JP2011097706A - Motor cooling controller for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To control an amount of cooling of a motor by predicting heat generation in a heat source which exerts a thermal effect on the motor. <P>SOLUTION: A motor cooling controller for vehicle is equipped with in-wheel motors each provided at right and left wheels, and an engine that exerts the thermal effect on the in-wheel motors. The motor cooling controller for vehicle includes: a temperature rise predicting (step S1) means which predicts an increase in heating value of the engine; and a cooling amount increasing means (steps S2 and S3) which increases an amount of cooling to the in-wheel motors before the temperature of the in-wheel motors rises when an increase in the heating value of the engine is predicted by the temperature rise predicting means (step S1). The controller improves the cooling performance before the temperature of the in-wheel motor rises, thereby preventing or suppressing excessive rise in temperature of the in-wheel motors or the restriction on output torque due to temperature. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a vehicle including an electric motor as a driving force source for traveling, and more particularly to an apparatus for controlling cooling of the electric motor.

  In order to improve vehicle fuel efficiency or suppress greenhouse gas emissions, electric motors have come to be used as a driving force source for vehicles. As this type of vehicle, a hybrid vehicle, an electric vehicle, or a wheel is used. An in-wheel motor vehicle provided with an electric motor is known. When the temperature of these electric motors rises, output suppression control may be activated and desired torque may not be output. Therefore, a cooling device and a control device that suppress the temperature rise of the electric motor have been developed, and the device described in Patent Document 1 cools the traction motor by removing heat generated when the load of the traction motor increases. An apparatus is described. This device cools using the lubricating oil of the traction motor, and includes a drive motor for the lubricating oil pump. And the apparatus described in patent document 1 is comprised so that a traction motor may be cooled by changing the rotation speed of the drive motor of lubricating oil according to the load of a traction motor.

  In addition, the temperature of the switching elements and regulators of the inverter electrically connected to the motor is detected, and if any of those temperatures rises to an allowable temperature, the motor is cut off and the temperature rises further. A control device to be suppressed is described in Patent Document 2. Further, in a vehicle equipped with a navigation system, Patent Document 3 discloses a temperature rise prediction device that detects a travel route from a current location to a destination and predicts a rise temperature of a drive motor from a travel route situation such as a gradient of the travel route. It is described in.

JP 2008-179189 A JP 2002-191190 A JP 2007-183205 A

  The cooling device described in Patent Document 1 described above cools the traction motor by changing the rotational speed of the drive motor of the lubricating oil pump in accordance with the load of the motor. However, the temperature increase of the traction motor may increase due to the influence of heat from outside the motor in addition to the heat generated from the traction motor itself. Therefore, in terms of controlling the temperature by cooling the motor so that it always operates at the desired performance, there is room for improvement to perform cooling in consideration of the influence of heat other than the motor.

  Further, the control device described in Patent Document 2 is a control device that cuts off power to the motor when the temperature of a controller such as an inverter switching element or a regulator reaches an allowable temperature, and prevents further temperature increase. Furthermore, the device described in Patent Document 3 is a device that predicts the temperature rise of the motor from the travel path to the destination, but does not consider the cooling performance of the motor, and the motor operates normally. There is still room for improvement in terms of temperature management so that the performance can be output at all times.

  The present invention has been made against the background described above, and prevents or suppresses an increase in the temperature of the motor by predicting the heat generation at the heat source that affects the motor and controlling the cooling amount of the motor. It is an object of the present invention to provide an electric motor cooling control apparatus for a vehicle that can perform such a process.

  In order to achieve the above object, the invention of claim 1 is directed to an electric motor cooling control apparatus for a vehicle, comprising: an electric motor that outputs power for running; and a heat generation source that heats the electric motor. A temperature rise prediction means for predicting an increase in the heat generation amount of the source, and a cooling amount for the motor before the temperature of the motor rises when an increase in the heat generation amount of the heat generation source is predicted by the temperature rise prediction means. And a cooling amount increasing means for increasing.

