JP2004183560A - Engine starter for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an engine starter for a vehicle capable of realizing size and weight reductions for a motor generator while restraining extension of the time necessary for engine start and wear to a clutch mechanism. <P>SOLUTION: With the clutch mechanism 7 disengaged in advance, a rotor of the motor generator 2 is rotated near the maximum torque position, and the clutch mechanism 7 is engaged later and the motor generator 2 is energized for engine start. Thus, engine start can be conducted even by the small-sized motor generator 2. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a vehicle engine starting device having a motor generator for starting an engine and generating power.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a vehicle engine starting device equipped with a motor generator that at least performs engine starting and power generation after engine starting is known. Also, a technology for connecting an engine and a motor generator through a clutch mechanism, connecting an auxiliary device (for example, a compressor for an air conditioner) to the motor generator, generating power while the engine is operating, and driving the auxiliary device when the engine is stopped. (Also referred to as an engine stop-time accessory driving technique) has been proposed.
[0003]
The technology of performing the above-described engine start and power generation with one AC rotating electric machine can reduce the number of rotating electric machines as compared with a conventional vehicle electric system using a DC motor and an AC rotating electric machine dedicated to power generation, Since there is no need to worry about commutator wear, the reliability of idle-stop vehicles that require frequent engine startup can be improved.
[0004]
However, the above-described AC rotating electric machine (usually a synchronous machine) for both engine start and power generation has a significantly larger physique and weight than the conventional AC electric rotating machine dedicated to power generation because of the large torque required for engine start. There was a problem of increasing.
[0005]
On the other hand, in the following Patent Document 1, the clutch mechanism is disconnected at the time of starting the engine, the motor generator is rotated to a certain number of revolutions, and then the clutch mechanism is joined to use the inertia energy of the motor generator for starting the engine. It has been proposed to reduce the required torque of the motor generator, thereby reducing its size and weight.
[0006]
[Patent Document 1] Japanese Patent Application Laid-Open No. 2002-89417
[Problems to be solved by the invention]
However, in the engine starting method disclosed in the above-mentioned publication (hereinafter also referred to as an inertial starting method), the time required for starting the engine is extended by the time required for starting the rotation speed of the motor generator. In addition to the disadvantage that the clutch mechanism cannot be joined with the rotating shaft pair in a stationary state, there is a problem that the clutch mechanism is consumed.
[0008]
The present invention has been made in view of the above problems, and provides a vehicle engine starting device capable of realizing a small and lightweight motor generator while suppressing an increase in the time required for starting the engine and the consumption of a clutch mechanism. That is the purpose.
[0009]
[Means for Solving the Problems]
The vehicle engine starter of the present invention is suitably applied to a so-called idle stop vehicle, has a rotation angle sensor for detecting the rotation angle of the motor generator, and has a bidirectional power supply to the engine via a clutch mechanism. A motor generator comprising a synchronous machine communicably connected to the motor generator, a DC power source and an electric load disposed between the motor generator and the motor generator for performing bi-directional orthogonal power conversion, and the motor generator operates when the motor generator operates electrically. An inverter circuit for applying a pulse voltage or a stepwise step voltage to the generator; and controlling the inverter circuit based on the rotation angle at the time of inputting an engine start command to thereby reduce the generated torque of the motor generator to the clutch mechanism. And a controller for performing an engine start operation for starting the engine by transmitting the engine to the engine through the engine In the engine starting device,
The controller performs a rotor preliminary rotation operation of rotating the rotor to near a maximum torque position in a state where the clutch mechanism is disconnected in advance before performing the engine start operation. As a result, it is possible to prevent an increase in the time required for starting the engine when the engine is started using the motor generator that performs engine start and power generation, and to reduce the size and weight of the motor generator while suppressing wear of the clutch mechanism. Can be.
