JP5868940B2 - Method for determining the power of an electric motor of a hybrid compressor - Google Patents

Description

  The present invention relates to a method for determining the electric power of an electric motor of a hybrid compressor used in an air conditioning circuit of an automobile equipped with an engine.

  The invention can be applied particularly advantageously in the field of air conditioning in engine-driven vehicles equipped with an automatic stop and restart system, in a system capable of performing a function known as “stop and start”. Is.

  The “stop and start” function automatically stops the engine completely when the vehicle stops under certain conditions, and then automatically, for example, depending on the driver's behavior, which is interpreted as a restart request. This is a function to restart.

  A typical case for performing a “stop and start” function is when it stops with a red light. When the vehicle stops with a signal, the “stop” mode of the “stop and start” function drives an automatic stop of the engine, after which the vehicle enters the “start” mode. As a result, the engine can be automatically restarted without using a means (for example, a contact key) for initial starting of the motor. When the signal turns blue, the “start” mode is activated by the steering system with the vehicle start function, so that the driver steps on the clutch pedal, the accelerator pedal, or the driver restarts his vehicle. Upon detecting any behavior that is interpreted as having a will, the alternator starter is used to automatically restart the motor. The “stop and start” function is advantageous in terms of saving energy and reducing pollution, especially in urban areas.

  Furthermore, it is known that an air conditioning circuit of a vehicle equipped with an engine includes a cooling fluid compressor. The cooling fluid compressor is driven by the shaft of the engine crankshaft using a belt and a pulley mechanically coupled to the compressor's compression rod. That is, the vehicle air conditioning circuit can only operate when the engine is driving the compressor. Therefore, during the compressor drive interruption phase by the engine, especially during the vehicle stop phase in the “stop and start” function, the compressor is not driven by the engine and the air conditioning is deactivated. ing. Therefore, there is a possibility that the set temperature inside the vehicle interior cannot be maintained during this stop phase. As a result, the passengers of the vehicle feel uncomfortable.

  In order to ensure that the temperature in the passenger compartment is maintained during the compressor shutdown phase by the engine, a normal compressor driven by the vehicle engine is used, for example in two separate compression chambers. It has been proposed to replace a hybrid compressor having One of these hybrid compressors is called a mechanical compressor, and the compression rods of the mechanical compressor are driven by the engine in the same manner as a normal compressor. The other is called an electric compressor, and the compression rods of the electric compressor are driven by auxiliary electric motors. The compression rods in the two compression chambers are independent of each other.

  Outside of the stop phase driven by the “stop and start” function, when the engine is running, the cooling fluid circulates in the air conditioning circuit through a mechanical compressor driven by the shaft of the engine crankshaft. . At this time, the electric compressor is turned off. Conversely, during the stop phase in the “stop and start” function, the cooling fluid is directed towards the electric compressor, which is driven by an electric motor. Therefore, even when the engine is stopped, the continuous operation of the air conditioning circuit and the maintenance of a comfortable temperature in the passenger compartment are performed by the electric compressor.

  However, during the shutdown phase of the air-conditioning circuit, in particular during the engine shutdown phase imposed by the “stop and start” function, the passenger compartment is generally conditioned to comfortable conditions and therefore lasts several tens of seconds. In order to maintain this condition over time, the cooling power to be supplied by the electric motor is lower than that to be supplied by the engine, at least 1/2 to 1/3. Therefore, a compression chamber with a small capacity can be used for the electric compressor.

  As a technique for reducing the capacity, a hybrid compressor having a single variable capacity compression chamber has been proposed. This single variable volume compression chamber comprises a compression rod, which is driven by the engine in the normal operating conditions of the air conditioning circuit and by the engine's drive interruption phase (especially by the "stop and start" function). In the engine stop phase, which is driven, it is driven by an electric motor. Thereby, the capacity of the compression chamber varies between a large stroke volume and a small stroke volume. For large stroke volumes, the compression chamber is driven by the engine, and for small stroke volumes, the compression chamber is driven by an electric motor.

The operation of an automotive air conditioning circuit usually comprises a first stage called the temperature drop stage (also known as “cool-down”). This temperature decrease stage occurs when the vehicle is started when the temperature in the passenger compartment exceeds a comfortable temperature required by the passenger (for example, about 18 ° C.) because the vehicle has been stopped for a long time. During this temperature drop phase, the heat output to be supplied to reach a comfortable temperature is relatively high, with a temperature of 25 ° C. to 45 ° C. and a relative humidity of 50 under 1000 W · m ² sunshine. When exposed to% to 60% of outside air, it becomes about 6 kW.