  The invention of claim 2 further comprises an oil pump for supplying cooling oil to the electric motor according to the invention of claim 1, wherein the electric motor is provided for each wheel of the vehicle and each wheel is provided. An in-wheel motor that is driven individually, and the heat generation source includes at least one of an internal combustion engine mounted on the vehicle and an inverter that controls the in-wheel motor, and the temperature rise prediction means is provided for the vehicle. Means for predicting an increase in the heat generation amount of the heat source based on an output increase request, and the cooling amount increase means includes means for increasing the supply amount of lubricating oil to the in-wheel motor by the oil pump. 1 is a motor cooling control device for a vehicle.

  Further, the invention of claim 3 is the invention of claim 1 or 2, further comprising road information acquisition means for acquiring road information of the planned travel path of the vehicle, wherein the temperature rise prediction means is the road information acquisition means. And a means for predicting an output increase request for the vehicle based on the road information of the obtained scheduled road and predicting an increase in the amount of heat generated by the heat source based on the predicted output increase request. This is an electric motor cooling control device for a vehicle.

  According to the first aspect of the present invention, when an increase in the amount of heat generated by the heat source that has a thermal effect on the motor is predicted, the amount of cooling of the motor is increased before the temperature of the motor rises due to the thermal effect. It is done. Therefore, even if the heat from the heat source reaches the electric motor, at least some of the heat is carried away from the electric motor due to the increase in the cooling amount, and as a result, the temperature of the electric motor rises excessively or the output torque of the electric motor Can be prevented in advance.

  According to the second aspect of the present invention, it is possible to increase the amount of lubricating oil discharged from the oil pump and used for cooling the electric motor when an increase in the heat generation amount of the internal combustion engine or the inverter is predicted. It is possible to prevent or suppress the in-wheel motor from being heated by the heat of the internal combustion engine or the inverter to increase its temperature.

  According to the invention of claim 3, since the increase in the heat generation amount of the heat generation source is predicted based on the road information ahead on the planned travel route of the vehicle, the increase in the cooling amount of the electric motor or the in-wheel motor is accurately performed. Temperature rise can be avoided or suppressed in advance.

It is a flowchart for demonstrating an example of the control performed with the control apparatus which concerns on this invention. It is a figure which shows typically the map which defined the relationship between the engine load used in the example of control shown in FIG. 1, and an oil pump rotation speed. It is a flowchart for demonstrating the other example of the control performed with the control apparatus which concerns on this invention. It is a figure which shows typically the map which defined the relationship between the estimated output torque used by control of FIG. 3, and an oil pump rotation speed. It is a flowchart for demonstrating an example of the control which controls an oil pump rotation speed according to an inverter load. It is a figure which shows typically the map which defined the relationship between the inverter load used by control of FIG. 5, and an oil pump rotation speed. It is the schematic of the vehicle which shows an example of the vehicle made into object by the cooling control apparatus which concerns on this invention. It is the schematic of the vehicle which shows the other example of the vehicle made into object by the cooling control apparatus which concerns on this invention. It is the schematic of the vehicle which shows the further another example of the vehicle made into object by the cooling control apparatus which concerns on this invention.

  Next, the present invention will be described based on specific examples. First, a vehicle that can be a subject of the present invention will be described. The present invention is a vehicle that includes an electric motor for traveling and a heat generation source that exerts heat on the electric motor. It may be an electric motor provided in place of an engine (internal combustion engine) mounted on a conventional vehicle such as an electric vehicle or a fuel cell vehicle, or provided for each wheel like a so-called in-wheel motor vehicle. In-wheel motors may be used, and furthermore, a hybrid electric motor used in combination with an engine may be used like a so-called hybrid vehicle. On the other hand, the heat source generates heat by operating, and the heat reaches the electric motor. For example, in an electric vehicle, a fuel cell vehicle, and an in-wheel motor vehicle, it is an inverter, a battery, a fuel cell stack, or the like. In a hybrid vehicle, the engine (internal combustion engine) and its exhaust system correspond to the heat source in the present invention.