[0010]
That is, when a pulse voltage or a stepwise changing step voltage is applied to the motor generator, the magnitude of the electric torque may periodically change due to a change in the rotation angle of the rotor, more precisely, a change in the position of the rotor magnetic pole. Are known. For example, in a three-phase synchronous machine, a generated torque maximum position point occurs at every electrical angle π / 3.
[0011]
In the device configuration in which the motor generator is connected to the engine through the clutch mechanism, the present inventor has disclosed that the clutch mechanism can be disconnected and the motor generator can be freely rotated while the engine is stopped, and that the motor generator can be rotated periodically. It focuses on a combination with a simple torque fluctuation phenomenon, and the motor generator is preliminarily rotated to the maximum position of the generated torque in the above-mentioned periodic fluctuation before starting the engine using the free rotation function of the motor generator. As a result, the torque of the motor generator, that is, the engine starting torque at the time of subsequent engine start can be maximized, so that the motor generator can be downsized accordingly, and further, the abrasion of the clutch mechanism is reduced because the above-mentioned inertial start is not performed. can do.
[0012]
In a preferred aspect, the motor generator is connected to a predetermined auxiliary machine without passing through the clutch mechanism, and the controller is configured to control the motor generator to drive the auxiliary machine when the engine start command is input. It is characterized in that the engine starting operation is performed without performing the rotor preliminary rotation operation.
[0013]
Thus, for example, in a motor generator device having an engine start / power generation / independent auxiliary device driving function for an idle stop vehicle that drives an auxiliary device (usually a compressor for an air conditioner) when the engine is stopped, the motor generator drives the auxiliary device. In this case, the engine can be started immediately by using its own inertial energy without performing the rotor pre-rotation operation, and it is necessary to start the engine by performing the rotor pre-rotation operation after the input of the engine start command. It is possible to solve the problem that the time is long, and as a result, even when the motor generator is stopped or when the auxiliary machine is driven, quick engine start can be realized by the small motor generator.
[0014]
In a preferred aspect, the controller performs the rotor pre-rotation operation immediately after the engine is stopped or immediately after the driving of the auxiliary device by the motor generator is stopped. Thus, the engine start operation can be started immediately when the engine start command is input, and the time required for the engine start is not extended by the preliminary rotation. The rotor preliminary rotation operation can be performed by rotating the rotor slowly at the end of the deceleration period of the motor / generator for stopping the engine or the auxiliary machine, so that the motor or the auxiliary machine is stopped. Power consumption for the rotor preliminary rotation operation can be reduced as compared with the case where the rotor preliminary rotation operation is performed again after the generator is stopped.
[0015]
In a preferred aspect, the controller performs an engine stop position setting operation for stopping the engine near a load torque minimum position when the engine is stopped, and then performs the rotor preliminary rotation operation by disconnecting the clutch mechanism. , The operation of engaging the clutch mechanism is performed.
[0016]
The load torque of the engine mainly consists of a load torque component caused by frictional force and a load torque component caused by pumping work.The latter periodically changes depending on the rotation angle of the engine. It becomes the largest when starting over the static friction force. Therefore, in this embodiment, when starting the engine, the load torque of the engine is minimum and the generated torque of the motor generator is maximum, so that the torque required for starting the engine is further reduced and the motor generator is downsized. be able to.
[0017]
In a preferred aspect, the controller rotates the rotor of the motor generator in a range from a maximum torque position of −10 degrees to a maximum torque position of +10 degrees by the preliminary rotation. Thereby, the engine starting torque generated by the motor generator can be increased satisfactorily.
[0018]
In a preferred aspect, the motor generator comprises a three-phase synchronous machine, and controls the energization of the inverter circuit by 120 degrees at least at the initial stage of the engine start. If the engine speed exceeds a predetermined value, the inverter circuit rotates the inverter circuit by 180 degrees. Control energization.
