JP7551238B2 - vehicle - Google Patents

Description

The present invention relates to vehicles such as hybrid vehicles (HVs).

In an engine (reciprocating engine), the intake, compression, expansion, and exhaust processes are repeated, causing fluctuations in the explosive torque (instantaneous torque), which in turn causes fluctuations in the rotation speed. As the fluctuations in the engine rotation speed become greater, the NV (noise and vibration) characteristics of the vehicle in which the engine is installed deteriorate.

One possible solution to this problem is to store in memory a map of motor torque that represents a waveform that is the average waveform of the explosive torque in the range of crank angles 0 to 720° CA, which is the rotation angle (phase angle) of the engine crankshaft, and output a motor torque according to the crank angle, thereby offsetting the fluctuations in the engine explosive torque with the motor torque.

JP 2001-342886 A

Since crank angle detection is necessary for engine control, the E/G-ECU (Electronic Control Unit) that controls the engine is connected to an angle sensor that outputs a pulse signal each time the crankshaft rotates a certain angle, and a cylinder discrimination sensor that outputs a pulse signal when a specific cylinder is at a certain crank angle.

The E/G-ECU and the PCU (Power Control Unit) that controls the generator motor are connected so that they can communicate using the CAN (Controller Area Network) communication protocol, so the PCU can receive the crank angle detected by the E/G-ECU via communication. However, because there is a limit to the communication speed, there is a delay in the crank angle received by the PCU compared to the actual crank angle. If the angle sensor and cylinder discrimination sensor are connected to the PCU so that their pulse signals are input directly to the PCU, the problem of communication delays can be avoided, but this would increase costs due to new wiring and create a new risk of the wiring breaking.

The object of the present invention is to provide a vehicle that can accurately estimate the engine crank angle using a control device that controls the generator.

Another object of the present invention is to provide a vehicle that can suppress fluctuations in engine speed.

To achieve the above object, a vehicle according to one aspect of the present invention includes an engine, a generator, a meshing mechanism interposed between the engine crankshaft and the generator rotating shaft and transmitting power by meshing of teeth, a resolver that outputs an electrical signal according to the rotation angle of the rotating shaft, and a control device to which the electrical signal from the resolver is input to control the generator, and the control device calculates the rotation angle from the resolver electrical signal, determines fluctuations in the rotation speed of the rotating shaft from the resolver electrical signal, identifies the engine cylinders from the fluctuations, and estimates the engine crank angle from the calculated rotation angle and the result of cylinder identification.

According to this configuration, in order to control the generator, an electrical signal corresponding to the rotation angle of the generator's rotating shaft (hereinafter referred to as the "generator rotation angle") is input from the resolver to the control device. The control device calculates the generator rotation angle from the resolver's electrical signal. The control device also determines the fluctuation in the rotation speed of the generator's rotating shaft (hereinafter referred to as the "generator rotation speed") from the resolver's electrical signal, and identifies the engine cylinders from the fluctuation in the generator rotation speed. The engine crank angle is then estimated from the generator rotation angle and the result of cylinder identification.

Fluctuations in engine explosive torque (instantaneous torque) cause fluctuations in engine speed, which in turn causes fluctuations in generator speed. For example, if the engine is a three-cylinder, four-stroke engine, the exhaust top dead center (TDC) of cylinder 1 is set as the crank angle reference (0° CA), and cylinders 1, 2, and 3 are ignited in that order. In one cycle, the crank angle changes between 0° and 720° CA, and the stroke phase difference between the cylinders is 240° CA. Therefore, cylinders 1 and 3 are ignited within the range of 0° to 359° CA, and cylinder 2 is ignited within the range of 360° CA to 720° CA (ignition timing is advanced). Therefore, the generator speed bottoms out twice in the range of 0° to 359° CA, and once in the range of 360° CA to 720° CA. Therefore, it is possible to distinguish between cylinders (distinguishing the engine operating stroke for each cylinder) from the fluctuations in the generator speed.

The engine and generator are assembled based on a reference for the generator rotation angle and a reference for the crank angle, so the engine crank angle can be estimated with high accuracy based on the generator rotation angle and the results of cylinder discrimination.