  The present invention will be described more specifically with reference to the drawings. FIG. 7 schematically shows an example of a vehicle targeted by the present invention. In the vehicle shown here, motors MFR and MFL are built in left and right front wheels FR and FL, respectively, front wheels FR and FL are driven by the motors MFR and MFL, and rear wheels RR and RL are internal combustion engines. 1 is an example configured to be driven by power generated in 1. The engine 1 corresponds to a heat source in the present invention, and is a gasoline engine, a diesel engine, an LPG engine, or the like. Further, the front wheels FR and FL are configured to be steered by a steering device (not shown), and each of the motors MFR and MFL provided in each has a motor having a power generation function such as a permanent magnet type synchronous motor. It has been adopted. Each motor MFR, MFL is electrically connected to a power storage device (not shown) via a controller such as an inverter INV. Therefore, when the vehicle is running, electric power is supplied from the power storage device to function as a motor, and during braking, the motor is forcibly rotated to generate power and charge the power storage device. ing.

  The motors MFR and MFL provided on the left and right front wheels FR and FL are so-called in-wheel motors, a traction motor constituted by a stator and a rotor, a cooling mechanism 2 for cooling the traction motor, and the traction motor. Is equipped with a speed reduction mechanism that increases the torque output by.

  The cooling mechanism 2 includes a cooling lubricant, an oil pump that supplies the cooling lubricant, an oil cooler that cools the lubricant, and the like, and supplies the cooling lubricant to the traction motor. It is what cools. The oil pump is provided with a motor for driving the oil pump so as to be driven independently of the traction motor. Therefore, since the cooling lubricant can be supplied regardless of the rotation of the traction motor, the supply amount of the cooling lubricant can be appropriately controlled when the traction motor needs to be cooled.

  Next, the rear wheel drive system will be briefly described. The output shaft of the engine 1 is connected to a transmission (T / M) 3, and the output of the transmission 3 is transmitted from a power transmission device such as a propeller shaft or a final reduction gear (differential). It is transmitted to the left and right rear wheel shafts via a gear). The transmission 3 is a stepped transmission, a continuously variable transmission, a hybrid transmission having a motor, or the like.

  In the engine 1, when the vehicle is accelerating or traveling on an ascending slope, the engine load increases and the engine temperature rises according to the output request by the driver's accelerator opening. In the example of the vehicle that is the subject of the present invention, the engine 1 is mounted in front of the vehicle and is close to the motors MFR and MFL provided on the front wheels FR and FL, so that the motors MFR and MFL are Under the influence of heat generated in the engine 1, the temperature or cooling performance of the motors MFR, MFL is affected. Therefore, the control device according to the present invention is configured to perform the following control so that the outputs of the motors MFR and MFL are not limited due to the thermal influence from the heat source such as the engine 1.

  FIG. 1 is a flowchart for explaining the control flow. The routine shown in FIG. 1 is executed every predetermined short time when the vehicle is in an operating state such as when the main switch of the vehicle is turned on. Repeatedly executed. First, the load on the engine 1 is measured (detected) (step S1). In a gasoline engine or a diesel engine, this can be detected based on the throttle opening, the accelerator opening, or the intake air amount. If the engine load is large, the power output from the engine 1 increases, and the heat generation amount in the engine 1 increases accordingly. Therefore, in step S1, an increase in the heat generation amount of the engine 1 corresponding to the heat generation source in the present invention is predicted. Will be. That is, the functional means for executing step S1 corresponds to the temperature rise prediction means in the present invention.

  Next, the oil pump command rotational speed is obtained based on the measured or detected engine load (step S2). The oil pump is an oil pump that supplies lubricating oil for cooling the motors MFR and MFL that are affected by heat from the engine 1, and the number of revolutions is determined based on the engine load. The oil pump command rotational speed can be determined as a function of engine load, and can be obtained from a map in which the oil pump command rotational speed is determined for each engine load. FIG. 2 shows an example of the map, and the oil pump command rotational speed is configured to be higher as the engine load is larger. Then, the oil pump is driven to achieve the oil pump command rotational speed determined in this way (step S3). As the number of revolutions of the oil pump increases, the amount of lubricating oil discharged increases, so that the amount of heat taken from the motors MFR, MFL supplied with the lubricating oil, that is, the cooling amount, increases as the engine load increases. Be made. Therefore, the functional means for executing the control in steps S2 and S3 corresponds to the cooling amount increasing means in the present invention.