[0019]
The starting torque of the synchronous machine is maximized when the 120-degree conduction control is performed, but the torque at high speed is larger when the control is controlled by 180-degree conduction or sine wave conduction. Therefore, according to this aspect, the torque at the start of the engine start, that is, the start torque is improved, and the increase in the engine speed after the engine speed is increased by the engine start is increased (improved blow-up). The time required for starting the engine can be further reduced.
[0020]
BEST MODE FOR CARRYING OUT THE INVENTION
A preferred embodiment of the vehicle engine starter according to the present invention will be described below with reference to the block diagram shown in FIG.
[0021]
(Description of overall configuration)
In FIG. 1, 1 is an engine, 2 is a motor generator, 3 is a rotation angle sensor, 4 is a battery, 5 is an electric load, 6 is an inverter circuit, 7 is a clutch mechanism, 8 is a controller, 9 is a belt, and 10 is an air conditioner. Compressor (auxiliary equipment).
[0022]
The engine 1 is connected to the engine pulley through a clutch mechanism 7 built in the engine pulley. The engine pulley is connected to a pulley and a belt 9 fixed to the rotating shafts of the motor generator 2 and the compressor (auxiliary machine) 10 for an air conditioner. Are linked.
[0023]
The motor generator 2 is composed of a three-phase synchronous machine, exchanges power with the battery 4 through the inverter circuit 6 and supplies power to the motor generator 2.
[0024]
The inverter circuit 6 connects the motor generator 2 and the battery 4 so that bidirectional orthogonal power conversion is possible, and converts DC power supplied from the battery 4 to three-phase AC power in the electric operation of the motor generator 2 to generate electric power. The power is supplied to the generator 2, and the three-phase AC power generated by the motor generator 2 in the power generation operation of the motor generator 2 is subjected to three-phase full-wave rectification and supplied to the battery 4 and the electric load 5. In this embodiment, the inverter circuit 6 is a three-phase inverter circuit having three upper arms and three lower arms, and each arm includes a switching element and a diode connected in anti-parallel to the switching element. When a MOS transistor is used, the switching element can also serve as a diode. The th controller 8 configures each arm of the inverter circuit 6 based on a rotation angle signal output by the rotation angle sensor 3 when the motor generator 2 operates electrically. In addition to intermittently controlling the switching element to be operated, the disengagement of the electromagnetic clutch constituting the clutch mechanism 7 is controlled.
[0025]
The above-described vehicle engine starting device has a well-known configuration, and further detailed description will be omitted.
[0026]
FIG. 2 shows an electric circuit system of the vehicle engine starter shown in FIG. In FIG. 2, reference numeral 2a denotes a rotor of the motor generator 2, and 2b denotes three phase coils constituting stator coils of the motor generator 2.
[0027]
FIG. 3 illustrates the torque fluctuation phenomenon of the motor generator 2. When sine wave energization control (see FIG. 4) for energizing a sine wave to the three-phase stator coil of the motor generator 2 is performed, there is almost no periodic fluctuation of the electric torque, but 120 degree energization control (see FIG. 6). ) Or 180-degree energization control (see FIG. 5), torque ripple occurs at a 60-degree electrical angle cycle. The cause of the torque ripple is that in the 120-degree conduction control and the 180-degree conduction control, the applied voltage waveform is considerably distorted from the sine wave, and the torque fluctuates in accordance with the distortion.
[0028]
(Description of torque pulsation of synchronous motor)
Next, the difference in the starting torque at the time of starting the motor due to the difference in each energization control method will be described below with reference to FIGS. 7 to 12 show vector voltages of respective phases in the U, V, and W coordinate systems in which the U-phase vector voltage is set in the vertical direction on the paper surface and their combined vector voltages. It is assumed that a vector voltage in the same direction as the arrow symbol on the U, V, and W coordinate axes has a voltage value in the positive direction, and a vector voltage in the opposite direction has a voltage value in the negative direction. The length of each vector voltage indicates the magnitude of the voltage, the number described near each vector voltage indicates the magnitude of the vector voltage, and the number described in bold indicates the magnitude of the three-phase combined vector voltage.