Moreover, the resolver's electrical signal is input to the control device for purposes other than estimating the crank angle. Therefore, there is no need to install new wiring to input the resolver's electrical signal to the control device in order to estimate the crank angle. This makes it possible to avoid the increased costs of installing new wiring and the risk of the wiring breaking.

The meshing mechanism may be a mechanism that transmits power by meshing the teeth of a male spline provided on one of the engine crankshaft and the generator rotating shaft with the teeth of a female spline provided on the other of them, or a mechanism that transmits power by meshing the teeth of a gear supported on the engine crankshaft so as not to rotate relative to the generator rotating shaft with the teeth of a gear supported on the generator rotating shaft so as not to rotate relative to the engine crankshaft.

It is preferable that the control device uses the estimated crank angle to control the generator so that a generator torque in the opposite phase to the instantaneous torque of the engine is applied to the engine.

This control allows fluctuations in the engine's explosive torque to be offset by the generator torque of the opposite phase. As a result, fluctuations in the engine's speed can be suppressed, improving the vehicle's NV (noise and vibration) characteristics.

A vehicle according to another aspect of the present invention is a vehicle equipped with an engine, a generator that generates electricity using engine power, a drive motor that generates power for traveling, and a control device that controls the generator, and the control device controls the generator so that a generator torque in the opposite phase to the engine explosion torque is applied to the engine regardless of the traveling state of the vehicle.

With this configuration, while the engine is running, fluctuations in the engine's explosive torque can be offset by the generator torque of the opposite phase, regardless of the vehicle's running state. As a result, fluctuations in the engine's rotation speed can be suppressed, improving the vehicle's noise and vibration characteristics.

According to the present invention, the engine crank angle can be accurately estimated by a control device that controls a generator. In addition, by applying a generator torque to the engine from the generator that is the same magnitude as the explosion torque corresponding to the estimated crank angle but in the opposite direction, it is possible to suppress fluctuations in the engine speed and improve the NV characteristics of the vehicle.

1 is a block diagram showing a configuration of a hybrid vehicle according to an embodiment of the present invention; FIG. 2 is a diagram showing the relationship between the crank angle of the engine and the explosion torque (E/G torque). FIG. 4 is a diagram showing the relationship between the crank angle of the engine and the MG1 torque output by the generator motor.

The following describes in detail an embodiment of the present invention with reference to the attached drawings.

<Hybrid vehicle>
FIG. 1 is a block diagram showing a configuration of a hybrid vehicle 1 according to an embodiment of the present invention.

The hybrid vehicle 1 is equipped with a series hybrid system 2. The hybrid system 2 includes an engine (E/G) 11, a generator motor (MG1) 12, a drive motor (MG2) 13, a battery 14, and a PCU (Power Control Unit) 15.

Engine 11 is, for example, a three-cylinder, four-stroke gasoline engine. Engine 11 is equipped with an electronic throttle valve for adjusting the amount of air intake into the combustion chamber, an injector (fuel injection device) for injecting fuel into the intake air, and a spark plug for generating an electrical discharge in the combustion chamber.

The generator motor 12 is, for example, a permanent magnet synchronous motor.

The crankshaft 21 of the engine 11 and the motor shaft 22 of the generator motor 12 are connected via a meshing mechanism 23 that transmits power by meshing teeth. The meshing mechanism 23 includes, for example, a male spline provided on one of the crankshaft 21 and the motor shaft 22, and a female spline provided on the other, and is a mechanism that enables power to be transmitted between the crankshaft 21 and the motor shaft 22 by meshing the teeth of the male spline with the teeth of the female spline.

The drive motor 13 is, for example, a permanent magnet synchronous motor that is larger than the generator motor 12. The motor shaft of the drive motor 13 is connected to a drive system 16 of the hybrid vehicle 1. The drive system 16 includes a differential gear, and the power of the drive motor 13 is transmitted to the differential gear, and is then distributed and transmitted from the differential gear to drive wheels 17 consisting of the left and right front wheels or rear wheels. This causes the left and right drive wheels 17 to rotate, and the hybrid vehicle 1 moves forward or backward.

