Air Conditioning Compressors - Delphi

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A C o m p r e s s o r R a n g e One frequently hears a need expressed with phrases such as: ”I want the most efficient and lightest component possible.” In reality however, it is not possible to optimise against two independent parameters at the same time - the most efficient possible will not necessa- rily be the lightest and vice-versa (other than by coincidence). While optimisation against a single parameter is possible, the significance of the second can only then be expressed as a limit or a constraint. “I want the most efficient component possible weighing less than 1kg.” It is generally recognised that the automotive industr y sources against the single optimisation parameter – cost. While there are ver y many other constraints within which they have to operate – both applications and market based constraints – these can only be expressed as limiting values. The target will always be to acquire the product that meets the needs of the application at the lowest possible cost. Since the needs expressed as constraints var y greatly, depending upon application, a supplier needs to offer an extensive range of compressors offering a spectrum of balances between sophistication and cost in order to stand a chance of meeting the needs of a significant proportion of the market. This will extend from simple fixed compressors to meet the most straightfor ward applications to electronically controlled variable compressors where performance, accuracy and efficiency play a more important role. As means of illustration the Delphi compressor product range for R134a is indicated below. Compressors are shown with the I n c r e a s i n g d i s p l a c e m e n t S P 0 8 F i x e d S P10 S P13 S P15 S P17 S P21 SP - fixed displacement ## - displacement in cc/10 Wo b b l e Plate 12 3 V 5 i 13 2 V 5 i 14 4 V 5i 15 1 V 5i 15 6V5i 15 6V5e D e l p h i e n g i n e - d r i ve n R 13 4 a c o m p r e s s o r r a n g e trend for both increasing sophistication and cost going from left to right and increasing displacement going from top to bottom. The SP range of fixed swash-plate compressors each with five double acting pistons represents the lowest cost solution for applications that can tolerate the implications of a cycling clutch. The double piston configuration means that in effect there are a total of ten compression cavities which yields very low levels of pres- sure fluctuation. This feature combined with the smoothness of the swash-plate drive results in an inherently quiet compressor. The V5 range of wobble plate variable compressors has already been described as the original Delphi variable compressor. It has seen con- siderable refinement over the years and whilst it cannot compete with the CVC swash-plate range for quietness and efficiency it represents a very cost-effective introduction to variable compressor technology. The dual PTFE piston rings contribute to low blow-by and good oil retention. The Compact Variable Compressor (CVC) range of compressors uses swash-plate technology to ensure that a/c system generated noise and vibration is kept to a minimum. Internally and externally controlled versions are available. The externally controlled range of CVC compressors are offered with and without clutch. In the clutchless compressor the ability to upstroke again after destroke to a minimum that is only 1 or 2% of maximum stroke is ensured by the very tight tolerances of the piston and cylinder bore dimensions. They ensure very low blow-by which helps maintain low parasitic losses and ensure that upstroke can be achieved when required. Variable Swash-Plate I n c r e a sing sophistication and cost trend ### - displacement in cc V - wobble plate 179V7e # - number of cylinders i - internal control e - external control 5CVC120i 6CVC125i 6CVC135i 6CVC140i 6CVC160i 7CVC165i 7CVC185i # - number of pistons 5CVC120c CVC - variable swash-plate 6CVC125c 6CVC135c ### - max displacement in cc 6CVC140c 6CVC160c 7CVC165c 7CVC185c 5CVC120e 6CVC125e 6CVC135e 6CVC140e i - internal control c - clutchless 6CVC160e 7CVC165e e - external control 7CVC185e