  Therefore, according to the control device according to the present invention configured to execute the control shown in FIG. 1, it is predicted that the heat generation amount of the engine 1 arranged close to the motors MFR and MFL will increase. Then, even if the temperatures of the motors MFR and MFL are not particularly increased, the supply amount of the lubricating oil to the motors MFR and MFL is increased in advance. As a result, even if the output of the engine 1 increases and the motors MFR and MFL are affected by the heat from the engine 1 or the ambient temperature of the motors MFR and MFL becomes high and the heat radiation amount is suppressed. The temperature is prevented or suppressed so that the outputs of the motors MFR and MFL are limited. In other words, it is possible to prevent or suppress a decrease in the power performance of the vehicle.

  The above-described control shown in FIG. 1 is an example configured to predict an increase in the amount of heat generated by the engine 1 because a factor that increases the amount of heat generated by the engine 1 or a factor that increases the temperature has already occurred. In the present invention, the present invention is not limited to this, and an increase in the amount of heat generation or a temperature increase is predicted in a state where the above-described increase factor of the heat generation amount or temperature increase factor has not yet occurred, and the motor MFR, The cooling amount of the MFL can be increased. An example thereof is shown in FIG. 3, and the example shown here is an example configured to predict the heat generation amount and temperature rise of the engine 1 by approaching a forward gradient or a corner on the planned traveling road of the vehicle. .

  Specifically, first, map information around the host vehicle is read by an information acquisition system such as a navigation system, and data indicating the running state of the vehicle such as the vehicle speed and the accelerator opening is read (step S11). Navigation systems are widely known in the past, and include map information and road information. A map of the own vehicle is provided by radio navigation using GPS (global positioning system) or dead reckoning navigation that detects the movement of the own vehicle. It is configured to obtain the above position and further guide the vehicle to the destination using the position of the vehicle and map information. Then, by inputting the destination, the planned travel route is obtained, and the road information of the planned travel route, that is, the type of road such as a general road or an expressway, information such as an uphill road or a downhill road is detected. It is configured. Therefore, the functional means for executing the control in step S11 corresponds to the road information acquisition means in the present invention.

  Therefore, using the information read in step S11, it is determined whether or not the vehicle has approached a gradient (for example, an uphill road) or a corner (step S12). At the slope or corner, the output request increases, for example, the accelerator pedal is depressed. Therefore, at step S12, it is determined whether an output request or a corresponding increase in the heat generation amount of the engine 1 will occur soon. Note that the determination of “approach” is based on time or distance. Therefore, the threshold of the determination is used in experiments, simulations, and the like as long as the cooling amounts of the motors MFR and MFL are not unnecessarily increased. You can decide based on it.

  If a negative determination is made in step S12, the process returns. On the other hand, if a positive determination is made in step S12 due to approaching a slope or a corner, a wheel for increasing torque is determined (step S12). S13). This is mainly control when turning in a corner, and the torque of the wheel on the outer ring side is increased to improve turning performance. In such a case, the wheel on the outer ring side becomes a torque increasing wheel. In the case of an understeer tendency, the front wheel is a torque increasing wheel, and in the case of an oversteer tendency, the rear wheel is a torque increasing wheel.

  In order to increase the driving torque to be generated by the wheels, the output of the engine 1 is increased. Accordingly, the amount of heat generated by the engine 1 increases and the temperature thereof increases. Therefore, in the next step S14, the oil pump command rotational speed is obtained. That is, since the expected output torque can be determined based on the accelerator opening read in step S11, the oil pump speed corresponding to the predicted output torque is obtained. Similar to the control in step S2 described above, this can be obtained by a preset function or a map, and an example of the map is shown in FIG. Therefore, the oil pump speed increases as the expected output torque increases. Then, the oil pump is driven to achieve the oil pump command rotational speed determined in this way (step S15). Since the oil pump discharges more lubricating oil as the rotational speed increases, the amount of heat deprived from the motors MFR and MFL to which the lubricating oil is supplied, that is, the cooling amount, approaches a gradient or a corner. Also, it is increased according to the expected output torque at that time. Therefore, the functional means for executing the control in steps S14 and S15 corresponds to the cooling amount increasing means in the present invention.