Battery 14 is a battery pack made up of multiple secondary batteries (e.g., lithium ion batteries). Battery 14 outputs DC power of, for example, about 200 to 350 V (volts).

The PCU 15 is a unit for controlling the driving of the generator motor 12 and the drive motor 13. Although not shown, the PCU 15 includes an MG1 inverter, which is the drive circuit of the generator motor 12, an MG2 inverter, which is the drive circuit of the drive motor 13, and a converter that is connected to the DC side of the MG1 inverter and the MG2 inverter and is also connected to the battery 14 to step up and step down the DC voltage between the MG1 inverter and the MG2 inverter and the battery 14.

The hybrid vehicle 1 is also equipped with an HV-ECU 31 and an E/G-ECU 32 as ECUs (Electronic Control Units) for the hybrid system 2.

The PCU 15, HV-ECU 31, and E/G-ECU 32 each have a built-in microcontroller (microcontroller unit). The microcontroller includes, for example, a CPU, a non-volatile memory such as a flash memory, and a volatile memory such as a dynamic random access memory (DRAM).

The PCU 15, HV-ECU 31, and E/G-ECU 32 are also connected to enable two-way communication using the Controller Area Network (CAN) communication protocol (hereinafter referred to as "CAN communication").

The HV-ECU 31 is an ECU that provides overall control of the hybrid system 2. It receives various information from the PCU 15 and the E/G-ECU 32 via CAN communication, and transmits motor control commands and engine control commands to the PCU 15 and the E/G-ECU 32, respectively.

A resolver 33 is connected to the PCU 15. The resolver 33 is attached to the generator motor 12 and outputs the change in the rotation angle of the motor shaft 22 of the generator motor 12 as a change in two-phase AC voltage. The resolver 33 is provided with an R/D (resolver/digital) converter that converts the analog signal of the two-phase AC voltage output by the resolver 33 into a digital signal, and the digital signal output from the R/D converter is input as a resolver signal to the microcomputer of the PCU 15 as a signal required for motor control. The microcomputer of the PCU 15 controls the drive of the generator motor 12 via the MG1 inverter and controls the drive of the drive motor 13 via the MG2 inverter according to the motor control command transmitted from the HV-ECU 31. In addition, the microcomputer of the PCU 15 controls the step-up and step-down of the DC voltage by the converter as necessary.

A crank angle sensor 34 is connected to the E/G-ECU 32. The crank angle sensor 34 outputs a detection signal corresponding to the rotation angle of the crankshaft 21. The detection signal from the crank angle sensor 34 is input to the microcomputer of the E/G-ECU 32. The microcomputer of the PCU 15 controls the operation of the electronic throttle valve, the injectors, and the spark plugs, such as the amount and timing of fuel injection by the injectors, according to engine control commands sent from the HV-ECU 31.

When the engine 11 is started, the PCU 15 and E/G-ECU 32 perform control according to motor control commands and engine control commands from the HV-ECU 31, and the DC power output from the battery 14 is boosted by the converter, and the boosted DC power is converted to AC power by the MG1 inverter, and the AC power is supplied to the generator motor 12. This causes the generator motor 12 to operate in powered mode, and the engine 11 is motored (cranked) by the generator motor 12. When the rotation speed of the crankshaft 21 of the engine 11 has increased to the rotation speed required for starting due to motoring, the electronic throttle valve, injector, and spark plug are controlled to start the engine 11.

When the hybrid vehicle 1 is running, the drive motor 13 is powered and generates power.

When the sum of the outputs required for the generator motor 12 and the drive motor 13 is less than the output of the battery 14, the hybrid vehicle 1 runs in EV mode. That is, the engine 11 is stopped, no power is generated by the generator motor 12, and power is supplied from the battery 14 to the drive motor 13, which is then used to drive the drive motor 13.

On the other hand, when the total output required for the generator motor 12 and the drive motor 13 exceeds the output of the battery 14, the hybrid vehicle 1 runs in HV mode. That is, the engine 11 is operated and the generator motor 12 is operated to generate electricity (regenerative operation), so that the power of the engine 11 is converted to AC power by the generator motor 12. The AC power from the generator motor 12 is then converted to DC power by the MG1 inverter, and the DC power output from the MG1 inverter is converted to AC power by the MG2 inverter, and this AC power is supplied to the drive motor 13, thereby driving the drive motor 13.

