JP3549873B2 - Hybrid vehicle - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a so-called hybrid vehicle in which a propulsion force of a vehicle is obtained from at least one of motive powers using an engine and an electric motor capable of generating power.
[0002]
[Prior art]
2. Description of the Related Art In recent years, an electric motor (hereinafter referred to as a motor / generator) capable of generating an engine and a power transmission mechanism connected to driving wheels of a vehicle has been used for the purpose of saving fuel for driving the engine and reducing exhaust gas generated by combustion of the fuel. To assist the driving by a motor generator as needed during traveling, transmit the power input from the driving wheels to the motor generator during deceleration, and perform a regenerative operation by the motor generator. A hybrid vehicle has been developed in which the deceleration energy is converted into regenerative energy to charge the power storage device as electric energy (JP-A-11-350995, etc.).
[0003]
Incidentally, it is necessary to prevent overheating of the motor / generator. A conventional method for preventing overheating of a motor generator is to reduce (or limit) the output of the motor generator when the temperature of the motor generator rises or is estimated to have risen. The rise was avoided (JP-A-7-170800, JP-A-2000-184502, etc.).
[0004]
[Problems to be solved by the invention]
However, if overheating is prevented by limiting the output of the motor generator as in the prior art, the output that the motor generator can output depends on the temperature of the motor generator, so that the vehicle driving force can be maintained even under the same operating conditions (same vehicle speed and same throttle opening). Therefore, in order to obtain the same vehicle driving force, the driver has to adjust the depression amount of the accelerator pedal, and there is a problem that drivability deteriorates.
[0005]
When an electronically controlled throttle (hereinafter, abbreviated as DBW) is provided, a decrease in the output of the motor generator can be compensated for by an increase in the engine output. DBW has a problem that control is complicated and expensive.
Therefore, the present invention provides a hybrid vehicle that can prevent overheating of the electric motor without limiting the output of the electric motor.
[0006]
[Means for Solving the Problems]
In order to solve the above problems, the invention described in claim 1, the engine (e.g., engine 2 in the second embodiment to be described later) and the power generation motor capable (e.g., in the second embodiment described below A motor / generator 3) is provided as a power source, and at least one of the power of the engine and the electric motor is provided via a transmission (for example, a transmission 4 in a second embodiment described later) to an output shaft (for example, described later). In a hybrid vehicle (for example, a hybrid vehicle 1 according to a second embodiment described later) which transmits to an axle shaft 5a) according to the second embodiment and serves as a propulsion force of the vehicle, a temperature detecting unit that detects a temperature of the electric motor. (e.g., motor temperature sensor 14 in the second embodiment to be described later) and, to the transmission from the engine and the electric motor Lockup clutch (e.g., the lock-up clutch 31 in the second embodiment to be described later) for controlling the power transmission and a, in accordance with the temperature of the motor detected by said temperature detecting means, engagement of the lock-up clutch change the degree to change the rotational speed of the electric motor, and controlling the operating point of the electric motor to the high speed and low torque.
As a characteristic of the motor, in the low rotation region (orthogonal region), the torque of the motor is determined by the current value, and the heat generated by the motor is dominated by copper loss determined by the current value and the winding resistance. However, the operating point on the high rotation and low torque side generates less heat than the low rotation and high torque operation point. Therefore, with the above configuration, the amount of heat generated can be reduced without limiting the output of the electric motor.
[0009]
According to a second aspect of the present invention, in the first aspect of the invention, the degree of engagement of the lock-up clutch is reduced as the temperature of the electric motor detected by the temperature detecting means is higher.
With this configuration, the higher the temperature of the electric motor, the higher the number of revolutions of the electric motor and the lower the amount of heat generated.
[0010]
According to a third aspect of the present invention, in the first or second aspect of the present invention, when the number of rotations of the electric motor is changed according to the temperature of the electric motor, the changeable rotation region is within the orthogonal region. There is a feature.
With this configuration, overheating of the motor can be prevented without changing the output of the motor.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of a hybrid vehicle according to the present invention will be described below with reference to FIGS.
[0012]
[First Embodiment]
First, a first embodiment of a hybrid vehicle according to the present invention will be described with reference to the drawings of FIGS.
FIG. 1 is a schematic configuration diagram of a power transmission system of the hybrid vehicle 1 according to the first embodiment.