  For air conditioning circuits, the conditions for temperature drop can be defined such that the circuit evaporator is at a set temperature between 4 ° C. and 8 ° C. when a comfortable temperature is reached. This temperature ensures that most of the moisture contained in the air blown into the passenger compartment is removed and also prevents the growth of odorous bacteria in the passenger compartment. It is a possible temperature. However, as the maximum temperature in the vicinity of the evaporator, a temperature of 12 ° C. to 16 ° C. can be allowed. The reason for this is that the vehicle passengers feel discomfort due to humidity and bacteria only when this temperature (called the air conditioning discomfort threshold) is exceeded.

  The second stage following the first temperature drop stage is characterized by the heat output to be supplied in order to maintain a comfortable temperature. The heat output to be supplied is a considerably low value (about 3 kW) as compared with about 6 kW required for maintaining the passenger compartment at a comfortable temperature.

  Under normal compressor drive conditions, the engine is responsible for maintaining the cabin temperature at a comfortable temperature.

  According to the principle of the hybrid compressor, the electric motor plays the role of maintaining the comfort conditions in the passenger compartment during the drive interruption phase of the compressor by the engine. In this case, the electric power to be supplied to the electric motor in order to maintain the heat output of 3 kW is about 1500 W.

  "Mild hybrid" and "full hybrid" equipped with a DC network of high voltage (60V to 150V for "mild hybrid" vehicles, 500V to 600V for "full hybrid" vehicles) In the case where 1500 W of electric power is supplied to the electric motor of the hybrid compressor for the hybrid vehicle belonging to No. 1, no problem occurs. The problem is in the case of a vehicle belonging to a “micro hybrid” equipped with an engine and an alternator starter in order to perform a “stop and start” function. The vehicle in this case only has a 12V low voltage network. The required current strength is too high, and in a vehicle-mounted network, the necessary maintenance power may not be supplied to the electric motor. Under such a condition, the same comfort level cannot be maintained during the compressor suspension by the engine as compared with the stage during which the engine maintains the comfortable temperature.

  The object of the invention is a method for determining the electric power of an electric motor adapted to drive a hybrid compressor of an air conditioning circuit during the suspension of the drive of the hybrid compressor by the engine of a motor vehicle equipped with an engine. Is to provide. According to the present invention, even in a vehicle belonging to a “microhybrid” having only a low voltage network for supplying electric power to the electric motor of the hybrid compressor, the vehicle interior of the vehicle is interrupted during the drive interruption phase by the engine. Can maintain a comfortable level.

That is, the method of determining the electric power of the motor for driving the hybrid compressor of the air conditioning circuit of the automobile equipped with the engine during the stage in which the driving of the hybrid compressor by the engine is interrupted. ,
- a step of provisions the maximum temperature measured at one location of the air conditioning circuit,
- setting a reference duration for interruption phases of the drive of the hybrid compressor according to the engine,
- at the end of the reference duration, the temperature in which the measured at one location of the air-conditioning circuit, to be equal to or less than the said maximum temperature, and a step of determining the power of the electric motor,
The maximum temperature is measured at a location where heat exchange is performed between the cooling fluid circulating in the air conditioning circuit and the air blowing toward the passenger compartment of the automobile, and the maximum temperature is set as an air conditioning discomfort threshold. It is characterized by that.

In practice, in the present invention, the maximum temperature measured at the evaporator of the air conditioning circuit.

  The reference duration is a duration that coincides with the duration observed for the engine drive interruption phase. This reference duration is, for example, 35 seconds.

  Therefore, the electric motor power determined by the method according to the invention is the power that is considered necessary to maintain the evaporator temperature between 4 ° C. and 8 ° C. (as mentioned before, on the order of 1500 W). It can be seen that it can be significantly lower than If the temperature measured at the evaporator reaches the air conditioning discomfort threshold of, for example, 12 ° C. to 16 ° C. at the end of the 35 second reference duration, 500 W to 800 W It is sufficient to use a low power motor, which can be supplied directly by the vehicle's 12V low voltage network.

  In the present invention, the ratio of the electric motor power to the power required to keep the temperature at the location of the air conditioning circuit equal to the temperature at the start of the engine interruption phase is 0.2-0. .8, and more specifically, 0.3 to 0.55.

  In a first application example of the method of the present invention, the interruption of the drive is an engine stop. More specifically, the engine stop is an automatic stop of the vehicle engine and an automatic stop determined by a restart function (“stop and start”).

  In a second application of the method according to the invention, the interruption of the drive is a disconnection of the engine from the hybrid compressor as determined by the vehicle acceleration demand.

  The invention and its embodiments will become apparent from the following description of the accompanying drawings. This description is a non-limiting example.

1 is an air conditioning circuit comprising a hybrid compressor having two compression chambers. FIG. 1 is a diagram of an air conditioning circuit comprising a hybrid compressor having a single compression chamber. FIG. FIG. 4 is a diagram showing temperature changes at the evaporator of an air conditioning circuit having a hybrid compressor for various stages of operation of the compressor.

FIG. 1 shows a typical air conditioning circuit of a motor vehicle driven by an engine. The air conditioning circuit includes a cooling fluid compressor 10, which is an organic fluid, an inorganic fluid, or a eutectic fluid. As a non-limiting example, mention may be made of supercritical carbon dioxide CO ₂ or R134A,, known refrigerant as 1234yf or GAR, (Global Alternative Refrigerant). The pressurized cooling fluid passes through the heat exchanger 11 toward the downstream of the compressor 10. The heat exchanger 11 is called a “gas cooler” for carbon dioxide. For R134A, it is called a “condenser”. The reason is that in this case, the refrigerant initially in the gas phase exits the condenser in liquid phase.

  In the example shown in FIG. 1, the heat exchanger 11 is a water-type heat exchanger or an air-type heat exchanger that is directly cooled by external air.

  Thereafter, the cooling fluid is directed towards the pressure reducing valve 12, and the cooling fluid is cooled before entering the evaporator 13. In the evaporator 13, heat exchange is performed between the cooled refrigerant and the air blown toward the vehicle interior of the vehicle.

  The cooling fluid that is reheated and exits the evaporator 13 then returns to the compressor 10 to perform a new thermal cycle.

  As can be seen from FIG. 1, the compressor 10 is a hybrid compressor having two separate compression chambers (ie, a first compression chamber 101 and a second compression chamber 102). The first compression chamber 101 includes a first compression rod 111, which is driven by a crankshaft shaft of a vehicle engine (not shown) via a belt and a pulley 30. Is done. The pulley 30 is mechanically coupled to the compression rod 111 by a clutch 31. The second compression chamber 102 includes a second compression rod 112. The second compression rod 112 can be driven by the electric motor 20 separately from the first compression rod 111.

During normal operation of the air conditioning circuit, the compression rod 111 of the first compression chamber 101 is driven by the engine, and the pulley 30 is coupled to the compression rod 111 by a clutch 31. Thus, the cooling fluid circulates through the first compression chamber 111 and the volume of the first compression chamber (on the order of 100 cm ³ ) is hybrid regardless of the temperature outside the vehicle cabin, sunlight, and relative humidity. The compressor 10 is selected so that the interior of the vehicle interior can be maintained at an optimal comfort level.

  However, in some circumstances, the air conditioning compressor 10 is not already driven by the vehicle engine, and therefore the air conditioning circuit may cease to operate and the maintenance of a comfortable temperature inside the vehicle interior may not be guaranteed. obtain. This is especially the case when the vehicle is in the engine stop phase as determined by the automatic engine stop and restart system. This stop is performed by an automatic engine stop and restart system on a vehicle equipped with a “stop and start” function.

  In order to ensure continuous air conditioning in the passenger compartment, the circulation of the cooling fluid is switched from the first compression chamber 101 to the second compression chamber 102 by a valve device inside the hybrid compressor 10. The electric motor 20 starts operation and drives the second compression rod 112 to keep the air conditioning circuit in operation during this stop phase.

  When the electric motor 20 operates taking over the stopped engine, in principle, the vehicle compartment is already at a comfortable temperature. Therefore, considering the fact that the duration of the stop phase is generally limited to a few tens of seconds, the cooling power to be supplied by the electric motor 20 can be relatively low.

Therefore, the capacity of the second compression chamber 102 may be a limited value as compared with the capacity of the first compression chamber 101, for example, about 20 cm ³ .

  FIG. 2 shows another type of hybrid compressor 10 '. The hybrid compressor 10 ′ includes a variable capacity compression chamber 100. The compression rod 110 of the variable displacement compression chamber 100 can be driven by the electric motor 20 or the shaft of the crankshaft of a vehicle engine (not shown). This driving is performed via a belt and a pulley 30. Pulley 30 can be mechanically coupled to compression rod 110 by clutch 31.

  Here, it is necessary to emphasize the following. That is, the hybrid air-conditioning compressor has a single compression chamber and only a single compression rod, unlike two separate compression chambers with independent compression rods, as shown in FIG. It is of a different type from the compressor. However, the compression rod is driven by an engine or an electric motor, and in either case, it can operate well.

During normal operation, the compression rod 110 of the compression chamber 100 is driven by the engine and the pulley 30 is coupled to the compression rod 110 by a clutch 31. Therefore, the capacity of the compression chamber is a large stroke volume value (for example, 90 cm ^{3 to} 110 cm ³ ) close to the maximum capacity. Under this condition, the hybrid compressor 10 ′ can maintain an optimal comfort level inside the vehicle compartment regardless of the external temperature, sunshine, and relative humidity.

  As with the hybrid compressor 10 having two compression chambers shown in FIG. 1, during the engine shutdown phase determined by the “stop and start” type automatic stop and restart function, the air conditioning compressor 10 ′ It is not already driven by the vehicle engine. Therefore, the air conditioning circuit stops operating, and it is not guaranteed that the comfortable temperature inside the vehicle interior is maintained.

  Under this condition, the electric motor 20 is in an operating state, and the electric motor 20 drives the compression rod 110 to perform continuous air conditioning. That is, it can be considered that the function of driving the compression chamber 100 is replaced by an electric motor from the engine. Needless to say, the engine is preferably disconnected from the compression rod 110.

As already mentioned above, the cooling power to be supplied by the electric motor 20 during operation is relatively low, so the capacity of the compression chamber 100 is reduced to a small stroke volume value compared to normal operating conditions. Can be made. This value is the minimum capacity and approximately equal, for example, be between 20cm ³ ~40cm ^3.

  It goes without saying that a large stroke volume and a small stroke volume are simply a maximum capacity and a minimum capacity.

  The compression chamber 100 is switched in binary form between these two capacities depending on whether the drive to the compression rod of the compression chamber is an engine or an electric motor.

  FIG. 3 shows three typical values of temperature change measured at the evaporator 13 in an air conditioning circuit with a hybrid compressor. This hybrid compressor may be the compressor 10 having the two compression chambers shown in FIG. 1 or the compressor 10 'having the single compression chamber shown in FIG.

The first stage is the temperature drop stage (or “cool-down”), which is generally the stage immediately after the vehicle that has been stopped for a long time starts moving. Since the vehicle has been stopped for a long time, the temperature of the evaporator 13 in the passenger compartment has reached a relatively high value T _ext (25 ° C. to 45 ° C.), which is generally about 18 ° C. It is higher than the comfortable temperature.

  This temperature lowering step is performed by driving the first compression chamber 101 of the hybrid compressor 10 shown in FIG. 1 or the single compression chamber 100 of the hybrid compressor 10 ′ shown in FIG. 2 by a vehicle engine. Is done. The capacity of the compression chamber 100 is a large stroke volume.

Parameters relating to the air conditioning circuit can be set so that the interior of the passenger compartment is at a comfortable temperature. This comfortable temperature is generated by a certain kind of bacteria when the set temperature T _cons of the evaporator 13 is between 4 ° C. and 8 ° C., and the humidity of the air introduced into the passenger compartment is removed. It is a temperature that can prevent malodors. The maximum acceptable temperature T _max at the evaporator 13 may be equal to the air conditioning discomfort threshold (about 12 ° C. to 16 ° C.). Beyond this value, the odor produced by the bacteria is uncomfortable for the passengers of the vehicle.

  As described above, in the temperature lowering stage, a heat output of about 6 kW needs to be generated by the engine.

When the temperature of the evaporator 13 reaches the desired set temperature T _cons , the air conditioning circuit enters a second stage called maintaining comfortable temperature.

  Under normal operating conditions, this maintenance phase is guaranteed by the engine. It goes without saying that the heat output to be delivered is lower (approximately 3 kW, not 6 kW) than in the temperature drop phase.

On the other hand, at the stage of stopping the compressor driven by the engine, in particular at the stop stage determined by the “stop and start” function, or at the stage of disconnecting the motor from the compressor after the vehicle acceleration request, the electric motor 20 However, it must ensure that comfort is maintained inside the vehicle. In order to supply the necessary heat output of 3 kW, electric power W _{0 of} about 1500 W is required.

  As explained above, supplying this amount of power is difficult for a “micro hybrid” vehicle having an engine and an alternator starter. This is because a “micro hybrid” vehicle has only a 12V low voltage electrical network.

  Accordingly, the present invention proposes a method for determining the power of the electric motor 20 that is also suitable for a 12V in-vehicle network. Moreover, the method of the invention guarantees sufficient comfort for the passengers of the vehicle during the possible stopping phase (generally a short period of time).

As shown in FIG. 3, the maximum temperature _{Tmax at} a certain point of the air conditioning circuit (here, the temperature measured at the evaporator 13 of the air conditioning circuit is set to 12 ° C. to 16 ° C.). Thereafter, a reference duration t _ref is determined for the stage of interruption of driving by the engine. The duration t _ref can be obtained as an average value of durations observed for the interruption stage (for example, 35 seconds).

Next, the electric power W _elec of the electric motor 20 is determined such that the temperature measured at the evaporator 13 is equal to or lower than the maximum temperature T _max at the end of the reference duration t _ref . In the example shown in FIG. 3, the temperature of the evaporator is set equal to the temperature T _max .

Under these conditions, the power W _elec, for example, can be reduced to a value between 500W～800W. This value is compatible with the 12V voltage of the low-voltage vehicle-mounted network in the intended type of vehicle, and can prevent the generation of malodor that can occur at high temperatures.

For a power W ₀ value of 1500 W to be supplied to maintain the evaporator 13 at the set temperature T _cons , the power determined by the method of the present invention is approximately 0.2-0.8, and preferably , Between 0.3 and 0.55.

  Furthermore, it should be pointed out that the method according to the invention for determining the electric power of an electric motor of a hybrid compressor is also applicable to “mild hybrid” vehicles and “full hybrid” vehicles. There is. The reason is that the reduction of the electrical energy to be supplied by the in-vehicle network is an advantage that cannot be ignored for these vehicles.

10, 10 'hybrid compressor 11 heat exchanger 12 pressure reducing valve 13 evaporator 20 electric motor 30 pulley 31 clutch 40 battery 100 variable capacity compression chamber 101 first compression chamber 102 second compression chamber 110 compression rod 111 first Compression rod 112 second compression rod

Claims (9)

Hybrid compressor of the air conditioning circuit of a motor vehicle equipped with an engine (10, 10 '), during the stage of driving of the hybrid compressor according to the engine is interrupted, the power of the motor (20) for driving (W _elec ), a method for determining
- a step of defining the maximum temperature _{(T max)} measured at one location (13) in the air conditioning circuit,
-Setting a reference duration (t _ref ) for the interruption phase of driving of the hybrid compressor (10, 10 ') by the engine;
- At the end of the reference duration _{(t ref),} the temperature of the measured at one location (13) of the air-conditioning circuit, the maximum temperature _{(T max)} such that below the electric motor (20) Determining power (W _elec ) ,
The maximum temperature (T _max ) is measured at a point (13) where heat is exchanged between the cooling fluid circulating in the air conditioning circuit and the air blowing toward the passenger compartment of the automobile, and the maximum temperature A method characterized in that the temperature (T _max ) is used as an air conditioning discomfort threshold . 2. Method according to claim 1, characterized in that the maximum temperature ( _Tmax ) is measured in an evaporator (13) of the air conditioning circuit. The temperature in the evaporator (13) before Symbol air conditioning circuit, in order to maintain to be equal to the temperature (T _cons) at the start of the interruption phases of the drive by the engine, the electric power the electric motor requires (W The method according to claim 1 or 2 , characterized in that the ratio of the electric power (W _elec ) of the electric motor (20 ) to ₀ ) is between 0.2 and 0.8. 4. The method of claim 3 , wherein the ratio is between 0.3 and 0.55. Said hybrid compressor (10) includes a first compression chamber can be driven (101) by the engine, during the interruption phase of the drive of the hybrid compressor (10) by the engine, by the electric motor (20) characterized in that it comprises a drivable second compression chamber (102), the method according to any one of claims 1-4. The hybrid compressor (10 ') comprises a variable displacement compression chamber (100), which has a large stroke volume , can be driven by the engine, and is a hybrid compressor with the engine. between the interruption phases of the drive (10 '), smaller in stroke volume, characterized in that the drivable by an electric motor (20), the method according to any one of claims 1-4 . Interruption of the drive, characterized in that due to stop of the engine, the method according to any one of claims 1-6. Stop of the engine is characterized in that according to the automatic stop determined by the function of the automatic stop us and restarting of the vehicle engine ( "stop and start"), The method of claim 7. Interruption of the drive is determined by the vehicle acceleration request, characterized in that by disconnecting from the hybrid compressor of said engine (10, 10 '), the method according to any one of claims 1 to 6 .

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