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Technical Paper

Leakage Reduction on Seal Parts of HFC134a MAC Compressors

Typical belt-driven Mobile Air-Conditioning (MAC) compressors require durable seals between a rotating driveshaft and stationary casing in addition to casing and hose connection O-ring seals. This paper explores the experiential and theoretical relationships of HFC134a seal design and materials and also suggests possible improvements. Testing revealed that shaft and O-ring permeation comprised a large part of the total leak rate of HFC134a MAC compressors during static-state leak-rate measurements. Furthermore, testing and Taguchi statistical analysis methods clarified equations concerning permeation area, distance and leak rate. Resulting design and material improvements reduced compressor HFC134a Leak Flow Rates (LFR) by approximately fifty percent.
Technical Paper

Development of Inverter Integrated Electric Compressor

Achieving lower fuel consumption and lower total emissions is today's demand from the international automobile industry. The electrically driven compressor (the term Electric Compressor is used hereafter) is the one of the technical innovations designed to meet these goals in future automotive products. The inverter integrated compressor in comparison with non-integrated types benefits the vehicle in that the inverter integrated compressor does not require supplemental cooling equipment. This paper relates how the inverter integrates onto the compressor and considers the results and requirements of changes in package size.
Technical Paper

The Development of a Fixed-Displacement Single-Sided Swash Plate A/C Compressor

Traditionally there have been two types of automotive fixed-displacement air-conditioning compressors on the market. One is the wobble plate (single sided) compressor, and the other is an opposed (double sided) swash plate compressor. Due to the increasing demand for high speed, high performance, quiet compressors, a single sided, swash plate compressor with a fixed displacement was developed. This compressor combines the positive attributes from both types of compressors into a new superior product designed to surpass market requirements.
Technical Paper

Recent Progress in Technology of the 5-Cylinder Wobbleplate Type Compressor for Automotive Air Conditioning

The SD-5 Series, five cylinder wobble plate compressors have again been improved to meet the requirements of further size and weight reduction; rapid car interior cool down at the lower speed range; yet maintain an adequate capacity saturation in the high speed range, and lower operating noise. Featured in this paper is an explanation of how the new technology is incorporated. 1) Use of dual TFE piston ring technique, 2) Reduction in the oil circulation ratio in the refrigerant circuit. 3) Optimizing of bore to stroke ratio.
Technical Paper

Lubricant Screening for HFC-134a Car Air Conditioning Compressor Reliability

Certain important factors must be considered when the current refrigerant for automotive air conditioning systems, (A/C), is changed from CFC12 to the ozone safe HFC134a. This paper will focus on lubricant compatibility by presenting a screening process which will cover: a screening table of essential physical properties general information on types of available lubricants tests of chemical stability lubricity compatibility with elastomers methods for testing compressor durability service engineering
Technical Paper

Historical Review of the Wobbleplate and Scroll Type Compressors

In commemoration of the 50th anniversary of the world's automotive air conditioning technology, this historical review is given of the compressor in general, and then of the wobbleplate and scroll types specifically. Sanden has been producing these for the world market since 1971 and 1981, respectively. A new era of the two types of compressors embodying the variable capacity feature is also described.
Technical Paper

Air Conditioning Electric Vehicles with an Electronically Driven Variable Speed Scroll Type Compressor

A realistic air conditioning system for electric vehicles, (EV), which minimizes the sacrifice of drive range is proposed in this paper. A variable speed semi-hermetic scroll compressor and an automatic louver outlet air temperature control method for a small delivery van are used to attain suitable cooling performance and interior temperature controllability with acceptable noise characteristics. This air conditioning system, (A/C), offers a pre-cooling feature simply by tapping power from commercial electricity outlets before departing for service. The effect of a practical heat influx reduction applied to the vehicle, and of condenser improvement, is evaluated in terms of the electric power consumption and the actual sacrifice of the vehicle's drive range.
Technical Paper