In the hybrid vehicle 1, an engine 2 and a motor (hereinafter, referred to as a motor / generator) 3 capable of generating electricity are directly connected, and at least one of the power of the engine 2 and the power of the motor / generator 3 drives the vehicle via a transmission 4. It is configured to be transmitted to the wheel 5. The transmission 4 is a belt-type continuously variable transmission (CVT), which includes a drive pulley 41 connected to an output shaft 3a of the motor / generator 3 and a differential gear (not shown) mounted on an axle shaft (output shaft) 5a of the drive wheel 5. And a drive pulley 41 and an endless belt 43 wound around the driven pulley 42. The transmission 4 can change the gear ratio steplessly by increasing and decreasing the effective radius of both pulleys 41 and 42, and each of the pulleys 41 and 42 drives to increase or decrease the effective radius. Parts 41a and 42a are provided. By supplying the hydraulic pressure controlled by the control valve 6 to the drive units 41a and 42a, the effective radius of the drive pulley 41 and the driven pulley 42 can be increased or decreased as desired. Obtainable.
[0013]
When the driving force is transmitted from the driving wheels 5 to the motor generator 3 when the hybrid vehicle 1 is decelerated, the motor generator 3 functions as a generator to generate a so-called regenerative braking force, and to reduce the kinetic energy of the vehicle body. The battery 8 is recovered as electric energy and charged into the battery 8 via the power drive unit (PDU) 7. The regenerative output at this time is controlled by the ECU 9 via the PDU 7.
The motor generator 3 is driven by consuming the electric energy charged in the battery 8, and is controlled by the ECU 9 via the PDU 7. Note that a capacitor can be used instead of the battery 8.
[0014]
The engine 2 is a multi-cylinder reciprocating type engine, and has an intake / exhaust control device (cylinder deactivating means) 10 for controlling the operation of intake and exhaust valves for performing intake / exhaust for each cylinder, fuel injection control for each cylinder, and And a fuel injection / ignition control device 11 for controlling ignition of the injected fuel. These control devices 10 and 11 are controlled by the ECU 9.
In this hybrid vehicle, fuel supply stop control (hereinafter abbreviated as F / C control) for stopping fuel supply to all cylinders of the engine 2 by the fuel injection / ignition control device 11 is possible, if necessary. As required, the intake / exhaust control device 10 can perform cylinder deactivation control (also referred to as cylinder deactivation control) for fully closing the intake / exhaust valves of all cylinders of the engine 2.
The ECU 9 receives a signal from a throttle opening sensor 12 for detecting a throttle opening, a signal from a vehicle speed sensor 13 for detecting a vehicle speed, and a motor temperature sensor 14 for detecting a winding temperature of the motor generator 3. Is input.
[0015]
Next, the principle of preventing overheating of the motor / generator 3 will be described.
FIG. 2 is a TN characteristic diagram showing a relationship between the torque and the number of revolutions of the motor generator 3. As is well known, the torque of the motor generator 3 is determined by the current value in the low rotation region (the orthogonal region where the field weakening is not required). In the low rotation region, heat generated by the motor generator 3 is dominated by copper loss determined by the current value and the winding resistance. Therefore, when the operating point of the motor / generator 3 is changed from the low rotation high torque side (for example, point A in FIG. 2) to the high rotation low torque side (for example, point B in FIG. 2), the heat generation is performed without limiting the output. The amount can be reduced.
Therefore, in the first embodiment, the temperature of the motor generator 3 is monitored by the motor temperature sensor 14, and when the temperature of the motor generator 3 exceeds a predetermined temperature T1, the transmission 4 By changing the gear ratio, the number of revolutions of the motor / generator 3 is increased, and the operating point of the motor / generator 3 is changed to a higher rotation / lower torque side than at a steady temperature (at T1 or less).
[0016]
In the hybrid vehicle 1, the gear ratio of the transmission 4 can be determined by determining the required rotation speed (hereinafter abbreviated as NDRCMD) of the drive pulley 41 of the transmission 4. This is because the rotation speed of the driven pulley 42 can be calculated from the vehicle speed detected by the vehicle speed sensor 13, and the speed ratio of the transmission 4 can be calculated from the rotation speed of the driven pulley 42 and NDRCMD. .