[0029]
7 to 9 show the vector voltages of the respective phases and their combined vector voltages when the rotor is at electrical positions of 0 degree, 30 degrees, 60 degrees, and 90 degrees in order from the left, respectively. Reference numeral 12 denotes a combined vector voltage (indicated by a solid line) when the rotor is located at an electrical angle of 0 degree, 15 degrees, and 30 degrees in order from the left, and a projected vector voltage obtained by projecting the combined vector voltage onto an axis having a predetermined phase ( (Indicated by a broken line).
[0030]
The axis having the predetermined phase is an axis having an energization phase that maximizes the torque generated by the electric motor, and is indicated by a chain line in the figure. Actually, the energization phase slightly changes depending on conditions such as current and rotor specifications, but here it is assumed that the phase is simply advanced by 90 degrees electrical angle from the main magnetic flux of the rotor.
[0031]
FIG. 7 shows a phase vector voltage and a composite vector voltage in the case where sine wave energization control is performed. In the sine wave energization control, the resultant vector voltage continuously rotates at the same magnitude continuously following the rotor position.
[0032]
FIG. 8 shows the phase vector voltage and the combined vector voltage when performing the 180-degree conduction control. In the 180-degree energization control, a combined vector voltage having the same magnitude as that of the sine-wave energization control intermittently follows the rotor position and rotates (switches) at an electrical angle of 60 degrees.
[0033]
FIG. 9 shows changes in the phase vector voltage and the combined vector voltage when the 120-degree conduction control is performed. In the 120-degree energization control, the magnitude of the combined vector voltage is larger than in the sine-wave energization control or the 180-degree energization control, but the phase intermittently follows the rotor position at 60-degree intervals as in the 180-degree energization control. Rotate (switch).
[0034]
FIG. 10 shows the phase relationship between the combined vector voltage and the rotor in the sine wave energization control. Since the rotor always rotates synchronously with the resultant vector voltage, a constant torque is always generated regardless of the phase (rotational position) of the rotor.
[0035]
FIG. 11 shows the phase relationship between the combined vector voltage and the rotor in the 180-degree conduction control. As described above, in the 180-degree energization control, the phase of the combined vector voltage is switched in a stepwise manner. For example, at an electrical angle of 0 degree or 15 degrees, the combined vector voltage phase and the rotor phase are shifted. The vector component (voltage component that generates torque) projected on the one-dot chain line becomes small, and eventually the torque fluctuates in a cycle of 60 electrical degrees according to the rotation of the rotor.
[0036]
FIG. 12 shows the phase relationship between the combined vector voltage and the rotor in the 120-degree conduction control. As described above, even in the 120-degree conduction control, the phase of the combined vector voltage is switched stepwise. For example, at an electrical angle of 15 degrees or 30 degrees, the combined vector voltage phase and the rotor phase are shifted. The vector component (voltage component that generates torque) projected on the one-dot chain line becomes small, and eventually the torque fluctuates in a cycle of 60 electrical degrees according to the rotation of the rotor.
[0037]
As shown in FIG. 3, the maximum torque in the 120-degree conduction control is about 15% larger than the maximum torque in the 180-degree conduction control. Therefore, at the start of the engine start, it is preferable to employ the 120-degree conduction control. However, despite this, the reason why the 180-degree conduction control is usually adopted is that the 180-degree conduction control has a higher effective average voltage than the 120-degree conduction control.
[0038]
(Explanation of engine start control)
Next, a control example of the vehicle engine starter of this embodiment described above will be described below with reference to a flowchart shown in FIG.