An Experimental Study of the Electromagnetic Clutch for the Automotive Air Conditioning Compressor

Various physical conditions of the friction surfaces were studied to increase the breakaway torque of the electromagnetic clutch for the automotive air conditioning compressor. The conventional ground steel-ground-steel combination had a disadvantage of low breakaway torque in the running-in period of engagement cycles. This situation was greatly improved by using the combination of the ground armature plate and the machined rotor with zinc plating. In this new technique, the pitch and depth of the machining mark relative to the plating thickness was found to be important. Combinations of machined armature plates and the machined rotors, with or without zinc plating, were also promising, and the mechanism of friction with these surface combinations were analyzed.
Technical Paper

The Scroll Type Variable Capacity Compressor for Automotive Air Conditioners

A variable capacity compressor, designated the TRV, was developed by applying an intermediate stage bypassing method to the already proven SCROLL compressor. The purposes were: 1. to attain better temperature control 2. to reduce the horsepower requirement and to eliminate the torque surge 3. to accomplish continuous capacity control in a wide operating range 4. to maintain an excellent cool down with a very limited chance of cycling for the minimum displacement of 25%, and 5. to utilize the SCROLL machine concept for low noise and smooth operation. Experimental data of the compressor and A/C system simulation results were discussed to show that all the expected features were realized.
Technical Paper

Possible Compressor Problems in Handling HFC-134a Car Air Conditioning Systems

Several field problems are anticipated with HFC-134a systems. To be evaluated and clarified are the impacts upon: compressors and systems of chlorine based solvents left in the system from flushing or parts cleaning; mixing in CFC-12; mixing the new lubricants with mineral oil; the effects of certain lubricants and HFC-134a's high hygroscopicity and others. The whole industry should share information and endeavor to maintain the reliability of the new systems from a service engineering standpoint. STARTING IN 1991 the ozone safe HFC-134a refrigerant is expected to replace the conventional CFC-12 in car air conditioning systems and in model years 1994-1995 the major portion of the market will be the new systems. The components/elements and parts used in the new air conditioning systems will embody different designs with new materials which are now considered to be compatible with the new refrigerant-lubricant mixtures.
Technical Paper

Scroll Compressor Wall Strength Improvement

Scroll wall strength is of critical importance to compressor reliability and durability. This is most critical at the center portion of the scroll wall as it is exposed to the highest working gas pressure in the A/C system as well as to high discharge gas temperatures. This paper will focus on a method to achieve stress reduction at the center portion of the scroll wall by using Finite Element Methods (FEM) analysis. Scroll wall endurance was evaluated utilizing an accelerated durability test which covered the following: Optimization method of scroll wall center portion geometry. Effect of stress reduction by optimization of fillet radius. Impact of discharge gas temperature on scroll wall endurance.
Technical Paper

Wobble Plate Type Compressor NVH Reduction through Valve Plate Assembly Improvement

The discharge valve impact force on the valve retainer and valve plate play a critical role on the NVH characteristics of the wobble plate compressor. Another contributing factor to compressor NVH is in-cylinder bore over-pressure. In order to improve the NVH characteristics, a reduction in the valve impact forces and in-cylinder over-pressure is essential. The focus of this paper will be a new valve plate assembly change utilizing a unique design arrangement. This new design change significantly improved compressor NVH characteristics due to reduction in the the valve impact force as well as in-cylinder over-pressure. A slight reduction in compressor cooling capacity was observed. Research efforts are continuing to overcome this reduction.
Technical Paper

Improvement of Scroll Compressor for Vehicle Air Conditioning Systems

Mobile Air Conditioning Compressors with the scroll mechanism design are superior in noise, vibration and harshness (NVH) levels, and in efficiency. For further NVH improvements; for improved comfortability; to enhance the manufacturability to meet the increasing market volumes; and to give better vehicle compatibility in weight reduction and increased durability, the New Type TR Compressor is presented.