The invention relates to a method and a corresponding apparatus for preconditioning a heating and/or cooling unit of a motor vehicle at a standstill, the heating and/or cooling unit drawing its energy for heating and/or cooling from an electric store.
In order for it to be possible to control the temperature in an optimum manner of vehicles which are at a standstill, various apparatuses and methods are known at present. For instance, DE 197 31 071 A1 discloses a system for controlling the temperature of the vehicle interior of a motor vehicle at a standstill, in which the residual heat of a heat source and residual cold of a cold source which are still present in the vehicle are utilized.
Since the utilization of residual heat and/or residual cold is possible only when the heat sources and/or cold sources which are used for this purpose are in a state in which they can emit heat and/or cold, as a rule therefore immediately after (relatively long) operation of the motor vehicle, systems of this type are often not sufficient to make optimum temperature control of the vehicle interior at a standstill possible.
In addition to the stated apparatuses for controlling the temperature of the vehicle interior at a standstill, auxiliary heating units or parking heating units or electrically driven cooling devices are often used to heat or cool the vehicle at a standstill, which units or devices obtain their energy as a rule with the aid of internal combustion engines or thermal energy stores. Heating and/or cooling units of this type have considerable fuel consumption and, associated with this, high levels of pollutant emissions.
Novel vehicle concepts, in particular hybrid vehicles, suggest the approach of utilizing the necessary energy for operating the heating and/or cooling units at a standstill from the existing electric energy stores. For instance, DE 10 2005 004 950 A1 discloses an air conditioning system for a hybrid vehicle, in which air conditioning system the pre-air conditioning is made possible by means of an electric refrigerant compressor which is already serially present in the system and is actuated by a traction battery of the vehicle. Although systems of this type have the advantage that pre-air conditioning is possible without emissions from an internal combustion engine or a fuel-powered heating unit, the pre-air conditioning is possible only for a limited time period on account of the storage capacities of the electric stores. As soon as the charging state lies or falls below a predefined limit value, pre-air conditioning is not possible (any longer), since otherwise the operation of the motor vehicle might be jeopardized. This leads to considerable comfort sacrifices for the driver.
EP 2 117 857 B1 has already disclosed a method for pre-air conditioning of a motor vehicle at a standstill by means of a heating and/or cooling unit which draws its energy from an electric store of the vehicle, it being possible for the heating and/or cooling unit to be operated at at least two performance levels. Here, when the heating and/or cooling unit of the parked vehicle is initially activated, the heating and/or cooling unit is initially operated at a first performance level with a low energy consumption, and is switched from the first performance level to the second performance level with a higher energy consumption only when a vehicle door is unlocked or opened.
It is an object of the invention to improve the abovementioned method with regard to the energy consumption, with optimum air conditioning of the vehicle being taken into consideration.
This object is achieved by way of a method and system of the independent. Advantageous developments arise from the dependent claims.
A basic concept of the invention is that in principle an excessive amount of energy must not be used in the case of pre-air conditioning at a standstill of the vehicle (and/or when the vehicle is locked and left), in which the energy for pre-air conditioning the vehicle interior is drawn from electric stores, in order for it to continue to be possible to ensure complete functional capability of the vehicle. If, however, only weakened interior preconditioning is performed, the customer loses a large part of the preconditioning effect as a result of one or more vehicle doors being opened. The interior very rapidly feels too warm or too cold on account of the surfaces being temperature controlled to too little an extent.
Based on this, the method according to the invention for preconditioning a heating and/or cooling unit in a motor vehicle at a standstill, in which the heating and/or cooling unit draws its energy for heating and/or cooling from an electric store, is in principle configured in such a way that, when the vehicle is at a standstill, the heating and/or cooling unit is initially activated at a first performance level upon a signal of a remote starting device and is switched from the first performance level to a second performance level of the heating and/or cooling unit only depending on predefined conditions. According to the invention, the first performance level is configured in such a way that, in the case of ventilating flaps which are at least virtually closed, internal preconditioning of the air in order to reach a predefined setpoint temperature is performed by way of corresponding actuation of the heating and/or cooling unit within the heating and/or cooling circuit. In other words, only or virtually only the air within the heating and/or cooling unit is temperature controlled correspondingly at the first performance level. The complete or virtually complete closure of the ventilating flaps prevents the air which has already been temperature controlled from escaping into the vehicle interior and the heating and/or cooling unit having to start from the beginning again with the air quantity which is newly sucked in and is hardly preconditioned precisely at the beginning of the temperature control.