[0039]
First, it is determined whether or not the motor generator 2 is rotating based on an input signal from the rotation angle sensor 3 (S100). If the motor generator 2 is rotating, a command is issued to the clutch mechanism 7 (S102). To start the engine 1 by controlling the current of the motor generator 2 (S104). When the engine speed or the number of revolutions of the motor generator 2 reaches a predetermined value, it is determined that the engine has been started (S105). End the start control. The fact that the motor generator 2 is rotating usually means that the motor generator 2 is driving the air conditioner compressor (auxiliary machine) 10. In this case, since the motor generator 2 starts the engine using its own inertial energy (kinetic energy), the engine can be started without any problem even if the generated torque is slightly small.
[0040]
Next, when it is determined in step S100 that the engine 1 is stopped, the rotor rotation position is set near the maximum torque generation position stored in advance based on the input signal from the rotation angle sensor 3 (+/- electrical angle before and after that). (In the range of −10 degrees) (S106). Otherwise, the current rotor rotational position is read (S108), and the maximum (or predetermined) maximum torque generation position closest to the current rotor rotational position is determined. Is calculated (S110), the stator coil of the motor generator 2 is energized for a predetermined time in order to rotate the rotor in a direction to reduce the phase difference (S112), and the routine returns to step S106. Repeatedly, the rotor rotation position is set near the maximum torque generation position.
[0041]
In step S106, when the rotor rotation position is near the maximum torque generation position stored in advance, the process proceeds to step S114, where the clutch mechanism 7 is instructed to engage (S114), and it is determined whether the rotor rotation speed exceeds a predetermined value. If it does not exceed (S116), the motor generator 2 is started by the 120-degree energization control (S118), and the process returns to step S116. If the rotor speed exceeds the predetermined value in step S116, the control is switched to the 180-degree energization control to drive the motor generator 2 (S120), and the process proceeds to step S105.
[0042]
(Modification)
FIG. 14 shows a modification of the above embodiment.
[0043]
In this modification, the clutch mechanism 7 is built in a pulley of the motor generator 2. In this case, the same operation and effect as described above can be obtained.
[0044]
(Modification)
FIG. 15 shows a modification of the above embodiment.
[0045]
In this modification, the clutch mechanism 7 is built in the pulley of the motor generator 2 (or is disposed between the motor generator pulley and the rotating shaft of the motor generator 2), and the auxiliary machine 10 is omitted. I have. In this case, the same operation and effect as described above can be obtained. In this modification, it is also possible to directly connect an auxiliary machine to the rotating shaft of the motor generator 2.
[0046]
(Modification)
In the above embodiment, the preliminary rotation shown in steps S106 to S112 was performed at the time of starting the engine, but it is also preferable to perform the preliminary rotation at the time of stopping the engine. The control operation in this case will be described below with reference to the flowchart shown in FIG.
[0047]
First, it is determined whether or not an engine stop command has been input. When the engine stop command has been input, the engine 1 is stopped, and the engine stop position is determined by the torque from the motor generator 2 in the final stage of the engine deceleration operation. 1 is a position where the load torque is minimized.
[0048]
Next, the clutch mechanism 7 is disengaged, and thereafter, the rotation of the motor generator 2 is controlled (preliminary rotation), the rotor of the motor generator 2 is guided to the maximum torque generating position, and the process returns to the main routine. . In this way, the size of the motor generator 2 can be further reduced.
[0049]
Even when the motor generator 2 drives the air conditioner compressor (auxiliary machine) 10 and then stops, the same effect can be obtained by stopping the rotor at the maximum torque generating position as described above. .
[Brief description of the drawings]
FIG. 1 is a block diagram showing a preferred embodiment of a vehicle engine starter according to the present invention.
FIG. 2 is a circuit diagram showing a main part of an electric circuit of the vehicle engine starter shown in FIG.
FIG. 3 is a timing chart showing a torque fluctuation phenomenon of the motor generator.
FIG. 4 is a timing chart showing a sine wave energization control for applying a sine wave to a three-phase stator coil of the motor generator.
FIG. 5 is a timing chart showing a change in each phase voltage when the motor generator is controlled to conduct 120 degrees.
