GB2356926A - Air conditioning system for a motor vehicle with electronically controlled variable stroke compressor - Google Patents
Air conditioning system for a motor vehicle with electronically controlled variable stroke compressor Download PDFInfo
- Publication number
- GB2356926A GB2356926A GB9928214A GB9928214A GB2356926A GB 2356926 A GB2356926 A GB 2356926A GB 9928214 A GB9928214 A GB 9928214A GB 9928214 A GB9928214 A GB 9928214A GB 2356926 A GB2356926 A GB 2356926A
- Authority
- GB
- United Kingdom
- Prior art keywords
- heat exchanger
- temperature
- air
- compressor
- conditioning system
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60H—ARRANGEMENTS OF HEATING, COOLING, VENTILATING OR OTHER AIR-TREATING DEVICES SPECIALLY ADAPTED FOR PASSENGER OR GOODS SPACES OF VEHICLES
- B60H1/00—Heating, cooling or ventilating [HVAC] devices
- B60H1/32—Cooling devices
- B60H1/3204—Cooling devices using compression
- B60H1/3222—Cooling devices using compression characterised by the compressor driving arrangements, e.g. clutches, transmissions or multiple drives
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60H—ARRANGEMENTS OF HEATING, COOLING, VENTILATING OR OTHER AIR-TREATING DEVICES SPECIALLY ADAPTED FOR PASSENGER OR GOODS SPACES OF VEHICLES
- B60H1/00—Heating, cooling or ventilating [HVAC] devices
- B60H1/32—Cooling devices
- B60H1/3204—Cooling devices using compression
- B60H1/3205—Control means therefor
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60H—ARRANGEMENTS OF HEATING, COOLING, VENTILATING OR OTHER AIR-TREATING DEVICES SPECIALLY ADAPTED FOR PASSENGER OR GOODS SPACES OF VEHICLES
- B60H1/00—Heating, cooling or ventilating [HVAC] devices
- B60H1/32—Cooling devices
- B60H1/3204—Cooling devices using compression
- B60H1/3205—Control means therefor
- B60H1/3208—Vehicle drive related control of the compressor drive means, e.g. for fuel saving purposes
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60H—ARRANGEMENTS OF HEATING, COOLING, VENTILATING OR OTHER AIR-TREATING DEVICES SPECIALLY ADAPTED FOR PASSENGER OR GOODS SPACES OF VEHICLES
- B60H1/00—Heating, cooling or ventilating [HVAC] devices
- B60H1/32—Cooling devices
- B60H1/3204—Cooling devices using compression
- B60H1/3205—Control means therefor
- B60H1/3211—Control means therefor for increasing the efficiency of a vehicle refrigeration cycle
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60H—ARRANGEMENTS OF HEATING, COOLING, VENTILATING OR OTHER AIR-TREATING DEVICES SPECIALLY ADAPTED FOR PASSENGER OR GOODS SPACES OF VEHICLES
- B60H1/00—Heating, cooling or ventilating [HVAC] devices
- B60H1/32—Cooling devices
- B60H2001/3236—Cooling devices information from a variable is obtained
- B60H2001/3255—Cooling devices information from a variable is obtained related to temperature
- B60H2001/326—Cooling devices information from a variable is obtained related to temperature of the refrigerant at a condensing unit
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60H—ARRANGEMENTS OF HEATING, COOLING, VENTILATING OR OTHER AIR-TREATING DEVICES SPECIALLY ADAPTED FOR PASSENGER OR GOODS SPACES OF VEHICLES
- B60H1/00—Heating, cooling or ventilating [HVAC] devices
- B60H1/32—Cooling devices
- B60H2001/3236—Cooling devices information from a variable is obtained
- B60H2001/3255—Cooling devices information from a variable is obtained related to temperature
- B60H2001/3261—Cooling devices information from a variable is obtained related to temperature of the air at an evaporating unit
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60H—ARRANGEMENTS OF HEATING, COOLING, VENTILATING OR OTHER AIR-TREATING DEVICES SPECIALLY ADAPTED FOR PASSENGER OR GOODS SPACES OF VEHICLES
- B60H1/00—Heating, cooling or ventilating [HVAC] devices
- B60H1/32—Cooling devices
- B60H2001/3269—Cooling devices output of a control signal
- B60H2001/327—Cooling devices output of a control signal related to a compressing unit
- B60H2001/3275—Cooling devices output of a control signal related to a compressing unit to control the volume of a compressor
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60H—ARRANGEMENTS OF HEATING, COOLING, VENTILATING OR OTHER AIR-TREATING DEVICES SPECIALLY ADAPTED FOR PASSENGER OR GOODS SPACES OF VEHICLES
- B60H1/00—Heating, cooling or ventilating [HVAC] devices
- B60H1/32—Cooling devices
- B60H2001/3269—Cooling devices output of a control signal
- B60H2001/328—Cooling devices output of a control signal related to an evaporating unit
- B60H2001/3282—Cooling devices output of a control signal related to an evaporating unit to control the air flow
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60H—ARRANGEMENTS OF HEATING, COOLING, VENTILATING OR OTHER AIR-TREATING DEVICES SPECIALLY ADAPTED FOR PASSENGER OR GOODS SPACES OF VEHICLES