In this embodiment, the drive pulley 41 is connected to the output shaft 3a of the motor / generator 3, and the engine 2 and the motor / generator 3 are directly connected. The number of rotations of 3 is always the same.
[0017]
Next, the NDRCMD calculation process of the drive pulley 41 will be described with reference to the flowchart shown in FIG. As described above, in this embodiment, the rotation speed of the drive pulley 41 is the same as the rotation speed of the output shaft 3a of the motor generator 3, and therefore, the process of calculating NDRCMD includes the required rotation speed of the motor generator 3. It can also be called a number calculation process.
The NDRCMD calculation processing routine shown in the flowchart of FIG.
[0018]
First, in step S101, NDRCMD (hereinafter, referred to as basic NDRCMD and abbreviated as BNDRCMD) when the temperature of the motor generator 3 is at a steady temperature (T1 or lower) is calculated. Here, in this embodiment, BNDRCMD is a drive pulley 41 determined from the most efficient gear ratio in consideration of the engine efficiency and the transmission efficiency of the transmission 4 when the vehicle runs with only the driving force of the engine 2. Required rotation speed. BNDRCMD is calculated based on the vehicle speed V detected by the vehicle speed sensor 13 and the throttle opening TH detected by the throttle opening sensor 12 with reference to a map (not shown) prepared in advance.
[0019]
Next, the process proceeds to step S102, and a motor temperature correction term TNDRCMD is calculated based on the temperature of the motor generator 3 detected by the motor temperature sensor 14 with reference to a TNDRCMD map prepared in advance. FIG. 4 shows an example of the TNDRCMD map. In this example, TNDRCMD = 0 when the temperature of the motor generator 3 is equal to or lower than T1, and TNDRCMD increases linearly as the temperature increases from T1 to T2. Then, at T2 or more, it becomes constant at, for example, 500 rpm.
[0020]
Next, the process proceeds to step S103, and NDRCMD is calculated from the following equation.
NDRCMD = BNDRCMD + TNDRCMD
Next, the process proceeds to step S104, referring to an NDRlim map (not shown) prepared in advance, based on the vehicle speed V detected by the vehicle speed sensor 13 and the throttle opening TH detected by the throttle opening sensor 12, the upper limit NDRCMD ( Hereinafter, abbreviated as NDRlim).
[0021]
Next, the process proceeds to step S105, in which the NDRCMD limit process is executed, and the execution of this routine is temporarily ended. The NDRCMD limit process is a process for limiting NDRCMD to NDRlim or less. If NDRCMD calculated in step S103 is larger than NDRlim, NDRlim is set to NDRCMD, and if NDRCMD calculated in step S103 is less than NDRlim, step The NDRCMD calculated in S103 is set as NDRCMD.
By executing the NDRCMD limit process, even if the temperature of the motor generator 3 rises during low-speed low-power operation such as during idling, the rotation speed of the motor generator 3 is not increased so that the driver feels uncomfortable. Can be
[0022]
Then, the speed ratio of the transmission 4 is calculated from the NDRCMD of the drive pulley 41 calculated as described above and the rotation speed of the driven pulley 42 calculated based on the vehicle speed, and the ECU 9 controls the speed ratio to be the speed ratio. By controlling the valve 6, a hydraulic pressure of a predetermined hydraulic value is supplied to the driving units 41a and 42a to change the effective radii of the drive pulley 41 and the driven pulley 42 to a predetermined value. Thereby, the rotation speed of the output shaft 3a of the motor generator 3 can be made higher than that at the time of the steady temperature, and as a result, the current flowing through the motor generator 3 decreases, and the operating point of the motor generator 3 is output. It is possible to change to a higher rotation and lower torque side than the steady temperature without changing, and it is possible to suppress heat generation of the motor generator 3 and prevent overheating.
[0023]
Note that, even during deceleration regeneration, overheating of the motor generator 3 can be prevented by the same gear ratio change control as described above.
In the above-described embodiment, the motor temperature correction term TNDRCMD is increased as a linear function as the temperature of the motor generator 3 rises. However, as shown in FIG. May be increased stepwise.