FIG. 6 is a timing chart showing a change in each phase voltage when a 180-degree energization control of the motor generator is performed.
FIG. 7 is a vector diagram showing vector voltages of respective phases and their combined vector voltages in the sine wave energization control.
FIG. 8 is a vector diagram showing vector voltages of respective phases and their combined vector voltages in the 180-degree energization control.
FIG. 9 is a vector diagram showing vector voltages of respective phases and their combined vector voltages in 120-degree conduction control.
FIG. 10 is a vector diagram showing a phase relationship between a combined vector voltage and a rotor in sine wave energization control.
FIG. 11 is a vector diagram showing a phase relationship between a combined vector voltage and a rotor in 180-degree energization control.
FIG. 12 is a vector diagram showing a phase relationship between a combined vector voltage and a rotor in 120-degree conduction control.
FIG. 13 is a flowchart showing an engine start control operation in this embodiment.
FIG. 14 is a block diagram showing a modified embodiment of the vehicle engine starter of the present invention.
FIG. 15 is a block diagram showing a modified embodiment of the vehicle engine starter of the present invention.
FIG. 16 is a flowchart showing an engine stop control operation according to a modified embodiment.
[Description of sign]
Reference Signs List 1 engine 2 motor generator 3 rotation angle sensor 4 battery 5 electric load 6 inverter circuit 7 clutch mechanism 8 controller 9 belt 10 compressor for air conditioner (auxiliary machine)

Claims (6)

A motor generator comprising a synchronous machine having a rotation angle sensor for detecting a rotation angle of the motor generator and being coupled to the engine via a clutch mechanism so as to be capable of bidirectional power transmission;
A pulse voltage or a step voltage that changes stepwise is applied to the motor generator when the motor generator operates electrically while being arranged between a DC power supply and an electric load and the motor generator to perform bidirectional orthogonal power conversion. An inverter circuit,
A controller for performing an engine start operation of starting the engine by transmitting the generated torque of the motor generator to the engine through the clutch mechanism by controlling the inverter circuit based on the rotation angle at the time of inputting an engine start command;
In a vehicle engine starter comprising:
The controller is
An engine starting device for a vehicle, wherein a preliminary rotation operation of a rotor for rotating the rotor to a position near a generated torque maximum position in a state where the clutch mechanism is disengaged in advance is performed before performing the engine starting operation. . The engine starting device for a vehicle according to claim 1,
The motor generator is connected to a predetermined accessory without passing through the clutch mechanism,
The controller is
An engine starting device for a vehicle, wherein the engine starting operation is performed without performing the rotor preliminary rotation operation when the motor generator drives the auxiliary machine at the time of inputting the engine starting command. The vehicle engine starting device according to claim 1 or 2,
The controller is
The engine starting device for a vehicle, wherein the rotor preliminary rotation operation is performed immediately after the engine is stopped or immediately after the driving of the auxiliary device by the motor generator is stopped. The engine starting device for a vehicle according to claim 3,
The controller is
At the time of stopping the engine, an engine stop position setting operation for stopping the engine near the minimum load torque position is performed, then the clutch mechanism is disconnected to perform the rotor preliminary rotation operation, and then the clutch mechanism is engaged. A vehicle engine starting device that performs operations. The engine starting device for a vehicle according to claim 1,
The controller is
A vehicle engine starting device for rotating the rotor of the motor generator in a range from a maximum generated torque position −10 degrees to a maximum generated torque position +10 degrees by the preliminary rotation. The vehicle engine starting device according to any one of claims 1 to 5,
The motor generator comprises a three-phase synchronous machine,
The controller is
An engine starting device for a vehicle, wherein the inverter circuit is energized by 120 degrees at least at an early stage of the engine start, and the inverter circuit is energized by 180 degrees or sine wave energized when the engine speed exceeds a predetermined value.

Images