JP3418357B2 - Vehicle drive assist device and control method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle drive assist device having an electric motor with a speed reducer, and more particularly to a vehicle drive assist device and control method suitable for use in a drive device and a starter of a four-wheel drive vehicle. It is about.

[0002]

2. Description of the Related Art An automobile is equipped with various types of electric motors with reduction gears such as a drive device for driving wheels of a four-wheel drive vehicle and a starter for driving an engine at the time of start as an assist device for driving the vehicle.

First, a vehicle drive assist device will be described by taking a wheel drive device of a four-wheel drive vehicle as an example. A four-wheel drive vehicle has a function of assisting the starting force by increasing the driving force of the rear wheels at the time of starting. Especially, the starting assist from a low μ road such as a snow road or an icy road surface, a step or a road surface with a rut It is suitable for vehicle start assistance or continuous uphill driving on low μ roads.

When the four-wheel drive vehicle turns, it is necessary to make the rotation speeds of the front wheels and the rear wheels different from each other, and it is necessary to provide a rotation difference absorbing means in the power transmission path from the engine to the rear wheels. In a conventional drive device for a four-wheel drive vehicle, for example, Japanese Patent Application Laid-Open No. 2-2
As described in Japanese Patent No. 34846, a rotation difference absorbing means including a reduction mechanism including gears and carriers and carrier drive control means is provided in a power transmission path from an engine to a rear wheel side through a propeller shaft. Things are known.

Further, in a hybrid vehicle in which the front wheels are driven by an engine and the rear wheels are driven by an electric motor with a speed reducer, when the vehicle starts, a starting acceleration corresponding to the road surface condition is obtained, and the electric motor is controlled so as to obtain this acceleration. However, the one having improved start-up acceleration property is described in Japanese Patent Laid-Open No. 5-131858.

Further, the four-wheel drive system comprises a generator, an electric motor, and drive control means, the generator converts the energy of the internal combustion engine into electric energy, and the drive control means controls the supply of electric energy to operate the electric motor. However, JP-A-7
No. 231508. Electric power is supplied to the drive control means from a 12V system battery. FIG. 4 of this publication shows that the rear wheel drive unit 15 is constituted by the differential 31, the gearbox 32, and the clutch mechanism 33.

Also, in a hybrid vehicle in which the front wheels are driven by the engine and the rear wheels are driven by an electric motor with a speed reducer, the electric motor drive section is efficiently housed in the tunnel of the vehicle body to prepare an effective space on the passenger compartment floor. The one that can be obtained is described in JP-A No. 11-099838.

Further, in a front and rear wheel drive vehicle in which one of the front and rear wheels is driven by an engine and the other is driven by an electric motor,
Japanese Patent Application Laid-Open No. 9-2090 discloses a method in which the driving torque of wheels driven by an engine is detected at the time of starting on a low μ road where starting assistance is required and the electric motor is operated when the driving torque is smaller than a predetermined value. It is described in Japanese Patent Publication No.

On the other hand, from the viewpoint of environment and fuel consumption, it is detected that the vehicle is temporarily stopped (accelerator-off) due to people getting on and off, loading and unloading luggage, waiting for a signal, etc., and the engine is automatically operated. An engine with an automatic idle stop function to stop the engine is being developed. In this case, the vehicle drive assist device must promptly start the vehicle and increase the vehicle speed so that the vehicle can smoothly start traveling when the accelerator is depressed after the idle stop.

[0010]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
In the case where the propeller shaft is interposed in the power transmission path to the rear wheels by using the engine as the power source like the one described in Japanese Patent Publication No. 6, a delay in power transmission via the propeller shaft cannot be avoided and the vehicle is started. It is inferior in start acceleration on low μ roads that require assistance.

Further, as described in Japanese Patent Laid-Open No. 9-2090, the electric motor is operated after the driving torque of the wheels driven by the engine is detected, in other words, the vehicle starts to move. The vehicle is inferior in start-up acceleration because the vehicle start speed, that is, the vehicle speed is zero when the vehicle start assist cannot be obtained.

Further, in the conventional example, the system in which the rear wheel is driven by the electric motor with a speed reducer in order to improve the starting acceleration property has a complicated structure, is large, and is high in cost. In order to reduce the cost of the motor, it is possible to adopt a DC motor with a simple control circuit, but in order to extend the life of the brush, it is necessary to increase the radial length,
Not suitable for mounting in a narrow space under the vehicle floor.

Further, as shown in FIG. 4 of Japanese Patent Application Laid-Open No. 7-231508, the rear wheel drive unit 1 includes a differential 31, a gear box 32 and a clutch mechanism 33.
In the structure in which 5 is integrally configured and the rotation of the electric motor is transmitted to the rear wheel drive unit 15, the transmission torque of the clutch cannot be increased, and therefore, the electric motor with the reduction gear can be downsized. Has a limit, and it is difficult to secure the space required for mounting it under the floor of the vehicle.

On the other hand, since the electric motor with reduction gear as a starter for driving the engine at the time of starting has a meshing coupling system of the pinion and the ring gear, there is a collision between the pinion and the ring gear at the time of meshing and a large diameter at the time of starting. If the ring gear continues to run idly, the pinion, the ring gear, and the wear are likely to occur, and the durability as a starter is usually 200,000 to 400,000 times. If such a starter is used in an engine with an automatic idle stop function that frequently starts and stops, it cannot be used for a long period of time due to restrictions in terms of durability. There is a need for a vehicle drive assist device that is more durable as a starter.

