Mitsubishi Heavy Industries Technical Review Vol. 51 No. 2 (June 2014)44

Air-conditioning System for
Mitsubishi Motors OUTLANDER PHEV

M i ts u b i s h i H e a v y I n d u s t r i e s
A u t o m o t i v e T h e r m a l S y s t e m s C o . , L td .

In January 2013, Mitsubishi Motors Corporation launched the Outlander PHEV (Plug-inHybrid Electric Vehicle), the world's first plug-in hybrid electric vehicle in the 4WD and SUV
categories. For the Outlander PHEV, Mitsubishi Heavy Industries Automotive Thermal Systems
Co., Ltd. supplies the system controlling the temperature inside of the lithium ion battery pack inaddition to air conditioning in the cabin. This system includes an HVAC (Heating, Ventilation andAir Conditioning) unit, an electrically-driven A/C compressor and an electric water heater forelectrification, as well as a battery cooling unit. This paper presents a summary of the air
conditioning system that Mitsubishi Heavy Industries Automotive Thermal Systems Co., Ltd.
developed for the Outlander PHEV.

|1. Features(1)

HVAC unit
The HVAC unit of the developed system is equipped with a thin type evaporator forcooling, a thin type heater core for heating, a built-in blower fan, and a thin walled plastic
casing in order to realize a compact packaging. As a result, it achieved an approximately 15%
reduction in weight compared with the existing one (the HVAC unit for the previous model ofthe Outlander).
The controller of the air conditioning system features newly developed hardware andsoftware applicable to the new PHEV system, while its operation and display panel is carriedover from that of the existing Outlander. The air conditioning system is operated to the optimalA/C condition along with the vehicle driving condition in order to reduce energy consumption,
noise and vibration while the air conditioner is on (Figure 1).

Figure 1 HVAC unit and controller of air conditioner(2)

Electrically-driven A/C compressor
An electrically-driven scroll compressor is applied to the developed system, which has
the same displacement (24 cc/rev) as that used in the i-MiEV and Minicab MiEV series of EVs(Electric Vehicles) manufactured by Mitsubishi Motors. The electrical A/C compressor isoptimized to the Outlander PHEV in order to improve efficiency and suppress noise andvibration. As a result, the Outlander PHEV has sufficient air-conditioning performance in spiteof the larger cabin volume than the i-MiEV and Minicab MiEV (Figure 2).

Mitsubishi Heavy Industries Technical Review Vol. 51 No. 2 (June 2014)45

Figure 2(3)

Electrically-driven A/C compressor

Battery cooling unit
A battery cooling unit was newly developed for the Outlander PHEV. The cooling unit isinstalled in the lithium ion battery pack. This unit can be independently operated, and therefore,
it can cool down the battery according to the temperature inside the lithium ion battery pack,without being affected by the operation of the cabin air conditioning. Consequently it
contributes to the improvement of reliability and the extension of the service life of the highvoltage lithium ion battery (Figure 3).

Figure 3 Battery cooling unit

(4)

Electric water heater (optional)
In a typical A/C system without an electric water heater, engine coolant (hot water) is
circulated to the heater core in the HVAC unit for heating operation (hot water heating system),and then the engine becomes a heat source whenever heating mode is necessary for cabin airconditioning, even if the battery power (charge level) is sufficient.
On the other hand, in the system of the Outlander PHEV, an electric water heater unit
similar to that used in the i-MiEV and Minicab MiEV is added to the typical A/C system as
optional equipment. The combined use of the electric water heater unit using battery power andthe existing system using engine coolant realized the creation of a heat source for heating modeusing electricity only when the battery power (charge level) is sufficient. Accordingly, thesystem can reduce the engine operating time period in comparison with the existing system andtherefore contributes to the improvement of the fuel efficiency of the vehicle (Figure 4).

Figure 4 Electric water heater (optional)Mitsubishi Heavy Industries Technical Review Vol. 51 No. 2 (June 2014)46|2. Specifications
Table 1 shows the specifications of the air conditioning system components for theOutlander PHEV and Figure 5 shows their layout on the vehicle.
Table 1

Specifications of Outlander PHEV air conditioning system components
HVAC unit

Battery cooling unit
Electric water heater
Refrigerant

Figure 5

Cooling capability
Heating capability
Cooling capability
Heating capability

5,500W
5,700W
1,000W
4,000W
HFC-134a 590g

Layout of Outlander PHEV air conditioning system components