When the remaining capacity of the battery 14 falls below a predetermined level, the engine 11 is put into operation and the generator motor 12 is operated to generate electricity, regardless of whether the drive motor 13 is running or stopped. At this time, the AC power from the generator motor 12 is converted to DC power by the MG1 inverter, the DC power output from the MG1 inverter is stepped down by the converter, and the stepped-down DC power is supplied to the battery 14, thereby charging the battery 14.

When the hybrid vehicle 1 decelerates, the drive motor 13 is operated in regenerative mode, and the power transmitted from the drive wheels 17 to the drive motor 13 is converted to AC power. At this time, the drive motor 13 acts as a resistor in the driving system, and this resistance acts as a braking force (regenerative braking force) that brakes the hybrid vehicle 1. At this time, in the PCU 15, the AC power supplied from the drive motor 13 to the MG2 inverter is converted to DC power by the MG2 inverter, and the DC power output from the MG2 inverter is stepped down by the converter. The stepped-down DC power is then supplied to the battery 14, thereby charging the battery 14.

<Crank angle detection>
FIG. 2 is a diagram showing the relationship between the crank angle of the engine 11 and the explosion torque (E/G torque).

When the engine 11 is operating, four strokes are repeated: intake, compression, expansion, and exhaust. The explosion torque (instantaneous torque) of each cylinder of the engine 11 changes in such a way that it rises sharply during the expansion stroke, decreases during the exhaust stroke, becomes nearly zero during the intake stroke, and becomes negative during the compression stroke. Fluctuations in the explosion torque of the engine 11 cause fluctuations in the rotation speed of the crankshaft 21 of the engine 11. Because the crankshaft 21 of the engine 11 and the motor shaft 22 of the generator motor 12 are connected via a meshing mechanism 23, the rotation speed of the motor shaft 22 fluctuates in sync with the fluctuations in the rotation speed of the crankshaft 21.

In the PCU 15, the microcomputer calculates the rotation angle of the motor shaft 22 (hereinafter referred to as the "motor rotation angle") from the resolver signal. In addition, in the PCU 15, the microcomputer determines the fluctuation in the rotation speed of the motor shaft 22 (hereinafter referred to as the "motor rotation speed") from the resolver signal, and identifies the cylinder of the engine 11 from the fluctuation in the motor rotation speed. The crank angle of the engine 11 is then estimated from the motor rotation angle and the result of the cylinder identification.

For example, if the exhaust top dead center (TDC) of the first cylinder of a three-cylinder, four-stroke engine 11 is set as the crank angle reference (0° CA), and the first, second, and third cylinders are ignited in that order, the crank angle changes in one cycle from 0° to 720° CA, and the stroke phase difference between the cylinders is 240° CA, so the first and third cylinders are ignited within the range of 0° to 359° CA, and the second cylinder is ignited within the range of 360° CA to 720° CA (ignition timing is advanced). Therefore, the motor speed bottoms out twice within the range of 0° to 359° CA, and once within the range of 360° CA to 720° CA. Therefore, if the motor rotation speed bottoms out twice while the motor shaft 22 rotates 360°, it can be determined that the cylinders that were ignited during that time are cylinder 1 and cylinder 3, and if the motor rotation speed bottoms out once while the motor shaft 22 rotates 360°, it can be determined that the cylinder that was ignited during that time is cylinder 2.

The crankshaft 21 of the engine 11 and the motor shaft 22 of the generator motor 12 are connected via a meshing mechanism 23 with the reference crank angle (0° CA) and the reference motor rotation angle (0°) aligned. Therefore, the PCU 15 can accurately estimate the crank angle of the engine 11 from the motor rotation angle and the results of cylinder discrimination.

<Torque fluctuation suppression>
FIG. 3 is a diagram showing the relationship between the crank angle of the engine 11 and the MG1 torque output by the generator motor 12. As shown in FIG.