Here, the activation of the preconditioning of the heating and/or cooling unit by means of the remote starting device (at the first performance level) can take place in various ways. Thus, for example, the remote starting device can be part of a separate radio remote control or can be integrated into the key unit. As an alternative, the remote starting device can also be part of a software function which is integrated into a smartphone or tablet PC.
This method may be suitable, in particular, in vehicles with an electric drive, in which the electric energy for the drive is drawn from an electric store.
Furthermore, in the method according to the invention, the fan is advantageously deactivated or is operated only with low performance at the first performance level for internal preconditioning of the heating and/or cooling unit, since operation is not necessary on account of the (virtually) closed ventilating flaps. In addition, no additional energy or only a small amount of additional energy is used as a result of the deactivation of the fan or the operation of the fan with low performance.
If, during the first performance level for internal preconditioning of the heating and/or cooling unit in order to reach the predefined setpoint temperature, the setpoint temperature or a value which correlates with the setpoint temperature is reached or exceeded, the actuation of the heating and/or cooling unit can be ended or interrupted at least temporarily in one advantageous development of the invention. If, in the case of ended or interrupted actuation of the heating and/or cooling unit during the first performance level, the temperature within the heating and/or cooling unit deviates from the setpoint temperature or a value which correlates with the setpoint temperature by more than a predefined differential value, or if a defined time interval has elapsed, the actuation is advantageously activated again, with the result being that it can be ensured that there is sufficient preconditioning of the heating and/or cooling unit, and therefore rapid air conditioning of the vehicle interior upon activation of the second performance level is achieved.
A further aspect of the invention lies at the switchover time from the first performance level to the second performance level. Since the switchover time should be selected in such a way that the driver, as soon as he/she enters the vehicle, is to be given the feeling that his/her desire for pre-air conditioning of the vehicle interior has been taken into account, a switchover is then carried out from the first performance level to the second performance level in one advantageous refinement of the invention if the trunk or a vehicle door, preferably the driver's vehicle door, is unlocked or opened. Depending on the configuration of the unlocking system of the motor vehicle, unlocking of the vehicle takes place if the driver actuates a corresponding operating element of a remote control unit, if a radio unit is detected within a predefined region around the vehicle, or if the vehicle is unlocked manually by means of a key at the lock of a door or the trunk. It can be fixedly predefined whether an activation of the second performance level takes place during unlocking of the vehicle or during opening of a vehicle door or the driver's vehicle door, or takes place depending on the charging state of the electric store. In the case of a low charging state, the switchover operation from the first performance level to the second performance level may not take place until as late as possible, preferably only when the driver's door of the motor vehicle is opened.
In order for it to be possible to ensure that the driver finds or assumes an optimally temperature controlled vehicle interior when entering the vehicle, this feeling has to be imparted to the driver by way of a corresponding second performance level. The second performance level is advantageously configured in such a way that the ventilating flaps which have been at least virtually closed up to this point are opened and/or the fan performance is increased, with the result being that the air which is pre-temperature controlled within the heating and/or cooling unit exits into the vehicle interior. As a result, the driver immediately has the requested cold or warm air available at the vents, without a large amount of energy being necessary in the run-up. Viewed subjectively, the vehicle user therefore experiences a greater effect than in the case of pre-air conditioning known from the prior art, with only low energy consumption.
In order for it to be possible to ensure, furthermore, that the air is preconditioned to an optimum extent within the heating and/or cooling unit, the system according to the invention for preconditioning the heating and/or cooling unit in the motor vehicle at a standstill according to the above-described method is configured in such a way that an air return means for returning the conditioned air to the intake section of the fan is provided within the heating and/or cooling unit. Said air return means results in an at least virtually closed air circuit, through which the air can circulate during the first performance level.
It can advantageously also be ensured by way of a corresponding configuration of the system that the preconditioned air can circulate within the heating and/or cooling unit merely at the first performance level. Thus, a pressure relief valve can advantageously be provided at the inlet of the air return means, which pressure relief valve opens at a correspondingly great air pressure, with the result being that the preconditioned air can flow through the air return means to the intake section of the fan. This correspondingly high pressure is set when the ventilating flaps are at least virtually closed and therefore the path into the vehicle interior is shut off.
As an alternative, instead of the pressure relief valve, an electrically actuatable valve can also be provided at the inlet of the air return means, which valve is partially or completely open at least temporarily during the first performance level.
The method according to the invention and a possible apparatus for carrying out the method according to the invention will now be explained in greater detail in accordance with one exemplary embodiment.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.