  In the control example shown in FIG. 3, the output torque required for the vehicle is predicted, so that not only the engine 1 but also the output torques of the motors MFR and MFL are predicted. Therefore, the increase in the cooling amount of the motors MFR, MFL may include a part of the increase in the cooling amount to cope with heat generation based on the increase in the output of the motors MFR, MFL itself.

  Therefore, according to the control device according to the present invention configured to execute the control shown in FIGS. 3 and 4, when an increase in the drive torque is predicted, an operation or control for increasing the drive torque is still not performed. When not executed, the supply amount of lubricating oil to the motors MFR and MFL is increased in advance. As a result, the output of the engine 1 increases and the motors MFR and MFL are affected by the heat from the engine 1 or the ambient temperature of the motors MFR and MFL increases and the heat dissipation amount is suppressed. However, the temperature is prevented or suppressed from becoming so high that the outputs of the motors MFR and MFL are limited. In other words, it is possible to prevent or suppress a decrease in the power performance of the vehicle.

  If the amount of lubricating oil supplied from the oil pump for the motors MFR, MFL is increased, the cooling amount of the motors MFR, MFL increases, and even if heat is generated, the temperature rise can be suppressed. In parallel with the prediction of the increase in the heat generation amount of the heat generation source, the load of the motors MFR and MFL and the increase in the heat generation amount may be predicted and the cooling amount may be increased. For example, as shown in FIG. 5, the heat generation amounts of the motors MFR and MFL are measured (detected) as inverter loads (step S21). Based on the result of the measurement, an oil pump command rotational speed is obtained (step S22), and the oil pump is driven so as to obtain the obtained rotational speed (step S23). An example of a map that can be used in the control of step S22 is shown in FIG.

  On the other hand, the target vehicle in the present invention is not limited to the configuration shown in FIG. 7 described above, and may be a vehicle configured as shown in FIG. 8 or FIG. That is, the vehicle shown in FIG. 8 has motors MRR and MRL built in the left and right rear wheels RR and RL, respectively, and the rear wheels RR and RL are driven by these motors MRR and MRL. . This motor is an in-wheel motor similar to the front wheel of the vehicle example described above, and the configuration of the in-wheel motor is the same as that described above. The front wheels FR and FL are driven by the power generated by the engine 1. The engine 1 is a gasoline engine, a diesel engine, an LPG engine, or the like, similar to the example of the vehicle described above. The transmission system for driving force to the front wheels FR, FL is such that the output shaft of the engine 1 and the transmission 3 are connected, and the output shaft of the transmission 3 is connected to each front wheel FR via a final reduction gear (differential gear). , FL are connected to the drive shaft. Further, an exhaust pipe 4 for exhausting from the engine 1 is provided. The exhaust pipe 4 extends from the engine 1 mounted in the front of the vehicle to the rear of the vehicle, and the exhaust pipe 4 branches left and right at the rear of the vehicle. is doing.

  Then, the temperature of the exhaust pipe 4 may become high due to the influence of the heat of the exhaust discharged from the engine 1 and the heat generated by the chemical reaction of the exhaust purification catalyst. Therefore, when the load on the engine 1 increases and the engine temperature rises, the temperature of the exhaust from the engine 1 also rises, so that the temperature of the exhaust pipe 4 also rises under the influence. Therefore, the heat of the exhaust pipe 4 branching left and right at the rear of the vehicle may affect the motors MRR and MRL mounted on the rear wheels RR and RL, and may affect the motor temperature or cooling performance. There is.