- B60H1/00—Heating, cooling or ventilating [HVAC] devices
- B60H1/32—Cooling devices
- B60H2001/3286—Constructional features
Landscapes
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Air-Conditioning For Vehicles (AREA)
Abstract
An air conditioning system (10) for a passenger compartment of a motor vehicle has heat exchangers (14) and (18) connected by fluid passages (22) and (24). An expansion device (16) and a variable stroke compressor (12) are located in these passages. A blower motor (40) is connected to a manual switch (52) driving a fan (42) which passes air over the heat exchanger (18) inside the passenger compartment. Sensors (36) and (46) output signals indicating the temperature of the air leaving heat exchanger (18) T<SB>ACC</SB> and the external air temperature T<SB>EXT</SB>. Control unit (30) receives output signals from sensors (36) and (46) and reads the selected fan speed from switch (52), determines the desired air temperature of the passenger compartment from these values and controls the stroke compressor (12), reducing the difference between T<SB>ACC</SB> and this desired temperature to zero. Assists in reducing load on compressor (12).
Description
2356926 AIR CONDITIONING SYSTEM FOR A MOTOR VEHICLE
Technical Field
The present invention relates to an air conditioning system for the passenger compartment of a motor vehicle; and to a method of operating such an air conditioning system.
Background of the Invention
Air conditioning systems for the passenger compartments of motor vehicles are well known. In general, these systems comprise an inside heat exchanger (located within the passenger compartment) and an outside heat exchanger (located outside the passenger compartment). A pair of fluid passages connect the heat exchangers to allow the circulation of fluid through 0 c 1 the heat exchangers. An expansion device is positioned in one of the fluid passages. A compressor and accumulator/dryer is positioned in the other fluid passage. When fluid is pumped by the compressor through the outside heat exchanger, the expansion device, the inside heat exchanger and the accumulator/dryer in succession, air passing through the inside heat exchanger 00 0 0 is cooled as the air flows into the passenger compartment. The operation (stroke) of the compressor can be controlled dependent on a temperature sensor located inside the passenger compartment. In certain situations this can lead to a high load being placed on the compressor.
Summary of the Invention
It is an object of the present invention to overcome the above mentioned problem.
An air conditioning system in accordance with the present invention for a passenger compartment of a motor vehicle comprises a first heat exchanger positionable outside the passenger compartment; a second heat exchanger positionable inside the passenger compartment; a first fluid passage 2 between the first and second heat exchangers; a second fluid passage between the first and second heat exchangers; an expansion device positioned in the first fluid passage; an electronically controlled variable stroke compressor positioned in the second fluid passage for pumping fluid in a direction sequentially through the first heat exchanger, the expansion device, and the second heat exchanger; a blower motor for blowing air through the second heat exchanger; first sensing means providing a first output signal indicative of the actual temperature of the air leaving the second heat exchanger; second sensing means providing a second output signal indicative of the temperature of external air; switch means for manually selecting the speed of the blower motor; and control means electrically connected to the first and second sensing means, to the switch means, and to the compressor, for receiving the first and second output signals, for receiving an indication of the selected speed of the blower motor, for determining the desired temperature of the air leaving the second heat exchanger dependent on the second output signal and the selected speed of the blower motor; for determining the temperature difference between the desired temperature of the air leaving the second heat exchanger and the actual temperature of the air leaving the second heat exchanger, and for controlling the stroke of the compressor to adjust the temperature difference to substantially zero.
Because of the use of an electronically controlled variable stroke compressor, the present invention allows more precise control of the pumping capacity of the compressor when the air conditioning system is cooling the passenger compartment. The present invention provides an air conditioning system which operates without the need for an internal temperature sensor in the passenger compartment, thereby providing lower loads on the compressor.