In the above-described embodiment, BNDRCMD is determined based on the efficiency of the engine 2 during engine running and the transmission efficiency of the transmission 4 in the BNDRCMD calculation processing in step S101. However, the present invention is not limited to this. BNDRCMD may be determined based on the efficiency of the motor / generator 3 during running by the generator 3, the friction of the engine 2, and the transmission efficiency of the transmission 4.
[0024]
The overheating prevention of the motor / generator 3 by the speed ratio change control of the first embodiment is not limited to the application to the hybrid vehicle 1 having the configuration shown in FIG. The present invention is also applicable to so-called parallel hybrid vehicles 1 having various configurations.
In the hybrid vehicle 1 shown in FIG. 6, the power of the engine 2 is transmitted to the drive wheels 5 via the first transmission 15 and the output shaft 16, and the power of the motor / generator 3 is transmitted to the second transmission 17 and The power is transmitted to the output shaft 16 via the gear 18 and further transmitted to the drive wheels 5. Also in this hybrid vehicle 1, either or both of the power of the engine 2 and the motor / generator 3 can be used as the propulsion force of the vehicle, and the second transmission 17 can be used in accordance with the temperature of the motor / generator 3. Changing the speed of the output shaft 3a of the motor / generator 3 by changing the speed ratio of the motor / generator 3, and changing the operating point of the motor / generator 3 to the high rotation / low torque side to prevent overheating of the motor / generator 3. Can be.
[0025]
In the hybrid vehicle 1 shown in FIG. 7, the power of the engine 2 is transmitted to the front wheels (wheels) 23 via the first transmission 21 and the output shaft 22, and the power of the motor generator 3 is transmitted to the second transmission 24 and The power is transmitted to a rear wheel (wheel) 26 via an output shaft 25. That is, in the hybrid vehicle 1, all of the front and rear wheels are drive wheels, the front wheels 23 are driven by the engine 2, and the rear wheels 26 are driven by the motor generator 3. Also in this hybrid vehicle 1, either or both of the power of the engine 2 and the motor / generator 3 can be used as the propulsion force of the vehicle, and the second transmission 24 according to the temperature of the motor / generator 3. Changing the speed of the output shaft 3a of the motor / generator 3 by changing the speed ratio of the motor / generator 3, and changing the operating point of the motor / generator 3 to the high rotation / low torque side to prevent overheating of the motor / generator 3. Can be. In the case of the hybrid vehicle 1, the connection between the two power sources and the front and rear wheels is reversed so that the power of the engine 2 is transmitted to the rear wheels 26 and the power of the motor generator 3 is transmitted to the front wheels 23. Is also good.
Further, in the case of the hybrid vehicle 1 configured as shown in FIG. 6 or 7, only the rotation speed of the motor / generator 3 can be changed without changing the rotation speed of the engine 2.
6 and 7, the configuration of a control system such as a PDU and an ECU is omitted.
[0026]
[Second embodiment]
Next, a second embodiment of the hybrid vehicle according to the present invention will be described with reference to FIG.
FIG. 8 is a schematic configuration diagram of a power transmission system of the hybrid vehicle 1 according to the second embodiment.
The differences between the hybrid vehicle 1 of the second embodiment and the hybrid vehicle 1 of the first embodiment are as follows.
In the hybrid vehicle 1, a torque converter 32 having a lock-up clutch 31 is provided between the motor generator 3 and the transmission 4. As is well known, the torque converter 5 transmits torque between the output shaft 3a of the motor / generator 3 and the input shaft 4a of the transmission 4 via a fluid when the lock-up clutch 31 is released. When the lock-up clutch 31 is engaged, the output shaft 3a of the motor / generator 3 and the input shaft 4a of the transmission 4 are substantially directly connected, and the output shaft 3a and the input shaft 4a are independent of the fluid. Is transmitted directly between the two.
[0027]
The degree of engagement of the lock-up clutch 31 is made variable by controlling the operating oil pressure of the lock-up clutch 31, and the operating oil pressure is controlled by a hydraulic circuit 33 based on a command from the ECU 9.
Other configurations are the same as those of the first embodiment, and therefore, the same reference numerals are given to the same aspects, and description thereof will be omitted.
[0028]
Next, the operation of the hybrid vehicle according to the second embodiment will be described.