  That is, the influence of heat on the motors MRR and MRL mounted on the rear wheels RR and RL is considered to increase as the load on the engine 1 increases. Therefore, the control device of the present invention measures the engine load in the same manner as the vehicle example described above, reads the rotational speed of the oil pump corresponding to the engine load from a predetermined oil pump drive map (see FIG. 2), The oil pump is driven at the rotation speed of the loaded oil pump. Therefore, when the engine load is large, that is, when the amount of heat generated by the engine 1 increases, it is determined that more cooling lubricating oil is supplied to the motor.

  In the two vehicle examples described above, the engine 1 is mounted, and the number of revolutions of the oil pump of the cooling oil for the motor mounted on the wheel is controlled according to the load of the engine 1. Although the amount of cooling is controlled before being affected by the heat from the exhaust pipe 4, the present invention can also be applied to a vehicle not equipped with the engine 1, such as the vehicle shown in FIG. It is.

  The vehicle shown in FIG. 9 is a schematic diagram of an electric vehicle or a fuel cell vehicle, and includes motors MFR, MFL, MRR, MRL on front, rear, left and right wheels FR, FL, RR, RL, and motors MFR, MFL, MRL, A battery 6 or a fuel cell (FC stack) 7 is connected via a controller such as an inverter 5 electrically connected to the MRR and MRL. Motors MFR, MFL, MRR, MRL provided on the respective wheels FR, FL, RR, RL have the same configuration as the in-wheel motor of the vehicle described above, and a traction motor constituted by a stator and a rotor and its motor It is composed of a cooling lubricant for cooling the traction motor or an oil pump for supplying the cooling lubricant.

  The inverter 5, the battery 6 or the fuel cell 7 supplies electricity to the motor in accordance with the amount of accelerator depression by the driver, such as when the vehicle is accelerated, and generates heat based on the amount of electricity supplied. . Accordingly, the heat generated in each member affects the motor, like the vehicle engine 1 and the exhaust pipe 4 described above. Therefore, in this invention, the load state of any one of these members is measured, and the number of revolutions of the oil pump of the cooling oil for the motor is controlled according to the load state, and the motor is affected by the heat from these members. The motor cooling amount is controlled before receiving.

  The present invention is not limited to the above-described vehicle and control parameters. In short, when a member that increases the amount of heat generated due to a travel load has a thermal effect on the motor, the control parameter is a parameter that detects or predicts the travel load. If the running load is predicted, the amount of cooling oil supplied to the motor is increased, and the cooling performance is improved before the motor is heated.

  DESCRIPTION OF SYMBOLS 1 ... Engine, 2 ... Cooling mechanism, 3 ... Transmission (T / M), 4 ... Exhaust pipe, 5 ... Inverter, 6 ... Battery, 7 ... Fuel cell (FC stack), FR, FL, RR, RL ... Wheel, MFR, MFL, MRR, MRL ... In-wheel motor.

Claims (3)

In an electric motor cooling control device for a vehicle provided with an electric motor that outputs power for traveling and a heat generation source that heats the electric motor,
A temperature rise prediction means for predicting an increase in the amount of heat generated by the heat source;
And a cooling amount increasing means for increasing a cooling amount for the motor before the temperature of the motor rises when an increase in the heat generation amount of the heat source is predicted by the temperature rise prediction means. A motor cooling control device for a vehicle. An oil pump for supplying cooling lubricant to the electric motor;
The electric motor includes an in-wheel motor provided for each wheel of the vehicle and individually driving each wheel,
The heat source includes at least one of an internal combustion engine mounted on the vehicle and an inverter that controls the in-wheel motor,
The temperature increase prediction means includes means for predicting an increase in the amount of heat generated by the heat source based on an output increase request to the vehicle,
The motor cooling control apparatus for a vehicle according to claim 1, wherein the cooling amount increasing means includes means for increasing a supply amount of lubricating oil to the in-wheel motor by the oil pump. Road information acquisition means for acquiring road information of the planned traveling road of the vehicle,
The temperature rise prediction means predicts an output increase request for the vehicle based on road information of a planned travel route obtained by the road information acquisition means, and generates heat from the heat source based on the predicted output increase request. 3. The motor cooling control apparatus for a vehicle according to claim 1, further comprising means for predicting an increase in the amount.

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