Brief Description of the Drawings
The present invention will now be described, by way of example, with reference to the accompanying drawings, in which:- 3 Figure 1 is a schematic view of an air conditioning system in accordance with the present invention; Figure 2 is a cross-sectional view of a compressor and control valve for use in the air conditioning system of Figure 1; Figure 3 is a flow chart showing one example of control of the compressor of the air conditioning system of Figure 1; and Figure 4 is a graph showing evaporator air-off temperature against external temperature for different blower motor speeds which is used by the control unit for the compressor of the air conditioning system of Figure 1.
Description of the Preferred Embodiment
Referring to Figure 1 of the drawings, the air conditioning system 10 in accordance with the present invention is for use in a motor vehicle for cooling the passenger compartment (not shown) of the motor vehicle. The air conditioning system 10 comprises the usual components of a compressor 12, an outside heat exchanger or condenser 14, an orifice tube or c- t other expansion device 16 (such as a thermal expansion valve), an inside heat exchanger or evaporator 18, and an accumulatorldryer 20. A first fluid passage 22 fluidly connects the outside heat exchanger 14 with the inside heat exchanger 18 by way of the expansion device 16. A second fluid passage 24 fluidly connects the outside heat exchanger 14 with the inside heat exchanger 18 by way of the compressor 12 and the accumulatorldryer 20. The inside heat exchanger 18 is located in a duct 38. Air is blown through the duct 38, and through the inside heat exchanger 18, into the passenger compartment using a blower motor 40 which rotates a scroll fan 42.
During normal (cooling) operation of the air conditioning system 10, fluid flow is in the direction X such that air passing through the inside heat exchanger 18 is cooled so that the air conditioning system operates to cool the passenger compartment.
4 The compressor 12 is an electronically variable compressor the operation of which is controlled by an electronic displacement control valve 26. An example of a suitable compressor 12 and control valve 26 is shown in Figure 2. The compressor 12 shown in Figure 2 is a wobble plate compressor. As an alternative, a swash plate compressor may be used.
The compressor 12 includes a pulley 80 which is connected to a rotatable shaft 82, and which is driven by a belt 84. A wobble plate 86 is mounted on the shaft 82. The wobble plate 86 is connected to one or more pistons 88. A crankcase chamber 90 is positioned on one side of the pistons 88, with the wobble plate 86 positioned in the crankcase chamber. An outlet chamber 92 and an inlet chamber 94 are positioned on the opposite side of the pistons. The inlet chamber 94 is fluidly connected to the accumulator 20.
The outlet chamber 92 is fluidly connected to the outside heat exchanger 14.
The other components of the air conditioning system 10 are fluidly connected as shown in Figure 1. Fluid flow through the chambers 90, 92, 94, and hence 0 the fluid pressure in the chambers, is controlled by the control valve 26.
The control valve 26 has a first port 96 fluidly connected to the outlet chamber 92; a second port 98 fluidly connected to, and acting as an inlet to, the crankcase chamber 90; a third port 100 fluidly connected to, and acting as an outlet from, the crankcase chamber 90; and a fourth port 102 fluidly connected to the inlet chamber 94. The control valve 26 is electrically connected by a line 28 to a control unit 30 which is preferably a microprocessor or other computer control unit. The control unit 30 is electrically connected by a line 34 (Figure 1) to a temperature sensor 36 which monitors the temperature of the air (evaporator air-off temperature, EAOT) leaving the inside heat exchanger 18, and by a line 45 to a temperature sensor 46 monitoring the temperature of the air (the external temperature) entering the outside heat exchanger 14. The sensor 46 may be positioned elsewhere to monitor the external temperature. The control unit 30 is also electrically connected by a line 50 to a manually operated switch 52 located inside the passenger compartment and operable by a passenger in the motor vehicle to select a required blower speed for the blower motor 40.
The stroke of the compressor 12 (or, more precisely, the displacement or stroke of the pistons 88) is controlled by the operation of the control valve 26. The duty cycle of the control valve 26 is actuated to adjust crankcase fluid pressure Pc in the crankcase chamber 90; the inlet suction fluid pressure Ps in the inlet chamber 94; and the discharge fluid pressure Po in the outlet chamber 92. When the crankcase fluid pressure Pc is substantially the same as the inlet suction fluid pressure Ps, the stroke of the compressor 12 is at a maximum. When the crankcase fluid pressure Pc is greater than the inlet suction fluid pressure Ps, the stroke of the compressor 12 is reduced from the maximum stroke. By suitable control of the control valve 26, the stroke of the compressor 12 can be controlled.
