A vehicle cabin air filtration system has an electronic air filter which removes unwanted air particles from air prior to or after entry into a vehicle cabin. The vehicle cabin air filtration system also has a sensor configured to generate a signal indicative of a parameter and a controller operatively connected to the electronic air filter and the sensor. The controller receives the signal indicative of the parameter from the sensor, compares the parameter to a stored condition, and selectively activates or deactivates the electronic air filter based on the comparison.

A method for detecting a functional state of an ionizer in an air filtering system is provided, in particular for a motor vehicle, in which a measurement apparatus determines the amperage at a discharge electrode in the ionizer at an initial point in time t.sub.0, and sends this to a computer, the measurement apparatus measures at least one other parameter at the time t.sub.0 and sends this to the computer, the measurement apparatus measures the amperage at the discharge electrode and the at least one other parameter at a subsequent time t.sub.1 and sends the results to the computer, the computer obtains at least one comparison value from the measurement values detected by the measurement apparatus at the initial time t.sub.0 and the subsequent time t.sub.1 and compares this with a reference value, the computer generates a signal and/or takes appropriate measures if the comparison value differs from the reference value by a predefined value.

A lasting filtering effect is obtained therewith, even with worn filters.

Systems and methods for use in a vehicle can involve determining that a plurality of closures of a vehicle have been closed, running an HVAC system in a fresh air mode after determining that the plurality of closures have been closed, and thereafter recirculating air while adding newly filtered air to maintain a positive air pressure level in a passenger cabin of the vehicle. The determining can occur after one or more people enter the vehicle and being driving, and the recirculating and adding can involve activating a recirculation mode and a fresh air mode simultaneously. Adding newly filtered air maintains a positive air pressure level in a passenger cabin, which level can be set based on an amount of leaks, a user setting, a vehicle type and a pollution level. The determining, running, and recirculating and adding can occur again after determining a vehicle closure has been opened.

Consumed energy and cost relating to control of a carbon dioxide concentration is reduced. Each of CO.sub.2 concentration control systems (100 to 105) includes a measuring unit (20) that measures a CO.sub.2 concentration, a CO.sub.2 absorption unit (30) that has a CO.sub.2 absorption material (31) for absorbing CO.sub.2 at a rate depending on the temperature thereof, and a control unit (10) that controls the temperature of the CO.sub.2 absorption material (31) by using exhaust heat of a power system (40), so as to control a CO.sub.2 absorption rate of the CO.sub.2 absorption material (31).

An air filtration system for a passenger compartment of a vehicle includes a HEPA filter for filtering air from an air inlet into filtered air, the HEPA filter including a fine particulate filter and a gas filter, and air passageways formed in the vehicle and configured to convey the air from the air inlet to the HEPA filter, and to convey the filtered air from the HEPA filter to the passenger compartment

An air cleaning system for a vehicle includes: an air purification button generating an operation signal for purifying air in an interior of the vehicle; an inside air purification unit blocking air outside of the vehicle from being introduced into the interior of the vehicle and filtering and circulating air inside of the vehicle, when the air purification button is operated; a fog detection unit detecting a humidity of a window of the vehicle by detecting moisture on the window; and a controller controlling an operation of the inside air purification unit when the air purification button is operated and determining whether a defogging unit of the vehicle for removing the moisture on the window is to be operated based on a signal from the fog detection unit.

An automatic dust removal device for a vehicle is provided. The device constantly senses dust in the interior of the vehicle and automatically removes the detected dust. The device includes a dust sensor that senses dust concentration in the interior of the vehicle and a controller that operates an air-conditioning device. The controller determines whether dust in the interior of the vehicle requires removal based on a signal from the dust sensor. An air-conditioning device for removing dust from the air is operated to activate a dust removal mode based on a signal from the controller. Thus, an intake door is closed to block inflow of external air into the interior of the vehicle and the air in the interior of the vehicle passes through an air filter and is circulated by a blower.

A carbon dioxide concentration control device (10) is provided with a control unit (15) that controls an absorption amount of carbon dioxide of a carbon dioxide absorbent (16) per unit hour, and a regeneration control unit (14) that generates the carbon dioxide absorbent (16), and a second drive energy supply unit (13) which is different from a first drive energy supply unit (11) that supplies power to the control unit (15) supplies power to the regeneration control unit (14), and thus a carbon dioxide concentration in a space is controlled to be an appropriate value for long periods of time.

An air filtration system for a passenger compartment of a vehicle comprises: a HEPA filter for filtering air from an air inlet into filtered air, the HEPA filter comprising a fine particulate filter and a gas filter; and air passageways formed in the vehicle and configured to convey the air from the air inlet to the HEPA filter, and to convey the filtered air from the HEPA filter to the passenger compartment

An air filter monitoring system and method includes a plenum, a pressurization blower, a first motor driving the pressurization blower, a first motor current sensor, a recirculation blower, a second motor driving the recirculation blower, a second motor current sensor, a speed selector, a fresh air filter, a recirculation air filter, a pressurization blower speed sensor, a recirculation blower speed sensor, and a non-transitory computer readable medium comprising a program instruction for permitting a controller to monitor the HVAC system. The program instruction is adapted to produce a first and a second motor control signal to drive independently the pressurization blower and the recirculation blower, respectively. The first and second motor control signals are a function of the speed sensor signals to maintain a constant speed. Comparing a first and second motor current sensor signal to a baseline and triggers a replacement action when either signal falls below a threshold.