1 Centre-Mounted A/C Unit
In comparison to conventional blower units, the size of the blower unit used in the center-mounted compact A/C unit has been reduced by half through the development of a compact blower fan. In addition, a 20% reduction in A/C unit size has been realized by smoothing the flow of air, and decreasing the space used to mix the heating and cooling air streams. Conventional A/C units consisted of separate cooling and blower units, with the blower unit positioned above the passenger seat floorboard. However, the compact A/C unit features an integrated construction with the blower unit placed on top of the cooling unit. This integrated construction allows the A/C unit to be mounted at the center of the vehicle, which contributes to an increase in passenger seat foot space.

1.1 Compact Blower Fan
DENSO has developed a compact, high efficiency blower fan. The compact blower fan achieves a uniform and smooth airflow, as well as a reduction in running noise by making each of the blades that constitute the fan thinner at the tips, and thicker at the center.

2 TSB10 Type Compressor
The TSB10 is a one-way swash plate, externally-controlled, continuous variable capacity type compressor. Driven via the magnetic clutch, the TSB10 has six cylinders, and a 100 cc discharge capacity. Compared to conventional variable capacity compressors, the TSB10 type is equipped with the following new technologies.

Part Name

Function and Role

Refrigerant Flow Volume Sensor

Measures refrigerant flow volume. The engine ECU uses this flow volume to estimate more accurate compressor load conditions, and to achieve a reduction in engine power consumption

Crank Suction (CS) Valve

Quickly discharges the liquid refrigerant accumulated in the compressor to promote faster cooling.

Variable Suction Throttle (VST)

Adjusts the compressor suction quantity to reduce operating noise caused by suction pulsations.

Oil Separator

Improves cooling efficiency by separating the compressor oil from the refrigerant to reduce the quantity of oil circulating in the refrigeration cycle.

Variable Capacity Control
Just as with conventional one-way swash plate, externally-controlled, continuous variable capacity type compressors, the TSB10 varies the discharge quantity by controlling crank chamber pressure via a control valve to alter the swash plate angle. Therefore, changes in swash plate angle are dependent on changes in crank chamber pressure. When the swash plate angle is varied, the piston stroke also changes, leading to a change in discharge quantity.

2.1 Refrigerant Flow Volume Sensor
The refrigerant flow volume sensor measures the flow volume of the refrigerant. The engine ECU then uses this information to estimate compressor load conditions, and optimize engine control. As a result, reduced power consumption is achieved. Conventionally, the correlation between compressor load conditions and refrigerant flow volume was estimated from the control valve current value. However, the newly developed refrigerant flow volume sensor measures actual refrigerant flow volume to improve accuracy, making further reductions in power consumption possible.

Construction and Operation
When refrigerant flows through the throttle in the refrigerant flow path, a differential pressure (difference between pressures PdH, and PdL) is generated before and after the throttle. This differential pressure changes according to the refrigerant flow volume. When the spool moves up or down due to the differential pressure, the distance between the magnet integrated with the upper portion of the spool and the Hall IC changes. As such, the density of the magnetic flux passing through the Hall IC also changes. By using the Hall IC to measure themagnetic flux, the spool position is detected, resulting in a measurement of the refrigerant flow volume.

2-2 CS Valve
When a vehicle is left sitting for a long time, there are rare cases in which liquid refrigerant accumulates inside the compressor. When liquid refrigerant accumulates in an externallycontrolled, continuous variable capacity type compressor, the discharge quantity cannot be increased until the liquid refrigerant is discharged. Under these circumstances, cooling efficiency cannot be increased. In addition to the refrigerant discharge path contained in conventional externally-controlled, continuous variable capacity type compressors, the TSB10 has a CS valve placed inside the control valve. The CS valve discharges liquid refrigerant only when there is a buildup within the compressor. As such, the CS valve greatly reduces the time required to discharge the liquid refrigerant, thereby promoting fast cooling.

2-3 VST
The VST reduces the operating noise caused by suction pulsations when compressor variable capacity control is operating. When operating at maximum discharge capacity, the VST opening is maximized to reduce suction losses. When operating under variable capacity control, the VST opening is restricted in accordance with the refrigerant flow volume. As a result, the suction quantity is adjusted to reduce operating noise.

2-4 Oil Separator
The oil separator improves cooling efficiency by separating the compressor oil from the refrigerant to reduce the quantity of oil circulating in the refrigeration cycle. The oil separator is built into the compressor. The compressor oil and gaseous refrigerant are first separated centrifugally in the separation chamber, then the gaseous refrigerant is circulated back into the refrigeration cycle. The compressor oil circulates within the compressor through the following path: separation chamber, oil accumulation chamber, suction chamber, cylinder, discharge chamber, separation chamber.