An object of the present invention is to provide a vehicle drive assist device and a control method as a vehicle drive assist device having a motor with a reduction gear, which is compact and has high performance and can be easily installed even in a narrow space such as under the floor of the vehicle. To do.

Another object of the present invention is to provide, as a vehicle drive assist device having an electric motor with a speed reducer, a vehicle drive assist device which is inexpensive, compact, and easily mountable in a narrow space such as under the floor of the vehicle. Especially.

Another object of the present invention is to provide a vehicle drive assist device which is excellent in durability and is suitable for a starter of an engine having an automatic idle stop function.

[0018]

A feature of the present invention is a vehicle drive assist device including an electric motor with a speed reducer, wherein the electric motor with a speed reducer includes a DC shunt winding motor and a DC shunt winding motor. A decelerator for decelerating the rotation of the armature shaft and transmitting it to the decelerator shaft, and an electromagnetic clutch for connecting a clutch shaft to the decelerator shaft are integrally formed. And a plurality of bearings are arranged such that the shafts of the electromagnetic clutch are on the same axis.

Another feature of the present invention is a vehicle drive assist device including an electric motor with a speed reducer, wherein the electric motor with a speed reducer has a structure in which a DC shunt winding motor, a speed reducer and an electromagnetic clutch are integrated. The relationship between the diameter D of the armature core of the DC shunt winding motor and the radial thickness L of the field winding is L≈1 / 2 (1 ± 0.2) D.

Another feature of the present invention is a vehicle drive assist device including an electric motor with a speed reducer, wherein the electric motor with a speed reducer has a structure in which a DC shunt winding motor, a speed reducer and an electromagnetic clutch are integrated. Each of the DC shunt winding motor, the speed reducer, and the shaft of the electromagnetic clutch is provided with a plurality of bearings arranged on the same axis, and the maximum armature current of the DC shunt winding motor is set. 200-400
A, the maximum field current is about 20 A or less, and the relationship between the diameter D of the armature core and the radial thickness L of the field winding is L≈1 / 2 (1 ± 0.2)
It is called D.

Another feature of the present invention is a four-wheel drive vehicle in which either the front wheel or the rear wheel of the vehicle is driven by the engine, and the vehicle drive assist device assists the drive of the other wheel during a predetermined operation. Drive device.

Another feature of the present invention is that in a vehicle drive device including an engine and a starter for driving the engine at the time of starting, the starter is the vehicle drive assist device.

According to the present invention, by forming the electric motor, the speed reducer, and the electromagnetic clutch as an integral structure in advance as the electric motor with the speed reducer of the vehicle drive assist device,
The shaft accuracy can be improved and the air gap of the electromagnetic clutch can be made highly accurate, and the electromagnetic clutch can be downsized on the premise of aging in the state of the integrated structure.

Further, the input circuit to the shunt winding motor constituting the motor with a speed reducer of the vehicle drive assist device is configured by parallel circuits for armature winding and field winding, and the armature of the shunt winding motor is provided. By supplying a large current to the windings and a small current to the field windings, it is possible to reduce the external dimensions of the electric motor while generating the drive torque required for the electric motor.

As described above, according to the present invention, the integrated structure of the vehicle drive assist device, that is, the electric motor, the speed reducer, and the electromagnetic clutch can be compactly assembled, so that the space required for mounting the vehicle under the floor can be reduced. .

The motor of the vehicle drive assist device is a DC shunt winding motor, and the maximum armature current is 20.
By setting the field current to about 0 to 400 A and the maximum field current to about 20 A or less, the input circuit to the shunt winding motor is configured by a parallel circuit for armature winding and field winding to supply the field current. By incorporating the system and its control circuit into the existing control circuit and sharing the microcomputer, the current supply system and its control circuit can be made inexpensive and the burden on the battery can be reduced.

Further, by supplying a large current to the armature winding and a small current to the field winding of the DC shunt winding electric motor of the vehicle drive assist device, the electric motor can be generated while generating the driving torque required for the electric motor. The outer dimensions of the brush can be reduced, and the brush length can be increased to prolong the life of the brush.

Further, since the electric motor with speed reducer for the vehicle drive assist device of the present invention has a high durability and a high torque transmission efficiency of the electromagnetic clutch, if it is used as a starter for an engine with an automatic idle stop function, it will reduce environmental impact and fuel consumption. Exerts an excellent effect on.

[0029]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment in which the present invention is applied to a wheel drive device of a four-wheel drive vehicle will be described below with reference to the drawings. FIG. 1 shows the overall configuration of a four-wheel drive vehicle that employs a drive device according to an embodiment of the present invention. The front wheel 3 of the four-wheel drive vehicle 1 is driven by the engine 2, and the rear wheel 4 is driven by the DC motor 5. An alternator 6 is driven by the engine 2 and its output is stored in the battery 7. The electric motor 5 integrally includes a speed reducer and an electromagnetic clutch 8 (electric motor with a speed reducer), and is connected to the axle of the rear wheel 4 via a differential gear 9 and a drive shaft. When the electromagnetic clutch 8 is turned on, the output shaft of the speed reducer driven by the electric motor 5 is connected to the differential gear 9 via the electromagnetic clutch 8.
When the electromagnetic clutch 8 is turned off, the electric motor 5 is disconnected from the rear wheel 4 side. It is desirable that the electric motor 5 be a DC shunt winding electric motor that allows easy switching between forward and reverse rotation.