The relationship between the crank angle of the engine 11 and the explosive torque (E/G torque) is stored in the form of a map in the non-volatile memory of the microcomputer built in the PCU 15. In FIG. 3, the characteristic line showing the relationship between the crank angle of the engine 11 and the explosive torque is shown by a broken line. In the microcomputer of the PCU 15, the explosive torque corresponding to the crank angle estimated from the motor rotation angle and the result of cylinder discrimination is read from the map stored in the non-volatile memory while the engine 11 is operating, regardless of the running state of the hybrid vehicle 1. Then, the power generation operation of the power generation motor 12 is controlled so that a torque having the same absolute value as the explosive torque corresponding to the crank angle of the engine 11 but different in positive and negative is output from the power generation motor 12 as the MG1 torque. As a result, the MG1 torque output from the power generation motor 12 changes in the opposite phase to the explosive torque according to the crank angle of the engine 11, as shown by the solid line in FIG. 3.

<Action and effect>
As described above, in the PCU 15, the motor rotation angle is calculated from the resolver signal of the resolver 33, and the fluctuation in the motor rotation speed is obtained, and the cylinder of the engine 11 is identified from the fluctuation in the motor rotation speed. Furthermore, the crank angle of the engine 11 is estimated from the motor rotation angle and the result of the cylinder identification. Then, the generator motor 12 is controlled so that the generator motor 12 outputs an MG1 torque having the same magnitude and the opposite direction as the explosion torque corresponding to the estimated crank angle. This control makes it possible to offset the fluctuation in the explosion torque of the engine 11 with the MG1 torque having the opposite phase. As a result, the fluctuation in the rotation speed of the engine 11 can be suppressed, and the NV (noise vibration) characteristics of the hybrid vehicle 1 can be improved.

The resolver signal of the resolver 33 is input to the PCU 15 to control the generator motor 12, regardless of whether the crank angle is estimated by the PCU 15. Therefore, there is no need to install new wiring to input the resolver signal to the PCU 15 to estimate the crank angle. This makes it possible to avoid the increase in costs due to new wiring and the risk of the wiring breaking. As a result, the weight of the hybrid vehicle 1 can be reduced and its reliability can be improved.

<Modification>
Although one embodiment of the present invention has been described above, the present invention can be embodied in other forms.

For example, in the above embodiment, a hybrid vehicle 1 equipped with a series hybrid system 2 was described, but the method of estimating the crank angle is not limited to the hybrid vehicle 1, and may be applied to conventional vehicles that use only an engine as a driving source for running, as long as the vehicle is equipped with an engine and a generator directly connected to the engine.

In addition, although the engine 11 is described as a three-cylinder, four-stroke gasoline engine, it is not limited to three cylinders, and may be four or more cylinders, or two or less cylinders. However, an odd number of cylinders allows the cylinders to be more easily identified using the cylinder identification method described above. In addition, the number of strokes of the engine 2 is not limited to four strokes, and may be, for example, two strokes.

In addition, various design modifications may be made to the above-mentioned configuration within the scope of the claims.

1: Hybrid vehicle (vehicle)
11: Engine 12: Generator motor (generator)
13: Drive motor 15: PCU (control unit)
21: Crankshaft 22: Motor shaft (rotating shaft)
23: Meshing mechanism 33: Resolver

Claims (2)

A four-stroke engine and
A generator,
a meshing mechanism that is interposed between the crankshaft of the engine and the rotating shaft of the generator and transmits power by meshing of teeth;
a resolver that outputs an electrical signal according to a rotation angle of the rotary shaft;
a control device to which an electrical signal from the resolver is input for controlling the generator,
the control device calculates the rotation angle from the electrical signal of the resolver, obtains fluctuations in the rotation speed of the rotating shaft from the electrical signal of the resolver, performs cylinder discrimination of the engine from the number of bottoms of the rotation speed within a range of 0 to 359° CA and the number of bottoms of the rotation speed within a range of 360 to 720° CA, and estimates a crank angle of the engine from the calculated rotation angle and the result of the cylinder discrimination. The vehicle according to claim 1, wherein the control device uses the estimated crank angle to control the generator so that a generator torque in antiphase with the instantaneous torque of the engine is applied to the engine.

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