I t c a n b e s e e n t h a t t h e C VC range is ver y c o m p r e h e n s i ve . N o t s how n h e r e is the f u r t h e r f l ex i b i l i t y o ffe r ed by a ver y wide r a n g e o f p o s s i b l e p i p ing c o n f igurations w h i ch t o g e t h e r c a rr y t h e implication that a l a r g e n u m b e r o f d i ffe r e nt c ompressor con- f i g u r a t i o n s m u s t p a s s d ow n t h e p roduction l i n e s . I t h a s b e e n c o n c l u d e d by s ome that t h i s c o m plex i t y i s l i ke l y t o have a negative e ffe c t o n p r o d u c t q u a l i t y w h e n i n fact the o p p o s i t e is t ru e . To m a n a g e t h e c omplexit y a s ys t e m k n ow n a s R F I D – radio f requency i d e n t i f i c a t i o n – i s u s e d i n w hich each individ- u a l c o m p ressor c a rries a ch i p w i t h it down t h e p r o d u c t i o n l i n e . D u ring t h e passage d ow n the line the ch i p reads and verifies all t h e i n fo r m a t i o n a b o u t t he i n dividual compo- n e n t s a s t h ey a r e a s s e m b l e d (manufacturing d a t e s , d i m e n s i o n s , e t c ) a n d c ommunicates i t b a ck t o a c e n t r a l c o m puter fo r filing . This d a t a o n e a ch i n d i v i d u a l c ompressor is then ava i l a b l e fo r l a t e r a c c e s s s h o uld there be p r o b l e m s f u r t h e r d ow n t h e l i n e o r problems f r o m t h e f i e l d . Th e ava i l a b ilit y o f a ll this com- p r e h e n s i ve a n d d e t a i l e d d a t a c o n t ributes to t h e e s t a b l i s h m e n t a n d maintenance of the ve r y h i g h l eve l s o f r e l i a b ilit y r e q u i red by the a p p l i c a t i o n . N e w Te c h n o l o g i e s I n r e c e n t ye a r s a s e r i ous i n t e r est in the u s e o f R 74 4 a s r e f r i g e rant i n a u tomotive a i r c o n d i tioning s ys t e m s has b een gene- r a t e d . E uropean l e g i s l a tion h as recently b e e n p a s s e d t h a t w i l l fo r c e t h e industr y t o m ove away f r o m R 13 4a a n d R744 has b e c o m e t h e l e a d i n g c o n t e n d e r. As a result D e l p h i i s d eve l o p i n g a r a n g e o f s wash-plate c o m p r e s s o r s t o m e e t t his n e e d. Current p r o t o t y p e s h ave f i ve p i s tons a n d maximum d i s p l a c e m e n t o f 3 0 c c a l though t h e number o f p i s t o n s i n t h e f i n a l p roduct r a nge is still u n d e r d eve l o p m e n t . Bo t h f ixe d a n d variable ve r s i o n s o f d i s p l a c e m e nts o f 15 , 21 and 3 0 c c a r e p l a n n e d . I t i s e nvisaged that for l ow d i s p l a c e m e n t t h e n umber o f pistons w i l l b e b e t we e n 5 a n d 7, a t t h e high end it C o n c l u s i o n will be bet ween 7 and 9. The reason for this uncert aint y is that the appropriate balance bet ween cost and noise/durabilit y has not yet been est ablished. D e l p h i C O 2 c o m p r e s s o r It can be seen that as a result of the ver y different fluid properties, the displacements offered are ver y much lower than for R134a. The range features shaft sealing by face seal and internal oil separator. The need for the latter comes from the significant evaporator performance degradation that occurs with CO 2 if excess oil is allowed to circulate. The second new technology concerns compressors for future powertrains, whether hybrid or fuel cell – the electrically driven compressor. Under development is a family of scroll compressors driven by 315 volt brushless electric motors. Scroll displacements are 28 and 38cc for cooling capacities of 5.6 and 7.1 kW respectively. The motors are cooled using the low temperature refrigerant vapour from the evaporator with a result ant motor efficiency of 94%. The inverter is cooled by conduction from the same refrigerant and it too has efficiency in the 94 to 98% range. 1 S e c t i o n t h r o u g h D e l p h i E l e c t r i c C o m p r e s s o r 1 S c r o l l C o m p r e s s o r 2 Pe r m a n e n t M a g n e t M o t o r 3 I nve r t e r a n d I n t e g r a t e d E l e c t r o n i c s This paper has aimed to present the technical requirements of the compressor for use in automotive air conditioning applications and to show how the diverse requirements of the application mean that a supplier must have available a range of technologies and specifi- cations to be able to meet these needs. It goes on to show how the Delphi compressor product range is designed to give comprehensive coverage and finishes with consideration of compressors for developmental technologies that are likely to become significant in the relatively near future. 2 3
Page 1: Air Conditioning Compressors
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Page 6 and 7: Th e p r e fe rred c o n f i g u r
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Air Conditioning Compressors - Delphi

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