Reference numeral 10 denotes an electric motor controller equipped with a microcomputer, which generates a signal for controlling the armature current of the electric motor 5 based on the vehicle speed signal S and the like,
It controls the output of the power module 11 arranged between the electric motor 5 and the battery 7 which is the power source thereof. It also supplies a controlled field current to the field winding of the electric motor 5.

The external dimensions of the integrated structure of the electric motor 5, the speed reducer and the electromagnetic clutch 8 (electric motor with speed reducer) is preferably equal to or less than the external dimension of the differential gear 9, for example, 200 mm or less. And

The front wheel 3 and the rear wheel 4 of the four-wheel drive vehicle 1 are provided with wheel speed sensors 21, and the ABS control unit 71 equipped with a microcomputer detects the road surface speed based on the output of each wheel speed sensor 21. The friction coefficient μ is calculated, and the ABS actuator 72 is operated so that the braking force corresponding to the value of μ is applied to the brake 20 corresponding to each wheel. On the other hand, 73 is an engine control unit that includes a microcomputer and controls the engine 2.

FIG. 2 shows a circuit configuration example relating to the power supply and control of the embodiment shown in FIG. Reference numeral 100 is a power control unit corresponding to the power module 11 of FIG. 1, and 120 is a signal control unit corresponding to the electric motor controller 10 of FIG. The signal control unit 120 includes a microprocessor 122 that generates a drive signal for the H-bridge driver, an H-bridge driver 125, and an H that includes switching elements MOS3 to MOS6.
It is composed of a bridge 126. The microprocessor 122 includes a CPU and a memory that holds a program and data for controlling the electric motor, and has an I / O 121 and an A / D.
The direction of the field current of the electric motor 5 and the armature current value are calculated based on the information of the vehicle speed sensor 21, the gear position detector 31, and the accelerator opening sensor 32 input via the conversion device 122, and the result is It is output via the I / O 121. The microprocessor 122 may have a function of controlling the alternator 6 in order to maintain the voltage of the battery 7 at a predetermined value.

The input circuit to the shunt winding motor 5 is composed of parallel circuits for armature winding and field winding. That is, the battery 7 has two batteries, that is, a 36V battery 7A and a 12V battery 7B, and correspondingly, there are also two alternators, an alternator 6A having an output of 42V and an alternator 6B having an output of 14V.

The armature winding 51 of the electric motor 5 has 36
36V power is supplied from the V battery 7A through the power line 12 and the power switch MOS1 104 of the power control unit 100.

On the other hand, in the field winding 52 of the electric motor 5, from the 12V battery 7B to the power line 13, the H bridge 126 (MOS3 of the signal control unit 120).
6), 12V power is supplied through the power line 14. H bridge 126 by H bridge driver 125
The switching element is driven to switch the direction of the field current between forward and reverse.

In the present invention, a parallel circuit is adopted, and the input current to the field winding is increased by increasing the input current to the armature winding by changing the diameter and the number of turns of the armature winding and the field winding. Can be set small. For example, the maximum armature current is 200-400A
The field current is set to about 20 A or less at the maximum.

The microprocessor 122 of the signal control unit 120 controls the power based on the output of the vehicle speed sensor 21, the accelerator opening sensor 32, etc., and the detection value of the current sensor 102 for detecting the current of the armature winding 51. Power switch MO of unit 100
A signal G1 for controlling S1 104 is generated to drive the power switch MOS1 104 via the signal line 128.

Further, the microprocessor 122 generates an on / off signal of the electromagnetic clutch 8 to generate a power switch M.
The OS2 106 is driven to turn on / off the power supply line 129 of the electromagnetic coil 81 of the electromagnetic clutch 8.

In the present invention, since the field current is set to a small value of about 20 A, the field current supply system, that is, the power lines 13 and 14 are provided on the same board as the signal control unit 120 including the microprocessor 122. Can be formed within. The signal lines to and from the microprocessor 122 can of course be formed on the same substrate as the signal control unit 120. Further, since the current flowing through the power supply line 129 of the electromagnetic coil 81 of the electromagnetic clutch 8 is about 10 A, it can be formed together with the power switch MOS2 106 on the same substrate as the signal control unit 120.

Next, FIGS. 3 and 4 show examples of the configuration of the electric motor with reduction gear shown in FIG. FIG. 3 is a vertical cross-sectional view of the electric motor with reduction gear, and FIG. 4 is a horizontal cross-sectional view of the electric motor portion of the electric motor with reduction gear shown in FIG. The electric motor 5 is integrated with the speed reducer 54 and the electromagnetic clutch 8 to form one electric motor with a speed reducer.

