Cooling system of electric vehicle

• US 8,909,398 B2
• Filed: 10/27/2010
• Issued: 12/09/2014
• Est. Priority Date: 10/29/2009
• Status: Active Grant

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Sawada, Itsuro, Osaka, Tadashi, Yokoyama, Atsushi, Nasu, Shingo, Imanishi, Yuto, Sekiya, Sachio
• Primary Examiner(s): Cheung, Calvin
• Assistant Examiner(s): MARTINEZ BORRERO, LUIS A
• Application Number:
  US12/912,986
• Publication Number:
  US 20110106358A1
• Time in Patent Office: 1,504 Days
• Field of Search: 701/29, 701/22, 701/31.7, 701/102, 180/65.275, 180/287, 180/65.31, 180/65.4, 180/65.2, 180/65.1, 165/202, 165/205, 165/200
• US Class Current: 701/22
• CPC Class Codes: B60K 11/02 with liquid cooling
• CPC Class Codes: B60L 2200/26 Rail vehicles
• CPC Class Codes: B60L 2240/425 Temperature
• CPC Class Codes: B60L 2240/525 Temperature of converter or components thereof
• CPC Class Codes: Y02T 10/64 Electric machine technologies in electromobility
• CPC Class Codes: Y02T 10/72 Electric energy management in electromobility

Abstract

A cooling system of an electric vehicle includes a cooling medium circulation path that circulates a cooling medium to an electrically powered drive unit of a vehicle, a heat exchange unit between the cooling medium and external air, a cooling medium circulation unit, a blower unit that blows air against the heat exchange unit, and a control unit that controls the cooling medium circulation unit and the blower unit, thus controlling cooling of the electrically powered drive unit. The control unit controls the cooling medium circulation unit and the blower unit in a first cooling mode, when a drive force for the vehicle is in a first operational region, and controls in a second cooling mode that provides a higher cooling capability than the first cooling mode, when the drive force for the vehicle is in a second operational region that is higher than the first operational region.

Claims

1. A cooling system of an electric vehicle, comprising:

a cooling medium circulation path in which a cooling medium is circulated to an electrically powered drive unit that drives a vehicle by electrical power;

a heat exchange unit that performs exchange of heat between the cooling medium and external air;

a cooling medium circulation unit that circulates the cooling medium along the cooling medium circulation path between the heat exchange unit and the electrically powered drive unit;

a blower unit that blows air against the heat exchange unit; and

a control unit that controls the cooling medium circulation unit and the blower unit, thus controlling cooling of the electrically powered drive, wherein

the control unit;

when a drive force for the vehicle provided by the electrically powered drive unit is in a first operational region, controls the cooling medium circulation unit and the blower unit in a first cooling mode; and

, when the drive force for the vehicle provided by the electrically powered drive unit is in a second operational region that is higher than the first operational region, controls the cooling medium circulation unit and the blower unit in a second cooling mode that provides a higher cooling capability than that provided in the first cooling mode, and

the control unit obtains a target temperature for the electrically powered drive unit at which a sum of loss generated by the electrically powered drive unit for obtaining drive force for the vehicle, and electrical power consumed by the cooling medium circulation unit and the blower unit for cooling generated heat accompanying the loss, becomes a minimum, and controls the cooling medium circulation unit and the blower unit so that a temperature of the electrically powered drive unit attains the target temperature.

2. A cooling system of an electric vehicle according to claim 1, wherein:

when the drive force for the vehicle is generated continuously in the first operational region by the electrically powered drive unit, a cooling capability in the first cooling mode is a cooling capability that maintains a temperature of the electrically powered drive unit less than or equal to an upper limit temperature; and

, when drive force for the vehicle is generated for a short time period in the second operational region by the electrically powered drive unit, a cooling capability in the second cooling mode is a cooling capability that maintains a temperature of the electrically powered drive unit less than or equal to the upper limit temperature.

3. A cooling system of an electric vehicle according to claim 1, further comprising a temperature detection unit that detects an external air temperature;

and wherein the control unit makes the first operational region narrower and makes the second operational region wider, the higher is the external air temperature detected by the temperature detection unit.

4. A cooling system of an electric vehicle according to claim 1, further comprising:

an identification unit that identifies a driver of the vehicle; and

a storage unit that stores driving history for each driver; and

wherein

the control unit determines a driving tendency of the driver by reading out the driving history of the driver from the storage unit, and changes boundary between the first operational region and the second operational region according to the driving tendency of this determination results.

5. A cooling system of an electric vehicle according to claim 1, wherein the heat exchange unit includes another cooling medium circulation path different from the cooling medium circulation path, and comprises, in this another cooling medium circulation path:

a compressor that compresses another cooling medium;

a condenser that condenses the another cooling medium after compression with dissipating heat therefrom to external air;

an expansion valve that lowers a pressure of the another cooling medium after condensation; and

an evaporator that vaporizes the another cooling medium and absorbs heat from the cooling medium upon the cooling medium circulation path.

6. A cooling system of an electric vehicle according to claim 1, wherein the electrically powered drive unit comprises an electric motor that drives the vehicle to travel and an electrical power converter that drives the electric motor, and the electrical power converter is provided on an upstream side of the cooling medium circulation path while the electric motor is provided on a downstream side thereof.

7. A cooling system of an electric vehicle according to claim 1, further comprising:

a vehicle speed detection unit that detects the speed of the vehicle; and

an accelerator pedal depression amount detection unit that detects an accelerator pedal depression amount, wherein

the control unit obtains the drive force for the vehicle based on a speed detected by the vehicle speed detection unit and on the accelerator pedal depression amount detected by the accelerator pedal depression unit, and selects the first cooling mode or the second cooling mode according to whether an operating point of torque and rotational speed of the electrically powered drive unit corresponding to the drive force for the vehicle lies in the first operational region or the second operational region.

8. A cooling system of an electric vehicle according to claim 7, further comprising:

a path search unit that searches for a path to a destination;

a current position detection unit that detects a current position of the vehicle;

an acquisition unit that acquires a road information; and

a forecasting unit that forecasts operating point of the electrically powered drive unit upon a road of the path based on the road information for the path; and

wherein

the control unit changes over from the first cooling mode to the second cooling mode even if the operating point of the electrically powered drive unit at the current position is in the first operational region if, based on results of forecasting by the forecasting unit, there is a road within a predetermined distance forward of the current position for which the second operational region will be applied.

9. A cooling system of an electric vehicle according to claim 7, further comprising:

a changeover control member for a human being manually to change over between the first cooling mode and the second cooling mode; and

wherein the control unit changes over from the first cooling mode to the second cooling mode even if the operating point of the electrically powered drive unit is in the first operational region if the second cooling mode has been selected by the changeover control member.