In the first embodiment described above, when the temperature of the motor generator 3 rises, the speed ratio of the transmission 4 is changed to change the rotation speed of the output shaft 3a of the motor generator 3, and the motor generator 3 Is changed to the high rotation and low torque side to prevent overheating of the motor / generator 3, but in the second embodiment, when the temperature of the motor / generator 3 rises, the gear ratio of the transmission 4 becomes Without changing, by decreasing the degree of engagement of the lock-up clutch 31, the rotation speed of the output shaft 3a of the motor / generator 3 is increased, whereby the current flowing through the motor / generator 3 is reduced, and the operation of the motor / generator 3 is reduced. By changing the point to a higher rotation and lower torque side than the steady temperature without changing the output, the heat generation of the motor generator 3 is suppressed, and To stop.
[0029]
In the case of the second embodiment, it is also possible to control so that the degree of engagement of the lock-up clutch 31 is reduced as the temperature of the motor generator 3 increases. By doing so, the lower the degree of engagement of the lock-up clutch 31 is, the higher the number of revolutions of the motor generator 3 can be increased. That is, by controlling the degree of engagement of the lock-up clutch 31, , The amount of increase in the number of rotations can be controlled.
Further, the second embodiment is also applicable to a so-called parallel type hybrid vehicle 1 having various configurations as shown in FIG. 6 or FIG. 7, similarly to the case of the first embodiment.
[0030]
[Other embodiments]
Note that the present invention is not limited to the above-described embodiment.
For example, in the above-described embodiment, a motor temperature sensor is used as temperature detecting means for detecting the temperature of the motor generator 3, and the temperature of the winding is directly detected. It is also possible to configure so as to estimate the temperature of the motor / generator 3 based on how the generator 3 is used. That is, the temperature detecting means may directly detect the temperature of the motor / generator 3 or may indirectly detect the temperature.
Further, the transmission is not limited to the continuously variable transmission, and a stepped transmission can be employed.
[0031]
【The invention's effect】
As described above, according to the first to third aspects of the present invention, since the amount of heat generated by the motor can be reduced without limiting the output of the motor, overheating of the motor can be prevented. Excellent effects are achieved.
According to the second aspect of the present invention, the higher the temperature of the motor, the higher the number of revolutions of the motor and the lower the amount of heat generated, so that overheating of the motor can be reliably prevented. There is.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a power transmission system in a first embodiment of a hybrid vehicle according to the present invention.
FIG. 2 is a TN characteristic diagram showing a relationship between a torque and a rotation speed of a motor generator.
FIG. 3 is a flowchart illustrating an NDRCMD calculation process according to the first embodiment.
FIG. 4 is a diagram illustrating an example of a TNDRCMD map used in an NDRCMD calculation process.
FIG. 5 is a diagram showing another example of the TNDRCMD map.
FIG. 6 is a diagram showing another configuration example of the power transmission system of the hybrid vehicle according to the first embodiment.
FIG. 7 is a diagram showing still another configuration example of the power transmission system of the hybrid vehicle according to the first embodiment.
FIG. 8 is a schematic configuration diagram of a power transmission system in a second embodiment of the hybrid vehicle according to the present invention.
[Explanation of symbols]
1 Hybrid vehicle 2 Engine 3 Motor / generator (electric motor)
4 Transmission 5a Axle shaft (output shaft)
14 Motor temperature sensor (temperature detection means)
31 Lock-up clutch

Claims (3)

A hybrid vehicle comprising an engine and an electric motor capable of generating electric power as a power source, and transmitting at least one of the power of the engine and the electric motor to an output shaft via a transmission to be a propulsion force of the vehicle,
Temperature detection means for detecting the temperature of the electric motor ,
A lock-up clutch that controls power transmission from the engine and the electric motor to the transmission ,
Depending on the temperature of the motor detected by said temperature detecting means, by changing the degree of engagement of the lock-up clutch to change the rotational speed of the electric motor, to control the operating point of the electric motor to the high speed and low torque Features hybrid vehicle. 2. The hybrid vehicle according to claim 1 , wherein the higher the temperature of the electric motor detected by the temperature detector, the lower the degree of engagement of the lock-up clutch . 3. 3. The hybrid vehicle according to claim 1 , wherein when the number of rotations of the electric motor is changed according to the temperature of the electric motor, a changeable rotation range is within an orthogonal range . 4.

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