The speed reducer 54 is composed of three planetary gears 56 meshing with gears provided on the armature shaft 57 of the electric motor 5 and one internal gear 55 inwardly rotating these planetary gears 56. A speed reducer shaft 58 is connected to 55. The reduction gear ratio is set to be slightly larger, 10 to 15, and the reduction gear shaft side is made smaller. This also allows the pulley to be arranged outside the electromagnetic clutch 8.

The electromagnetic coil of the electromagnetic clutch 8 is arranged on the outer periphery of the speed reducer shaft 58, and
8 and a pair of disks connected to the clutch shaft 59 are engaged and disengaged by an electromagnetic coil. In addition, since the radius of the clutch 8 portion is increased in order to increase the clutch torque, the outer diameter of the clutch 8 is the largest in the motor with a reduction gear.

As described above, 36 V of electric power is supplied to the armature winding 51 of the electric motor 5, 12 V of electric power is supplied to the field winding 52, and the input current to the armature winding is large. The input current to the field winding is set small. Since high-voltage, large-current power is supplied to the armature winding 51, the number of turns can be reduced and the armature core 51A can be miniaturized, that is, the radius can be reduced. On the other hand, since the field winding 52 is supplied with electric power of lower voltage and smaller current, the number of turns is increased.

As described above, the armature winding 51 and the field winding 52 (field core 52A) are supplied with electric powers of different magnitudes from the two power sources, and the radius 1 / 2D of the armature core 51A of the shunt winding motor 5 and the field. One of the characteristics of the present invention is that the thickness L of the winding wire 52 in the radial direction is made substantially equal.

Since the radius of the armature core 51A becomes smaller, the radius of the commutator 53A also becomes smaller, and the length of the brush 53 in the radial direction can be made sufficiently long to prolong the life of the brush. In consideration of the installation space under the floor of the vehicle, the length of the brush 53 is sufficiently set by setting the outer diameter of the portion of the electric motor 5 in which the brush 53 is accommodated to the maximum size corresponding to the outer diameter of the speed reducer 54. Can be long.

Further, the armature shaft 5 of the electric motor 5
Bearings 60 to 64 are arranged on the shafts of 7, the speed reducer shaft 58, and the clutch shaft 59 so as to be on the same axis, and the shaft accuracy of each of these bearings can be improved. As a result, the air gap of the electromagnetic clutch can be highly accurate to about 0.3 mm. This increases the suction torque of the electromagnetic clutch 8. As an example, in the case of an electric motor with a reducer having an integrated structure of an electric motor, a speed reducer and an electromagnetic clutch, it is possible to generate about 2.5 times as much transmission torque as compared with a structure in which the electric motor, the speed reducer and the electromagnetic clutch have different structures. Therefore, the electromagnetic clutch can be downsized.

In particular, since the electric motor, the speed reducer and the electromagnetic clutch are integrally formed, aging can be performed in the state of these integrated structures and the adsorption force of the electromagnetic clutch can be set to a predetermined value. According to the experiment, when 100N is required as the attraction force of the electromagnetic clutch, the electromagnetic clutch portion having a diameter of 135 mm and a thickness of 45 mm is initially 40N.
It was possible to aging the one having a suction force of 100 N by performing aging in the state of the integral structure to 100N. On the other hand, in the conventional method, that is, in the case where the clutch is provided on the side of the differential gear of the vehicle body, it is impossible to perform aging with the electric motor, the speed reducer and the electromagnetic clutch integrated. The electromagnetic clutch has to be made larger so that a suction force of 100 N can be obtained in this state. Considering that an adsorption force of 100 N can be obtained under the same conditions as those of the above-mentioned integral structure, the clutch portion needs to have a diameter of 150 mm and a thickness of 55 mm. Since the electric motor with reduction gear of the present invention can be manufactured on the premise of aging in the state of an integral structure, the electromagnetic clutch can be miniaturized.

As described above, since the electromagnetic clutch can be miniaturized, the integrated structure of the electric motor, the speed reducer and the electromagnetic clutch can be compacted, and the space required for mounting the vehicle under the floor can be reduced. That is, it is easy to make the external dimensions of these integrated structures equal to or less than the external dimensions of the differential gear 9, for example, 200 mm or less.

Next, the operation of the microprocessor 122 of the controller 10 will be described with reference to the flowchart of FIG. First, it is first judged from the vehicle speed signal whether or not the vehicle speed is 0 km (step 502). If the vehicle speed is 0 km / h (while stopped), then the power switch MOS2 106 is turned on to turn on the electromagnetic clutch 8. Issue a command to If the vehicle speed is not 0 km / h, the routine proceeds to step 510, the electromagnetic clutch 8 is turned off (MOS2 = off), then the power switch MOS1104 for controlling the armature current is turned off (step 512), and the procedure returns to the first step.

Immediately after turning on the key switch, the vehicle speed is 0 km / h.
After turning on the electromagnetic clutch 8, step 50
Go to 6. In step 506, it is determined whether the accelerator is stepped on, that is, whether the accelerator opening is equal to or greater than a predetermined value θ0. If the accelerator is not stepped on, there is no intention to start the vehicle, and therefore start assist is unnecessary.
Proceeding to 10, the electromagnetic clutch 8 is turned off.

If the accelerator is stepped on, next, at step 508, it is judged if the vehicle speed is 20 km / h or more. If the speed is 20 Km / h or less, the required torque is obtained based on a map 514 showing the relationship between the vehicle speed and the required torque. This is because in order to operate the electric motor 5 at the time of starting on a low μ road where starting assistance is required, the required torque decreases as the vehicle speed increases within a range below a predetermined value from the time of starting, as shown in FIG. It gives the property to do. For example, from the time of starting and starting (0 km / h), the vehicle speed is between 6 and 8 km / h, and the required torque is constant,
The required torque continuously decreases as the vehicle speed increases until the speed reaches 20 km / h. Therefore, in the range where the required torque is constant, the maximum armature current is about 200 to 400 A and the maximum field current is 2 A.
Within a range in which the required torque T is continuously reduced to about 0 A, the armature current Ia and the field current If are appropriately changed to perform traveling assistance according to the respective driving conditions such as start, acceleration, and reverse.

A characteristic map giving the relationship between the vehicle speed and the required torque T is recorded and held in the memory in advance. When the required torque is obtained, next, the current value Ia0 for generating the required torque in the shunt winding motor 5 is set (step 51).
6). The armature current Ia can be calculated by the relational expression of T = KΦIa (where K is a constant,
Φ is a magnetic flux), and a characteristic map that gives the relationship between the required torque T and the current value Ia0 is recorded and held in the memory. Then, the current supplied to the shunt winding motor 5 is controlled based on the current value Ia0 (step 518).

Further, the gear position is determined (step 52
0), if the gear position is the drive position D, the normal rotation is performed and the MOS3 and MOS6 of the H bridge 126 are turned on (step 522) and the process returns to step 506. If the gear position is reverse R (step 524), the H bridge 12
6 turns on MOS4 and MOS5 (step 52
6) and returns to step 506. Then, in a driving state in which the accelerator is stepped on and the vehicle speed is less than 20 km / h, the control of steps 514 to 526 is repeated. If the vehicle speed exceeds 20 km / h, no driving assistance is required, so the electromagnetic clutch 8 is turned off in step 510, and then the power switch MOS1 10 for controlling the armature current.
Turn off 4 and go back to the first step. Therefore, when the vehicle speed becomes 20 km / h or more, only the front wheels are driven by the engine to travel, and the rear wheels are free from the engine and the electric motor and rotate as the vehicle travels.

FIG. 7 shows details of the current control processing procedure in step 518. First, the measured value Ia0 of the armature current of the electric motor 5 is compared with the set value Ia (step 5181). The measured value Ia0 of the armature current is the set value I
If it is smaller than a, the on-duty of the power switch MOS1 104 in the current control is Duty = Duty +
1 (step 5182), and the measured value Ia0 is the set value Ia.
If it is larger than the above, the on-duty of the power switch MOS1 104 is set to Duty = Duty−1 (step 5
183), and based on these Duty, the power switch MOS1 104 is turned on / off, and current control is performed so that the armature current of the electric motor 5 becomes the set value Ia (step 5184). The same process is repeated thereafter.

According to the present invention, the electric motor 5 is controlled independently of the engine. That is, a predetermined value (for example, 20 Km /
h) Only when the vehicle travels forward or backward within the following range, the electromagnetic clutch is turned on to drive the rear wheels of the vehicle, and the vehicle speed is 20
When the speed exceeds Km / h, turn off the electromagnetic clutch and drive only with the engine. Compared to the one that drives the rear wheels of the vehicle from the engine via the propeller shaft, the transmission mechanism from the engine and the propeller shaft are not required, and the four-wheel drive mechanism is made smaller and lighter, and at the same time, above a certain value. The rear wheel side is separated from the front wheel side, which also contributes to improved fuel efficiency. Further, the starting acceleration is excellent because the starting assist can be obtained at the time of start-up, that is, when the vehicle speed is zero.

According to the present invention, the armature shaft 56 of the electric motor 5, the reduction gear shaft 57, and the clutch shaft 5
Each shaft of No. 8 has bearings 60 to so that they are on the same axis.
64 is arranged, and by forming these electric motor, speed reducer and electromagnetic clutch as an integrated structure in advance, the starting acceleration is superior to the structure in which the electric motor, speed reducer and electromagnetic clutch are different. ing. In addition, the integrated structure improves gear efficiency and can generate a larger transmission torque, so the electromagnetic clutch can be miniaturized, and the integrated structure of the electric motor, the speed reducer and the electromagnetic clutch can be made compact, The space required for mounting under the floor can be reduced.

Further, according to the present invention, the input circuit to the shunt winding motor 5 is composed of parallel circuits for the armature winding and the field winding, and the armature winding 51 and the field winding 52 are connected to each other. By supplying power from power sources having different voltages, the field current can be set to a small value of about 20A. Therefore, the field current supply system, that is, the intermediate portions of the power lines 13 and 14 can be formed on the same substrate as the signal control unit 120 including the microprocessor 122. The signal lines to and from the microprocessor 122 can of course be formed on the same substrate as the signal control unit 120. Further, the current flowing through the power supply line 129 of the electromagnetic coil 81 of the electromagnetic clutch 8 is 10A.
Since it is about the degree, with the power switch MOS2 106,
It can be formed on the same substrate as the signal control unit 120.

Further, since the field current is small, the field current supply system of the electric motor 5 and its control circuit, the power supply line 129 of the electromagnetic clutch 8 and the like can be formed on the same substrate as the ABS control unit 71. Further, the field current supply system of the electric motor 5 and its control circuit, the power supply line 129 of the electromagnetic clutch 8 and the like may be formed on the same substrate as the engine control unit 73. Alternatively, these may be formed on the same substrate as the ABS control unit 71 and the engine control unit 73. This makes it possible to reduce the cost of the field current supply system of the shunt motor 5 and its control circuit.

FIG. 8 shows the field current supply system of the electric motor 5, its control circuit, and the power supply line 1 of the electromagnetic clutch 8.
An electric motor controller 120 including 29 and the like is formed in the same substrate 200 as the ABS control unit 71,
It shows an example in which a microcomputer is shared. The ABS control unit 71 uses the wheel speed calculation processing unit 20 based on the output Wn of the wheel speed sensor 21.
In step 2, the speed VR of each wheel is calculated, the estimated vehicle speed calculation unit 204 calculates the estimated vehicle speed VREF from this VR, and the wheel deceleration calculation unit 206 calculates -a. Further, the slip ratio calculator 208 calculates slip ratios λ1 and λ2 from VR and VREF. Finally, the μ calculation unit 210 calculates the friction coefficient μ of the road surface from the slip ratios λ1, λ2 and −a, and ABS so that the braking force corresponding to the value of μ is applied to the brake 20 corresponding to each wheel. The actuator 72 operates.

In this way, the field current supply system and its control circuit, and the power supply line 129 of the electromagnetic clutch 8 are provided.
By incorporating the above in an existing control circuit and sharing the microcomputer, the current supply system and its control circuit can be made inexpensive, and the load on the battery can be reduced. In particular, the electric motor controller mainly operates as a driving assist at the time of starting and accelerating the vehicle.
The BS control unit controls braking during deceleration of the vehicle, and the operation timings of the two are different. Therefore, the control circuit can be made inexpensive by configuring and controlling the electric motor controller and the ABS control unit by a common microcomputer.

Further, according to the present invention, the input circuit to the shunt winding motor 5 is constituted by a parallel circuit for armature winding and field winding, and the mature winding 51 and the field winding 52 are connected to each other. By supplying power from power sources of different voltages, the radius 1 / 2D of the armature core 51A of the shunt winding motor 5 and the radial thickness of the field winding 52 become substantially equal. With such a configuration, the drive torque required for the electric motor 5 can be generated, and the outer dimensions of the electric motor 5 can be reduced.

Further, since the radius of the armature core 51A becomes smaller, the length of the brush 53 (in the armature radius direction) can be increased and the life of the brush can be extended. In consideration of the installation space under the floor of the vehicle, the outer diameter of the portion of the electric motor 5 in which the brush is housed can be set to the maximum size corresponding to the outer diameter of the speed reducer. The length can be increased.

FIG. 9 shows the diameter D of the armature core 51A and the radial thickness L of the field winding 52 in the present invention.
Shows the relationship. In order to reduce the external dimensions of the electric motor 5 while generating the drive torque required for the electric motor 5,
As shown in the figure, the relationship between D and L is L ≈ 1/2 (1 ±
0.2) D is desirable.

When L is smaller than 1/2 (1 ± 0.2) D, the number of turns of the field winding is reduced and the low voltage (12
V) In order to supply the necessary power from the power supply, the wire diameter must be increased and the current value must be increased, and the field current supply system and its control circuit must be built into the existing control circuit. Cannot be shared.

On the contrary, when L is larger than 1/2 (1 ± 0.2) D, the radius of the armature core 51A becomes large, so that the outer dimension of the electric motor 5 becomes large. In particular, it becomes impossible to prolong the life of the brush 53 by increasing the length of the brush 53.

The above-described embodiment is a drive device in which the front wheels of a vehicle are driven by the engine and the electric motor assists the driving of the rear wheels during a predetermined operation. The present invention can be similarly applied to a drive device of a four-wheel drive vehicle in which driving of the front wheels is assisted by an electric motor.

Next, a vehicle drive assist device according to another embodiment of the present invention will be described with reference to FIGS. In this embodiment, the electric motor with reduction gear of the above-mentioned embodiment is used as a starter of an engine. In FIG. 10, the clutch shaft 59 of the starter 50 is connected to the crankshaft of the engine by a silent chain drive mechanism 70 such as a belt.

FIG. 11 shows an example of a circuit configuration related to power supply and control of the starter 50. 110 is a power control unit and 130 is a signal control unit. The microprocessor 122 of the signal control unit 130 includes a CPU and a memory that holds programs and data for controlling the electric motor, and the vehicle speed sensor 21 and the gear position detector that are input via the I / O 121 and the A / D conversion device 122. 31 based on the information of the accelerator opening sensor 32, the on / off timing of the field current of the electric motor 5, the armature current value, and the on / off timing of the electromagnetic clutch are calculated, and the result is calculated via the I / O 121 to the power switch MOS1.
104, power switch MOS2 106 and MOS
It is output as a drive signal of 30 133. The signal control unit 130 is used as the engine control unit 73 or the ABS control unit 7
It may be formed in the same substrate as 1 and.

The input circuit to the shunt winding motor 5 is composed of parallel circuits for armature winding and field winding. In the present invention, the parallel circuit is adopted, and the input current to the armature winding is increased and the input current to the field winding is set small by changing the diameter and the number of turns of the armature winding and the field winding. be able to.

Further, the microprocessor 122 takes in signals from the engine speed sensor 33 in addition to the vehicle speed sensor 21, and the vehicle is in a idling state in which the vehicle is temporarily stopped by people getting on and off, waiting for a signal, loading and unloading luggage, and the like. Is detected, an idle stop command for automatically stopping the engine is generated, and the engine control unit 73
Send to. The electromagnetic clutch 8 is turned on and the engine is started by the starter 50 in order to start traveling immediately after the idling stop state ends.

According to this embodiment, since the starter 50 is connected to the engine 2 via the clutch 8 and the silent chain drive mechanism 70 at the time of starting the engine, the pinion and the ring gear are engaged with each other. The durability of the connecting part is significantly improved compared to the one in which the starter and the engine are connected. Experiments show that in the case of the pinion and ring gear meshing coupling method, the pinion and ring gear collide during meshing and the large diameter ring gear keeps idling at startup, causing pinion and ring gear damage and wear. Therefore, the durability as a starter is 200,000 to 400,000 times. On the other hand, in the case of the electromagnetic clutch coupling system of the present invention, the electromagnetic clutch coupling system is used and the impact is small and the durability is improved up to 700,000 times or more. Further, in the case of the electromagnetic clutch, there is no end surface slip or clutch slip, and the torque transmission efficiency is good. Moreover, there is no impact noise at the time of engagement, and the starting noise is reduced.

Thus, the electric motor with reduction gear of the present invention is
The durability of the connecting part is significantly improved and the torque transmission efficiency is good, so there is no problem even if it is used for a starter of an engine with an automatic idle stop function.

The conventional starter of the intermeshing and coupling system of the pinion and the ring gear is poor in durability, and therefore is not suitable for a vehicle with an automatic idle stop function that needs to be started frequently. Since the electric motor with a reducer of the present invention has good durability and good torque transmission efficiency, it can be used as a starter for an engine with an automatic idle stop function against the environment,
Exhibits excellent fuel economy. Experiment shows that fuel consumption is 1
4% improvement.

[0075]

As described above, according to the present invention, an electric motor as a speed reducer-equipped electric motor of an assist device for driving a vehicle,
By forming the speed reducer and the electromagnetic clutch as an integral structure in advance, the shaft accuracy can be improved and the air gap of the electromagnetic clutch can be made highly accurate, and the electromagnetic clutch can be downsized on the premise of aging in the state of the integrated structure. it can. Moreover, the input circuit to the shunt winding motor is configured by a parallel circuit for the armature winding and the field winding so that a large current flows in the armature winding of the shunt winding motor and a small current flows in the field winding. As a result, the outer dimensions of the electric motor can be reduced while generating the drive torque required for the electric motor.

As described above, the vehicle drive assist device, that is, the integrated structure of the electric motor, the speed reducer and the electromagnetic clutch can be compactly assembled, so that the space required for mounting the vehicle under the floor can be reduced.

Further, the field current supply system and the control circuit for the field current of the vehicle drive assist device can be made inexpensive, the cost of the electric motor with reduction gear can be reduced, and the radial length of the brush can be increased to prolong the life of the brush. Can be achieved.

Further, since the vehicle drive assist device of the present invention has high durability and high torque transmission efficiency, when it is used as a starter for an engine with an automatic idle stop function, it exhibits excellent effects on environment and fuel consumption.

[Brief description of drawings]

FIG. 1 shows an overall configuration of a four-wheel drive vehicle that employs a vehicle drive assist device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a circuit configuration example relating to power supply and control of the embodiment shown in FIG.

FIG. 3 is a vertical cross-sectional view of the electric motor with reduction gear of the embodiment shown in FIG.

4 is a cross-sectional view of an electric motor portion of the electric motor with reduction gear shown in FIG.

FIG. 5 is a flowchart illustrating an operation of a microprocessor in the electric motor controller 10.

FIG. 6 is an explanatory diagram of a map that gives a relationship between vehicle speed and required torque.

FIG. 7 is a diagram showing details of a current control processing procedure in the flowchart of FIG. 5;

FIG. 8 is a diagram showing a configuration example of a control circuit of a vehicle drive assist device according to another embodiment of the present invention.

FIG. 9 is a diagram showing a relationship between a diameter D of an armature core 51A and a radial thickness L of a field winding 52 in the present invention.

FIG. 10 is a diagram showing an example in which a vehicle drive assist device is used as a starter of an engine as another embodiment of the present invention.

11 is a diagram showing an example of a circuit configuration related to power supply and control of a starter in the embodiment shown in FIG.

[Explanation of symbols]

1 ... 4-wheel drive vehicle, 2 ... engine, 3 ... front wheel, 4 ... rear wheel,
5 ... DC shunt winding motor, 6 ... Alternator, 7 ... Battery, 8 ... Electromagnetic clutch, 9 ... Differential gear, 10 ... Electric motor controller, 11 ... Power module, 20 ... Brake, 21 ... Wheel speed sensor, 71 ... A
BS control unit, 73 ... engine control unit, 100 ... power control unit, 1
04 ... Power switch MOS1, 106 ... Power switch MOS2, 120 ... Signal control unit, 12
2 ... Microprocessor, 125 ... H bridge driver, 126 ... H bridge,

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI B60K 17/04 B60L 11/14 B60L 11/14 F02D 29/02 D F02D 29/02 B60K 9/00 E (72) Inventor Fukasaku Yoshinori, Takata, Hitachi, Ibaraki 2520 Takaba, Hitachi, Ltd., Automotive Equipment Division (72) Inventor, Mitsutoshi Abe 2477, Takaba, Hitachinaka, Ibaraki, Hitachi Car Engineering (72) Inventor, Keiichi Masuno Hitachi, Hitachi, Ibaraki 2520 Takaba, Oita City, Hitachi, Ltd. (72) Inventor, Tadashi Sakuma, Hitachinaka City, Ibaraki 2520, Takaba, Hitachi, Ltd., Automotive Equipment Division (56) Reference: Japanese Patent Laid-Open No. 9-88778 ( JP, A) JP 61-160358 (JP, A) JP 7-15915 (JP A) JP-A-8-14145 (JP, A) JP-A-11-125129 (JP, A) JP-A-10-331749 (JP, A) Actually open 5-46883 (JP, U) (58) Survey Areas (Int.Cl. ⁷ , DB name) B60K 17/356 B60K 6/04 B60K 17/04 B60L 11/14 F02D 29/02

Claims (8)

(57) [Claims] 1. A vehicle drive assist device for assisting a vehicle drive by an engine with a DC shunt winding motor with a speed reducer, wherein the driving force from the DC shunt winding motor is transmitted to the shaft of the speed reducer by reducing the rotation of an armature shaft. A speed reducer, an electromagnetic clutch integrally formed on the shaft of the speed reducer and connecting a clutch shaft, a plurality of DC shunt winding motors, the speed reducer, and each shaft of the electromagnetic clutch configured on the same axis. In the bearing and the DC shunt winding motor, the radial thickness L of the field winding is L≈ (1/2) (1 ± 0.
2)) Outside the portion of the DC shunt winding motor in which the brushes of the DC shunt winding motor are accommodated, within the range of D, and the outer diameter dimensions of the DC shunt winding motor and the speed reducer are smaller than the outer diameter dimension of the electromagnetic clutch. A vehicle drive assist device, which is an electric motor having a diameter within an outer diameter of an electromagnetic clutch, and assists driving of the vehicle by a driving force of the electric motor in a predetermined operating state. 2. The vehicle according to claim 1, wherein the DC shunt winding motor with a speed reducer has a maximum armature current of 200 to 400 A and a field current of 20 A at the maximum. Drive assist device. 3. The engine according to claim 1, wherein either one of a front wheel and a rear wheel of the vehicle is driven by the engine,
An assist device for driving a vehicle, wherein assist driving is performed by the DC shunt winding motor when the other is in a predetermined operating state. 4. The method of claim 1 or 2, wherein the vehicle driving assist apparatus, reduction gear, is coupled to the other wheel via the electromagnetic clutch and the differential gear, ABS control for controlling the braking force applied to each wheel A vehicle drive assist device comprising a unit, and a field current supply system of the electric motor and its control circuit are formed in the ABS control unit substrate. 5. The method of claim 1 or 2, a vehicle driving assist apparatus characterized by starting driving the engine by the electric motor and the electromagnetic clutch ON at the time of starting of the engine. 6. The method of Claim 5, wherein the engine is a vehicle driving assist apparatus characterized by assisting the drive an automatic idling stop function engine. 7. The engine control unit according to claim 5, further comprising an engine control unit for controlling the engine by a microcomputer, wherein a field current supply system of the electric motor and its control circuit are formed on the same substrate as the engine control unit. An assist device for driving a vehicle, which is characterized in that 8. A vehicle in which either one of a front wheel and a rear wheel of the vehicle is driven by an engine, and a DC shunt motor with a speed reducer drives the other wheel to assist the drive by the engine in a predetermined operating state. In the drive assist control method, the radial thickness L of the field winding is L≈ (1/2) (1) with respect to the diameter D of the armature core of the DC shunt winding motor. ±
0.2)) D, the outer diameter of the DC shunt winding motor and the speed reducer is smaller than the outer diameter of the electromagnetic clutch, and the brush of the DC shunt winding motor is accommodated. Is an electric motor whose outer diameter is within the outer diameter of the electromagnetic clutch, and is a DC shunt winding electric motor with a speed reducer connected to the other wheel via a speed reducer and an electromagnetic clutch, and a motor controller for controlling the electric motor The ABS control unit is configured by a common microcomputer, and the electromagnetic clutch is turned on by the controller when the vehicle speed is traveling from zero to a predetermined vehicle speed value, and the required torque decreases as the vehicle speed increases. The other wheel is supplied with an armature current of 200 to 400 A at maximum and a field current of 20 A at maximum to the electric motor. When driving, the electromagnetic clutch is turned off when the vehicle speed exceeds the predetermined vehicle speed value, and the braking force for each wheel is controlled by the microcomputer during deceleration braking of the vehicle. Assist control method.