In an alternative arrangement, the stroke of the compressor 12 may be controlled by an electronic control valve that meters fluid flow from the outlet chamber 92 to the crankcase chamber 90 and uses a fixed bleed from the crankcase chamber to the inlet chamber 94. In a further alternative, the reverse arrangement may be used - that is metering fluid flow from the tore crankcase chamber 90 to the inlet chamber 94 and using a fixed bleed from the outlet chamber 92 to the crankcase chamber. As with the duty cycle arrangement described above, these alternative arrangements also control the stroke of the compressor 12 by effecting the pressure in the crankcase chamber 90 and the pressure balance across the piston 88.
In accordance with the present invention, the control unit 30 monitors the signals from the sensors 36,46 and the position of the switch 52, and controls the operation of the control valve 26, and hence the operation of the compressor 12 dependent on the sensed signals and the switch position.
Such an arrangement provides more precise control of the pumping capacity of the compressor 12 during the cooling cycle of the air conditioning system 10.
The control sequence performed by the control unit 30 for the operation of the compressor 12 during passenger compartment cooling is 6 shown in Figure 3. The sequence begins with an initial request, step 54, for passenger compartment cooling. The control unit 30 actuates the control valve 26 to provide a minimum operating stroke for the compressor 12 at step 56. The control unit 30 then checks that any delay criteria are met at step 58.
If not, the control unit returns to step 56. If yes, the control unit 30 proceeds to step 60 and actuates the control valve 26 to increase the stroke of the compressor 12. Next, at step 62, the control unit 30 monitors the actual EAOT reading TACC from the sensor 36. At step 64, the control unit 30 monitors the external temperature reading TEXTfrom the sensor 46. The control unit 30, at step 66, monitors the position S of the switch 52. Next, at step 68, the control unit 30 determines the desired value of EAOT TDEs from the measured readings TEXTfrom the sensor 46 and the switch position S using the predetermined figures shown in Figure 4 (which are stored in a memory in the control unit 30). The value of TDES is a predetermined desired value for the temperature of the air leaving the inside heat exchanger 18 and entering the passenger compartment. The predetermined values for TDES as shown in Figure 4 may be determined experimentally or by calculation, and the figures shown in Figure 4 may change from one motor vehicle to another. Next, at step 70, the control unit 30 compares the value of TDEs determined at step 68 to the value of TACCmeasured at step 62. If TDES is above TACC, the control unit 30 actuates the control valve 26 to reduce the stroke of the compressor 12 at step 72. If TDES is below TACC, the control unit 30 actuates the control valve 26 to increase the stroke of the compressor 12 at step 74. If TDES is equal to TACC, the control unit 30 leaves the control valve 26 unchanged to maintain the stroke of the compressor 12 at step 76. Following step 72, or step 74, or step 76, the control unit 30 returns to step 62 and repeats the subsequent sequence, or goes to step 78 if passenger compartment cooling is no longer required.
The present invention therefore provides open-loop control of the operation of the compressor 12 based on EAOT and blower motor speed, without the use of an internal temperature sensor, which helps to lower the load on the compressor.
7 Rather than direct measurement of the actual EAOT and the external air temperature, other arrangements may be used to determine these values.
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Claims (11)
1. An air conditioning system for a passenger compartment of a motor vehicle comprises a first heat exchanger positionable outside the passenger compartment; a second heat exchanger positionable inside the passenger compartment; a first fluid passage between the first and second heat exchangers; a second fluid passage between the first and second heat exchangers; an expansion device positioned in the first fluid passage; an electronically controlled variable stroke compressor positioned in the second fluid passage for pumping fluid in a direction sequentially through the first heat exchanger, the expansion device, and the second heat exchanger; a blower motor for blowing air through the second heat exchanger; first sensing means providing a first output signal indicative of the actual temperature of the air leaving the second heat exchanger; second sensing means providing a second output signal indicative of the temperature of external air; switch means for manually selecting the speed of the blower motor; and control means electrically connected to the first and second sensing means, to the switch means, and to the compressor, for receiving the first and second output signals, for receiving an indication of the selected speed of the blower motor, for determining the desired temperature of the air leaving the second heat exchanger dependent on the second output signal and the selected speed of the blower motor; for determining the temperature difference between the desired temperature of the air leaving the second heat exchanger and the actual temperature of the air leaving the second heat exchanger, and for controlling the stroke of the compressor to adjust the temperature difference to substantially zero.
