systems for vehicles Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Air conditioning systems for vehicles patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. Start now! - Receive info on patent apps like Air conditioning systems for vehicles or other areas of interest. ### Previous Patent Application: Pump and pump control circuit apparatus and method Next Patent Application: Variable displacement swash plate compressor Industry Class: Pumps ### FreshPatents.com Support Thank you for viewing the Air conditioning systems for vehicles patent info. 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