AIR CONDITIONING SYSTEM FOR A MOTOR VEHICLE

Abstract

A system includes a casing configured to allow air to flow towards a vehicle interior or cabin. An air treatment cavity contains a heater core of a cooling circuit. A control unit is provided which is configured to control the temperature of the air. An interface device provides the control unit with a required temperature command. An actuator is configured to adjust, in a controlled way by the control unit, the opening of a flow control valve situated upstream of the heater core. The system further includes a temperature sensor configured to detect temperature data representative of the temperature reached by the air flowing into the air treatment cavity downstream of the heater core. The control unit is also configured to control the actuator also as a function of the temperature data as a function of the temperature command.

Claims

1. A HVAC system for a vehicle equipped with an engine; said system comprising: a casing having an inlet opening configured to receive air, an outlet opening configured to allow air to flow towards the vehicle interior or cabin, and an air treatment cavity situated between said inlet opening and said outlet opening and through which an air flow can pass; a heater core of a cooling circuit associated with said engine being contained in said air treatment cavity; a control unit configured to control a temperature of the air flow flowing through said heater core and exiting from said outlet opening; an interface device manually operable by a user to provide as an input a required temperature command to the control unit representative of a desired temperature to be reached by the air flow exiting from the outlet opening; an actuator configured to adjust, in a controlled way by said control unit, opening of a flow control valve situated upstream of said heater core and configured to control a flow rate of cooling water flowing to said heater core as a function of said required temperature command received from said interface device a temperature sensor configured to detect actual temperature data representative of the temperature reached by the air flowing into said air treatment cavity downstream of said heater core; and wherein, as a function of said requested temperature command, the control unit is configured to control said actuator as a function of said actual temperature data detected by said temperature sensor; and wherein said control unit is configured to: calculate a temperature difference between said requested temperature command and said actual temperature data; determine an optimized operative position of said flow control valve as a function of said temperature difference; and control said actuator in such a way as to bring said flow control valve into said optimized operative position.

2. The system according to claim 1, wherein said predefined operative position is determined based on a tabular logic.

3. The system according to claim 2, wherein memory means are associated with and/or related to the control unit which store a table containing: a plurality of temperature difference ranges and a respective plurality of predetermined operative positions, wherein each predetermined operative positions is related to a corresponding temperature difference range.

4. The system according to claim 3, wherein said control unit is configured to select the predetermined operative position corresponding to the temperature difference range in which said temperature difference is comprised as the optimized operative position.

5. The system according to claim 1, wherein said temperature sensor is situated in the air treatment cavity next to the outer surface of said heater core.

6. The system according to claim 1, wherein said temperature sensor is a thermistor.

7. The system according to claim 6, wherein said thermistor is of the comprises a negative temperature coefficient (NTC) thermistor.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] FIG. 1 is a block diagram of an HVAC system for a motor vehicle, the system being provided according to an exemplary embodiment of the present invention.

[0018] FIG. 2 represents a non-limiting example of a table by means of which a control unit of the system shown in FIG. 1 can operate.

[0019] For the sake of completeness, the following is a list of the alphanumeric references used to identify parts, elements and components illustrated in the drawings summarised above. [0020] V. Vehicle [0021] E. Engine [0022] T.sub.R Requested temperature command [0023] T.sub.A. Actual temperature data [0024] ΔT. Temperature difference [0025] ΔT.sub.MIN,i, ΔT.sub.MAX,i. Temperature difference range [0026] p*. Optimized operative position [0027] p.sub.i. Predetermined operative position [0028] 10. HVAC system [0029] 12. Casing [0030] 14. Inlet opening [0031] 16. Outlet opening [0032] 18. Air treatment cavity [0033] 20. Fan [0034] 22. Control unit [0035] 24. Interface device [0036] 26. Actuator [0037] 28. Temperature sensor [0038] 100. Refrigeration circuit [0039] 102. Compressor [0040] 104. Condenser [0041] 106. Expansion valve [0042] 108. Evaporator [0043] 200. Cooling circuit [0044] 202. Pump [0045] 204. Thermostat [0046] 206. Radiator [0047] 208. Heater core [0048] 210. Flow control valve

DETAILED DESCRIPTION OF THE INVENTION

[0049] With reference to FIG. 1, reference number 10 generally indicates an HVAC system for a vehicle V equipped with an engine E, in particular an internal combustion engine. System 10 is provided according to a purely exemplary embodiment of the present invention.

[0050] In particular but not exclusively, system 10 can be applied to the agricultural vehicle field, for example to a tractor, the special vehicle field, and the off-road vehicle field.

[0051] System 10 cooperates with a cooling circuit 200 intended for cooling engine E and belonging to vehicle V. In particular, system 10 also cooperates with a refrigeration circuit 100, also belonging to vehicle V.

[0052] In the illustrated embodiment, refrigeration circuit 100 comprises a compressor 102 which is mechanically driven by engine E and configured to make a coolant fluid circulate. Refrigeration circuit 100 further comprises a condenser 104, an expansion valve 106 and an evaporator 108.

[0053] In the illustrated embodiment, cooling circuit 200 provides a circulation of cooling water (e.g. a mixture of water and a product with antifreeze properties) which is in heat exchange with engine E (e.g. with the liners of the combustion chambers of engine E). Circulation through cooling circuit 200 is preferably provided by a pump 202. Cooling circuit 200 further comprises a thermostat 204 configured to receive the cooling water exiting the engine E and to distribute the cooling water flow between a radiator 206 and a heater core 208. Between thermostat 204 and heater core 208, a flow control valve 210 is provided which is configured to control the flow rate of cooling water flowing to the heater core 208. Moreover, pump 202 is configured to receive inlet water from radiator 206 and heater core 208.

[0054] System 10 comprises a casing 12 having an inlet opening 14 configured to receive air and an outlet opening 16 configured to allow air to flow towards the vehicle interior or cabin. Furthermore, the casing comprises an air treatment cavity 18 situated between inlet opening 14 and outlet opening 16. An air flow from inlet opening 14 and directed to outlet opening 16 towards vehicle interior or cabin V can pass through air treatment cavity 18.

[0055] In the illustrated embodiment, system 10 further comprises a fan 20, for example, controlled by an electric motor. Fan 20 is configured to generate the air flow through air treatment cavity 18 from inlet opening 14 to outlet opening 16.

[0056] In the illustrated embodiment, air treatment cavity 18 contains heater core 208 of engine cooling circuit 200 of HVAC system 10 and, in particular, evaporator 108 of refrigeration circuit 100 of HVAC system 10. In accordance with methods and principles per se known, evaporator 108 is configured to cool the air flow, while heater core 208 is configured to heat the air flow through air treatment cavity 18 from inlet opening 14 to outlet opening 16.

[0057] System 10 further comprises a control unit 22. In particular, control unit 22 is configured to control the temperature of the air flow flowing through heater core 208 and exiting outlet opening 16.

[0058] System 10 comprises an interface device 24, for example a knob, configured to be manually operated by the user. Interface device 24 therefore provides at the inlet of control unit 22 with a requested temperature command T.sub.R associated with the desired temperature to be reached by the air flow exiting from outlet opening 16. For example, the angular position of the knob can be assigned a temperature value to be reached—by means of control unit 22—by the air flow and corresponding to requested temperature command T.sub.R.

[0059] System 10 comprises an actuator 26 configured to adjust the opening of flow control valve 210 in a way controlled by said control unit 22. For example, actuator 26 is a stepper-type actuator.

[0060] As will be further described more in details, control unit 22 controls actuator 26 as a function of the requested temperature command T.sub.R received by interface device 24.

[0061] System 10 comprises a temperature sensor 28 configured to detect actual temperature data T.sub.A representative of the temperature reached by the air flowing into said air treatment cavity 18 downstream of heater core 208. In particular, temperature sensor 28 is situated next to the outer surface of heater core 208. In the illustrated embodiment, temperature sensor 28 is situated in air treatment cavity 18 between heater core 208 and outlet opening 16.

[0062] As will be further described below, besides as a function of requested temperature command T.sub.R, control unit 22 is also configured to control actuator 26 as a function of actual temperature data T.sub.A detected by temperature sensor 28.

[0063] Preferably, temperature sensor 28 is a thermistor, for example, of the negative temperature coefficient or NTC type.

[0064] The control mode implemented by control unit 22 will now be described in detail.

[0065] Control unit 22 is configured to calculate a temperature difference ΔT between requested temperature command T.sub.R and actual temperature data T.sub.A. In particular, the temperature difference is obtained through ΔT=T.sub.R−T.sub.A formula.

[0066] Then, control unit 22 determines an optimized operative position p* of flow control valve 210 as a function of the previously calculated temperature difference ΔT.

[0067] Furthermore, control unit 22 controls actuator 26 in such a way as to bring the flow control valve 210 into optimized operative position p* determined by such control unit 22. Preferably, optimized operative position .sub.P* is determined based on a tabular logic.

[0068] In particular, memory means are associated with and/or related to control unit 22 which store a table containing [0069] a plurality of temperature difference ranges ΔT.sub.MIN,1, ΔT.sub.MAX,1; . . . ; ΔT.sub.MIN,i, ΔT.sub.MAX,i; . . . ; ΔT.sub.MIN,n, ΔT.sub.MAX,n; and [0070] a respective plurality of predetermined operative positions p.sub.1; . . . ; p.sub.i; . . . ; p.sub.n, wherein each predetermined operative position pi is related to a corresponding temperature difference range ΔT.sub.MIN,i, ΔT.sub.MAX,i.

[0071] Each of the n temperature difference ranges is defined by a respective temperature difference minimum value ΔT.sub.MIN,i and a respective temperature difference maximum value ΔT.sub.MAX,i, wherein the i index can vary between 1 and n.

[0072] Preferably, control unit 22 is configured to select the predetermined operative position p.sub.i corresponding to the temperature difference range ΔT.sub.MIN,i, ΔT.sub.MAX,i in which temperature difference ΔT is comprised as optimized operative position p*.

[0073] In FIG. 2, an example of a table drawn as previously described is represented. In said table, requested temperature command T.sub.R and actual temperature data T.sub.A (and therefore relevant temperature difference ΔT) are defined by sizes or measurements expressed in Celsius degrees (° C.). On the other hand, predetermined operative positions p.sub.1; . . . ; p.sub.i; . . . ; p.sub.n, are expressed in terms of the percentage of opening of associated flow control valve 210.

[0074] Below, a non-limiting example of control unit 22 operation is provided.

[0075] Consider a user handling the knob of interface device 24 in such a way as to provide control unit 22 with a requested temperature command T.sub.R input equal to 22° C. and a temperature sensor 28 detecting actual temperature data T.sub.A equal to 19° C. Control unit 22 calculates temperature difference ΔT (calculated as T.sub.R−T.sub.A) equal to 3° C. Based on the table illustrated in FIG. 2, the predetermined operative position equal to 41% of opening of flow control valve 210 is selected by control unit 22 as optimized operative position p*. Consequently, control unit 22 controls actuator 26 so that it brings flow control valve 210 into the above-mentioned predetermined operative position equal to 41% of opening.

[0076] Naturally, without prejudice to the principle of the invention, the embodiments and implementation details may be widely varied with respect to what is described and illustrated purely by way of non-limiting example, without thereby departing from the scope of the invention as defined in the appended claims.