2. An air conditioning system as claimed in Claim 1, wherein the control means comprises a microprocessor electrically connected to the first and second sensing means, to the switch means, and to a control valve connected to the compressor and operated by the microprocessor to control the stroke of the compressor.
9
3. An air conditioning system as claimed in Claim 1 or Claim 2, wherein the first sensing means is a temperature sensor which measures the temperature of the air leaving the second heat exchanger.
4. An air conditioning system as claimed in any one of Claims 1 to 3, wherein the second sensing means is positioned on the air inlet side of the first heat exchanger.
5. An air conditioning system as claimed in any one of Claims 1 to 4, wherein the second sensing means is a temperature sensor which measures the temperature of the external air.
6. A method of operating an air conditioning system as claimed in any one of Claims 1 to 5, comprising the steps of determining the actual temperature of the air leaving the second heat exchanger; determining the temperature of the external air; obtaining an indication of the selected speed of the blower motor; determining the desired temperature for the air leaving the second heat exchanger based on the determined temperature of the external air and the selected speed of the blower motor; determining the temperature difference between the determined desired temperature for the air leaving the second heat exchanger and the determined actual temperature of the air leaving the second heat exchanger; and controlling the stroke of the compressor to adjust the determined temperature difference to substantially zero.
7. A method as claimed in Claim 6, wherein the desired temperature for the air leaving the second heat exchanger is determined from predetermined values of the desired temperature which have been derived experimentally from measured values of the temperature of the external air and from the selected blower motor speed, the predetermined values being stored in the control means.
8. A method as claimed in Claim 6 or Claim 7, wherein the step of determining the actual temperature of the air leaving the second heat exchanger comprises measuring the temperature of the air leaving the second heat exchanger.
9. A method as claimed in any one of Claims 6 to 8, wherein the step of determining the temperature of the external air comprises measuring the temperature of the external air.
10. An air conditioning system substantially as herein described with reference to, and as shown in, the accompanying drawings.
11. A method substantially as herein described with reference to the accompanying drawings.
& 0 4 c c A 6 a
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9928214A GB2356926A (en) | 1999-11-30 | 1999-11-30 | Air conditioning system for a motor vehicle with electronically controlled variable stroke compressor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9928214A GB2356926A (en) | 1999-11-30 | 1999-11-30 | Air conditioning system for a motor vehicle with electronically controlled variable stroke compressor |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB9928214D0 GB9928214D0 (en) | 2000-01-26 |
| GB2356926A true GB2356926A (en) | 2001-06-06 |
Family
ID=10865376
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB9928214A Withdrawn GB2356926A (en) | 1999-11-30 | 1999-11-30 | Air conditioning system for a motor vehicle with electronically controlled variable stroke compressor |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2356926A (en) |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0392774A2 (en) * | 1989-04-13 | 1990-10-17 | Motor Panels (Coventry) Limited | Control systems for automotive air conditioning systems |
| US5305613A (en) * | 1991-11-27 | 1994-04-26 | Honda Giken Kogyo Kabushiki Kaisha | Air conditioning system suitable for use in a electric vehicle |
| US5388421A (en) * | 1992-05-25 | 1995-02-14 | Nissan Motor Co., Ltd. | Heat pump type air conditioner for automotive vehicle |
| US5499511A (en) * | 1994-04-19 | 1996-03-19 | Nissan Motor Co., Ltd. | Heat pump type air conditioner for vehicle |
| US5634348A (en) * | 1994-07-06 | 1997-06-03 | Honda Giken Kogyo Kabushiki Kaisha | Air conditioner for vehicles |
-
1999
- 1999-11-30 GB GB9928214A patent/GB2356926A/en not_active Withdrawn
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0392774A2 (en) * | 1989-04-13 | 1990-10-17 | Motor Panels (Coventry) Limited | Control systems for automotive air conditioning systems |
| US5305613A (en) * | 1991-11-27 | 1994-04-26 | Honda Giken Kogyo Kabushiki Kaisha | Air conditioning system suitable for use in a electric vehicle |
| US5388421A (en) * | 1992-05-25 | 1995-02-14 | Nissan Motor Co., Ltd. | Heat pump type air conditioner for automotive vehicle |
| US5499511A (en) * | 1994-04-19 | 1996-03-19 | Nissan Motor Co., Ltd. | Heat pump type air conditioner for vehicle |
| US5634348A (en) * | 1994-07-06 | 1997-06-03 | Honda Giken Kogyo Kabushiki Kaisha | Air conditioner for vehicles |
Also Published As
| Publication number | Publication date |
|---|---|
| GB9928214D0 (en) | 2000-01-26 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |